Fracking Kit for Testing Contaminates in Drinking Water

Many links between hydraulic fracturing or “fracking” to contamination of groundwater and drinking water supplies have recently been discovered. There are a number of chemicals that are used in fracking — some of them are relatively non-toxic while others are highly toxic. The composition of fracking fluid is also widely variable but all fracking fluids have some components in common. According to EPA documents, the following constituents were detected in all tested fracking fluid samples: barium ion, benzene, boron, chloride ion, ethyl benzene, gross beta (radioactive beta particle emission), naphthalene, nickel ion, sulfate ion, toluene, total xylenes, TMB, and TEPH.  Many of these constituents were detected in all tested produced water (i.e., underground water brought to the surface during drilling and then often used for fracking). Some of these constituents occur naturally in groundwater but may be found at far higher and thus toxic concentration levels in water that has been contaminated by fracking.

Water analyses performed by commercial contract laboratories are expensive and require trained chemists. The problem is that drinking water should be monitored on a regular basis. Until recently, the only option for monitoring drinking water on a regular basis has been to use fracking test kits that involve messy, complicated, time-consuming procedures.  The toxic chemicals used in many fracking test kits must be properly disposed of which is a hidden complication and additional expense.

The Forston Labs Fracking Kit easily measures increased concentrations of barium ion, chloride ion, nickel ion, sulfate ion, bromide ion, potassium ion, turbidity and changes in acidity. There are no messy, complicated procedures to follow and no toxic chemicals to be disposed.

The Fracking Kit consists of a LabNavigator (required for all measurements), a full-range heavy-duty pH Sensor, a Turbidity Sensor, a Conductivity Sensor and a clear-language informative user’s guide for the non-chemist. It works by simply connecting one or more of the sensors to the LabNavigator, ensuring the accuracy by using one of the included non-toxic standards, dipping the sensor into a sample of well water and pressing a button which stores the test results for future use. The digital readout on the LabNavigator shows the results in an instant.

For more information contact us at 800-301-1259 or 970-237-4389 or visit www.forstonlabs.com

Custom Assay Design Service for High-Sample Throughput Amplicon Resequencing

Fluidigm Corporation unveiled a new custom assay design service for high-sample throughput amplicon resequencing on Illumina platforms at last week's Advances in Genome Biology and Technology (AGBT) meeting. The Access Array™ Target-Specific Primers, when used with the Fluidigm Access Array System, allow for fast, simple, and inexpensive preparation of up to 480 amplicons per sample at a time. This capability is ideal for analysis of large sample sets across focused genomic regions to better understand human genetic variation.

"Access Array Target-Specific Primers allow researchers to quickly and specifically amplify their target of interest, incorporate sample-specific barcodes and add sequencer-specific adaptors - all at the same time.  This by-passes library preparation altogether," said Gajus Worthington, Fluidigm President and CEO.

"With our new Access Array Target-Specific Primers, we increase the number of amplicons per sample by 10X compared to our traditional solution. In conjunction with our Access Array Barcode Library for Illumina Sequencers, up to 384 unique samples can be multiplexed per sequencing run. This will help scientists capture the maximum output of their sequencers and provide the broadest coverage possible for their human genetic variation studies," Worthington concluded.

The Fluidigm Access Array System prepares amplicons for resequencing without the need for any additional library preparation and can operate with any next-generation sequencer (NGS) on the market. It prepares these amplicons in just hours, instead of days, and performs the sample preparation for less than $10 per sample. In addition, using the Access Array Barcode Libraries developed for the Illumina, Roche, and Ion Torrent sequencing platforms, researchers can test the same amplicon pools to cross-validate sequencing results across different NGS platforms.

Fluidigm (NASDAQ:FLDM) develops, manufactures and markets microfluidic systems for growth markets in the life science and agricultural biotechnology, or Ag-Bio, industries. Fluidigm's proprietary microfluidic systems consist of instruments and consumables, including chips, assays and other reagents. These systems are designed to significantly simplify experimental workflow, increase throughput and reduce costs, while providing the excellent data quality demanded by customers. Fluidigm actively markets three microfluidic systems, including eight different commercial chips, to leading pharmaceutical and biotechnology companies, academic institutions and Ag-Bio companies.  For more information, please visit www.fluidigm.com.

Just Published: Analytica Chimica Acta

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Analytica Chimica Acta
http://rss.sciencedirect.com/publication/science/5216

Selected papers from the latest issue:

Dual-color upconversion fluorescence and aptamer-functionalized magnetic nanoparticles-based bioassay for the simultaneous detection of Salmonella Typhimurium and Staphylococcus aureus

26 March 2012, 09:47:20

Publication year: 2012
Source:Analytica Chimica Acta, Volume 723
Nuo Duan, Shijia Wu, Changqing Zhu, Xiaoyuan Ma, Zhouping Wang, Ye Yu, Yuan Jiang
A sensitive luminescent bioassay for the simultaneous detection of Salmonella Typhimurium and Staphylococcus aureus was developed using aptamer-conjugated magnetic nanoparticles (MNPs) for both recognition and concentration elements and using upconversion nanoparticles (UCNPs) as highly sensitive dual-color labels. The bioassay system was fabricated by immobilizing aptamer 1 and aptamer 2 onto the surface of MNPs, which were employed to capture and concentrate S. Typhimurium and S. aureus. NaY0.78F4:Yb0.2,Tm0.02 UCNPs modified aptamer 1 and NaY0.28F4:Yb0.70,Er0.02 UCNPs modified aptamer 2 further were bond onto the captured bacteria surface to form sandwich-type complexes. Under optimal conditions, the correlation between the concentration of S. Typhimurium and the luminescent signal was found to be linear within the range of 10¹–10⁵ cfumL⁻¹ (R ² =0.9964), and the signal was in the range of 10¹–10⁵ cfumL⁻¹ (R ² =0.9936) for S. aureus. The limits of detection of the developed method were found to be 5 and 8cfumL⁻¹ for S. Typhimurium and S. aureus, respectively. The ability of the bioassay to detect S. Typhimurium and S. aureus in real water samples was also investigated, and the results were compared to the experimental results from the plate-counting methods. Improved by the magnetic separation and concentration effect of MNPs, the high sensitivity of UCNPs, and the different emission lines of Yb/Er- and Yb/Tm-doped NaYF4 UCNPs excited by a 980nm laser, the present method performs with both high sensitivity and selectivity for the two different types of bacteria.

Graphical Abstract

Graphical abstract Highlights

Fabrication process of biofunctionalized nanoparticles and principle of the performed bioassay. First, aptamer 1 and aptamer 2 were immobilized onto the surface of MNPs and the surface of NaY0.78F4:Yb0.2, Tm0.02 UCNPs, and NaY0.28F4:Yb0.70, Er0.02 UCNPs. Next, S. Typhimurium and S. aureus were added and, due to the highly affinity of aptamer to corresponding bacteria, the aptamer 1-MNPs-S. Typhimurium complex bind NaY0.78F4:Yb0.2, Tm0.02 UCNPs modified aptamer 1, and the aptamer 2-MNPs-S. aureus bind NaY0.28F4:Yb0.70, Er0.02 UCNPs modified aptamer 2. Finally, the luminescent signal was effectively amplified with the help of a magnetic field. ► Simultaneous detection of two kind of bacteria. ► Bacteria-specific aptamer recognition. ► Dual-color upconversion luminescent nanoparticles labeling. ► Aptamer conjugated-magnetic nanoparticles-based separation and concentration.

Semi-automated alignment and quantification of peaks using parallel factor analysis for comprehensive two-dimensional liquid chromatography–diode array detector data sets

26 March 2012, 09:47:20

Publication year: 2012
Source:Analytica Chimica Acta, Volume 723
Robert C. Allen, Sarah C. Rutan
Parallel factor analysis was used to quantify the relative concentrations of peaks within four-way comprehensive two dimensional liquid chromatography–diode array detector data sets. Since parallel factor analysis requires that the retention times of peaks between each injection are reproducible, a semi-automated alignment method was developed that utilizes the spectra of the compounds to independently align the peaks without the need for a reference injection. Peak alignment is achieved by shifting the optimized chromatographic component profiles from a three-way parallel factor analysis model applied to each injection. To ensure accurate shifting, components are matched up based on their spectral signature and the position of the peak in both chromatographic dimensions. The degree of shift, for each peak, is determined by calculating the distance between the median data point of the respective dimension (in either the second or first chromatographic dimension) and the maximum data point of the peak furthest from the median. All peaks that were matched to this peak are then aligned to this common retention data point. Target analyte recoveries for four simulated data sets were within 2% of 100% recovery in all cases. Two different experimental data sets were also evaluated. Precision of quantification of two spectrally similar and partially coeluting peaks present in urine was as good as or better than 4%. Good results were also obtained for a challenging analysis of phenytoin in waste water effluent, where the results of the semi-automated alignment method agreed with the reference LC–LC MS/MS method within the precision of the methods.

Graphical Abstract

Graphical abstract Highlights

Three replicate injections of a localized region of a LC×LC–DAD data set. ► We describe a spectrally based alignment method for LC×LC–DAD data. ► Alignment between injections is not dependent on selection of a reference injection. ► The alignment process allows for non-linear peak shifting between injections. ► Simulated data sets aligned by this method produced % recoveries close to 100%. ► The method was able to align and quantify experimental data with overlapping peaks.

Tucker core consistency for validation of restricted Tucker3 models

26 March 2012, 09:47:20

Publication year: 2012
Source:Analytica Chimica Acta, Volume 723
Mohsen Kompany-Zareh, Yousef Akhlaghi, Rasmus Bro
In Tucker3 analysis of three-way data array obtained from a chemical or biological system, it is sometimes possible to use a priori knowledge about the system to specify what is called a restricted Tucker3 model. Often, the restricted Tucker3 model is characterized by having some elements of the core forced to zero. As a simple example, an F-component PARAFAC model can be seen as a restricted (F, F, F) Tucker3 model in which only superdiagonal elements of the core are allowed to be nonzero. The core consistency diagnostic was previously introduced by Bro and Kiers for determining the proper number of components in PARAFAC analysis. In the current study, this diagnostic is extended to other restricted Tucker3 models to validate the appropriateness of the applied constraints. The new diagnostic is named Tucker core consistency (TuckCorCon). When the dimensionality and the pattern of the restricted core is valid, the simple core of restricted Tucker3 model and a corresponding unrestricted core will be similar and in this case the TuckCorCon will be close to maximum (100%). A simulated chemical equilibrium data set and two experimental data sets were used to evaluate the applicability of the TuckCorCon to decide about the appropriateness of dimensionality and pattern of the core nonzero elements in the restricted Tucker3 models.

Graphical Abstract

Graphical abstract Highlights

. ► Tucker core consistency (TuckCorCon) parameter is presented for the first time. ► TuckCorCon can be used to evaluate the Tucker3 models with simplified cores. ► TuckCorCon is close to 100 for a good simple core and it is low for a bad one. ► TuckCorCon was tested and approved using simulated and experimental data sets. ► The TuckCorCon parameter helps to decide about the proper size of the core.

Electrochemical detection of a powerful estrogenic endocrine disruptor: Ethinylestradiol in water samples through bioseparation procedure

26 March 2012, 09:47:20

Publication year: 2012
Source:Analytica Chimica Acta, Volume 723
Noelia A. Martínez, Sirley V. Pereira, Franco A. Bertolino, Rudolf J. Schneider, Germán A. Messina, Julio Raba
The synthetic estrogen ethinylestradiol (EE2) is an active component of oral contraceptives (OCs), considered as an endocrine disrupting compound (EDC). It is excreted from humans and released via sewage treatment plant effluents into aquatic environments. EDCs are any environmental pollutant chemical that, once incorporated into an organism, affects the hormonal balance of various species including humans. Its presence in the environment is becoming of great importance in water quality. This paper describes the development of an accurate, sensitive and selective method for capture, preconcentration and determination of EE2 present in water samples using: magnetic particles (MPs) as bioaffinity support for the capture and preconcentration of EE2 and a glassy carbon electrode modified with multi-walled carbon nanotubes (MWCNTs/GCE) as detection system. The capture procedure was based on the principle of immunoaffinity, the EE2 being extracted from the sample using the anti-EE2 antibodies (anti-EE2 Ab) which were previously immobilized on MPs. Subsequently the analyte desorption was done employing a sulfuric acid solution and the determination of the EE2 in the pre-concentrated solution was carried out by square wave voltammetry (SWV). This method can be used to determine EE2 in the range of 0.035–70ngL⁻¹ with a detection limit (LOD) of 0.01ngL⁻¹ and R.S.D.<4.20%. The proposed method has been successfully applied to the determination of EE2 in water samples and it has promising analytical applications for the direct determination of EE2 at trace levels.

Graphical Abstract

Graphical abstract Highlights

► We developed an electrochemical method for the determination of ethinylestradiol in water samples. ► Modified magnetic particles were employed for the bioseparation and preconcentration procedures. ► The use of magnetic particles offers high selectivity due to antigen–antibody binding specificity. ► The detection was carried out by using a glassy carbon electrode modified with carbon nanotubes.

Electrochemical sensor for naphthols based on gold nanoparticles/hollow nitrogen-doped carbon microsphere hybrids functionalized with SH-β-cyclodextrin

26 March 2012, 09:47:20

Publication year: 2012
Source:Analytica Chimica Acta, Volume 723
Gangbing Zhu, Pengbo Gai, Yan Yang, Xiaohua Zhang, Jinhua Chen
Due to awfully harmful to the environment and human health, the qualitative and quantitative determinations of naphthols [1-naphthol (1-NAP) and 2-naphthol (2-NAP)] are of great significance and receive great attention. In this paper, gold nanoparticles (AuNPs)/hollow nitrogen-doped carbon microspheres (HNCMS) hybrids (AuNPs/HNCMS) were prepared and functionalized with thiolated-β-cyclodextrin (HS-β-CD) for the first time, and then applied successfully in sensitive and simultaneous electrochemical detection of naphthols. The results show that the oxidation peak currents of naphthols obtained on the HS-β-CD/AuNPs/HNCMS modified glassy carbon (GC) electrode are much higher than that on the AuNPs/HNCMS/GC, HNCMS/GC and bare GC electrodes. Additionally, compared with other electrochemical sensors developed previously, the proposed electrode results in improved detection limits of about four times for 1-NAP (1.0nM) and two orders of magnitude for 2-NAP (1.2nM). The linear response ranges of both 1-NAP and 2-NAP are 2–150nM.

Graphical Abstract

Graphical abstract Highlights

► HS-β-CD/AuNPs/hollow nitrogen-doped carbon microspheres hybrids were synthesized. ► A new electrochemical sensor for naphthols was developed based on the prepared hybrids. ► The sensor shows good analytical performance for simultaneous detection of naphthols.

Nonenzymatic glucose sensor based on CuO microfibers composed of CuO nanoparticles

26 March 2012, 09:47:20

Publication year: 2012
Source:Analytica Chimica Acta, Volume 723
Fei Cao, Jian Gong
Fluorine tin oxide (FTO) electrode modified by copper oxide microfibers (CuO-MFs) composed of numerous interconnected CuO nanoparticles (CuO-NPs) for nonenzymatic glucose sensor was prepared by electrospinning precursor containing high percentage content of copper nitrate with subsequent calcination. The results of scanning electron microscope (SEM) showed the size of CuO particles composing CuO-MFs depended on the percentage content of copper nitrate in precursor solution. With increasing the percentage content of copper nitrate, the interconnected CuO-NPs would gradually replace the large-size CuO particles to accumulate the CuO-MFs, which have the potential to provide larger surface area and more reaction sites for electrocatalytic activity toward glucose. As a glucose sensor, the CuO-MFs modified FTO electrode prepared by 40wt.% of copper nitrate exhibited a high sensitivity of 2321μAmM⁻¹ cm⁻² with a low detection limit of 2.2nM (signal/noise ratio (S/N)=3). Additionally, the application of the CuO-MFs modified FTO electrode as a glucose sensor for biological samples was demonstrated with satisfactory results.

Graphical Abstract

Graphical abstract Highlights

► Electrospinning CuO microfibers onto electrodes as glucose sensors were studied. ► The CuO microfibers were composed of CuO particles. ► Size of CuO particles relies on percentage content of copper nitrate in precursor. ► Performance of the sensor depends on size of CuO particles.

Bovine serum albumin recognition via thermosensitive molecular imprinted macroporous hydrogels prepared at two different temperatures

26 March 2012, 09:47:20

Publication year: 2012
Source:Analytica Chimica Acta, Volume 723
Dan Ran, Yuzhi Wang, Xiaopin Jia, Chan Nie
A novel temperature-sensitive molecular imprinted hydrogel composed of 2-acrylamido-2-methyl-propanosulfonic acid (AMPS), N-isopropylacrylamide (NIPAm) and acrylamide (AAm) has been prepared by free-radical cross-linking copolymerization in aqueous solution under two different temperatures (25°C and −20°C). Bovine serum albumin (BSA, pI 4.9, MW 66.0kDa) is used as the template protein. The influence of the external temperature stimuli on the affinity of the hydrogels was investigated, and the optimal binding conditions were tested. The adsorption capacity (Q max) and association constant (K) for the specific interaction between the hydrogel and the template protein were determined by Langmuir isotherm plots. Several types of reference protein, which are different in molecular weights and isoelectric points were chosen to investigate the selectivity of the hydrogels. It was shown that the shape memory and the charge effect were the major factors for the recognition. This imprinted hydrogel was used to specifically adsorb the BSA from the protein mixture and real sample, which demonstrated its potential selectivity.

Graphical Abstract

Graphical abstract Highlights

► The preparation of thermo-sensitive molecular imprinted hydrogel (MIH) for the template BSA. ► Choosing 2-acrylamido-2-methyl-propanosulfonic acid (AMPS), N-isopropylacrylamide (NIPAm) and acrylamide (AAm) as the monomers. ► Temperature, functional monomer and cross-linking degree were optimized respectively. ► The MIH were characterized by FT-IR and SEM, and investigated by different adsorption experiments. ► The selectivity of the MIH was verified by direct adsorption of single reference protein, protein mixture and real sample.

Cadmium (II) imprinted 3-mercaptopropyltrimethoxysilane coated stir bar for selective extraction of trace cadmium from environmental water samples followed by inductively coupled plasma mass spectrometry detection

26 March 2012, 09:47:20

Publication year: 2012
Source:Analytica Chimica Acta, Volume 723
Nan Zhang, Bin Hu
Cd(II) imprinted 3-mercaptopropyltrimethoxysilane (MPTS)-silica coated stir bar was prepared by sol–gel technique combining with a double-imprinting concept for the first time and was employed for stir bar sorptive extraction (SBSE) of trace Cd(II) from water samples followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. A tetramethoxysilane (TMOS) coating was first in situ created on the glass bar surface. Afterward, a sol solution containing MPTS as the functional precursor, ethanol as the solvent and both Cd(II) and surfactant micelles (cetyltrimethylammonium bromide, CTAB) as the template was again coated on the TMOS bar. The structures of the stir bar coating were characterized by FT-IR spectroscopy. Round-bottom vial was used for the extraction of Cd(II) by SBSE to avoid abrasion of stir bar coatings. The factors affecting the extraction of Cd(II) by SBSE such as pH, stirring rate and time, sample/elution volume and interfering ions have been investigated in detail, and the optimized experimental parameters were obtained. Under the optimized conditions, the adsorption capacities of non-imprinted and imprinted coating stir bars were found to be 0.5μg and 0.8μgbar⁻¹. The detection limit (3σ) based on three times standard deviations of the method blanks by 7 replicates was 4.40ngL⁻¹ and the relative standard deviation (RSD) was 3.38% (c =1μgL⁻¹, n =7). The proposed method was successfully applied for the analysis of trace Cd(II) in rain water, East Lake and Yangtze River water. To validate the proposed method, certified reference material of GSBZ 50009-88 environmental water was analyzed and the determined value is in a good agreement with the certified value. The developed method is rapid, selective, sensitive and applicable for the analysis of trace Cd(II) in environmental water samples.

Graphical Abstract

Graphical abstract Highlights

Ion imprinted 3-mercaptopropyltrimethoxysilane (MPTS) coated stir bar for selective extraction of trace Cd(II). ► Ion imprinted polymers were proposed as the coating for SBSE for the first time. ► Cd(II) imprinted MPTS-silica coating was prepared by a double-imprinting concept. ► A novel method of SBSE–ICP-MS was developed for the determination of Cd in waters. ► This method is rapid, selective, sensitive and applicable for determining trace Cd(II) in waters.

CHN Determination of Air Sensitive, Hygroscopic or Volatile Samples

Exeter Analytical has developed a reliable sample preparation technique that enables accurate determination of the percentage Carbon (C), Hydrogen (H) and Nitrogen (N) in difficult to analyze volatile samples.  The same sample preparation technique has been found to also generate excellent results from air sensitive and hygroscopic samples.

Knowledge of the CHN content of volatile petroleum products and lubricants can be useful in determining their performance characteristics.  However, the CHN microanalysis of such volatile samples, especially those with high hydrogen content, requires careful sample handling, wide detector linearity and easy sample residue removal.

The sample preparation technique, described in technical report 233, involves cold weld sealing samples into heavy walled tin capsules under an inert atmosphere inside a glove box.  This careful sample preparation technique together with controlled introduction of the sealed capsules into an Exeter Analytical Model 440 CHN analyzer is demonstrated to eliminate the problems associated with analysing air sensitive, hygroscopic and volatile samples.

For a copy of technical report 233 please contact Exeter Analytical on +44-2476-323223 / +1-978-251-1411 or email info@exeteranalytical.co.uk / sales@eai1.com.

Simplified Detection of DDK-Tagged Recombinant Proteins

Detection and purification of recombinant proteins has become even easier with conjugated anti DDK* antibodies from AMSBIO.

AMSBIO offers a family of anti-tag antibodies to optimize the detection and purification of recombinant tagged proteins. Most of AMSBIO's anti-tag antibodies are mouse monoclonal antibodies which have been screened and extensively validated for high sensitivity and specificity, in applications including Western Blot, Immunofluorescent Staining, Flow Cytometry and Immunoprecipitation.

The anti-DDK clone 4C5 antibody detects the DDK epitope which is widely used as tag in recombinant proteins and is included in the pCMV6-Entry vector that forms the backbone of the TrueORF cDNA series. It has been used to validate the expression of over 15,000 mammalian recombinant proteins, purify more than 5,000 human recombinant proteins from HEK293 cells and purify immunogens under native conditions for the development of antibodies.

The new conjugated anti-DDK antibodies (linked to HRP, Dylight 488/550**, Phycoerythrin and biotin) have been developed using the highest standards of production procedure and validation. Using these premium quality products researchers now have a simpler way to detect proteins with low expression levels and purify recombinant proteins with high purities and yields.

For further information visit http://www.amsbio.com/4C5-Anti-DDK-Monoclonal-Antibody-Anti-FLAG.aspx or contact AMSBIO on tel. +44-1235-828200 or email anti.ddk@amsbio.com.

Just Published: Journal of Chromatography B

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Journal of Chromatography B
http://rss.sciencedirect.com/publication/science/7220

Selected papers from the latest issue:

Determination of a highly selective mixed-affinity sigma receptor ligand, in rat plasma by ultra performance liquid chromatography mass spectrometry and its application to a pharmacokinetic study

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Seshulatha Jamalapuram, Pradeep K. Vuppala, Christophe Mesangeau, Christopher R. McCurdy, Bonnie A. Avery
A selective, rapid and sensitive ultra performance liquid chromatography mass spectrometry (UPLC/MS) method was developed and validated to quantitate a highly selective mixed-affinity sigma receptor ligand, CM156 (3-(4-(4-cyclohexylpiperazin-1-yl)butyl)benzo[d] thiazole-2(3H)-thione), in rat plasma. CM156 and the internal standard (aripiprazole) were extracted from plasma samples by a single step liquid–liquid extraction using chloroform. The analysis was carried out on an ACQUITY UPLC™ BEH HILIC column (1.7μm, 2.1mm×50mm) with isocratic elution at flow rate of 0.2mL/min using 10mM ammonium formate in 0.1% formic acid and acetonitrile (10:90) as the mobile phase. The detection of the analyte was performed on a mass spectrometer operated in selected ion recording (SIR) mode with positive electrospray ionization (ESI). The validated analytical method resulted in a run time of 4min and the retention times observed were 2.6±0.1 and 2.1±0.1min for CM156 and the IS, respectively. The calibration curve exhibited excellent linearity over a concentration range of 5–4000ng/mL with the lower limit of quantification of 5ng/mL. The intra- and inter-day precision values were below 15% and accuracy ranged from −6.5% to 5.0%. The mean recovery of CM156 from plasma was 96.8%. The validated method was applied to a pilot intravenous pharmacokinetic study in rats.

Determination of landiolol, an ultra-short-acting β1-receptor antagonist, in human plasma by liquid chromatography–tandem mass spectrometry

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Qun He, Meiyun Shi, Xidong Liu, Yantong Sun, Lianghai Hu, Yan Yang, J. Paul Fawcett, Jingkai Gu, Limei Zhao
A method for the determination of landiolol, an ultra-short-acting β1-adrenoreceptor antagonist, in human plasma has been developed and validated. With the addition of pyridostigmine bromide to stabilize landiolol in the blood/plasma samples, and bisoprolol as internal standard, plasma samples were subjected to liquid–liquid extraction with diethyl ether:dicholoromethane (60:40, v/v) prior to assay by liquid chromatography–tandem mass spectrometry. Separation was performed on a TC-C18 column (150mm×4.6mm, 5μm) using a mobile phase of methanol:10mM ammonium acetate containing 1% formic acid (65:35, v/v) in a run time of 3.5min. Detection involved electrospray ionization in the positive ion mode followed by multiple reaction monitoring of the precursor-to-product ion transitions of landiolol at m/z 510.1→157.2 and bisoprolol at m/z 326.3→116.1. The method was linear over the concentration range 0.5–500ng/ml with a lower limit of quantitation of 0.5ng/ml. Intra- and inter-day precisions (as relative standard deviation, RSD) were <4.4% and <10.0%, respectively, with accuracy (as relative error, RE) <10.0%. The method was successfully applied to a clinical pharmacokinetic study involving a continuous infusion of landiolol hydrochloride to healthy Chinese volunteers.

Gas chromatography–mass spectrometry determination of pharmacologically active substances in urine and blood samples by use of a continuous solid-phase extraction system and microwave-assisted derivatization

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Abdelmonaim Azzouz, Evaristo Ballesteros
A sensitive method based on gas chromatography–mass spectrometry was used to determine 22 pharmacologically active substances (frequently used in the treatment of human and animal's diseases) including analgesics, antibacterials, anti-epileptics, antiseptics, β-blockers, hormones, lipid regulators and non-steroidal anti-inflammatories in blood and urine samples. Samples were subjected to continuous solid-phase extraction in a sorbent column (Oasis HLB), and then the target analytes were eluted with ethyl acetate and derivatized in a household microwave oven at 350W for 3min. Finally, these products were determined in a gas chromatograph–mass spectrometer equipped with a DB-5 fused silica capillary column. The analyte detection limits thus obtained ranged from 0.2 to 1.3ngL⁻¹ for urine samples and 0.8–5.6ngL⁻¹ for blood samples. Recoveries from both blood and urine ranged from 85 to 102%, and within-day and between-day relative standard deviations were all less than 7.5%. The proposed method offers advantages in reduction of the exposure danger to toxic solvents used in conventional sample pretreatment, simplicity of the extraction processes, rapidity, and sensitivity enhancement. The method was successfully used to quantify pharmacologically active substances in human and animal (lamb, veal and pig) blood and urine. The hormones estrone and 17β-estradiol were detected in virtually all samples, and so were other analytes such as acetylsalicylic acid, ibuprofen, ketoprofen and triclosan in human samples, and florfenicol, pyrimethamine and phenylbutazone in animal samples.

A LC–MS/MS method to evaluate the hepatic uptake of the liver-specific magnetic resonance imaging contrast agent gadoxetate (Gd-EOB-DTPA) in vitro and in humans

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Jia Jia, Markus Keiser, Ali Nassif, Werner Siegmund, Stefan Oswald
Gadoxetate (Gd-EOB-DTPA, Primovist^®) is a frequently used liver-specific magnetic resonance imaging (MRI) contrast agent which disposition is so far not fully understood in humans. Here, we describe the development and validation of a selective and sensitive quantification method to measure cellular in vitro concentrations as well as human serum concentrations of gadoxetate. The drug was measured after protein precipitation with acetonitrile and ethyl acetate-mediated sample concentration using amoxicillin as internal standard and liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) for detection. Hydrophilic interaction chromatography (HILIC) was performed by using the column Atlantis^® HILIC Silica (2.1mm×100mm), a step-elution gradient with acetonitrile and ammonium acetate (5mM, pH 3.8) as mobile phases and a flow rate of 200μl/min. The MS/MS detection was done in the negative multiple reaction monitoring (MRM) mode by monitoring the m/z transitions 681.3/635.2 for gadotrexate and 363.8/222.7 for the internal standard. The method was validated between 5 and 4000ng/ml in serum and between 1.25 and 500ng/ml in cell lysates. The method was shown to possess sufficient specificity, accuracy, precision and stability without any matrix effects, thereby fulfilling current bioanalytical guidelines. The developed assay was successfully applied to quantify gadoxetate in cellular uptake studies in OATP1B1-transfected cell lines and to monitor serum concentrations-time profiles from a clinical pilot study performed in healthy volunteers carrying the wild-type or the functionally relevant variants T521C (*5) and A388G (*1b) of the hepatic uptake transporter OATP1B1.

Rapid determination of endogenous cytokinins in plant samples by combination of magnetic solid phase extraction with hydrophilic interaction chromatography–tandem mass spectrometry

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Zhao Liu, Bao-Dong Cai, Yu-Qi Feng
A 2-acrylamido-2-methyl-1-propanesulfonic acid-co-ethylene glycol dimethacrylate (Fe3O4/SiO2/P(AMPS-co-EGDMA)) copolymer was prepared and used as a magnetic solid phase extraction (MSPE) medium for recovery of endogenous cytokinins (CKs) from plant extracts. This magnetic porous polymer was characterized by electron microscopy, nitrogen sorption experiments, elemental analysis and Fourier-transformed infrared spectroscopy. It was demonstrated to have high extraction capacity toward CKs in plants due to its specificity, surface area and porous structure. Coupled with hydrophilic interaction chromatography–tandem mass spectrometry (HILIC–MS/MS), a rapid, simple, and effective MSPE–HILIC–MS/MS analytical method for the quantitative analysis of endogenous CKs in Oryza sativa (O. sativa) roots was successfully established. Good linearities were obtained for all CKs investigated with correlation coefficients (R ²)>0.9975. The results showed that LODs (S/N=3) were ranged from 0.18 to 3.65pgmL⁻¹. Reproducibility of the method was obtained with intra-day and inter-day relative standard deviations (RSDs) less than 16.1% and the recoveries in plant samples ranged from 72.8% to 115.5%. Finally, the MSPE–HILIC–MS/MS method was applied to several plant samples, and the amounts of endogenous CKs in O. sativa roots, leaves and Arabidopsis thaliana (A. thaliana) were successfully determined.

Measurements of polybrominated diphenyl ethers and polychlorinated biphenyls in a single drop of blood

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Dasheng Lu, Dongli Wang, Ho Sai Simon Ip, Frank Barley, Robert Ramage, Jianwen She
A quantitative method that requires only a small volume (50μL) of blood has been developed for the determination of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). Target analytes in both plasma sample (DBSV) and dried blood spot (DBS) were analyzed by a gas chromatography/high resolution mass spectrometer (GC/HRMS). Measurements of standard reference materials by the developed method were in agreement with those certified values. Linear correlation coefficients were found to be 0.9984 and 0.9965 for DBS and DBSV analysis, respectively. Other analytical criteria, such as limits of detection, recoveries, precision, accuracy and linearity of the proposed method are also reported. From recovery studies, the addition of formic acid to the extraction solvent was found to be effective in extracting PBDEs and PCBs from filter paper. The PBDE and PCB levels in spiked DBS were monitored at room temperature for up to 30 days and the variations of target analytes were found to be insignificant. Our results suggest that DBS sampling technique is feasible for PBDE and PCBs biomonitoring in human population.

LC–ESI-MS/MS determination of in vivo metabolites of almotriptan in rat plasma, urine and feces: Application to pharmacokinetics

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
R. Nageswara Rao, K. Guruprasad, Ch. Gangu Naidu, B. Raju, R. Srinivas
A highly sensitive and specific liquid chromatography–electrospray ionization tandem mass spectrometric (LC–ESI-MS/MS) method for investigating the in vivo metabolites of almotriptan in rat plasma, feces and urine was developed. Chromatographic separation was achieved on a Lichrospher RP-18 column (250mm×4.6mm, 5μm), using 20mM ammonium acetate (pH 3.5) and acetonitrile (60:40, v/v) as a mobile phase at 25°C. MS/MS detection was performed by positive ion electrospray ionization using target ions at m/z 336 [M+H]⁺, m/z 368 and m/z 282 [M+H]⁺ for almotriptan and its two metabolites, respectively. Two metabolites viz., γ-aminobutyric acid and sulfonamide were detected in plasma as well as feces after 24h of oral administration of almotriptan, while only γ-aminobutyric acid was found in urine. The method was sensitive with a lower limit of quantification of 1.43ng/mL and linear over the range of 1.43–5000ng/mL in plasma. The method was validated and successfully applied to a pharmacokinetic study of almotriptan in rat plasma using sumatriptan as an internal standard. The peak plasma concentration (C max) after 0.3h of 5mg/kg oral dose of almotriptan was determined to be 69.85ng/mL.

Directly suspended droplet microextraction coupled with high performance liquid chromatography: A rapid and sensitive method for acetaldehyde assay in peritoneal dialysis fluids

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Zarrin Es’haghi, Freshte Babazadeh
The aim of present study was to develop and validate a rapid, sensitive, inexpensive and reliable method for the detection of trace levels of acetaldehyde in peritoneal dialysis fluids (PDFs) by 2,4-dinitrophenylhydrazine (DNPH) derivatization and extraction. Separation and analysis of acetaldehyde via 2,4-dinitrophenylhydrazone (DNPH) was by reverse phase high performance liquid chromatography (HPLC). In order to remove co-eluting interferences and to pre-concentrate acetaldehyde, the extraction and clean-up of the sample has been performed using a liquid phase microextraction technique. In this research directly suspended droplet microextraction technique (DSDME) coupled with HPLC was used to determine acetaldehyde in PDFs. In DSDME method a free suspended droplet of an organic solvent (1-octanol) used as extraction phase. Important factors such as organic solvent, extraction time, droplet volume, sample and reagent solution volumes and rate of stirring were optimized. After extraction under optimal conditions the samples were analyzed by HPLC with UV detection at 360nm. The linearity ranged from 0.01 to 100mgL⁻¹ with a relative standard deviation (RSD%; n =3) 5.6 Enrichment factor and limit of detection (LOD; n =5) were 54 and 1.12μgL⁻¹, respectively.

Quantitative determination of oseltamivir and oseltamivir carboxylate in human fluoride EDTA plasma including the ex vivo stability using high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
W. Kromdijk, H. Rosing, M.P.H. van den Broek, J.H. Beijnen, A.D.R. Huitema
Oseltamivir, the ethyl ester prodrug of the neuramidase inhibitor oseltamivir carboxylate, is licensed for the treatment of patients with influenza virus infection. Here we describe the development and validation of an assay for the simultaneous quantification of oseltamivir and oseltamivir carboxylate in human fluoride EDTA plasma including the ex vivo stability using liquid chromatography coupled to tandem mass spectrometry. Sample pretreatment consisted of protein precipitation with 8% (v/v) trichloroacetic acid in water using only 50μL plasma. Chromatographic separation was performed on a reversed phase C18 column (150mm×2.0mm ID, particle size 4μm) with a stepwise gradient using 0.1% formic acid and methanol at a flow rate of 250μL/min. A triple quadrupole mass spectrometer operating in the positive ionization mode was used for detection and drug quantification. The method was validated over a range of 3–300ng/mL for oseltamivir and 10–10,000ng/mL for oseltamivir carboxylate. Deuterated oseltamivir and oseltamivir carboxylate were used as internal standards. The intra-assay accuracies and precisions for oseltamivir were between −8.8 and 16.3% at the LLOQ level, whereas for all other concentration levels this was −8.6 and 14.5%. For oseltamivir carboxylate the intra-assay accuracies and precisions were between −10.9 and 10.7% at all levels. Furthermore, oseltamivir was stable in plasma and whole blood ex vivo in commercially available fluoride EDTA tubes for at least 24h at 2–8°C. This method is now applied for the determination of both compounds in specific patient populations to evaluate current dosing guidelines.

Simultaneous determination of 1-(2′-deoxy-2′-fluoro-β-d-arabinofuranosyl) uracil (FAU) and 1-(2′-deoxy-2′-fluoro-β-d-arabinofuranosyl) 5-methyluracil (FMAU) in human plasma by liquid chromatography/tandem mass spectrometry

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Richard Wiegand, Jianmei Wu, Anthony F. Shields, Patricia LoRusso, Jing Li
A liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) assay was developed and validated for simultaneous determination of 1-(2′-deoxy-2′-fluoro-β-d-arabinofuranosyl) uracil (FAU) and its active metabolite 1-(2′-deoxy-2′-fluoro-β-d-arabinofuranosyl) 5-methyluracil (FMAU) in human plasma. FAU and FMAU were extracted from plasma samples using solid-phase extraction with Waters Sep-Pak^® Vac C18 cartridge. Chromatographic separation was achieved on a Waters Atlantis T3 C18 column with a gradient mobile phase consisting of methanol and water with 0.45% formic acid (v/v) running at a flow rate of 0.2ml/min. The analytes were monitored by triple quadrupole mass spectrometer under positive ionization mode. The lower limit of quantitation (LLOQ) was 10 and 2ng/ml for FAU and FMAU in plasma, respectively. Calibration curves were linear over FAU and FMAU plasma concentration range of 10–2000 and 2–1000ng/ml, respectively. The intra-day and inter-day accuracy and precision were within the generally accepted criteria for bioanalytical method (<15%). The method has been successfully employed to characterize the plasma pharmacokinetics of FAU and FMAU in cancer patients receiving 1-h intravenous infusion of FAU 50mg/m².

Systematic evaluation of supported liquid extraction in reducing matrix effect and improving extraction efficiency in LC–MS/MS based bioanalysis for 10 model pharmaceutical compounds

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Hongliang Jiang, Huachuan Cao, Yang Zhang, Douglas M. Fast
In past a few years, there has been a large increase in the application of supported liquid extraction (SLE) for LC–MS/MS based bioanalysis due to its distinct practical advantage in reduced time cost, ease of operation and the feasibility for automation. The main purpose of this study was to systematically evaluate supported liquid extraction in reducing matrix effect and improving extraction efficiency/recovery under various extraction conditions with 10 model pharmaceutical compounds in liquid chromatography coupled to electrospray tandem mass spectrometry (LC–ESI-MS/MS) analysis. Selected compounds have diverse physicochemical properties where log P ranges from 0.1 to 6.24 and pK a ranges from 4.0 to 11.1. The factors that may have the impact on the recovery of analytes and phospholipids (PL) were assessed. Over 75% recovery was achieved for every analyte under its respectively optimized extraction conditions where the selection of the polarity of extraction solvent and buffered pH can be critical for efficient recovery. Furthermore, the matrix effect was assessed by postextraction spike and postcolumn infusion method. The matrix effect was considerably reduced for all analytes under most extraction conditions evaluated for SLE, compared with protein precipitation (PPT) method. The correlation between matrix effect and residual phospholipids in sample extract was clearly shown. Although analyte-dependent matrix effect was observed prominently in sample extract prepared by PPT, it was minimized by SLE sample preparation process that effectively removes the majority of phospholipids. Sample extracted by ethyl acetate contained more phospholipids and demonstrated stronger matrix effect than by other organic solvents. Water-miscible organic content, such as methanol and acetonitrile in samples prior to loading has significant impact on PL recovery when eluting with methyl tert-butyl ether. However, isopropanol does not enhance the recovery of PL when adding to dichloromethane for elution. In addition, the compromise between improved extraction efficiency by SLE and reduced matrix effect is sometimes necessary to yield clean extract with acceptable recovery. The effective removal of phospholipids and reduction of matrix effect, while achieving good recovery for all pharmaceutical compounds with diverse physicochemical properties, demonstrated that SLE is a valuable alternative technique to liquid–liquid extraction (LLE) in high throughput LC–MS/MS based bioanalysis.

Plasma persistence of 2-aminothiazoline-4-carboxylic acid in rat system determined by liquid chromatography tandem mass spectrometry

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Ilona Petrikovics, Jorn C.C. Yu, David E. Thompson, Prashanth Jayanna, Brian A. Logue, Jessica Nasr, Raj K. Bhandari, Steven I. Baskin, Gary Rockwood
2-Aminothiazoline-4-carboxylic acid (ATCA) was intravenously injected to rats in order to investigate its plasma distribution. ATCA was extracted from plasma samples by solid phase extraction (SPE) and molecularly imprinted polymer stir bar sorption extraction (MIP-SBSE). Detection and quantification of ATCA were achieved by using liquid chromatography–tandem mass spectrometry (LC–MS/MS). It was found that the intravenously injected ATCA concentration quickly decreased to half within 2.5h in the rat system. However, after 2.5h, the concentration of ATCA in plasma stayed constant at least 5 folds above the endogenous ATCA level for more then 48h. This finding can be used for evaluating ATCA's diagnostic and forensic value as a biomarker for cyanide exposure.

Detection of allantoin in clinical samples using hydrophilic liquid chromatography with stable isotope dilution negative ion tandem mass spectrometry

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Rufus Turner, Lisa K. Stamp, Anthony J. Kettle
Allantoin is the major oxidation product of urate in humans and is a potential biomarker of oxidative stress. Several methods are used to measure allantoin in biological samples but they have inherent issues that can include lack of specificity and sensitivity, difficulty in sample preparation, or artefactual generation of allantoin. We have developed a method for measuring allantoin using hydrophilic liquid chromatography with stable isotope dilution tandem mass spectrometry (HILIC–MS/MS). It was validated for measuring allantoin in plasma, synovial fluid and urine from human subjects. The limit of quantification was determined to be 10fmol and the assay displayed excellent linearity for the wide range of concentrations found in clinical samples. Relative standard deviations were <5% for between-day and <7% for within-day variation. Accuracy was between 100% and 104%. Concentrations of allantoin in plasma of healthy controls (2.0μM; interquartile range 1.4–3.6μM, n =35) was significantly lower (p <0.001) than that in plasma from patients with rheumatoid arthritis (3.7μM; IQR 3.0–5.6μM, n =43) and in synovial fluid of patients with gout (3.3μM; IQR 2.8–5.8μM, n =10). This newer HILIC–MS/MS method is a simple and highly sensitive assay for detection of allantoin. It can be used to assess the level of oxidative stress in human pathologies.

Recovery of active anti TNF-α ScFv through matrix-assisted refolding of bacterial inclusion bodies using CIM monolithic support

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Krishnan Sushma, Chuvappumkal Joseph Bilgimol, Mookambeswaran A. Vijayalakshmi, Padikara Kutty Satheeshkumar
Anti TNF-α molecules are important as therapeutic agents for many of the autoimmune diseases in chronic stage. Here we report the expression and purification of a recombinant single chain variable fragment (ScFv) specific to TNF-α from inclusion bodies. In contrast to the conventional on column refolding using the soft gel supports, an efficient methodology using monolithic matrix has been employed. Nickel (II) coupled to convective interaction media (CIM) support was utilized for this purpose with 6M guanidine hydrochloride (GuHCl) as the chaotropic agent. The protein purified after solubilization and refolding proved to be biologically active with an IC50 value of 15μg. To the best of our knowledge, this is the first report showing the application of methacrylate based chromatographic supports for matrix-assisted refolding and purification of Escherichia coli inclusion bodies. The results are promising to elaborate the methodology further to exploit the potential positive features of monoliths in protein refolding science.

Separation of nucleobases and their derivatives with organic-high ionic strength aqueous phase systems by spiral high-speed counter-current chromatography

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Yoichi Shibusawa, Akio Yanagida, Atsushi Ogihara, Ying Ma, Xiaoyuan Chen, Yoichiro Ito
A set of nucleic acid constituents were separated with ultra polar two-phase solvent systems by a spiral multilayer coil mounted on the rotary frame of a type-J coil planet centrifuge. These two-phase systems were composed of 1-butanol/ethanol/50% saturated aqueous ammonium sulfate at various volume ratios. Nucleobases including adenine, cytosine, uracil, and thymine; nucleosides including adenosine, guanosine, cytidine, and uridine; and nucleotides including, AMP, GMP, CMP, UMP, and TMP are partitioned in each group with suitable solvent ratios. Adenine derivatives such as adenosine, AMP, ADP, and ATP were well resolved in the most polar solvent system composed of ethanol/50% saturated aqueous ammonium sulfate at a volume ratio of 1:2. It was found that cytosine and cytidine peaks showed some irregular two peaks probably due to their keto and enol isomers, while the separation of AMP forms two peaks especially when TMP was added in the sample solution, the mechanism of which is now under investigation in our laboratory.

In vitro enantioselective metabolism of TJ0711 hydrochloride by human liver microsomes using a novel chiral liquid chromatography–tandem mass spectrometry method

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Jiangeng Huang, Lei Hu, Li Xu, Minghui Sun, Zhaoze Fan, Jun Qiu, Gao Li, Luqin Si
A novel liquid chromatography–tandem mass spectrometry (LC–MS/MS) method employing chiral analytical techniques was developed and validated for in vitro enantioselective metabolic stability study of racemic 1-[4-(2-methoxyethyl) phenoxy]-3-[[2-(2-methoxyphenoxy) ethyl]amino]-2-propanol hydrochloride (TJ0711 HCl), a newly developed vasodilatory β-blocker. Robust enantiomeric separations were achieved on a chiral SUMICHIRAL OA-2500 column using ethanol and hexane (40:60, v/v) as a mobile phase. Metabolic stability results demonstrated that both TJ0711 enantiomers underwent a rapid phase I metabolism, but preferential metabolism of R-TJ0711 was observed. Our previously reported ultra-performance liquid chromatography-multiple reaction monitoring-information dependent acquisition-enhanced product ion (UPLC-MRM-IDA-EPI) method was finally chosen for metabolite profiling study of TJ0711 enantiomers, because the newly developed HPLC-based method resulted in compromised chromatographic separation, particularly for TJ0711 metabolites. A number of metabolic products were detected and the structures of formed metabolites were predicted. Similar to racemic TJ0711 HCl, demethylation and hydroxylation were proposed to be the principle metabolism pathways during in vitro incubations of each enantiomer with human liver microsomes.

Simultaneous determination of pimpinellin, isopimpinellin and phellopterin in rat plasma by a validated UPLC–MS/MS and its application to a pharmacokinetic study after administration of Toddalia asiatica extract

23 March 2012, 10:56:29

Publication year: 2012
Source:Journal of Chromatography B, Volumes 891–892
Zhigang Liu, Minyan Jiang, Xiumei Lu, Feng Qin, Yang Song, Jing Wen, Famei Li
A rapid and selective ultra performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed for simultaneous determination of three bioactive coumarins of Toddalia asiatica extract including pimpinellin, isopimpinellin and phellopterin in rat plasma for the first time. Phenacetin was used as the internal standard (IS). Plasma samples were extracted by liquid–liquid extraction with methyl tert-butyl ether. The chromatographic separation was carried out on an ACQUITY UPLC™ BEH C18 column with an isocratic mobile phase consisting of methanol-5mmol/L ammonium acetate (65:35, v/v). The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) via electrospray ionization (ESI) source with positive ionization mode. The method was linear for all analytes over investigated range with all correlation coefficients greater than 0.9942. The lower limits of quantification (LLOQ) were 25.0ng/mL for pimpinellin, 10.0ng/mL for isopimpinellin and 5.00ng/mL for phellopterin. The intra- and inter-day precision (RSD%) was within 12% and the accuracy (RE%) ranged from −2.3% to 5.5%. The rapid and sensitive method was fully validated and successfully applied to the pharmacokinetic study of pimpinellin, isopimpinellin and phellopterin in rats following oral administration of Toddalia asiatica extract.  

Just Published: Sensors & Actuators B: Chemical

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Sensors & Actuators B: Chemical
http://rss.sciencedirect.com/publication/science/5283

Selected papers from the latest issue:

A nanostructured SAW chip-based biosensor detecting cancer cells

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Patrick Bröker, Klaus Lücke, Markus Perpeet, Thomas M.A. Gronewold
A nanostructured chip surface was fabricated enabling binding via spaced antibodies specifically targeting surface proteins of cancer cells and detection of extremely low numbers of circulating tumor cells (CTC) without labeling using a sam^® 5 biosensor. The antibody surfaces mostly were generated by self assembly of antibodies to gold nanospots on the sensitive SiO2-surface of a sam^® 5 chip. Compared with a complete gold surface, only 40% of the amount of antibodies was bound to the nanospot surface, but structured such that 15-fold higher sensitivity to vital cancer cells was achieved. Human cancer cell lines JEG-3 (lymphoblastic leukemia) and MOLT-17 (placental choriocarcinoma) from cell cultures were successfully detected. The sensor showed significant responses on less than 10 cells injected in a single run. The extreme increase in sensitivity and its simple regeneration emphasizes the usefulness of its introduction in biomedical applications.

A novel surface acoustic wave-impedance humidity sensor based on the composite of polyaniline and poly(vinyl alcohol) with a capability of detecting low humidity

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Yang Li, Chao Deng, Mujie Yang
This paper presents a novel humidity sensor composed of a 433MHz surface acoustic wave (SAW) resonator and an interdigitated gold electrode connected in series. The gold electrode was covered with a sensitive film of a composite of processable conductive polyaniline and polyvinyl alcohol. The frequency response of the novel SAW-impedance humidity sensor toward relative humidity (RH) was investigated at room temperature. The sensitivity of the SAW-impedance humidity sensors increased with the increase in the conductivity of the sensitive film. The sensor showed a sensitivity of ∼7.4kHz/%RH at 30%RH, which was increased to 60kHz/%RH at 47%RH. Moreover, such sensors exhibited short response and recovery times and good repeatability. It is worth noting that the sensor showed a linear frequency response to humidity over the range of 0.4–20%RH with a good sensitivity of ∼2kHz/%RH, which reveals its potentials for detecting low humidity.

Comparison of gas sensor performance of SnO2 nano-structures on microhotplate platforms

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Mark A. Andio, Paul N. Browning, Patricia A. Morris, Sheikh A. Akbar
Metal oxide nano-structures on microhotplate platforms have attracted a great deal of interest in gas sensor research for their potential to create both highly responsive and extremely portable gas sensors. Much of the current research on these sensors has focused upon the creation of hierarchical nanostructures, as van der Waals attraction between nanoparticles leads to agglomeration that impair sensor performance. In this research article, ink-jet printing onto microhotplates was explored as a method of avoiding nanoparticle agglomeration to produce an open film microstructure. Scanning electron microscopy was used to study the deposited thin nanoparticle film featuring an open microstructure free of large agglomeration. Sensor response and response times of ink-jet printed SnO2 nanoparticles were found to be comparable to hierarchical particle films when exposed to methane and carbon monoxide in a background of dry air. Both the SnO2 nanoparticles and microspheres had superior response compared to SnO2 micron-size particles due to increased surface area of the nano-structures. This implies that proper control of the microstructure of the SnO2 nanoparticle films produces similar gas sensor performance to SnO2 hierarchical structures and has the potential for use in reproducibly manufacturing high-performance gas sensors.

On the hydrogen sensing characteristics of a Pd/AlGaN/GaN heterostructure field-effect transistor (HFET)

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Chi-Shiang Hsu, Huey-Ing Chen, Chung-Fu Chang, Tai-You Chen, Chien-Chang Huang, Po-Cheng Chou, Wen-Chau Liu
The interesting temperature-dependent hydrogen sensing characteristics of a Pd/AlGaN/GaN heterostructure field-effect transistor (HFET) are studied and demonstrated. Remarkable hydrogen sensing performance is found at a very low concentration of hydrogen gases (≤1ppm H2/air). In addition, a good transistor switching behavior with the high drain current on/off value of 93,680 is obtained for 1% ppm H2/air gas at 523K. The fast transient response as comparable with a Schottky-type hydrogen sensor is also observed. Based on these advantages, the studied device shows a promise for high-performance, high-temperature electronics, and micro electro-mechanical system (MEMS) applications.

Sensitive detection of indoor air contaminants using a novel gas sensor based on coral-shaped tin dioxide nanostructures

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Yuteng Wan, Huihua Li, Jinyun Liu, Fanli Meng, Zhen Jin, Lingtao Kong, Jinhuai Liu
In order to sensitively detect indoor air contaminants including benzene, formaldehyde, toluene, and acetone, an effective method using a gas sensor based on coral-shaped tin dioxide nanostructures is reported. It is found that the presented gas sensor exhibits obviously enhanced sensing performance toward indoor air contaminants compared with the ones based on some conventional nanostructures, like nanospheres and nanoparticle-based thin film. The mechanism for such fascinating improvement is demonstrated from the nanoscale size-dependent effect by following theoretical models. Our findings not only provide a promising environmental sensor for sensitively detecting indoor air contaminants, but also suggest a general strategy for utilizing the nanoscale effects of nanoparticles in other environmental and energy-related applications, like waste-water absorbents, catalysts, and solar cells.

Optical temperature sensing through extraordinary enhancement of green up-conversion emissions for Er–Yb–Mo:Al2O3

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
B. Dong, B.S. Cao, Z.Q. Feng, X.J. Wang, Y.Y. He
The extraordinary enhancement of green up-conversion emissions originated from the ²H11/2 → ⁴I15/2 and ⁴S3/2 → ⁴I15/2 transitions is obtained for the Er–Yb–Mo:Al2O3 with a 976nm laser diode excitation. It indicates that such green enhancement arises from the high excited state energy transfer with |²F7/2, ³T2> state of the Yb³⁺–MoO4 ²⁻ dimer to the ⁴F7/2 level of Er³⁺. Fluorescence intensity ratio (FIR) technique based on the green up-conversion emissions of the Er–Yb–Mo:Al2O3 has been studied as a function of temperature. With an excitation power of 2mW, the maximum of sensitivity and temperature revolution is approximately 0.0051K⁻¹ and 0.3K in the range of 294–973K, respectively. The Er–Yb–Mo:Al2O3 with intense green up-conversion emissions, a higher operating temperature and revolution indicates that it is a promising material for application in optical temperature sensing.

Lab-on-a-chip spectrophotometric characterization of porcine oocytes

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Rafał Walczak, Patrycja Śniadek, Jan A. Dziuban, Bartosz Kempisty, Marta Jackowska, Paweł Antosik, Jędrzej M. Jaśkowski
The method of quality assessment of the oocytes of breeding animals based on morphological criteria very often leads to unsuccessful in vitro fertilization and pure breeding result. In this paper we present a spectrophotometric methodology utilizing lab-on-a-chip techniques for optical and subjective characterization of porcine oocytes. A set of parameters describing the features of oocytes deduced from collected absorbance spectra of a single oocyte, has been proposed. Differentiation of the spectra of oocytes coming from different sizes of porcine follicle has been observed. The obtained results are the first step towards an objective quality assessment of porcine oocytes, which in the future may be extended to other breeding animals.

Highly sensitive and selective colorimetric detection of Ag(I) ion using 3,3′,5,5′,-tetramethylbenzidine (TMB) as an indicator

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Sen Liu, Jingqi Tian, Lei Wang, Xuping Sun
In this paper, we report on our recent finding that Ag⁺ can oxidize 3,3′,5,5′,-tetramethylbenzidine (TMB) to develop a blue color in aqueous solution, leading to a simple approach to colorimetric detection of Ag⁺ with a detection limit of 50nM. Most importantly, we demonstrate its practical application to detect Ag⁺ in real sample.

Chlorella sp. based biosensor for selective determination of mercury in presence of silver ions

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Jasminder Singh, Susheel K. Mittal
Whole cell based biosensor is prepared by immobilizing Chlorella sp. microbes over glassy carbon electrode. The proposed biosensor is optimized for characteristics like substrate concentration, pH, response time, and durability. The electrode responds linearly in concentration range of 10⁻¹⁴ M to 10⁻⁶ M for mercury and showed its rare selectivity over silver, alkali metals, alkaline earth metals and transition metals with an expected life of 14 days.

A spheroid-based biosensor for the label-free detection of drug-induced field potential alterations

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Andreas W. Daus, Paul G. Layer, Christiane Thielemann
A valuable method for evaluating the functional effects of promising candidates in cardiac drug discovery is the analysis of electrophysiological characteristics. In vitro techniques facilitate the investigation of physiological parameters, including action potential generation, conduction, arrhythmia and QT duration, to chemical provocation and at the same time benefit from defined experimental conditions as well as enhanced accessibility. A widespread approach to studying the electrophysiological properties of developing and mature cellular networks in vitro is the multichannel recording of cardiac cells cultured as monolayers on microelectrode arrays. However, common two-dimensional monolayer cell cultures do not accurately reflect in vivo conditions. Cells within a tissue are organized into a complex three-dimensional pattern, and cellular interactions are not limited to a two-dimensional environment. Here, we report on a biosensor that combines the microelectrode array technique with cardiac three-dimensional cellular networks. Fully dissociated primary cells from chicken embryonic hearts were re-aggregated into spheroids. We found that action potentials could be recorded with an excellent signal-to-noise-ratio for up to several weeks. The administration of cardioactive drugs significantly altered the electrophysiological characteristics of the spheroids. Cellular responses were investigated along with the biosensor's potential as a tool for estimating the effectiveness and the risk of adverse reactions of drugs.

WO3 sensing properties enhanced by UV illumination: An evidence of surface effect

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
A. Giberti, C. Malagù, V. Guidi
The behaviour of the conductance of a nanostructured WO3-based chemioresistive gas sensor under UV illumination was investigated in a synthetic air and in a pure nitrogen environment. The observed increase in conductance under illumination is expected to depend on interband electronic transitions, being the bandgap of the material smaller than the energy of the incident photons. In the present work we show an evidence that an important contribution to this increase is given by surface barrier modulation rather than interband transitions. Indeed, the conductance variation from the dark to the light was interpreted in terms of a direct effect of the light on the adsorbed oxygen ions.

An inward replacement/etching route to controllable fabrication of zinc sulfide nanotube arrays for humidity sensing

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Weixin Zhang, Cheng Feng, Zeheng Yang
Well-aligned arrays of polycrystalline ZnS nanotubes with close-tips have been successfully prepared by using ZnO nanorod arrays grown on zinc substrate as sacrificial precursors. The method is based on chemical conversion and inward etching of the ZnO sacrificial precursors. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images show that the highly ordered ZnS nanotube arrays are 300nm in average diameter, 6–8μm in length and about 60nm in wall thickness. A room temperature photoluminescence-type gas sensing device based on the nanostructured arrays has been established to investigate their humidity sensing properties. ZnS nanotube array-based sensor presents higher response and quicker response/recovery than the intermediate ZnO/ZnS nanorod arrays and the precursor ZnO nanorod arrays, respectively. Moreover, the ZnS nanotube array-based sensor exhibits good linearity in response to relative humidity (RH) and reliable reproducibility in a wide range of RH at room temperature. Compared with powder-form nanomaterials, the as-prepared nanotube arrays as the humidity sensing materials can provide much more open surfaces between neighboring nanotubes and inner surfaces inside the nanotubes and allow for easy diffusion and efficient transportation of sensed gas. As a prototype sensor, the nanotube arrays can avoid tedious process of fabricating a sensor from powder and may hold great potential applications in humidity sensing.

Various photonic crystal bio-sensor configurations based on optical surface modes

23 March 2012, 10:54:13

Publication year: 2012
Source:Sensors and Actuators B: Chemical, Volume 165, Issue 1
Hamza Kurt, Muhammed Necip Erim, Nur Erim
We design a new bio-sensor concept that incorporates photonic crystal (PC) surface modes to sense small refractive index changes. The initial attempt creates optical surface modes by first enlarging and then perforating the radii of rods residing along the end surface of the square-lattice PC. The strongly confined mode which decays both evanescently along transverse to propagation direction interacts with the substance while propagating along the PC-air interface. Due to index change of the ambient medium, the transmission spectrum experiences linear shift with a large dynamic range. The relocation of the surface defects enhances the sensitivity of bio-sensor from ∼8 to ∼93nm/RIU. The second type of investigated PC structure is based on triangular-lattice PC and it provides a surface state bio-sensor with a sensitivity of 117nm/RIU. In addition to these designs, we propose a final structure that incorporates air slot along one side of triangular-lattice PC. We succeeded to obtain a new sensitivity value of 396nm/RIU. The investigation shows that even higher sensitivities can be achieved. The different RIU values are reminiscent of group velocity of the relevant modes which can be extracted from the dispersion analysis. Compact, sensitive and label-free optical sensors based on surface modes may become part of the important applications in opto-fluidic technology and lab-on-a-chip.