World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Tuesday 10 September 2013

Just Published: Microchemical Journal

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:

Selected papers from the latest issue:

Visual enantioselective probe based on metal organic framework incorporating quantum dots

10 September 2013, 10:35:48
Publication date: Available online 7 September 2013
Source:Microchemical Journal
Author(s): Zhou Long , Jia Jia , Shanling Wang , Lu Kou , Xiandeng Hou , Michael J. Sepaniak
A new method was developed for visual enantioselective sensing based on quantum dots (QDs) doped metal organic framework (MOF), which firstly combined the chiral selectivity of MOF and sensing of QD quenching. A simple synthesis procedure with much less reaction time is developed, with small and homogenously-sized QD@MOF particles obtained, as well as a cheaper dispersant used. The proposed sensing method is proved to be direct, convenient, and visual. Qualification and preliminary quantification of enantiomers can be accomplished in a visual fashion. The proposed method also demonstrates practical utility, and it is expected to be expanded to enantioselective determination of other enantiomers.

Prediction of tyrosinase inhibitory activities of Morus alba root bark extracts from HPLC fingerprints

10 September 2013, 10:35:48
Publication date: Available online 4 September 2013
Source:Microchemical Journal
Author(s): Kyo Bin Kang , Dong Young Lee , Tae Bum Kim , Seung Hyun Kim , Hyo Jin Kim , Jinwoong Kim , Sang Hyun Sung
A correlation model between tyrosinase inhibitory activities and HPLC chromatograms of Morus alba root bark extracts was calibrated and validated. The correlational approach has been suggested as an alternative technique for quality control and study of natural products. However, this method requires a large number of various samples with similar chemical compositions. In the present study, 42 different extracts were obtained from 6 samples of Morus alba root bark under 7 different extraction solvent conditions using an automated pressurized liquid extraction system. HPLC chromatograms and mushroom tyrosinase inhibitory activities of these extract samples were obtained, and the chromatograms were preprocessed with asymmetric least square smoothing and correlation optimized warping algorithms. The partial least squares (PLS) regression model between the preprocessed chromatograms and the bioactivities of samples was created. The full cross validations were performed by changing the selection method of the test sets; plant sample based, extraction method based validation set selections were used for the validation tests. In the both of validation tests, the PLS models showed excellent performance of prediction. The predictive models showed averagely RMSEP of 9.4309 and R2 values of 0.8717 in the validation test based on plant samples, and RMSEP of 8.1541 and R2 values of 0.8778 in the validation test based on extraction methods. Additionally, an estimation of the bioactive component was made from the regression coefficient, and the result of the estimation was similar to the experimental results of reference papers.

Occurrence, transportation, monitoring and treatment of emerging micro-pollutants in waste water — A review from global views

10 September 2013, 10:35:48
Publication date: September 2013
Source:Microchemical Journal, Volume 110
Author(s): Jia-Qian Jiang , Z. Zhou , V.K. Sharma
This paper collects data from worldwide research groups and aims to critically review and analyse the advances of knowledge development in the area of occurrence, transportation, monitoring and treatment of emerging micro-pollutants from around the globe and to recommend the research needs in this research area. This review discovers that •A waste water treatment plant is one of pathways for micro-pollutants to transfer into surface waters; •Sample preparation, matrix effects and validation methods are challenges and more advanced analytical instrumentation and procedures are critical in analysing emerging micro-pollutants; •Traditional activated sludge and/or bio-filtration processes showed less efficiency to remove emerging micro-pollutants; •Advanced oxidation processes need to be validated for the efficiency and cost effectiveness; • More researches are needed to classify the type and toxicity of by-products resulting from the reactions between advanced oxidation processes and emerging micro-pollutants. The suggested future research needs from this review are challenges but provide us opportunities to effectively monitor and eliminate emerging micro-pollutants in the environment.

Selective separation of elements from complex solution matrix with molecular recognition plus macrocycles attached to a solid-phase: A review

10 September 2013, 10:35:48
Publication date: September 2013
Source:Microchemical Journal, Volume 110
Author(s): Ismail M.M. Rahman , Zinnat A. Begum , Hiroshi Hasegawa
Solid-phase extraction (SPE) approach was introduced approximately five decades ago, and until then development of SPE materials is seamlessly continued. Lately, the SPE-based research is increasingly focused in developing more explicit materials to achieve meticulous separation of elements from complex solution matrices with high concentrations of interfering ions. One group of SPE materials includes those with macrocyclic ligands immobilized on a solid-phase, which are capable of selective separation and pre-concentration of elements, and such selectivity in metal retention is generally termed as molecular recognition. In the process, the designed ‘host’ material possesses a high degree of recognition to specific elements or groups of elements called ‘guest’, and the recognition capability remains effective at the very low concentrations of the ‘guest’ species or when those present in complex matrices. The routes to the development of element-selective SPEs, the operating principles, applications and limitations are discussed in this review.

Solvent microextraction: A review of recent efforts at automation

10 September 2013, 10:35:48
Publication date: September 2013
Source:Microchemical Journal, Volume 110
Author(s): Lívia Kocúrová , Ioseph S. Balogh , Vasil Andruch
Innovations and trends in sample pretreatment techniques are currently focused on the development of methods that satisfy the principles of Green Analytical Chemistry. The increase in the number of publications devoted to solvent microextraction (SME) techniques testifies to the growing interest of analytical chemists in this field. In addition to miniaturization, we can see a greater than ever effort being made towards the automation of SME procedures. Rather than providing an exhaustive overview of the current state of this trend, we instead offer readers a look at what we consider to be some of the more interesting recently published solutions.

Graphical abstract

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Determination of selenium compounds in food supplements using reversed-phase liquid chromatography–inductively coupled plasma mass spectrometry

10 September 2013, 10:35:48
Publication date: September 2013
Source:Microchemical Journal, Volume 110
Author(s): Yu-Jhe Hsieh , Shiuh-Jen Jiang
A reversed phase HPLC–ICP-MS method for the speciation of selenium compounds is described. Chromatographic separation was performed in a gradient elution mode using 2mmolL−1 sodium 1-pentanesulfonate and 5mmolL−1 citric acid in 3% methanol (pH2.70) and 5mmolL−1 NaH2PO4 and 5mmolL−1 citric acid in 3% methanol (pH2.77). The potentially interfering 38Ar40Ar+ and 40Ar40Ar+ at selenium masses of m/z 78 and 80 were reduced in intensity significantly by using 1.0mLmin−1 CH4 as a reactive cell gas in the dynamic reaction cell. Calibration curves were linear in the range 0.1–10μgL−1. The detection limits of the procedure were in the range of 0.04–0.07μgSeL−1. This method has been applied to determine various selenium compounds in NIST SRM 1567a Wheat Flour and food supplements purchased locally. The accuracy of the method has been verified by comparing the sum of the concentration of individual species obtained by the present procedure with the total concentration of the element. The selenium compounds were quantitatively extracted with a mixture of Protease XIV and mobile phase solution in a microwave field at 37°C during a period of 30min. The extraction efficiency was better than 91%. The spike recoveries were in the range of 92–104% for all determinations. The electrospray ionization-mass spectrometer has been tested to identify the unknown selenium compounds detected in the food supplements. γ-glutamyl-methyl-Se-cysteine was identified in one brand of the Selenium Tablet.

Highlights

► Selenium compounds in food supplements were determined using HLPC–ICP-MS. ► Ar dimer ion interferences on Se determination were suppressed with CH4 as the DRC reaction gas. ► Selenium species were quantitatively extracted using microwave heating. ► γ-Glutamyl-methyl-Se-cysteine was identified in Selenium Tablet using ESI-MS/MS.

Transport of selenium species in Caco-2 cells: Analytical approach employing the Ussing chamber technique and HPLC-ICP-MS

10 September 2013, 10:35:48
Publication date: September 2013
Source:Microchemical Journal, Volume 110
Author(s): Denis Pick , Christian Degen , Matthias Leiterer , Gerhard Jahreis , Jürgen W. Einax
Essential trace elements such as selenium (Se) play a crucial role in health and diseases. Investigations of the transport and absorption of different Se species in vivo and in vitro consider only one Se species in a systematic manner. Thus, transport of four Se compounds (at concentrations of 100 and 400μgL−1) namely selenite (SeO3 2−), selenate (SeO4 2−), selenomethionine (SeMet), and Se-methylselenocysteine (MeSEC) was compared using the Caco-2 cell line and the Ussing chamber system. For analytical measurements, an HPLC-ICP-DRC-MS method was developed and characterized. For the investigated Se species, limits of quantification were 0.5μgL−1 while trueness was tested using the certified reference material SELM-1. Se species were added to the apical compartment of the Ussing chamber system either separately or simultaneously. Notably, no transport for SeO3 2− from apical to basolateral side was observed. Transport efficacy after 120min was the highest (9.1%) for SeMet in single species experiments, whereas SeO4 2− transport was the highest (7.9%) associated with simultaneous adding of Se species. Furthermore, changes in rank order of the apparent permeability coefficients Papp were obtained in mixture experiments as compared to the single species approaches. Finally, experimental data demonstrate alterations in transport of SeMet, MeSEC, and SeO4 2− suggesting interactions between Se species and changes in the transport behavior.

Highlights

► A simple and fast HPLC-ICP-DRC-MS method was developed for analysis of Se species. ► Se species were added to the Caco-2 cell model either simultaneously or separately. ► Selenite transport across Caco-2 cell monolayers is especially slow. ► Presence of other Se species influences the transport of selenate, SeMet, and MeSEC.

A portable fiber-optic Raman analyzer for fast real-time screening and identifying cocrystal formation of drug-coformer via grinding process

10 September 2013, 10:35:48
Publication date: September 2013
Source:Microchemical Journal, Volume 110
Author(s): Hong-Liang Lin , Gang-Chun Zhang , Po-Chun Hsu , Shan-Yang Lin
A portable Raman analyzer with a fiber-optic probe was first used to rapidly screen and identify the cocrystal formation between drug and coformer. Indomethacin (IMC) and anhydrous theophylline (TP) were selected as model drugs, but saccharin (SAC) and anhydrous citric acid (CA) were chosen as model coformers. The cocrystal formation that occurred in the solid-state IMC–SAC or TP–CA system via mechanical grinding process was investigated. Differential scanning calorimetry (DSC) was also used to investigate the possible cocrystal formation. The present study indicates that this new portable fiber-opticRaman spectroscopic technique was an easy and fast “real-time” method to screen and identify the progressive cocrystal formation in solid-state IMC–SAC or TP–CA system in the process of mechanical grinding by inserting the probe directly into the ground mixtures.  

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