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Automated capillary electrophoresis with on-line preconcentration by solid phase extraction using a sequential injection manifold and contactless conductivity detection
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Thanh Duc Mai, Benjamin Bomastyk, Hong Anh Duong, Hung Viet Pham, Peter C. Hauser
An extension of a capillary electrophoresis instrument coupled to a sequential injection analysis manifold was developed for automated measurements with on-line solid-phase extraction preconcentration. An in-house built capacitively coupled contactless conductivity detector was employed for sensitive detection with narrow capillaries of 25μm internal diameter. The system was assembled into standardized 19in. frames and racks for easy transport and mobile deployment. The system can be left running unattendedly without manual intervention with good operation stability. To demonstrate the application of the system, a method for the determination of four drugs, namely ibuprofen, diclofenac, naproxen and bezafibrate, was developed with enrichment factors of up to several hundreds. Detection of the drug residues down to the nM-scale was found possible and the method was found suitable for the detection of ibuprofen in the waste water of a hospital in Hanoi.
Source:Analytica Chimica Acta, Volume 727
Thanh Duc Mai, Benjamin Bomastyk, Hong Anh Duong, Hung Viet Pham, Peter C. Hauser
An extension of a capillary electrophoresis instrument coupled to a sequential injection analysis manifold was developed for automated measurements with on-line solid-phase extraction preconcentration. An in-house built capacitively coupled contactless conductivity detector was employed for sensitive detection with narrow capillaries of 25μm internal diameter. The system was assembled into standardized 19in. frames and racks for easy transport and mobile deployment. The system can be left running unattendedly without manual intervention with good operation stability. To demonstrate the application of the system, a method for the determination of four drugs, namely ibuprofen, diclofenac, naproxen and bezafibrate, was developed with enrichment factors of up to several hundreds. Detection of the drug residues down to the nM-scale was found possible and the method was found suitable for the detection of ibuprofen in the waste water of a hospital in Hanoi.
Graphical Abstract
Graphical abstract Highlights
. ► Robust preconcentration is possible with a syringe-driven sequential injection based manifold. ► Separation of pharmaceutical compounds was done with capillary electrophoresis. ► Contactless conductivity detection (C4D) was used for narrow capillaries of 25μm. ► Quantification down to the low nanomolar range was achieved.An efficient extraction method for quantitation of adenosine triphosphate in mammalian tissues and cells
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Junji Chida, Kazuhiko Yamane, Tunetomo Takei, Hiroshi Kido
Firefly bioluminescence is widely used in the measurement of adenosine 5′-triphosphate (ATP) levels in biological materials. For such assays in tissues and cells, ATP must be extracted away from protein in the initial step and extraction efficacy is the main determinant of the assay accuracy. Extraction reagents recommended in the commercially available ATP assay kits are chaotropic reagents, trichloroacetic acid (TCA), perchloric acid (PCA), and ethylene glycol (EG), which extract nucleotides through protein precipitation and/or nucleotidase inactivation. We found that these reagents are particularly useful for measuring ATP levels in materials with relatively low protein concentrations such as blood cells, cultured cells, and bacteria. However, these methods are not suitable for ATP extraction from tissues with high protein concentrations, because some ATP may be co-precipitated with the insolubilized protein during homogenization and extraction, and it could also be precipitated by neutralization in the acid extracts. Here we found that a phenol-based extraction method markedly increased the ATP and other nucleotides extracted from tissues. In addition, phenol extraction does not require neutralization before the luciferin–luciferase assay step. ATP levels analyzed by luciferase assay in various tissues extracted by Tris–EDTA–saturated phenol (phenol–TE) were over 17.8-fold higher than those extracted by TCA and over 550-fold higher than those in EG extracts. Here we report a simple, rapid, and reliable phenol–TE extraction procedure for ATP measurement in tissues and cells by luciferase assay.
Source:Analytica Chimica Acta, Volume 727
Junji Chida, Kazuhiko Yamane, Tunetomo Takei, Hiroshi Kido
Firefly bioluminescence is widely used in the measurement of adenosine 5′-triphosphate (ATP) levels in biological materials. For such assays in tissues and cells, ATP must be extracted away from protein in the initial step and extraction efficacy is the main determinant of the assay accuracy. Extraction reagents recommended in the commercially available ATP assay kits are chaotropic reagents, trichloroacetic acid (TCA), perchloric acid (PCA), and ethylene glycol (EG), which extract nucleotides through protein precipitation and/or nucleotidase inactivation. We found that these reagents are particularly useful for measuring ATP levels in materials with relatively low protein concentrations such as blood cells, cultured cells, and bacteria. However, these methods are not suitable for ATP extraction from tissues with high protein concentrations, because some ATP may be co-precipitated with the insolubilized protein during homogenization and extraction, and it could also be precipitated by neutralization in the acid extracts. Here we found that a phenol-based extraction method markedly increased the ATP and other nucleotides extracted from tissues. In addition, phenol extraction does not require neutralization before the luciferin–luciferase assay step. ATP levels analyzed by luciferase assay in various tissues extracted by Tris–EDTA–saturated phenol (phenol–TE) were over 17.8-fold higher than those extracted by TCA and over 550-fold higher than those in EG extracts. Here we report a simple, rapid, and reliable phenol–TE extraction procedure for ATP measurement in tissues and cells by luciferase assay.
Graphical Abstract
Graphical abstract Highlights
This study showed that phenol–TE extraction is suitable for measurement of ATP levels in various mammalian tissues (B, brain; H, heart; L, liver; S, spleen; M, muscle) with high protein concentrations and cells, and provided better and more efficient extraction than trichloroacetic acid (TCA) and ethylene glycol (EG), which are recommended in the commercially available ATP assay kits. The ATP levels extracted by phenol–TE were over 17.8-fold higher (depending on tissues) than those in TCA extracts and over 550-fold higher than those in EG extracts. We recommend this method for assay of ATP from mammalian tissues and blood. ► An extraction method for ATP and other nucleotides from mammalian tissues and blood. ► Phenol-based extraction provided better ATP extraction than chaotropic reagents. ► Phenol-based extraction does not require neutralization before the luciferase assay.Fabrication of novel nanoporous array anodic alumina solid-phase microextraction fiber coating and its potential application for headspace sampling of biological volatile organic compounds
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Zhuomin Zhang, Qingtang Wang, Gongke Li
In the study, nanoporous array anodic alumina (NAAA) prepared by a simple, rapid and stable two-step anodic oxidization method was introduced as a novel solid-phase microextraction (SPME) fiber coating. The regular nanoporous array structure and chemical composition of NAAA SPME fiber coating was characterized and validated by scanning electron microscopy and energy dispersive spectroscopy, respectively. Compared with the commercial polydimethylsiloxane (PDMS) SPME fiber coating, NAAA SPME fiber coating achieved the higher enrichment capability (1.7–4.7 folds) for the mixed standards of volatile organic compounds (VOCs). The selectivity for volatile alcohols by NAAA SPME fiber coating demonstrated an increasing trend with the increasing polarity of alcohols caused by the gradually shortening carbon chains from 1-undecanol to 1-heptanol or the isomerization of carbon chains of some typical volatile alcohols including 2-ethyl hexanol, 1-octanol, 2-phenylethanol, 1-phenylethanol, 5-undecanol, 2-undecanol and 1-undecanol. Finally, NAAA SPME fiber coating was originally applied for the analysis of biological VOCs of Bailan flower, stinkbug and orange peel samples coupled with gas chromatography–mass spectrometry (GC–MS) detection. Thirty, twenty-seven and forty-four VOCs of Bailan flower, stinkbug and orange peel samples were sampled and identified, respectively. Moreover, the contents of trace 1-octanol and nonanal of real orange peel samples were quantified for the further method validation with satisfactory recoveries of 106.5 and 120.5%, respectively. This work proposed a sensitive, rapid, reliable and convenient analytical method for the potential study of trace and small molecular biological VOCs by the novel NAAA SPME fiber coating.
Source:Analytica Chimica Acta, Volume 727
Zhuomin Zhang, Qingtang Wang, Gongke Li
In the study, nanoporous array anodic alumina (NAAA) prepared by a simple, rapid and stable two-step anodic oxidization method was introduced as a novel solid-phase microextraction (SPME) fiber coating. The regular nanoporous array structure and chemical composition of NAAA SPME fiber coating was characterized and validated by scanning electron microscopy and energy dispersive spectroscopy, respectively. Compared with the commercial polydimethylsiloxane (PDMS) SPME fiber coating, NAAA SPME fiber coating achieved the higher enrichment capability (1.7–4.7 folds) for the mixed standards of volatile organic compounds (VOCs). The selectivity for volatile alcohols by NAAA SPME fiber coating demonstrated an increasing trend with the increasing polarity of alcohols caused by the gradually shortening carbon chains from 1-undecanol to 1-heptanol or the isomerization of carbon chains of some typical volatile alcohols including 2-ethyl hexanol, 1-octanol, 2-phenylethanol, 1-phenylethanol, 5-undecanol, 2-undecanol and 1-undecanol. Finally, NAAA SPME fiber coating was originally applied for the analysis of biological VOCs of Bailan flower, stinkbug and orange peel samples coupled with gas chromatography–mass spectrometry (GC–MS) detection. Thirty, twenty-seven and forty-four VOCs of Bailan flower, stinkbug and orange peel samples were sampled and identified, respectively. Moreover, the contents of trace 1-octanol and nonanal of real orange peel samples were quantified for the further method validation with satisfactory recoveries of 106.5 and 120.5%, respectively. This work proposed a sensitive, rapid, reliable and convenient analytical method for the potential study of trace and small molecular biological VOCs by the novel NAAA SPME fiber coating.
Graphical Abstract
Graphical abstract Highlights
► Nanoporous array anodic alumina (NAAA) SPME coating was originally prepared. ► NAAA SPME coating achieved excellent enrichment capability and selectivity for VOCs. ► NAAA SPME coating can be applied for the headspace sampling of biological VOCs.Development of a fiber coating based on molecular sol–gel imprinting technology for selective solid-phase micro extraction of caffeine from human serum and determination by gas chromatography/mass spectrometry
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Afshin Rajabi Khorrami, Amene Rashidpur
In this work, a molecular sol–gel imprinting approach has been introduced to produce a fiber coating for selective direct immersion solid-phase microextraction (SPME) of caffeine. The polymerization mixture was composed of vinyl trimethoxysilane and methacrylic acid as vinyl sol–gel precursor and functional monomer, respectively. Caffeine was used as template molecule during polymerization process. The prepared fibers could be coupled directly to gas chromatography/mass spectrometry (GC/MS) and used for trace analysis of caffeine in a complex sample such as human serum. The parameters influencing SPME such as time, temperature and stirring speed were optimized. The prepared coating showed good selectivity towards caffeine in the presence of some structurally related compounds. Also, it offered high imprinting capability in comparison to bare fiber and non-imprinted coating. Linear range for caffeine detection was 1–80μgmL−1 and the limit of detection was 0.1μgmL−1. The intra-day and inter-day precisions of the peak areas for five replicates were 10 and 16%, respectively.
Source:Analytica Chimica Acta, Volume 727
Afshin Rajabi Khorrami, Amene Rashidpur
In this work, a molecular sol–gel imprinting approach has been introduced to produce a fiber coating for selective direct immersion solid-phase microextraction (SPME) of caffeine. The polymerization mixture was composed of vinyl trimethoxysilane and methacrylic acid as vinyl sol–gel precursor and functional monomer, respectively. Caffeine was used as template molecule during polymerization process. The prepared fibers could be coupled directly to gas chromatography/mass spectrometry (GC/MS) and used for trace analysis of caffeine in a complex sample such as human serum. The parameters influencing SPME such as time, temperature and stirring speed were optimized. The prepared coating showed good selectivity towards caffeine in the presence of some structurally related compounds. Also, it offered high imprinting capability in comparison to bare fiber and non-imprinted coating. Linear range for caffeine detection was 1–80μgmL−1 and the limit of detection was 0.1μgmL−1. The intra-day and inter-day precisions of the peak areas for five replicates were 10 and 16%, respectively.
Graphical Abstract
Graphical abstract Highlight
► We introduce a molecular sol–gel imprinting approach to produce a fiber coating. ► We used it for selective extraction of caffeine in a SPME procedure. ► Prepared fibers coupled to gas chromatography/mass spectrometry (GC/MS). ► Coating shows promising mechanical and thermal stability, excellent durability, wide linear range and good extraction efficiency. ► The developed fiber is an attractive tool for determination of caffeine in human serum.An electrochemically enhanced solid-phase microextraction approach based on molecularly imprinted polypyrrole/multi-walled carbon nanotubes composite coating for selective extraction of fluoroquinolones in aqueous samples
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Xue Liu, Xiaochun Wang, Feng Tan, Hongxia Zhao, Xie Quan, Jingwen Chen, Lianjun Li
In this study, an electrochemically enhanced solid-phase microextraction (EE-SPME) approach based on molecularly imprinted polypyrrole/multi-walled carbon nanotubes (MIPPy/MWCNTs) composite coating on Pt wire was developed for selective extraction of fluoroquinolone antibiotics (FQs) in aqueous samples. During the extraction, a direct current potential was applied to the MIPPy/MWCNTs/Pt fiber as working electrode in a standard three-electrode system, FQ ions suffered electrophoretic transfer to the coating surface and then entered into the shape-complimentary cavities by hydrogen-bonding and ion-exchange interactions. After EE-SPME extraction, the fiber was desorbed with desorption solvent for high-performance liquid chromatography (HPLC) analysis. Some parameters influencing EE-SPME extraction such as applied potential, extraction time, solution pH, ionic strength, and desorption solvent were optimized. EE-SPME showed good selectivity and higher extraction efficiency to FQs compared with that of traditional solid-phase microextraction. EE-SPME coupled with HPLC to determine FQs in water samples, the limits of detection (S/N=3) for the selected FQs are 0.5–1.9μgL−1. The proposed method was successfully used to the analysis of FQs spiked urine and soil samples, with recoveries of 85.1–94.2% for the urine samples and 89.8–95.5% for the soil samples.
Source:Analytica Chimica Acta, Volume 727
Xue Liu, Xiaochun Wang, Feng Tan, Hongxia Zhao, Xie Quan, Jingwen Chen, Lianjun Li
In this study, an electrochemically enhanced solid-phase microextraction (EE-SPME) approach based on molecularly imprinted polypyrrole/multi-walled carbon nanotubes (MIPPy/MWCNTs) composite coating on Pt wire was developed for selective extraction of fluoroquinolone antibiotics (FQs) in aqueous samples. During the extraction, a direct current potential was applied to the MIPPy/MWCNTs/Pt fiber as working electrode in a standard three-electrode system, FQ ions suffered electrophoretic transfer to the coating surface and then entered into the shape-complimentary cavities by hydrogen-bonding and ion-exchange interactions. After EE-SPME extraction, the fiber was desorbed with desorption solvent for high-performance liquid chromatography (HPLC) analysis. Some parameters influencing EE-SPME extraction such as applied potential, extraction time, solution pH, ionic strength, and desorption solvent were optimized. EE-SPME showed good selectivity and higher extraction efficiency to FQs compared with that of traditional solid-phase microextraction. EE-SPME coupled with HPLC to determine FQs in water samples, the limits of detection (S/N=3) for the selected FQs are 0.5–1.9μgL−1. The proposed method was successfully used to the analysis of FQs spiked urine and soil samples, with recoveries of 85.1–94.2% for the urine samples and 89.8–95.5% for the soil samples.
Graphical Abstract
Graphical abstract Highlights
► Novel molecularly imprinted polypyrrole/multi-walled carbon nanotubes (MIPPy/MWCNTs) composite coating. ► An electrochemically enhanced solid-phase microextraction (EE-SPME) approach. ► EE-SPME showed good selectivity and high extraction efficiency to fluoroquinolone antibiotics.Automatic microemulsion preparation for metals determination in fuel samples using a flow-batch analyzer and graphite furnace atomic absorption spectrometry
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Francisco Antônio S. Cunha, Rafael A. Sousa, David P. Harding, Solange Cadore, Luciano F. Almeida, Mário César U. Araújo
The principal thermodynamic advantages of using microemulsions over standard emulsions for flow metal analysis are the greatly increased analyte stability and emulsive homogeneity that improve both the ease of sample preparation, and the analytical result. In this study a piston propelled flow-batch analyzer (PFBA) for the determination of Cu, Cr and Pb in gasoline and naphtha by graphite furnace atomic absorption spectrometry (GF AAS) was explored. Investigative phase modeling for low dilution was conducted both for gasoline and naphtha microemulsions. Rheological considerations were also explored including a mathematical flow derivation to fine tune the system's operational parameters, and the GF AAS coupling. Both manual and automated procedures for microemulsion preparation were compared. The results of the paired t test at a 95% confidence level showed no significant differences between them. Further recovery test results confirmed a negligible matrix effect of the sample on the analyte absorption signals and an efficient stabilization of the samples (with metals) submitted to microemulsion treatment. The accuracy of the developed procedure was attested by good recovery percentages in the ranges of 100.0±3.5% for Pb in the naphtha samples, and 100.2±3.4% and 100.7±4.6% for Cu and Cr, respectively in gasoline samples.
Source:Analytica Chimica Acta, Volume 727
Francisco Antônio S. Cunha, Rafael A. Sousa, David P. Harding, Solange Cadore, Luciano F. Almeida, Mário César U. Araújo
The principal thermodynamic advantages of using microemulsions over standard emulsions for flow metal analysis are the greatly increased analyte stability and emulsive homogeneity that improve both the ease of sample preparation, and the analytical result. In this study a piston propelled flow-batch analyzer (PFBA) for the determination of Cu, Cr and Pb in gasoline and naphtha by graphite furnace atomic absorption spectrometry (GF AAS) was explored. Investigative phase modeling for low dilution was conducted both for gasoline and naphtha microemulsions. Rheological considerations were also explored including a mathematical flow derivation to fine tune the system's operational parameters, and the GF AAS coupling. Both manual and automated procedures for microemulsion preparation were compared. The results of the paired t test at a 95% confidence level showed no significant differences between them. Further recovery test results confirmed a negligible matrix effect of the sample on the analyte absorption signals and an efficient stabilization of the samples (with metals) submitted to microemulsion treatment. The accuracy of the developed procedure was attested by good recovery percentages in the ranges of 100.0±3.5% for Pb in the naphtha samples, and 100.2±3.4% and 100.7±4.6% for Cu and Cr, respectively in gasoline samples.
Graphical Abstract
Graphical abstract Highlights
► Micro-emulsion composition phase study to obtain low fuel dilutions. ► Automated and instantaneous in-line preparation of micro-emulsions for metals determinations. ► A versatile piston-driven form of “Flow-batch Analysis”. ► Rheological considerations explored including a mathematical derivation of flow parameters.A novel approach to the uniform distribution of liquid in multi-channel (electrochemical) flow-through cells
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Karel Lacina, Jiří Vondál, Petr Skládal
Four-channel flow-through electrochemical cell working in thin-layer regime was designed, fabricated and characterized experimentally and in computational fluid dynamics (CFD) simulations. The new principle of operation allows reproducible splitting of a stream of liquid into multiple flow channels. Systems comprising of 2-, 3-, 4- and 8-channels were tested. The proper function of the cell is given by the ratio of the cross-sections of the fluidic element collecting chamber and the particular flow paths among which the liquid is distributed. Suitable flow rates providing uniform liquid distribution were evaluated and the results were compared to CFD modeling. The flow-through cells designed according to the proposed principle can be simply incorporated in automated routine analysis as only one inlet and one common outlet are required.
Source:Analytica Chimica Acta, Volume 727
Karel Lacina, Jiří Vondál, Petr Skládal
Four-channel flow-through electrochemical cell working in thin-layer regime was designed, fabricated and characterized experimentally and in computational fluid dynamics (CFD) simulations. The new principle of operation allows reproducible splitting of a stream of liquid into multiple flow channels. Systems comprising of 2-, 3-, 4- and 8-channels were tested. The proper function of the cell is given by the ratio of the cross-sections of the fluidic element collecting chamber and the particular flow paths among which the liquid is distributed. Suitable flow rates providing uniform liquid distribution were evaluated and the results were compared to CFD modeling. The flow-through cells designed according to the proposed principle can be simply incorporated in automated routine analysis as only one inlet and one common outlet are required.
Graphical Abstract
Graphical abstract Highlights
► Novel approach to reliable splitting of the stream of liquid among multiple sensing channels. ► Combination of several channels and a shared output fluidic element-collecting chamber. ► Single inlet and single outlet, complete rejection of cross-talk effects. ► Experimental evaluation of the proposed principle on multi(2,3,4, and 8)-channel arrangements. ► Result verified using computational fluid dynamics (CFD) simulation.Multiple reaction monitoring-based determination of bovine α-lactalbumin in infant formulas and whey protein concentrates by ultra-high performance liquid chromatography–tandem mass spectrometry using tryptic signature peptides and synthetic peptide standards
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Jingshun Zhang, Shiyun Lai, Yu Zhang, Baifen Huang, Duo Li, Yiping Ren
The determination of α-lactalbumin in various dairy products attracts wide attention in multidiscipline fields because of its nutritional and biological functions. In the present study, we quantified the bovine α-lactalbumin in various infant formulas and whey protein concentrates using ultra-high performance liquid chromatography coupled to tandem mass spectrometer in multiple reaction monitoring mode. Bovine α-lactalbumin was quantified by employing the synthetic internal standard based on the molar equivalent relationship among the internal standard, bovine α-lactalbumin and their signature peptides. This study especially focused on the recovery rates of the sample preparation procedure and robust quantification of total bovine α-lactalbumin in its native and thermally denatured form with a synthetic internal standard KILDKVGINNYWLAHKALCSE. The observed recovery rates of bovine α-lactalbumin ranged from 95.8 to 100.6% and the reproducibility was excellent (RSD<6%) at different spiking levels. The limit of quantitation is 10mg/100g for infant formulas and whey protein concentrates. In order to validate the applicability of the method, 21 brands of infant formulas were analyzed. The acquired contents of bovine α-lactalbumin were 0.67–1.84g/100g in these infant formulas in agreement with their label claimed values. The experiment of heat treatment time showed that the loss of native α-lactalbumin enhanced with an increasing intensity of heat treatment. Comparing with Ren's previous method by analysis of only native bovine α-lactalbumin, the present method at the peptide level proved to be highly suitable for measuring bovine α-lactalbumin in infant formulas and whey protein concentrates, avoiding forgoing the thermally induced denatured α-lactalbumin caused by the technological processing.
Source:Analytica Chimica Acta, Volume 727
Jingshun Zhang, Shiyun Lai, Yu Zhang, Baifen Huang, Duo Li, Yiping Ren
The determination of α-lactalbumin in various dairy products attracts wide attention in multidiscipline fields because of its nutritional and biological functions. In the present study, we quantified the bovine α-lactalbumin in various infant formulas and whey protein concentrates using ultra-high performance liquid chromatography coupled to tandem mass spectrometer in multiple reaction monitoring mode. Bovine α-lactalbumin was quantified by employing the synthetic internal standard based on the molar equivalent relationship among the internal standard, bovine α-lactalbumin and their signature peptides. This study especially focused on the recovery rates of the sample preparation procedure and robust quantification of total bovine α-lactalbumin in its native and thermally denatured form with a synthetic internal standard KILDKVGINNYWLAHKALCSE. The observed recovery rates of bovine α-lactalbumin ranged from 95.8 to 100.6% and the reproducibility was excellent (RSD<6%) at different spiking levels. The limit of quantitation is 10mg/100g for infant formulas and whey protein concentrates. In order to validate the applicability of the method, 21 brands of infant formulas were analyzed. The acquired contents of bovine α-lactalbumin were 0.67–1.84g/100g in these infant formulas in agreement with their label claimed values. The experiment of heat treatment time showed that the loss of native α-lactalbumin enhanced with an increasing intensity of heat treatment. Comparing with Ren's previous method by analysis of only native bovine α-lactalbumin, the present method at the peptide level proved to be highly suitable for measuring bovine α-lactalbumin in infant formulas and whey protein concentrates, avoiding forgoing the thermally induced denatured α-lactalbumin caused by the technological processing.
Graphical Abstract
Graphical abstract Highlights
. ► A UHPLC–MS/MS method for quantification of bovine α-lactalbumin was developed. ► Tryptic fragment VGINYWLAHK was chosen as signature peptide of bovine α-lactalbumin. ► An optimal internal standard was designed and synthesized to measure α-lactalbumin. ► It can measure both native and heat thermally induced denatured bovine α-lactalbumin. ► Meet the growing demand to quantify bovine α-lactalbumin in infant formulas and WPC.Rapid and precise determination of Sr and Nd isotopic ratios in geological samples from the same filament loading by thermal ionization mass spectrometry employing a single-step separation scheme
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Chao-Feng Li, Xian-Hua Li, Qiu-Li Li, Jing-Hui Guo, Xiang-Hui Li, Yue-Heng Yang
Thermal ionization mass spectrometry (TIMS) offers the excellent precision and accuracy of the Sr and Nd isotopic ratio analysis for geological samples, but this method is labour intensive, expensive and time-consuming. In this study, a new analytical protocol by TIMS is presented that aims at improving analytical efficiency and cutting down experimental cost. Using the single-step cation exchange resin technique, mixed Sr and rare earth elements (REEs) fractions were separated from matrix and evaporated to dryness. Afterwards, mixed Sr+REEs fractions were dissolved and loaded onto the same Re filament using 1μL of 2M HCl. Then, Sr and Nd were sequentially measured without venting using TIMS. In contrast to conventional TIMS methods, the merits of this analytical protocol are its cost- and time-saving adaptations. The applicability of our method is evaluated by replicated measurements of 87Sr/86Sr and 143Nd/144Nd for nine international silicate rock reference materials, spanning a wide range of bulk compositions. The typical internal precision in this study is ca. 0.001% (RSE) for 87Sr/86Sr and 143Nd/144Nd; the analytical results obtained for these standard rocks show a good agreement with reported values, indicating the effectiveness of the proposed method.
Source:Analytica Chimica Acta, Volume 727
Chao-Feng Li, Xian-Hua Li, Qiu-Li Li, Jing-Hui Guo, Xiang-Hui Li, Yue-Heng Yang
Thermal ionization mass spectrometry (TIMS) offers the excellent precision and accuracy of the Sr and Nd isotopic ratio analysis for geological samples, but this method is labour intensive, expensive and time-consuming. In this study, a new analytical protocol by TIMS is presented that aims at improving analytical efficiency and cutting down experimental cost. Using the single-step cation exchange resin technique, mixed Sr and rare earth elements (REEs) fractions were separated from matrix and evaporated to dryness. Afterwards, mixed Sr+REEs fractions were dissolved and loaded onto the same Re filament using 1μL of 2M HCl. Then, Sr and Nd were sequentially measured without venting using TIMS. In contrast to conventional TIMS methods, the merits of this analytical protocol are its cost- and time-saving adaptations. The applicability of our method is evaluated by replicated measurements of 87Sr/86Sr and 143Nd/144Nd for nine international silicate rock reference materials, spanning a wide range of bulk compositions. The typical internal precision in this study is ca. 0.001% (RSE) for 87Sr/86Sr and 143Nd/144Nd; the analytical results obtained for these standard rocks show a good agreement with reported values, indicating the effectiveness of the proposed method.
Graphical Abstract
Graphical abstract Highlights
Our analytical protocol compared with traditional methods. ► Sr and Nd from the same filament loading were sequentially measured without venting using TIMS. ► This protocol shows a great improvement in the analytical efficiency. ► Experimental costs and labour intensity are significantly cut down.Lateral flow dipstick test for genotyping of 15 beta-globin gene (HBB) mutations with naked-eye detection
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Frantzeskos Papanikos, Alexandra Iliadi, Margarita Petropoulou, Penelope C. Ioannou, Theodore K. Christopoulos, Emmanuel Kanavakis, Jan Traeger-Synodinos
For definitive diagnosis of thalassemia carriers and patients, as well as for prenatal diagnosis, genotype analysis is of fundamental importance. We report a dry-reagent, lateral flow dipstick test that enables visual genotyping (detection by naked eye) of 15 mutations common in Mediterranean populations in the beta-globin gene (HBB). The method comprises 3 simple steps: (i) PCR amplification of a single 1896bp segment of the beta globin gene flanking all 15 mutations; (ii) a multiplex (10-plex and/or 30-plex) primer extension reaction of the unpurified amplification product using allele-specific primers. Biotin is incorporated in the extended product; (iii) a dry-reagent multi-allele (10-plex) dipstick assay for visual detection of the primer extension reaction products within minutes. The total time required for PCR, primer extension reaction and the dipstick assay is ∼2h. The method was evaluated by genotyping 45 DNA samples of known genotypes and 54 blind samples. The results were fully concordant with reference methods. The method is simple, rapid, and cost-effective. Detection by the dipstick assay does not require specialized instrumentation or highly qualified personnel. The proposed method could be a particularly useful tool in laboratories with limited resources and a basis for point-of-care diagnostics especially in combination with PCR amplification from whole blood.
Source:Analytica Chimica Acta, Volume 727
Frantzeskos Papanikos, Alexandra Iliadi, Margarita Petropoulou, Penelope C. Ioannou, Theodore K. Christopoulos, Emmanuel Kanavakis, Jan Traeger-Synodinos
For definitive diagnosis of thalassemia carriers and patients, as well as for prenatal diagnosis, genotype analysis is of fundamental importance. We report a dry-reagent, lateral flow dipstick test that enables visual genotyping (detection by naked eye) of 15 mutations common in Mediterranean populations in the beta-globin gene (HBB). The method comprises 3 simple steps: (i) PCR amplification of a single 1896bp segment of the beta globin gene flanking all 15 mutations; (ii) a multiplex (10-plex and/or 30-plex) primer extension reaction of the unpurified amplification product using allele-specific primers. Biotin is incorporated in the extended product; (iii) a dry-reagent multi-allele (10-plex) dipstick assay for visual detection of the primer extension reaction products within minutes. The total time required for PCR, primer extension reaction and the dipstick assay is ∼2h. The method was evaluated by genotyping 45 DNA samples of known genotypes and 54 blind samples. The results were fully concordant with reference methods. The method is simple, rapid, and cost-effective. Detection by the dipstick assay does not require specialized instrumentation or highly qualified personnel. The proposed method could be a particularly useful tool in laboratories with limited resources and a basis for point-of-care diagnostics especially in combination with PCR amplification from whole blood.
Graphical Abstract
Graphical abstract Highlights
► We develop a dipstick test for visual genotyping of 15 beta-globin gene mutations. ► We optimize various parameters affecting the performance of the genotyping test. ► The method was evaluated by analyzing samples of known genotypes and blind samples.Graphene oxide-based biosensor for sensitive fluorescence detection of DNA based on exonuclease III-aided signal amplification
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Xu-Hua Zhao, Qiu-Juan Ma, Xiang-Xiang Wu, Xin Zhu
Based on the super fluorescence quenching efficiency of graphene oxide and exonuclease III aided signal amplification, we develop a facile, sensitive, rapid and cost-effective method for DNA detection. In the presence of target DNA, the target-probe hybridization forms a double-stranded structure and exonuclease III catalyzes the stepwise removal of mononucleotides from the blunt 3′ termini of probe, resulting in the recycling of the target DNA and signal amplification. Therefore, our proposed sensor exhibits a high sensitivity towards target DNA with a detection limit of 20pM, which was even lower than previously reported GO-based DNA sensors without enzymatic amplification, and provides a universal sensing platform for sensitive detection of DNA.
Source:Analytica Chimica Acta, Volume 727
Xu-Hua Zhao, Qiu-Juan Ma, Xiang-Xiang Wu, Xin Zhu
Based on the super fluorescence quenching efficiency of graphene oxide and exonuclease III aided signal amplification, we develop a facile, sensitive, rapid and cost-effective method for DNA detection. In the presence of target DNA, the target-probe hybridization forms a double-stranded structure and exonuclease III catalyzes the stepwise removal of mononucleotides from the blunt 3′ termini of probe, resulting in the recycling of the target DNA and signal amplification. Therefore, our proposed sensor exhibits a high sensitivity towards target DNA with a detection limit of 20pM, which was even lower than previously reported GO-based DNA sensors without enzymatic amplification, and provides a universal sensing platform for sensitive detection of DNA.
Graphical Abstract
Graphical abstract Highlights
We have developed a novel GO-based biosensor for enzymatic amplified DNA detection. By taking advantage of the super fluorescence quenching efficiency of GO and exonuclease III aided signal amplification, our proposed sensor exhibits a high sensitivity towards target DNA with a detection limit of 20pM, which was even lower than previously reported GO-based DNA sensors without enzymatic amplification. Moreover, the sensing system is facile, rapid and cost-effective and can provide a universal sensing platform for sensitive detection of various DNA. ► Graphene oxide (GO) can be prepared in large quantities at very low cost. ► GO can selectively bind and quench a dye-labeled single stranded DNA probe. ► The probe is labeled with a single dye, which reduces the cost for DNA detection. ► Using Exo III can improve the versatility and sensitivity of the DNA assays. ► A sensitive, rapid and cost-effective method for DNA detection has been developed.Determination of bismuth in open ocean waters by inductively coupled plasma sector-field mass spectrometry after chelating resin column preconcentration
30 April 2012,
09:42:01
Publication year:
2012
Source:Analytica Chimica Acta, Volume 727
Kazuhiro Norisuye, Yoshiki Sohrin
A novel low-blank method is described for the analysis of bismuth in seawater based on preconcentration using an ethylenediaminetriacetic acid chelating resin column followed by determination with inductively coupled plasma sector-field mass spectrometry (ICPSFMS). A sample is siphoned into and drains through the column with the flow rate being kept constant by using a flotation device. Bi in 250mL of acidified seawater is extracted onto the column in this process and eluted with 2mL of 3M HNO3 followed by 3mL of ultra-high purity water. The concentration of Bi in the eluate is measured by ICPMS. The benefits of the method compared to others are its simplicity, a smaller amount of seawater, and lower procedural blanks and detection limits at pgkg−1 levels. Data on dissolved Bi in open ocean reference samples of SAFe and GEOTRACES programs are presented for the first time.
Source:Analytica Chimica Acta, Volume 727
Kazuhiro Norisuye, Yoshiki Sohrin
A novel low-blank method is described for the analysis of bismuth in seawater based on preconcentration using an ethylenediaminetriacetic acid chelating resin column followed by determination with inductively coupled plasma sector-field mass spectrometry (ICPSFMS). A sample is siphoned into and drains through the column with the flow rate being kept constant by using a flotation device. Bi in 250mL of acidified seawater is extracted onto the column in this process and eluted with 2mL of 3M HNO3 followed by 3mL of ultra-high purity water. The concentration of Bi in the eluate is measured by ICPMS. The benefits of the method compared to others are its simplicity, a smaller amount of seawater, and lower procedural blanks and detection limits at pgkg−1 levels. Data on dissolved Bi in open ocean reference samples of SAFe and GEOTRACES programs are presented for the first time.
Graphical Abstract
automate DNA extraction is not easy processing. certainly nice post.
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