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Multi-elemental characterization of tunnel and road dusts in Houston, Texas using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry: Evidence for the release of platinum group and anthropogenic metals from motor vehicles
20 June 2012,
14:15:59
Publication year:
2012
Source:Analytica Chimica Acta, Volume 735
Nicholas Spada, Ayse Bozlaker, Shankararaman Chellam
Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry (DRC-q-ICP–MS). Average Rh, Pd and Pt concentrations were 152±52, 770±208 and 529±130ngg−1 respectively in tunnel dusts while they varied between 6 and 8ngg−1, 10 and 88ngg−1 and 35 and 131ngg−1 in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However, all other elements including rare earths most likely arose from weathering, erosion and resuspension of crustal material. These are the first such detailed measurements in Houston, the largest city in TX and fourth largest in the United States. We posit that such investigations will assist in better understanding PGE concentrations in urban environments while providing elemental data necessary to better understand anthropogenic influences on their biogeochemical cycling.
Source:Analytica Chimica Acta, Volume 735
Nicholas Spada, Ayse Bozlaker, Shankararaman Chellam
Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry (DRC-q-ICP–MS). Average Rh, Pd and Pt concentrations were 152±52, 770±208 and 529±130ngg−1 respectively in tunnel dusts while they varied between 6 and 8ngg−1, 10 and 88ngg−1 and 35 and 131ngg−1 in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However, all other elements including rare earths most likely arose from weathering, erosion and resuspension of crustal material. These are the first such detailed measurements in Houston, the largest city in TX and fourth largest in the United States. We posit that such investigations will assist in better understanding PGE concentrations in urban environments while providing elemental data necessary to better understand anthropogenic influences on their biogeochemical cycling.
Graphical abstract
Graphical abstract Highlights
► Analytical method for PGEs, main group, transition and rare earth metals developed. ► Comprehensive characterization of road and tunnel dust samples was accomplished. ► PGEs in dusts arise from autocatalyst attrition. ► Mobile sources also contributed to Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. ► All other elements, including rare earths arose from crustal sources.Application of quantum dots as analytical tools in automated chemical analysis: A review
20 June 2012,
14:15:59
Publication year:
2012
Source:Analytica Chimica Acta, Volume 735
Christian Frigerio, David S.M. Ribeiro, S. Sofia M. Rodrigues, Vera L.R.G. Abreu, João A.C. Barbosa, João A.V. Prior, Karine L. Marques, João L.M. Santos
Colloidal semiconductor nanocrystals or quantum dots (QDs) are one of the most relevant developments in the fast-growing world of nanotechnology. Initially proposed as luminescent biological labels, they are finding new important fields of application in analytical chemistry, where their photoluminescent properties have been exploited in environmental monitoring, pharmaceutical and clinical analysis and food quality control. Despite the enormous variety of applications that have been developed, the automation of QDs-based analytical methodologies by resorting to automation tools such as continuous flow analysis and related techniques, which would allow to take advantage of particular features of the nanocrystals such as the versatile surface chemistry and ligand binding ability, the aptitude to generate reactive species, the possibility of encapsulation in different materials while retaining native luminescence providing the means for the implementation of renewable chemosensors or even the utilisation of more drastic and even stability impairing reaction conditions, is hitherto very limited. In this review, we provide insights into the analytical potential of quantum dots focusing on prospects of their utilisation in automated flow-based and flow-related approaches and the future outlook of QDs applications in chemical analysis.
Source:Analytica Chimica Acta, Volume 735
Christian Frigerio, David S.M. Ribeiro, S. Sofia M. Rodrigues, Vera L.R.G. Abreu, João A.C. Barbosa, João A.V. Prior, Karine L. Marques, João L.M. Santos
Colloidal semiconductor nanocrystals or quantum dots (QDs) are one of the most relevant developments in the fast-growing world of nanotechnology. Initially proposed as luminescent biological labels, they are finding new important fields of application in analytical chemistry, where their photoluminescent properties have been exploited in environmental monitoring, pharmaceutical and clinical analysis and food quality control. Despite the enormous variety of applications that have been developed, the automation of QDs-based analytical methodologies by resorting to automation tools such as continuous flow analysis and related techniques, which would allow to take advantage of particular features of the nanocrystals such as the versatile surface chemistry and ligand binding ability, the aptitude to generate reactive species, the possibility of encapsulation in different materials while retaining native luminescence providing the means for the implementation of renewable chemosensors or even the utilisation of more drastic and even stability impairing reaction conditions, is hitherto very limited. In this review, we provide insights into the analytical potential of quantum dots focusing on prospects of their utilisation in automated flow-based and flow-related approaches and the future outlook of QDs applications in chemical analysis.
Graphical abstract
Graphical abstract Highlights
► Review on quantum dots application in automated chemical analysis. ► Automation by using flow-based techniques. ► Quantum dots in liquid chromatography and capillary electrophoresis. ► Detection by fluorescence and chemiluminescence. ► Electrochemiluminescence and radical generation.Development of highly sensitive chemiluminescence enzyme immunoassay based on the anti-recombinant HC subunit of botulinum neurotoxin type A monoclonal antibodies
20 June 2012,
14:15:59
Publication year:
2012
Source:Analytica Chimica Acta, Volume 735
Zhijia Liu, Chaojun Song, Yongming Li, Fei Liu, Kui Zhang, Yuanjie Sun, Haitao Li, Yuying Wei, Zhuwei Xu, Chunmei Zhang, Angang Yang, Zhikai Xu, Kun Yang, Boquan Jin
Botulinum neurotoxins (BoNTs) are the most poisonous substances ever known. The early detection of these toxins could bear more time for appropriate medical intervention. The standard method for detecting BoNTs is the mouse bioassay, which is time consuming (up to 4 days) and requires a large number of laboratory animals. The immunologic detection methods could detect the toxins within a day, but most of these methods are less sensitive compared with the mouse bioassay due to the lack of high-affinity antibodies. Recently, the recombinant HC subunit of botulinum neurotoxin type A (rAHC) was expressed as an effective vaccine against botulism, indicating that the rAHC could be an effective immunogen that raises the monoclonal antibody (mAb) for detecting BoNT/A. After immunized BALB/c mice with rAHC, 56 mAbs were generated. Two of these mAbs were selected to establish a highly sensitive sandwich chemiluminescence enzyme immunoassay (CLEIA), in which FMMU-BTA-49 and FMMU-BTA-22 were used as capture antibody and detection antibody, respectively. The calculated limit of detection (LOD) based on molecular weight of rAHC and BoNT/A reached 0.45pgmL−1. This CLEIA can be used in the detection of BoNT/A in matrices such as milk and beef extract. This method has 20–40 fold lower LOD than that of the mouse bioassay and takes only 3h to complete the detection, indicating that it can be used as a valuable method to detect and quantify BoNT/A.
Source:Analytica Chimica Acta, Volume 735
Zhijia Liu, Chaojun Song, Yongming Li, Fei Liu, Kui Zhang, Yuanjie Sun, Haitao Li, Yuying Wei, Zhuwei Xu, Chunmei Zhang, Angang Yang, Zhikai Xu, Kun Yang, Boquan Jin
Botulinum neurotoxins (BoNTs) are the most poisonous substances ever known. The early detection of these toxins could bear more time for appropriate medical intervention. The standard method for detecting BoNTs is the mouse bioassay, which is time consuming (up to 4 days) and requires a large number of laboratory animals. The immunologic detection methods could detect the toxins within a day, but most of these methods are less sensitive compared with the mouse bioassay due to the lack of high-affinity antibodies. Recently, the recombinant HC subunit of botulinum neurotoxin type A (rAHC) was expressed as an effective vaccine against botulism, indicating that the rAHC could be an effective immunogen that raises the monoclonal antibody (mAb) for detecting BoNT/A. After immunized BALB/c mice with rAHC, 56 mAbs were generated. Two of these mAbs were selected to establish a highly sensitive sandwich chemiluminescence enzyme immunoassay (CLEIA), in which FMMU-BTA-49 and FMMU-BTA-22 were used as capture antibody and detection antibody, respectively. The calculated limit of detection (LOD) based on molecular weight of rAHC and BoNT/A reached 0.45pgmL−1. This CLEIA can be used in the detection of BoNT/A in matrices such as milk and beef extract. This method has 20–40 fold lower LOD than that of the mouse bioassay and takes only 3h to complete the detection, indicating that it can be used as a valuable method to detect and quantify BoNT/A.
Graphical abstract
Graphical abstract Highlights
► The rAHC could elict highly protective antibody titer as vaccine. ► Two anti-rAHC mAbs were selected to form the sensitive CLEIA for detecting BoNT/A. ► The CLEIA detecting BoNT/A is more sensitive than that of the ELISA reported.Native and denatured forms of proteins can be discriminated at edge plane carbon electrodes
20 June 2012,
14:15:59
Publication year:
2012
Source:Analytica Chimica Acta, Volume 735
Veronika Ostatná, Hana Černocká, Katarzyna Kurzątkowska, Emil Paleček
In an attempt to develop a label-free electrochemical method for detection of changes in protein structures based on oxidizability of tyrosine and tryptophan residues we tested different types of carbon electrodes. We found that using edge plane pyrolytic graphite electrode (EPGE) we can discriminate between native and denatured forms of human serum albumin (HSA) and of other proteins, such as bovine and chicken serum albumin, aldolase and concanavalin. Treatment of natively unfolded α-synuclein with 8M urea resulted only in a small change in the tyrosine oxidation peak, in a good agreement with absence of highly ordered structure in this protein. Using square wave voltammetry with EPGE we were able to follow the course of HSA denaturation at different urea concentrations. The electrochemical denaturation curve agreed reasonably well with that based on intrinsic fluorescence of tyrosine and tryptophan. It can be expected that the electrochemical method will be applicable to a large number of proteins and may become useful in biomedicine and proteomics.
Source:Analytica Chimica Acta, Volume 735
Veronika Ostatná, Hana Černocká, Katarzyna Kurzątkowska, Emil Paleček
In an attempt to develop a label-free electrochemical method for detection of changes in protein structures based on oxidizability of tyrosine and tryptophan residues we tested different types of carbon electrodes. We found that using edge plane pyrolytic graphite electrode (EPGE) we can discriminate between native and denatured forms of human serum albumin (HSA) and of other proteins, such as bovine and chicken serum albumin, aldolase and concanavalin. Treatment of natively unfolded α-synuclein with 8M urea resulted only in a small change in the tyrosine oxidation peak, in a good agreement with absence of highly ordered structure in this protein. Using square wave voltammetry with EPGE we were able to follow the course of HSA denaturation at different urea concentrations. The electrochemical denaturation curve agreed reasonably well with that based on intrinsic fluorescence of tyrosine and tryptophan. It can be expected that the electrochemical method will be applicable to a large number of proteins and may become useful in biomedicine and proteomics.
Graphical abstract
Graphical abstract Highlights
► Protein structure-sensitive oxidation signals depend on materials of carbon electrodes. ► Tracing the course of protein denaturation at edge plane pyrolytic graphite electrode. ► Picomoles of proteins are sufficient for voltammetric structure-sensitive analysis.Potentiometric stripping analysis of methyl and ethyl parathion employing carbon nanoparticles and halloysite nanoclay modified carbon paste electrode
20 June 2012,
14:15:59
Publication year:
2012
Source:Analytica Chimica Acta, Volume 735
Bankim J. Sanghavi, Gary Hirsch, Shashi P. Karna, Ashwini K. Srivastava
Carbon nanoparticles (CNPs) and halloysite nanoclay (HNC) modified carbon paste electrode (HNC–CNP–CPE) was developed for the determination of methyl parathion (MP) and ethyl parathion (EP). The electrochemical behavior of these molecules was investigated employing cyclic voltammetry (CV), chronocoulometry (CC), electrochemical impedance spectroscopy (EIS) and potentiometric stripping analysis (PSA). After optimization of analytical conditions employing this electrode at pH 5.0 in acetate buffer (0.1M), the peak currents were found to vary linearly with its concentration in the range of 1.55×10−9 to 3.67×10−6 M and 1.21×10−9 to 4.92×10−6 M for MP and EP, respectively. The detection limits (S/N=3) of 4.70×10−10 M and 3.67×10−10 M were obtained for MP and EP, respectively, using PSA. The prepared modified electrode showed several advantages such as simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. The proposed method was employed for the determination of MP and EP in fruits, vegetables, water and soil samples.
Source:Analytica Chimica Acta, Volume 735
Bankim J. Sanghavi, Gary Hirsch, Shashi P. Karna, Ashwini K. Srivastava
Carbon nanoparticles (CNPs) and halloysite nanoclay (HNC) modified carbon paste electrode (HNC–CNP–CPE) was developed for the determination of methyl parathion (MP) and ethyl parathion (EP). The electrochemical behavior of these molecules was investigated employing cyclic voltammetry (CV), chronocoulometry (CC), electrochemical impedance spectroscopy (EIS) and potentiometric stripping analysis (PSA). After optimization of analytical conditions employing this electrode at pH 5.0 in acetate buffer (0.1M), the peak currents were found to vary linearly with its concentration in the range of 1.55×10−9 to 3.67×10−6 M and 1.21×10−9 to 4.92×10−6 M for MP and EP, respectively. The detection limits (S/N=3) of 4.70×10−10 M and 3.67×10−10 M were obtained for MP and EP, respectively, using PSA. The prepared modified electrode showed several advantages such as simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. The proposed method was employed for the determination of MP and EP in fruits, vegetables, water and soil samples.
Graphical abstract
Graphical abstract Highlights
► Determination of methyl parathion (MP) and ethyl parathion (EP). ► Potentiometric stripping analysis for quantitation of MP and EP. ► Halloysite nanoclay and carbon nanoparticles modified carbon paste electrode used as working electrode. ► Analysis of MP and EP in fruits, vegetables, water and soil samples. ► Halloysite nanoclay used as a modifier for the first time in electrochemistry.Liquid-phase microextraction in a microfluidic-chip – High enrichment and sample clean-up from small sample volumes based on three-phase extraction
20 June 2012,
14:15:59
Publication year:
2012
Source:Analytica Chimica Acta, Volume 735
María D. Ramos Payán, Henrik Jensen, Nickolaj Jacob Petersen, Steen Honoré Hansen, Stig Pedersen-Bjergaard
In this work, a microfluidic-chip based system for liquid-phase microextraction (LPME-chip) was developed. Sample solutions were pumped into the LPME-chip with a micro-syringe pump at a flow rate of 3–4μLmin−1. Inside the LPME chip, the sample was in direct contact with a supported liquid membrane (SLM) composed of 0.2μL dodecyl acetate immobilized in the pores of a flat membrane of polypropylene (25μm thickness). On the other side of the SLM, the acceptor phase was present. The acceptor phase was either pumped at 1μLmin−1 during extraction or kept stagnant (stop-flow). Amitriptyline, methadone, haloperidol, loperamide, and pethidine were selected as model analytes, and they were extracted from alkaline sample solution, through the SLM, and into 10mM HCl or 100mM HCOOH functioning as acceptor phase. Subsequently, the acceptor phase was either analyzed off-line by capillary electrophoresis for exact quantification, or on-line by UV detection or electrospray ionization mass spectrometry for time profiling of concentrations. The LPME-chip was found to be highly effective, and extraction efficiencies were in the range of 52–91%. When the flow of acceptor phase was turned off during extraction (stop-flow), analyte enrichment increased linearly with the extraction time. After 10min as an example, amitriptyline was enriched by a factor of 42 from only 30μL sample solution, and after 120min amitriptyline was enriched by a factor of 500 from 320μL sample solution. This suggested that the LPME-chip has great potentials for very efficient analyte enrichments from limited sample volumes in the future.
Source:Analytica Chimica Acta, Volume 735
María D. Ramos Payán, Henrik Jensen, Nickolaj Jacob Petersen, Steen Honoré Hansen, Stig Pedersen-Bjergaard
In this work, a microfluidic-chip based system for liquid-phase microextraction (LPME-chip) was developed. Sample solutions were pumped into the LPME-chip with a micro-syringe pump at a flow rate of 3–4μLmin−1. Inside the LPME chip, the sample was in direct contact with a supported liquid membrane (SLM) composed of 0.2μL dodecyl acetate immobilized in the pores of a flat membrane of polypropylene (25μm thickness). On the other side of the SLM, the acceptor phase was present. The acceptor phase was either pumped at 1μLmin−1 during extraction or kept stagnant (stop-flow). Amitriptyline, methadone, haloperidol, loperamide, and pethidine were selected as model analytes, and they were extracted from alkaline sample solution, through the SLM, and into 10mM HCl or 100mM HCOOH functioning as acceptor phase. Subsequently, the acceptor phase was either analyzed off-line by capillary electrophoresis for exact quantification, or on-line by UV detection or electrospray ionization mass spectrometry for time profiling of concentrations. The LPME-chip was found to be highly effective, and extraction efficiencies were in the range of 52–91%. When the flow of acceptor phase was turned off during extraction (stop-flow), analyte enrichment increased linearly with the extraction time. After 10min as an example, amitriptyline was enriched by a factor of 42 from only 30μL sample solution, and after 120min amitriptyline was enriched by a factor of 500 from 320μL sample solution. This suggested that the LPME-chip has great potentials for very efficient analyte enrichments from limited sample volumes in the future.
Graphical abstract
Graphical abstract Highlights
► We demonstrate the first liquid-phase microextraction chip with flow conditions (LPME-chip). ► We demonstrate very high analyte enrichment from small sample volumes. ► We show an application of this LPME-chip for the study of drug metabolism.The application of an in vitro gastrointestinal extraction to assess the oral bioaccessibility of polycyclic aromatic hydrocarbons in soils from a former industrial site
20 June 2012,
14:15:59
Publication year:
2012
Source:Analytica Chimica Acta, Volume 735
Damien Lorenzi, Jane Entwistle, Mark Cave, Joanna Wragg, John R. Dean
The total and bioaccessible concentration of 16 polycyclic aromatic hydrocarbons (PAHs) in soil from a former industrial site was investigated. Typical total concentrations across the sampling sites ranged from 1.5mgkg−1 for acenaphthylene up to 243mgkg−1 for fluoranthene. The oral bioaccessibility of PAHs in soil was assessed using an in vitro gastrointestinal extraction (Fed Organic Estimation human Simulation Test, FOREhST method). The oral bioaccessibility data indicated that fluorene, phenanthrene, chrysene, indeno(1,2,3-cd)pyrene and dibenzo(a,h)anthracene had the highest % bioaccessible fraction (based on their upper 75th percentile values being >60%) while the other PAHs had lower % bioaccessible fractions (means ranging between 35 and 59%). Significantly lower bioaccessibilities were determined for naphthalene. With respect to method validation and inter-laboratory comparison, the total and bioaccessible concentrations of benzo(a)anthracene, benzo(b)anthracene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene and dibenzo(a,h)anthracene was compared to published data derived using the same samples. The total PAH concentrations at the site were compared with generic assessment criteria (GAC) using the residential land use scenario (with plant uptake at 6% soil organic matter). Concentrations of 7 of the PAHs investigated within the soils could lead to an unacceptable risk to human health at this site.
Source:Analytica Chimica Acta, Volume 735
Damien Lorenzi, Jane Entwistle, Mark Cave, Joanna Wragg, John R. Dean
The total and bioaccessible concentration of 16 polycyclic aromatic hydrocarbons (PAHs) in soil from a former industrial site was investigated. Typical total concentrations across the sampling sites ranged from 1.5mgkg−1 for acenaphthylene up to 243mgkg−1 for fluoranthene. The oral bioaccessibility of PAHs in soil was assessed using an in vitro gastrointestinal extraction (Fed Organic Estimation human Simulation Test, FOREhST method). The oral bioaccessibility data indicated that fluorene, phenanthrene, chrysene, indeno(1,2,3-cd)pyrene and dibenzo(a,h)anthracene had the highest % bioaccessible fraction (based on their upper 75th percentile values being >60%) while the other PAHs had lower % bioaccessible fractions (means ranging between 35 and 59%). Significantly lower bioaccessibilities were determined for naphthalene. With respect to method validation and inter-laboratory comparison, the total and bioaccessible concentrations of benzo(a)anthracene, benzo(b)anthracene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene and dibenzo(a,h)anthracene was compared to published data derived using the same samples. The total PAH concentrations at the site were compared with generic assessment criteria (GAC) using the residential land use scenario (with plant uptake at 6% soil organic matter). Concentrations of 7 of the PAHs investigated within the soils could lead to an unacceptable risk to human health at this site.
Graphical abstract
Graphical abstract Highlights
► Total/bioaccessible concentration of 16 PAHs assessed in former industrial site. ► Oral bioaccessibility was assessed using FOREhST method. ► Total PAH concentrations were compared with GAC (residential land use scenario). ► Levels of 7 PAHs could lead to an unacceptable risk to human health at this site.Fabrication of electrolytic cell for online post-column electrochemical derivatization in ion chromatography
20 June 2012,
14:15:59
Publication year:
2012
Source:Analytica Chimica Acta, Volume 735
Shuchao Wu, Wei Xu, Bingcheng Yang, Mingli Ye, Peimin Zhang, Chao Shen-Tu, Yan Zhu
An electrolytic cell (EC), composed of two ruthenium-plated titanium electrodes separated by cation-exchange membranes, was fabricated and evaluated for online postcolumn derivatization in ion chromatography (IC). Folic acid (FA) and methotrexate (MTX) were preliminarily used as prototype analytes to test the performance of EC. After separation by an anion exchange column, FA and MTX, which emit very weak fluorescence when excited, were electrochemically oxidized online in the anode chamber of the EC. The compounds with strong fluorescence, which are oxidation products, were detected by the fluorescence detector. The phosphate buffer solution (100mM KH2PO4) served as an optimal eluent for anion exchange chromatographic separation and a suitable supporting electrolyte for electro-oxidation, leading to ideal compatibility between IC separation and the postcolumn electrochemical derivatization. For the presently proposed method, the linear ranges were from 0.01mgL−1 to 5mgL−1 for both FA and MTX. The detection limits of FA and MTX were 1.8and 2.1μgL−1, and the relative standard deviations (RSD, n =7) were 2.9% and 3.6%, respectively. The method was applied for the simultaneous determination of FA and MTX in the plasma of patients being treated for rheumatoid arthritis. The determination of MTX in the urine of the patients of diffuse large B cell lymphoma was also demonstrated.
Source:Analytica Chimica Acta, Volume 735
Shuchao Wu, Wei Xu, Bingcheng Yang, Mingli Ye, Peimin Zhang, Chao Shen-Tu, Yan Zhu
An electrolytic cell (EC), composed of two ruthenium-plated titanium electrodes separated by cation-exchange membranes, was fabricated and evaluated for online postcolumn derivatization in ion chromatography (IC). Folic acid (FA) and methotrexate (MTX) were preliminarily used as prototype analytes to test the performance of EC. After separation by an anion exchange column, FA and MTX, which emit very weak fluorescence when excited, were electrochemically oxidized online in the anode chamber of the EC. The compounds with strong fluorescence, which are oxidation products, were detected by the fluorescence detector. The phosphate buffer solution (100mM KH2PO4) served as an optimal eluent for anion exchange chromatographic separation and a suitable supporting electrolyte for electro-oxidation, leading to ideal compatibility between IC separation and the postcolumn electrochemical derivatization. For the presently proposed method, the linear ranges were from 0.01mgL−1 to 5mgL−1 for both FA and MTX. The detection limits of FA and MTX were 1.8and 2.1μgL−1, and the relative standard deviations (RSD, n =7) were 2.9% and 3.6%, respectively. The method was applied for the simultaneous determination of FA and MTX in the plasma of patients being treated for rheumatoid arthritis. The determination of MTX in the urine of the patients of diffuse large B cell lymphoma was also demonstrated.
Graphical abstract
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