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papers from the latest issue:
On-line sample processing involving microextraction techniques as a front-end to atomic spectrometric detection for trace metal assays: A review
28 May 2013,
09:59:13
Publication date: 11 June
2013
Source:Analytica Chimica Acta, Volume 782
Author(s): Manuel Miró , Elo Harald Hansen
Within the last decade, liquid-phase microextraction (LPME) and micro-solid phase extraction (μSPE) approaches have emerged as substitutes for conventional sample processing procedures for trace metal assays within the framework of green chemistry. This review surveys the progress of the state of the art in simplification and automation of microextraction approaches by harnessing to the various generations of flow injection (FI) as a front end to atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS) or inductively coupled plasma atomic emission spectrometry or mass spectrometry (ICP-AES/MS). It highlights the evolution of flow injection analysis and related techniques as vehicles for appropriate sample presentation to the detector and expedient on-line matrix separation and pre-concentration of trace levels of metals in troublesome matrices. Rather than being comprehensive this review is aimed at outlining the pros and cons via representative examples of recent attempts in automating green sample preparation procedures in an FI or sequential injection (SI) mode capitalizing on single-drop microextraction, dispersive liquid-phase microextraction and advanced sorptive materials including carbon and metal oxide nanoparticles, ion imprinted polymers, superparamagnetic nanomaterials and biological/biomass sorbents. Current challenges in the field are identified and the synergetic combination of flow analysis, nanotechnology and metal-tagged biomolecule detection is envisaged.
Source:Analytica Chimica Acta, Volume 782
Author(s): Manuel Miró , Elo Harald Hansen
Within the last decade, liquid-phase microextraction (LPME) and micro-solid phase extraction (μSPE) approaches have emerged as substitutes for conventional sample processing procedures for trace metal assays within the framework of green chemistry. This review surveys the progress of the state of the art in simplification and automation of microextraction approaches by harnessing to the various generations of flow injection (FI) as a front end to atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS) or inductively coupled plasma atomic emission spectrometry or mass spectrometry (ICP-AES/MS). It highlights the evolution of flow injection analysis and related techniques as vehicles for appropriate sample presentation to the detector and expedient on-line matrix separation and pre-concentration of trace levels of metals in troublesome matrices. Rather than being comprehensive this review is aimed at outlining the pros and cons via representative examples of recent attempts in automating green sample preparation procedures in an FI or sequential injection (SI) mode capitalizing on single-drop microextraction, dispersive liquid-phase microextraction and advanced sorptive materials including carbon and metal oxide nanoparticles, ion imprinted polymers, superparamagnetic nanomaterials and biological/biomass sorbents. Current challenges in the field are identified and the synergetic combination of flow analysis, nanotechnology and metal-tagged biomolecule detection is envisaged.
Graphical abstract
On uniqueness and selectivity in three-component parallel factor analysis
28 May 2013,
09:59:13
Publication date: 11 June
2013
Source:Analytica Chimica Acta, Volume 782
Author(s): Nematollah Omidikia , Hamid Abdollahi , Mohsen Kompany-Zareh
Unambiguous recovery of profiles is a distinguishable advantage of Parallel Factor Analysis (PARAFAC) as a trilinear model and has made it a promising exploratory tool for data analysis. Linear dependency in profiles destroys trilinearity and will increase ambiguity in the curve resolution of three-way data sets. PARAFAC uniqueness deteriorates totally or partially in data sets with linearly dependent loadings. Exploiting a reliable method for determination and direct visualization of feasible bands in the PARAFAC model can be helpful not only in full characterization of uniqueness conditions but also in the investigation of the effects of constraints on the PARAFAC feasible solutions. The purpose of this paper is twofold. First, the calculation of rotational ambiguity in the PARAFAC model extends to three components system. The principle behind the algorithm is described in detail and tested for simulated and real data sets. Completely general and thoroughly investigated results are presented for the three component cases. Secondly, the effects of selective regions in the profiles on the resolution of systems that suffered from the rank deficiency problem, due to rank overlap, are emphasized. In the case of two-way data sets the effect of selectivity constraint on the unique recovery of profiles was investigated and applied. However, to our knowledge, in this report, for the first time, the effect of the presence of selective windows in the profiles, on the unique resolution of three-way data sets has been systematically investigated.
Source:Analytica Chimica Acta, Volume 782
Author(s): Nematollah Omidikia , Hamid Abdollahi , Mohsen Kompany-Zareh
Unambiguous recovery of profiles is a distinguishable advantage of Parallel Factor Analysis (PARAFAC) as a trilinear model and has made it a promising exploratory tool for data analysis. Linear dependency in profiles destroys trilinearity and will increase ambiguity in the curve resolution of three-way data sets. PARAFAC uniqueness deteriorates totally or partially in data sets with linearly dependent loadings. Exploiting a reliable method for determination and direct visualization of feasible bands in the PARAFAC model can be helpful not only in full characterization of uniqueness conditions but also in the investigation of the effects of constraints on the PARAFAC feasible solutions. The purpose of this paper is twofold. First, the calculation of rotational ambiguity in the PARAFAC model extends to three components system. The principle behind the algorithm is described in detail and tested for simulated and real data sets. Completely general and thoroughly investigated results are presented for the three component cases. Secondly, the effects of selective regions in the profiles on the resolution of systems that suffered from the rank deficiency problem, due to rank overlap, are emphasized. In the case of two-way data sets the effect of selectivity constraint on the unique recovery of profiles was investigated and applied. However, to our knowledge, in this report, for the first time, the effect of the presence of selective windows in the profiles, on the unique resolution of three-way data sets has been systematically investigated.
Graphical abstract
Elucidating the sorption mechanism of “mixed-mode” SPME using the basic drug amphetamine as a model compound
28 May 2013,
09:59:13
Publication date: 11 June
2013
Source:Analytica Chimica Acta, Volume 782
Author(s): Hester Peltenburg , Floris A. Groothuis , Steven T.J. Droge , Ingrid J. Bosman , Joop L.M. Hermens
We studied the sorption of amphetamine as a model drug to represent small, polar organic cations to a new SPME coating combining C18 and propylsulfonic acid. This combination of hydrophobic and strong cation exchange (SCX) groups was compared to conventional SPME fibers with polyacrylate (PA) or C18 coating. The affinity of amphetamine at physiological pH (PBS) was 20 to 180 times greater for the new C18/SCX coating than for C18 alone and PA of different coating thickness. As amphetamine is a base and >99% protonated at physiological pH, this enhanced affinity is attributed to the ion-exchange phase in the coating. Tests at pH above the pK a of amphetamine show that, when normalized to the coating volume, neutral amphetamine also has a higher affinity compared to PA. As ion-exchange groups are not unlimitedly present in the coating, amphetamine isotherms level off to a saturation concentration on the C18/SCX fiber at the highest tested aqueous concentrations. Also, other cations (Na+, K+, Ca2+) compete for the SCX sites and decrease the sorption coefficients, e.g. by 1.7log units when comparing Milli-Q water with PBS. The C18/SCX fiber provides improved sensitivity over some of the classic SPME fibers. However, care should be taken near the cation exchange capacity of the fiber and the fiber should be calibrated in an appropriate matrix so as to eliminate competition effects.
Source:Analytica Chimica Acta, Volume 782
Author(s): Hester Peltenburg , Floris A. Groothuis , Steven T.J. Droge , Ingrid J. Bosman , Joop L.M. Hermens
We studied the sorption of amphetamine as a model drug to represent small, polar organic cations to a new SPME coating combining C18 and propylsulfonic acid. This combination of hydrophobic and strong cation exchange (SCX) groups was compared to conventional SPME fibers with polyacrylate (PA) or C18 coating. The affinity of amphetamine at physiological pH (PBS) was 20 to 180 times greater for the new C18/SCX coating than for C18 alone and PA of different coating thickness. As amphetamine is a base and >99% protonated at physiological pH, this enhanced affinity is attributed to the ion-exchange phase in the coating. Tests at pH above the pK a of amphetamine show that, when normalized to the coating volume, neutral amphetamine also has a higher affinity compared to PA. As ion-exchange groups are not unlimitedly present in the coating, amphetamine isotherms level off to a saturation concentration on the C18/SCX fiber at the highest tested aqueous concentrations. Also, other cations (Na+, K+, Ca2+) compete for the SCX sites and decrease the sorption coefficients, e.g. by 1.7log units when comparing Milli-Q water with PBS. The C18/SCX fiber provides improved sensitivity over some of the classic SPME fibers. However, care should be taken near the cation exchange capacity of the fiber and the fiber should be calibrated in an appropriate matrix so as to eliminate competition effects.
Graphical abstract
Determination of naphthalene-derived compounds in apples by ultra-high performance liquid chromatography-tandem mass spectrometry
28 May 2013,
09:59:13
Publication date: 11 June
2013
Source:Analytica Chimica Acta, Volume 782
Author(s): X. Esparza , E. Moyano , J.R. Cosialls , M.T. Galceran
Naphthylacetic acid, naphthyloxy acetic acid and naphthylacetamide belong to a group of synthetic substances known as “auxin-like” compounds which are used as growth regulators in vegetables and fruits due to their structure similarities with the indoleacetic acid, the most important plant auxin. This paper reports a selective, sensitive and fast ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS) method for the determination of naphthylacetamide (NAD) and the isomers (α and β) of naphthylacetic acid (NAA) and naphthyloxy acetic (NOA) acid in apple samples. A baseline separation between the respective isomers was achieved using an RP-Amide column with gradient elution. The UHPLC-MS/MS method developed, using electrospray and selected reaction monitoring (SRM) acquisition mode led to a reliable determination of these family of compounds in apple samples at low quantitation levels, down to 1.0μgkg−1 and 0.25μgkg−1 respectively. For confirmation of NAA accurate mass measurement is proposed giving at these conditions quantitation limits of 10μgkg−1 for this compound. The UHPLC-MS/MS method developed was used for the analysis of apple samples harvested in three different apple fields from Lleida (Spain) during the blooming period. NAD and NAA were found in samples collected during 4–5 weeks after application at concentrations between the quantification limits and 43μgkg−1 and 24μgkg−1, respectively.
Source:Analytica Chimica Acta, Volume 782
Author(s): X. Esparza , E. Moyano , J.R. Cosialls , M.T. Galceran
Naphthylacetic acid, naphthyloxy acetic acid and naphthylacetamide belong to a group of synthetic substances known as “auxin-like” compounds which are used as growth regulators in vegetables and fruits due to their structure similarities with the indoleacetic acid, the most important plant auxin. This paper reports a selective, sensitive and fast ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS) method for the determination of naphthylacetamide (NAD) and the isomers (α and β) of naphthylacetic acid (NAA) and naphthyloxy acetic (NOA) acid in apple samples. A baseline separation between the respective isomers was achieved using an RP-Amide column with gradient elution. The UHPLC-MS/MS method developed, using electrospray and selected reaction monitoring (SRM) acquisition mode led to a reliable determination of these family of compounds in apple samples at low quantitation levels, down to 1.0μgkg−1 and 0.25μgkg−1 respectively. For confirmation of NAA accurate mass measurement is proposed giving at these conditions quantitation limits of 10μgkg−1 for this compound. The UHPLC-MS/MS method developed was used for the analysis of apple samples harvested in three different apple fields from Lleida (Spain) during the blooming period. NAD and NAA were found in samples collected during 4–5 weeks after application at concentrations between the quantification limits and 43μgkg−1 and 24μgkg−1, respectively.
Graphical abstract
Second-order advantage with excitation–emission photoinduced fluorimetry for the determination of the antiepileptic carbamazepine in environmental waters
28 May 2013,
09:59:13
Publication date: 11 June
2013
Source:Analytica Chimica Acta, Volume 782
Author(s): Valeria A. Lozano , Graciela M. Escandar
A photochemically induced fluorescence system combined with second-order chemometric analysis for the determination of the anticonvulsant carbamazepine (CBZ) is presented. CBZ is a widely used drug for the treatment of epilepsy and is included in the group of emerging contaminant present in the aquatic environment. CBZ is not fluorescent in solution but can be converted into a fluorescent compound through a photochemical reaction in a strong acid medium. The determination is carried out by measuring excitation–emission photoinduced fluorescence matrices of the products formed upon ultraviolet light irradiation in a laboratory-constructed reactor constituted by two simple 4W germicidal tubes. Working conditions related to both the reaction medium and the photoreactor geometry are optimized by an experimental design. The developed approach enabled the determination of CBZ at trace levels without the necessity of applying separation steps, and in the presence of uncalibrated interferences which also display photoinduced fluorescence and may be potentially present in the investigated samples. Different second-order algorithms were tested and successful resolution was achieved using multivariate curve resolution-alternating least-squares (MCR-ALS). The study is employed for the discussion of the scopes and yields of each of the applied second-order chemometric tools. The quality of the proposed method is probed through the determination of the studied emerging pollutant in both environmental and drinking water samples. After a pre-concentration step on a C18 membrane using 50.0mL of real water samples, a prediction relative error of 2% and limits of detection and quantification of 0.2 and 0.6ngmL−1 were respectively obtained.
Source:Analytica Chimica Acta, Volume 782
Author(s): Valeria A. Lozano , Graciela M. Escandar
A photochemically induced fluorescence system combined with second-order chemometric analysis for the determination of the anticonvulsant carbamazepine (CBZ) is presented. CBZ is a widely used drug for the treatment of epilepsy and is included in the group of emerging contaminant present in the aquatic environment. CBZ is not fluorescent in solution but can be converted into a fluorescent compound through a photochemical reaction in a strong acid medium. The determination is carried out by measuring excitation–emission photoinduced fluorescence matrices of the products formed upon ultraviolet light irradiation in a laboratory-constructed reactor constituted by two simple 4W germicidal tubes. Working conditions related to both the reaction medium and the photoreactor geometry are optimized by an experimental design. The developed approach enabled the determination of CBZ at trace levels without the necessity of applying separation steps, and in the presence of uncalibrated interferences which also display photoinduced fluorescence and may be potentially present in the investigated samples. Different second-order algorithms were tested and successful resolution was achieved using multivariate curve resolution-alternating least-squares (MCR-ALS). The study is employed for the discussion of the scopes and yields of each of the applied second-order chemometric tools. The quality of the proposed method is probed through the determination of the studied emerging pollutant in both environmental and drinking water samples. After a pre-concentration step on a C18 membrane using 50.0mL of real water samples, a prediction relative error of 2% and limits of detection and quantification of 0.2 and 0.6ngmL−1 were respectively obtained.
Graphical abstract
Detection of Panton-Valentine Leukocidin DNA from methicillin-resistant Staphylococcus aureus by resistive pulse sensing and loop-mediated isothermal amplification with gold nanoparticles
28 May 2013,
09:59:13
Publication date: 11 June
2013
Source:Analytica Chimica Acta, Volume 782
Author(s): Alice Kar Lai Yang , Haifei Lu , Shu Yuen Wu , Ho Chin Kwok , Ho Pui Ho , Samuel Yu , Anthony Ka Lun Cheung , Siu Kai Kong
This report describes a novel diagnostic assay for rapid detection of the Panton-Valentine Leukocidin (PVL) toxin of methicillin-resistant Staphylococcus aureus (MRSA) utilizing resistive pulse sensing (RPS), loop-mediated isothermal DNA amplification (LAMP) in combination with gold nanoparticles (AuNPs). The PVL DNA from MRSA was specifically amplified by LAMP using four primers at one temperature (65°C). The DNA products with biotin were then conjugated to a first AuNP1 (55±2nm) through biotin–avidin binding. A second AuNP2 (30±1.5nm) coated with a specific DNA probe hybridized with the LAMP DNA products at the loop region to enhance assay sensitivity and specificity, to generate supra-AuNP1-DNA-AuNP2 assemblies. Scanning electron microscopy confirmed the presence of these supra-assemblies. Using RPS, detection and quantitation of the agglomerated AuNPs were performed by a tunable fluidic nanopore sensor. The results demonstrate that the LAMP-based RPS sensor is sensitive and rapid for detecting the PVL DNA. This technique could achieve a limit of detection (LOD) up to about 500 copies of genomic DNA from the bacteria MRSA MW2 and the detection can be completed within two hours with a straightforward signal-to-readout setup. It is anticipated that this LAMP-based AuNP RPS may become an effective tool for MRSA detection and a potential platform in clinical laboratory to report the presence or absence of other types of infectious agents.
Source:Analytica Chimica Acta, Volume 782
Author(s): Alice Kar Lai Yang , Haifei Lu , Shu Yuen Wu , Ho Chin Kwok , Ho Pui Ho , Samuel Yu , Anthony Ka Lun Cheung , Siu Kai Kong
This report describes a novel diagnostic assay for rapid detection of the Panton-Valentine Leukocidin (PVL) toxin of methicillin-resistant Staphylococcus aureus (MRSA) utilizing resistive pulse sensing (RPS), loop-mediated isothermal DNA amplification (LAMP) in combination with gold nanoparticles (AuNPs). The PVL DNA from MRSA was specifically amplified by LAMP using four primers at one temperature (65°C). The DNA products with biotin were then conjugated to a first AuNP1 (55±2nm) through biotin–avidin binding. A second AuNP2 (30±1.5nm) coated with a specific DNA probe hybridized with the LAMP DNA products at the loop region to enhance assay sensitivity and specificity, to generate supra-AuNP1-DNA-AuNP2 assemblies. Scanning electron microscopy confirmed the presence of these supra-assemblies. Using RPS, detection and quantitation of the agglomerated AuNPs were performed by a tunable fluidic nanopore sensor. The results demonstrate that the LAMP-based RPS sensor is sensitive and rapid for detecting the PVL DNA. This technique could achieve a limit of detection (LOD) up to about 500 copies of genomic DNA from the bacteria MRSA MW2 and the detection can be completed within two hours with a straightforward signal-to-readout setup. It is anticipated that this LAMP-based AuNP RPS may become an effective tool for MRSA detection and a potential platform in clinical laboratory to report the presence or absence of other types of infectious agents.
Graphical abstract
Gold immunochromatographic strips for enhanced detection of Avian influenza and Newcastle disease viruses
28 May 2013,
09:59:13
Publication date: 11 June
2013
Source:Analytica Chimica Acta, Volume 782
Author(s): Jinfeng Li , Mingqiang Zou , Yan Chen , Qiang Xue , Fan Zhang , Beibei Li , Yanfei Wang , Xiaohua Qi , Yi Yang
A new technique that uses gold immunochromatographic strips enhances the detection sensitivity by inducing the clustering of additional gold nanoparticles (AuNPs) around the immunogold particles immobilized on nitrocellulose strips. The additional AuNPs provide an intense signal that can be detected by the naked eye. The AuNPs were synthesized and conjugated to monoclonal antibodies using self-assembly. Other antibodies were immobilized in a defined detection zone on the nitrocellulose membrane. The detection principle is based on a “sandwich” immunoreaction, where gold-labeled antibodies serve as signal vehicles. To improve the sensitivity of the strips, we use a mixture of 1% HAuCl4 and 10mmolL−1 NH2OH·HCl to “enlarge” the gold nanoparticles. The detecting limits of Avian influenza virus (AIV) and Newcastle disease virus (NDV) are significantly increased. Compared with commercial test strips, this method is 100-fold more sensitive. This method is easy to perform and can be carried out on-site in test laboratories.
Source:Analytica Chimica Acta, Volume 782
Author(s): Jinfeng Li , Mingqiang Zou , Yan Chen , Qiang Xue , Fan Zhang , Beibei Li , Yanfei Wang , Xiaohua Qi , Yi Yang
A new technique that uses gold immunochromatographic strips enhances the detection sensitivity by inducing the clustering of additional gold nanoparticles (AuNPs) around the immunogold particles immobilized on nitrocellulose strips. The additional AuNPs provide an intense signal that can be detected by the naked eye. The AuNPs were synthesized and conjugated to monoclonal antibodies using self-assembly. Other antibodies were immobilized in a defined detection zone on the nitrocellulose membrane. The detection principle is based on a “sandwich” immunoreaction, where gold-labeled antibodies serve as signal vehicles. To improve the sensitivity of the strips, we use a mixture of 1% HAuCl4 and 10mmolL−1 NH2OH·HCl to “enlarge” the gold nanoparticles. The detecting limits of Avian influenza virus (AIV) and Newcastle disease virus (NDV) are significantly increased. Compared with commercial test strips, this method is 100-fold more sensitive. This method is easy to perform and can be carried out on-site in test laboratories.
Graphical abstract
A highly sensitive fluorescence resonance energy transfer aptasensor for staphylococcal enterotoxin B detection based on exonuclease-catalyzed target recycling strategy
28 May 2013,
09:59:13
Publication date: 11 June
2013
Source:Analytica Chimica Acta, Volume 782
Author(s): Shijia Wu , Nuo Duan , Xiaoyuan Ma , Yu Xia , Hongxin Wang , Zhouping Wang
An ultrasensitive fluorescence resonance energy transfer (FRET) bioassay was developed to detect staphylococcal enterotoxin B (SEB), a low molecular exotoxin, using an aptamer-affinity method coupled with upconversion nanoparticles (UCNPs)-sensing, and the fluorescence intensity was prominently enhanced using an exonuclease-catalyzed target recycling strategy. To construct this aptasensor, both fluorescence donor probes (complementary DNA1–UCNPs) and fluorescence quencher probes (complementary DNA2–Black Hole Quencher3 (BHQ3)) were hybridized to an SEB aptamer, and double-strand oligonucleotides were fabricated, which quenched the fluorescence of the UCNPs via FRET. The formation of an aptamer–SEB complex in the presence of the SEB analyte resulted in not only the dissociation of aptamer from the double-strand DNA but also both the disruption of the FRET system and the restoration of the UCNPs fluorescence. In addition, the SEB was liberated from the aptamer–SEB complex using exonuclease I, an exonuclease specific to single-stranded DNA, for analyte recycling by selectively digesting a particular DNA (SEB aptamer). Based on this exonuclease-catalyzed target recycling strategy, an amplified fluorescence intensity could be produced using different SEB concentrations. Using optimized experimental conditions produced an ultrasensitive aptasensor for the detection of SEB, with a wide linear range of 0.001–1ngmL−1 and a lower detection limit (LOD) of 0.3pgmL−1 SEB (at 3σ). The fabricated aptasensor was used to measure SEB in a real milk samples and validated using the ELISA method. Furthermore, a novel aptasensor FRET assay was established for the first time using 30mol% Mn2+ ions doped NaYF4:Yb/Er (20/2mol%) UCNPs as the donor probes, which suggests that UCNPs are superior fluorescence labeling materials for food safety analysis.
Source:Analytica Chimica Acta, Volume 782
Author(s): Shijia Wu , Nuo Duan , Xiaoyuan Ma , Yu Xia , Hongxin Wang , Zhouping Wang
An ultrasensitive fluorescence resonance energy transfer (FRET) bioassay was developed to detect staphylococcal enterotoxin B (SEB), a low molecular exotoxin, using an aptamer-affinity method coupled with upconversion nanoparticles (UCNPs)-sensing, and the fluorescence intensity was prominently enhanced using an exonuclease-catalyzed target recycling strategy. To construct this aptasensor, both fluorescence donor probes (complementary DNA1–UCNPs) and fluorescence quencher probes (complementary DNA2–Black Hole Quencher3 (BHQ3)) were hybridized to an SEB aptamer, and double-strand oligonucleotides were fabricated, which quenched the fluorescence of the UCNPs via FRET. The formation of an aptamer–SEB complex in the presence of the SEB analyte resulted in not only the dissociation of aptamer from the double-strand DNA but also both the disruption of the FRET system and the restoration of the UCNPs fluorescence. In addition, the SEB was liberated from the aptamer–SEB complex using exonuclease I, an exonuclease specific to single-stranded DNA, for analyte recycling by selectively digesting a particular DNA (SEB aptamer). Based on this exonuclease-catalyzed target recycling strategy, an amplified fluorescence intensity could be produced using different SEB concentrations. Using optimized experimental conditions produced an ultrasensitive aptasensor for the detection of SEB, with a wide linear range of 0.001–1ngmL−1 and a lower detection limit (LOD) of 0.3pgmL−1 SEB (at 3σ). The fabricated aptasensor was used to measure SEB in a real milk samples and validated using the ELISA method. Furthermore, a novel aptasensor FRET assay was established for the first time using 30mol% Mn2+ ions doped NaYF4:Yb/Er (20/2mol%) UCNPs as the donor probes, which suggests that UCNPs are superior fluorescence labeling materials for food safety analysis.
Graphical abstract
Separation of phthalates by cyclodextrin modified micellar electrokinetic chromatography: Quantitation in perfumes
28 May 2013,
09:59:13
Publication date: 11 June
2013
Source:Analytica Chimica Acta, Volume 782
Author(s): Virginia Pérez-Fernández , Maria José González , Maria Ángeles García , Maria Luisa Marina
A new CE method has been developed for the simultaneous separation of a group of parent phthalates. Due to the neutral character of these compounds, the addition of several bile salts as surfactants (sodium cholate (SC), sodium deoxycholate (SDC), sodium taurodeoxycholate (STDC), sodium taurocholate (STC)) to the separation buffer was explored showing the high potential of SDC as pseudostationary phase. However, the resolution of all the phthalates was not achieved when employing only this bile salt as additive, being necessary the addition of neutral cyclodextrins (CD) and organic modifiers to the separation media. The optimized cyclodextrin modified micellar electrokinetic chromatography (CD-MEKC) method consisted of the employ of a background electrolyte (BGE) containing 25mM β-CD-100mM SDC in a 100mM borate buffer (pH 8.5) with a 10% (v/v) of acetonitrile, employing a voltage of 30kV and a temperature of 25°C. This separation medium enabled the total resolution of eight compounds and the partial resolution of two of the analytes, di-n-octyl phthalate (DNOP) and diethyl hexyl phthalate (DEHP) (Rs~0.8), in only 12min. The analytical characteristics of the developed method were studied showing their suitability for the determination of these compounds in commercial perfumes. In all the analyzed perfumes the most common phthalate was diethyl phthalate (DEP) that appeared in ten of the fifteen analyzed products. Also dimethyl phthalate (DMP), diallyl phthalate (DAP), dicyclohexyl phthalate (DCP), and di-n-pentyl phthalate (DNPP) were found in some of the analyzed samples.
Source:Analytica Chimica Acta, Volume 782
Author(s): Virginia Pérez-Fernández , Maria José González , Maria Ángeles García , Maria Luisa Marina
A new CE method has been developed for the simultaneous separation of a group of parent phthalates. Due to the neutral character of these compounds, the addition of several bile salts as surfactants (sodium cholate (SC), sodium deoxycholate (SDC), sodium taurodeoxycholate (STDC), sodium taurocholate (STC)) to the separation buffer was explored showing the high potential of SDC as pseudostationary phase. However, the resolution of all the phthalates was not achieved when employing only this bile salt as additive, being necessary the addition of neutral cyclodextrins (CD) and organic modifiers to the separation media. The optimized cyclodextrin modified micellar electrokinetic chromatography (CD-MEKC) method consisted of the employ of a background electrolyte (BGE) containing 25mM β-CD-100mM SDC in a 100mM borate buffer (pH 8.5) with a 10% (v/v) of acetonitrile, employing a voltage of 30kV and a temperature of 25°C. This separation medium enabled the total resolution of eight compounds and the partial resolution of two of the analytes, di-n-octyl phthalate (DNOP) and diethyl hexyl phthalate (DEHP) (Rs~0.8), in only 12min. The analytical characteristics of the developed method were studied showing their suitability for the determination of these compounds in commercial perfumes. In all the analyzed perfumes the most common phthalate was diethyl phthalate (DEP) that appeared in ten of the fifteen analyzed products. Also dimethyl phthalate (DMP), diallyl phthalate (DAP), dicyclohexyl phthalate (DCP), and di-n-pentyl phthalate (DNPP) were found in some of the analyzed samples.
Graphical abstract
Dimethyl(3,3,3-trifluoropropyl)silyldiethylamine—A new silylating agent for the derivatization of β-blockers and β-agonists in environmental samples
28 May 2013,
09:59:13
Publication date: 11 June
2013
Source:Analytica Chimica Acta, Volume 782
Author(s): Magda Caban , Katarzyna Mioduszewska , Piotr Stepnowski , Marek Kwiatkowski , Jolanta Kumirska
Research into alternative derivatizing agents remains a major task in the trace analysis of polar compounds using GC. DIMETRIS (dimethyl(3,3,3-trifluoropropyl)silyldiethylamine) is a new and interesting proposition in this field. This agent possesses strong nucleophilic properties and reacts selectively with hydroxyl groups. The derivatization reaction takes place in the absence of any catalysts. The derivatives possess good chromatographic properties and are easily detected by mass spectrometry. By introducing fluorine atoms into the structure of the derivatives, we were able to use an electron-capture detector for their GC determination. No degradation of new derivatives was observed after seven days of storage in a refrigerator or during the GC analyses. Unlike a number of acylation agents, DIMETRIS does not corrode the analytical equipment. In this work β-blockers and β-agonists were used for testing the derivatizing properties of DIMETRIS. Derivatization of these drugs was optimal at 30°C for 30min. The method quantification limits of the target compounds determined in tap water samples by SPE-GC–MS(SIM) ranged from 3 to 40ngL−1 and resembled those obtained with samples derivatized using a mixture of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1% chlorotrimethylsilane (TMCS) (hitherto regarded as optimal). This work confirmed that DIMETRIS is suitable for the trace analysis of pharmaceuticals in natural samples and provides an interesting alternative to silylating and acylating agents.
Source:Analytica Chimica Acta, Volume 782
Author(s): Magda Caban , Katarzyna Mioduszewska , Piotr Stepnowski , Marek Kwiatkowski , Jolanta Kumirska
Research into alternative derivatizing agents remains a major task in the trace analysis of polar compounds using GC. DIMETRIS (dimethyl(3,3,3-trifluoropropyl)silyldiethylamine) is a new and interesting proposition in this field. This agent possesses strong nucleophilic properties and reacts selectively with hydroxyl groups. The derivatization reaction takes place in the absence of any catalysts. The derivatives possess good chromatographic properties and are easily detected by mass spectrometry. By introducing fluorine atoms into the structure of the derivatives, we were able to use an electron-capture detector for their GC determination. No degradation of new derivatives was observed after seven days of storage in a refrigerator or during the GC analyses. Unlike a number of acylation agents, DIMETRIS does not corrode the analytical equipment. In this work β-blockers and β-agonists were used for testing the derivatizing properties of DIMETRIS. Derivatization of these drugs was optimal at 30°C for 30min. The method quantification limits of the target compounds determined in tap water samples by SPE-GC–MS(SIM) ranged from 3 to 40ngL−1 and resembled those obtained with samples derivatized using a mixture of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1% chlorotrimethylsilane (TMCS) (hitherto regarded as optimal). This work confirmed that DIMETRIS is suitable for the trace analysis of pharmaceuticals in natural samples and provides an interesting alternative to silylating and acylating agents.
Graphical abstract
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