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Selected papers from the latest issue:
Miniaturized molecularly imprinted matrix solid-phase dispersion coupled with high performance liquid chromatography for rapid determination of auxins in orange samples
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Hongyuan Yan, Fang Wang, Hui Wang, Gengliang Yang
A simple, convenient and high selective miniaturized molecularly imprinted matrix solid-phase dispersion (mini-MI-MSPD) technique using l-tryptophan-imprinted polymers as sorbents was proposed for simultaneous extraction of four auxins (indole-3-acetic acid (IAA), indole-3-propionic acid (IPA), indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA)) from orange samples coupled with high performance liquid chromatography–ultraviolet detection. The molecularly imprinted polymers (MIPs) synthesized using l-tryptophan as dummy template showed high affinity and selectivity to auxins, and so they were applied as the specific dispersant of MSPD to simultaneously eliminate the effect of template leakage on quantitative analysis. Under the optimized conditions, good linearity was obtained in a range of 0.02–2.00μgg−1 and the average recoveries of four auxins at three spiked levels ranged from 87.6% to 104.5% with the relative standard deviation (RSD) ≤4.4%. The presented mini-MI-MSPD method combined the advantages of MSPD for allowing the extraction, dispersion and homogenization in a single step and the advantages of MIPs for high affinity and selectivity towards four auxins, which could be applied to the determination of auxins in complicated vegetal samples.
Source:Journal of Chromatography A, Volume 1256
Hongyuan Yan, Fang Wang, Hui Wang, Gengliang Yang
A simple, convenient and high selective miniaturized molecularly imprinted matrix solid-phase dispersion (mini-MI-MSPD) technique using l-tryptophan-imprinted polymers as sorbents was proposed for simultaneous extraction of four auxins (indole-3-acetic acid (IAA), indole-3-propionic acid (IPA), indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA)) from orange samples coupled with high performance liquid chromatography–ultraviolet detection. The molecularly imprinted polymers (MIPs) synthesized using l-tryptophan as dummy template showed high affinity and selectivity to auxins, and so they were applied as the specific dispersant of MSPD to simultaneously eliminate the effect of template leakage on quantitative analysis. Under the optimized conditions, good linearity was obtained in a range of 0.02–2.00μgg−1 and the average recoveries of four auxins at three spiked levels ranged from 87.6% to 104.5% with the relative standard deviation (RSD) ≤4.4%. The presented mini-MI-MSPD method combined the advantages of MSPD for allowing the extraction, dispersion and homogenization in a single step and the advantages of MIPs for high affinity and selectivity towards four auxins, which could be applied to the determination of auxins in complicated vegetal samples.
Highlights
► A simple and rapid mini-MI-MSPD method for isolation of auxins in orange. ► MIP synthesized by tryptophan as dummy template show high affinity to auxins. ► Rapid screening of four auxins from orange samples with improved purification effect. ► Extraction efficiency was markedly increased with reduced equilibrium time. ► The mini-MI-MSPD–HPLC method improved the selectivity and eliminated the effect of template leakage on quantitative analysis.Ultrasonic-assisted water extraction and solvent bar microextraction followed by gas chromatography–ion trap mass spectrometry for determination of chlorobenzenes in soil samples
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Li Wang, Linling Wang, Jing Chen, Wenjun Du, Guoliang Fan, Xiaohua Lu
A novel and simple analytical method for the determination of chlorobenzenes (CBs) in soil samples was developed using ultrasonic-assisted water extraction (UAWE) coupled with solvent bar microextraction (SBME). Four chlorobenzenes, 1,2,3-trichlorobenzene (1,2,3-TCB), 1,2,3,4-tetrachlorobenzene (1,2,3,4-TeCB), hexachlorobenzene (HCB), and 1-chloro-4-nitrobenzene (1-C-4-NB), were used as model compounds to investigate the extraction performance. Parameters affecting the extraction efficiency were investigated in detail. UAWE was used for the extraction of CBs from 1.0g of sediment using 10mL of ultrapure water at 100W for 30min at 30–35°C. The extract was subsequently subjected to a single step SBME cleanup and enrichment procedure. Both ends of the solvent bar with about 4μL of 1-octanol were sealed by a sealing machine, and it was placed in the soil slurry for extraction. After extraction, analysis was carried out by gas chromatography–ion trap mass spectrometry (GC–ITMS) detection. The relative recoveries from the spiked soil sample varied between 93 and 105% for CBs, and exceeded levels achieved for conventional Soxhlet extraction. The method linearities were 10–150, 40–600, and 100–1500ngg−1 for different CBs. The limits of detection (LODs) and the limits of quantification (LOQs) were in the range of 0.7–27.3ngg−1 and 2.2–90.9ngg−1, respectively. Good reproducibilities were obtained with relative standard deviation (RSD) values below 6.8%. The analytical potential of the method was demonstrated by applying the method to spiked soil sample.
Source:Journal of Chromatography A, Volume 1256
Li Wang, Linling Wang, Jing Chen, Wenjun Du, Guoliang Fan, Xiaohua Lu
A novel and simple analytical method for the determination of chlorobenzenes (CBs) in soil samples was developed using ultrasonic-assisted water extraction (UAWE) coupled with solvent bar microextraction (SBME). Four chlorobenzenes, 1,2,3-trichlorobenzene (1,2,3-TCB), 1,2,3,4-tetrachlorobenzene (1,2,3,4-TeCB), hexachlorobenzene (HCB), and 1-chloro-4-nitrobenzene (1-C-4-NB), were used as model compounds to investigate the extraction performance. Parameters affecting the extraction efficiency were investigated in detail. UAWE was used for the extraction of CBs from 1.0g of sediment using 10mL of ultrapure water at 100W for 30min at 30–35°C. The extract was subsequently subjected to a single step SBME cleanup and enrichment procedure. Both ends of the solvent bar with about 4μL of 1-octanol were sealed by a sealing machine, and it was placed in the soil slurry for extraction. After extraction, analysis was carried out by gas chromatography–ion trap mass spectrometry (GC–ITMS) detection. The relative recoveries from the spiked soil sample varied between 93 and 105% for CBs, and exceeded levels achieved for conventional Soxhlet extraction. The method linearities were 10–150, 40–600, and 100–1500ngg−1 for different CBs. The limits of detection (LODs) and the limits of quantification (LOQs) were in the range of 0.7–27.3ngg−1 and 2.2–90.9ngg−1, respectively. Good reproducibilities were obtained with relative standard deviation (RSD) values below 6.8%. The analytical potential of the method was demonstrated by applying the method to spiked soil sample.
Highlights
► A novel method was developed for the determination of chlorobenzenes in soils. ► Ultrasonic-assisted water extraction was followed by solvent bar microextraction. ► Analysis was carried out by gas chromatography–ion trap mass spectrometry. ► Parameters affecting the extraction efficiency were investigated in detail. ► The technique for the preparation of solvent bar was modified.A practical interface designed for on-line polymer monolith microextraction: Synthesis and application of poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) monolith
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Lin-feng Zhou, Xu-gan He, Jun-qin Qiao, Hong-zhen Lian, Xin Ge, Hong-yuan Chen
A simple and facile needle-adapter was designed for constructing manual on-line polymer monolith microextraction-high performance liquid chromatography (PMME-HPLC). A capillary poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) [poly(VP-co-EGDMA)] monolith was prepared by in situ polymerization, using 4-vinylpyridine (VP) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. The synthesized monolith was used as the extraction medium for concentrating four EPA priority pollutants, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol, from water samples. The effect of the dosage of porogen polyethylene glycol 6000 (PEG) on back pressure and extraction performance of the capillary monolith was also investigated. Moreover, the influences of several parameters (such as extraction time, desorption time, content of MeOH in sample solution and sample pH) were examined to obtain the optimal PMME conditions. As a result, the established on-line PMME-HPLC protocol, with good extraction efficiency (80.6–91.7%), satisfactory recovery (94.7–106% and 76.8–86.3% for water and serum samples, respectively) and low detection limit (0.3–1.4μg/L), exhibited potential applicability for the analysis of chlorophenols in environmental and biological samples.
Source:Journal of Chromatography A, Volume 1256
Lin-feng Zhou, Xu-gan He, Jun-qin Qiao, Hong-zhen Lian, Xin Ge, Hong-yuan Chen
A simple and facile needle-adapter was designed for constructing manual on-line polymer monolith microextraction-high performance liquid chromatography (PMME-HPLC). A capillary poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) [poly(VP-co-EGDMA)] monolith was prepared by in situ polymerization, using 4-vinylpyridine (VP) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. The synthesized monolith was used as the extraction medium for concentrating four EPA priority pollutants, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol, from water samples. The effect of the dosage of porogen polyethylene glycol 6000 (PEG) on back pressure and extraction performance of the capillary monolith was also investigated. Moreover, the influences of several parameters (such as extraction time, desorption time, content of MeOH in sample solution and sample pH) were examined to obtain the optimal PMME conditions. As a result, the established on-line PMME-HPLC protocol, with good extraction efficiency (80.6–91.7%), satisfactory recovery (94.7–106% and 76.8–86.3% for water and serum samples, respectively) and low detection limit (0.3–1.4μg/L), exhibited potential applicability for the analysis of chlorophenols in environmental and biological samples.
Highlights
► Manual on-line PMME-HPLC system was constructed based on a facile needle-adapter. ► Poly(VP-co-EGDMA) monolith was prepared as a new PMME medium. ► The PMME-HPLC system can be used to extract and determine chlorophenols. ► Less sample consumption and shorter extraction time were needed for water and serum. ► Generally lower LODs relative to other off-line SPME-HPLC methods was another advantage.Optimization of pressurized liquid extraction using a multivariate chemometric approach and comparison of solid-phase extraction cleanup steps for the determination of polycyclic aromatic hydrocarbons in mosses
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
L. Foan, V. Simon
A factorial design was used to optimize the extraction of polycyclic aromatic hydrocarbons (PAHs) from mosses, plants used as biomonitors of air pollution. The analytical procedure consists of pressurized liquid extraction (PLE) followed by solid-phase extraction (SPE) cleanup, in association with analysis by high performance liquid chromatography coupled with fluorescence detection (HPLC–FLD). For method development, homogeneous samples were prepared with large quantities of the mosses Isothecium myosuroides Brid. and Hypnum cupressiforme Hedw., collected from a Spanish Nature Reserve. A factorial design was used to identify the optimal PLE operational conditions: 2 static cycles of 5min at 80°C. The analytical procedure performed with PLE showed similar recoveries (∼70%) and total PAH concentrations (∼200ngg−1) as found using Soxtec extraction, with the advantage of reducing solvent consumption by 3 (30mL against 100mL per sample), and taking a fifth of the time (24 samples extracted automatically in 8h against 2 samples in 3.5h). The performance of SPE normal phases (NH2, Florisil®, silica and activated aluminium) generally used for organic matrix cleanup was also compared. Florisil® appeared to be the most selective phase and ensured the highest PAH recoveries. The optimal analytical procedure was validated with a reference material and applied to moss samples from a remote Spanish site in order to determine spatial and inter-species variability.
Source:Journal of Chromatography A, Volume 1256
L. Foan, V. Simon
A factorial design was used to optimize the extraction of polycyclic aromatic hydrocarbons (PAHs) from mosses, plants used as biomonitors of air pollution. The analytical procedure consists of pressurized liquid extraction (PLE) followed by solid-phase extraction (SPE) cleanup, in association with analysis by high performance liquid chromatography coupled with fluorescence detection (HPLC–FLD). For method development, homogeneous samples were prepared with large quantities of the mosses Isothecium myosuroides Brid. and Hypnum cupressiforme Hedw., collected from a Spanish Nature Reserve. A factorial design was used to identify the optimal PLE operational conditions: 2 static cycles of 5min at 80°C. The analytical procedure performed with PLE showed similar recoveries (∼70%) and total PAH concentrations (∼200ngg−1) as found using Soxtec extraction, with the advantage of reducing solvent consumption by 3 (30mL against 100mL per sample), and taking a fifth of the time (24 samples extracted automatically in 8h against 2 samples in 3.5h). The performance of SPE normal phases (NH2, Florisil®, silica and activated aluminium) generally used for organic matrix cleanup was also compared. Florisil® appeared to be the most selective phase and ensured the highest PAH recoveries. The optimal analytical procedure was validated with a reference material and applied to moss samples from a remote Spanish site in order to determine spatial and inter-species variability.
Highlights
► Mosses were used for monitoring atmospheric polycyclic aromatic hydrocarbons (PAHs). ► Pressurized liquid extraction (PLE) was optimized with a chemometric approach. ► Solid phase extraction (SPE) with Florisil® appeared as the most efficient cleanup. ► The analytical procedure applied to Spanish moss samples showed satisfactory results.High polar organic–inorganic hybrid coating stir bar sorptive extraction combined with high performance liquid chromatography–inductively coupled plasma mass spectrometry for the speciation of seleno-amino acids and seleno-oligopeptides in biological samples
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Xiangju Mao, Bin Hu, Man He, Beibei Chen
In this work, partially sulfonated polystyrene-titania (PSP-TiO2) organic–inorganic hybrid stir bar coating was prepared by sol–gel and blending methods, and a new method of PSP-TiO2 coating stir bar sorptive extraction (SBSE)-high performance liquid chromatography (HPLC)–inductively coupled plasma mass spectrometry (ICP-MS) was established for the analysis of seleno-amino acids (selenocystine (SeCys2), methylseleno-cysteine (MeSeCys), selenomethionine (SeMet) and selenoethionine (SeEt)) and seleno-oligopeptides (γ-glutamyl-Se-methyl-selenocysteine (γ-GluMeSeCys) and selenodiglutathione (GS-Se-SG)) in biological samples. The prepared high polar PSP-TiO2 hybrid coating avoided the swelling of PSP and cracking of TiO2 coating by combining the good film-forming property of PSP with the high mechanical strength of TiO2. The scanning electron microscope (SEM) showed that no obvious swelling and damage occurred for the PSP-TiO2 hybrid stir bar coating after 30 extraction/desorption cycles. The preparation reproducibility of PSP-TiO2 coated stir bar, evaluated with the relative standard deviations (RSDs), was in the range of 6.7–12.6% (n =5) in one batch, and 9.9–17.6% (n =7) among different batches. The limits of detection (LODs) of the developed method for six target selenium species were in the range of 50.2–185.5ngL−1 (as 77Se) and 45.9–158.8ngL−1 (as 82Se) with the RSDs within 4.9–11.7%. The dynamic linear range was found to cover three orders of magnitude with correlation coefficient of 0.9995–0.9999. The developed method was applied for the analysis of Certified Reference Material SELM-1 selenium enriched yeast and the determined values were in good agreement with the certified values. The method has also been applied for the analysis of seleno-amino acids and seleno-oligopeptides in human urine and garlic samples. Different from the conventional organic polymer SBSE coatings (such as polydimethylsiloxane, PDMS), the extraction mechanism of PSP-TiO2 organic–inorganic hybrid SBSE coating was based on the cation exchange interaction, which made it feasible to directly extract high polar seleno-amino acids and seleno-oligopeptides in biological samples without derivatization. This coating could also be suitable for stir bar sorptive extraction of other cationic compounds from the environmental and biological samples.
Source:Journal of Chromatography A, Volume 1256
Xiangju Mao, Bin Hu, Man He, Beibei Chen
In this work, partially sulfonated polystyrene-titania (PSP-TiO2) organic–inorganic hybrid stir bar coating was prepared by sol–gel and blending methods, and a new method of PSP-TiO2 coating stir bar sorptive extraction (SBSE)-high performance liquid chromatography (HPLC)–inductively coupled plasma mass spectrometry (ICP-MS) was established for the analysis of seleno-amino acids (selenocystine (SeCys2), methylseleno-cysteine (MeSeCys), selenomethionine (SeMet) and selenoethionine (SeEt)) and seleno-oligopeptides (γ-glutamyl-Se-methyl-selenocysteine (γ-GluMeSeCys) and selenodiglutathione (GS-Se-SG)) in biological samples. The prepared high polar PSP-TiO2 hybrid coating avoided the swelling of PSP and cracking of TiO2 coating by combining the good film-forming property of PSP with the high mechanical strength of TiO2. The scanning electron microscope (SEM) showed that no obvious swelling and damage occurred for the PSP-TiO2 hybrid stir bar coating after 30 extraction/desorption cycles. The preparation reproducibility of PSP-TiO2 coated stir bar, evaluated with the relative standard deviations (RSDs), was in the range of 6.7–12.6% (n =5) in one batch, and 9.9–17.6% (n =7) among different batches. The limits of detection (LODs) of the developed method for six target selenium species were in the range of 50.2–185.5ngL−1 (as 77Se) and 45.9–158.8ngL−1 (as 82Se) with the RSDs within 4.9–11.7%. The dynamic linear range was found to cover three orders of magnitude with correlation coefficient of 0.9995–0.9999. The developed method was applied for the analysis of Certified Reference Material SELM-1 selenium enriched yeast and the determined values were in good agreement with the certified values. The method has also been applied for the analysis of seleno-amino acids and seleno-oligopeptides in human urine and garlic samples. Different from the conventional organic polymer SBSE coatings (such as polydimethylsiloxane, PDMS), the extraction mechanism of PSP-TiO2 organic–inorganic hybrid SBSE coating was based on the cation exchange interaction, which made it feasible to directly extract high polar seleno-amino acids and seleno-oligopeptides in biological samples without derivatization. This coating could also be suitable for stir bar sorptive extraction of other cationic compounds from the environmental and biological samples.
Highlights
► Polar PSP-TiO2 coated SBSE was proposed for simultaneous extraction of different Se species. ► PSP-TiO2 hydrid coating allows extraction of other cationic compounds by SBSE. ► SBSE-HPLC–ICP-MS was developed for speciation of Se in biological samples. ► The developed method is sensitive, accurate, simple, rapid and low-cost.Extraction and preconcentration of trace amounts of diazinon and fenitrothion from environmental water by magnetite octadecylsilane nanoparticles
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Bozorgmehr Maddah, Javad Shamsi
In this study, a method for extraction and preconcentration trace amounts of organophosphorus pesticides (OPPs) in environmental water was developed using magnetic solid phase extraction (magnetic-SPE) followed by high performance liquid chromatography (HPLC) with UV detection. Magnetite octadecylsilane nanoparticles were synthesized and characterized by X-ray diffraction, FTIR spectroscopy, vibrating sample magnetometry and scanning electron microscopy. These nanoparticles were applied for extraction and preconcentration of OPPs (residues of diazinon and fenitrothion, which are the most-widely used for pest control in Iran) in environmental water samples at low ngmL−1 concentration as magnetic-SPE adsorbent. The extraction conditions and efficiency of the nanoparticles for OPPs were investigated. The method was evaluated according to the reproducibility, enrichment factor, linearity range and limits of detection. Under optimized conditions, method showed good linearity between 0.03–0.06 and 30ngmL−1 with regression coefficients (R 2) of 0.997 and 0.998. Limits of detection were 0.019 and 0.014ngmL−1. The enrichment factors of this method were 172 and 184 and the analysis yielded good reproducibility with the RSD values 7.2% and 5.4% at the 10ngmL−1 level (n =5) for diazinon and fenitrothion, respectively. Determination of OPPs can be easily carried out with this fast, accurate, sensitive and simple method procedure.
Source:Journal of Chromatography A, Volume 1256
Bozorgmehr Maddah, Javad Shamsi
In this study, a method for extraction and preconcentration trace amounts of organophosphorus pesticides (OPPs) in environmental water was developed using magnetic solid phase extraction (magnetic-SPE) followed by high performance liquid chromatography (HPLC) with UV detection. Magnetite octadecylsilane nanoparticles were synthesized and characterized by X-ray diffraction, FTIR spectroscopy, vibrating sample magnetometry and scanning electron microscopy. These nanoparticles were applied for extraction and preconcentration of OPPs (residues of diazinon and fenitrothion, which are the most-widely used for pest control in Iran) in environmental water samples at low ngmL−1 concentration as magnetic-SPE adsorbent. The extraction conditions and efficiency of the nanoparticles for OPPs were investigated. The method was evaluated according to the reproducibility, enrichment factor, linearity range and limits of detection. Under optimized conditions, method showed good linearity between 0.03–0.06 and 30ngmL−1 with regression coefficients (R 2) of 0.997 and 0.998. Limits of detection were 0.019 and 0.014ngmL−1. The enrichment factors of this method were 172 and 184 and the analysis yielded good reproducibility with the RSD values 7.2% and 5.4% at the 10ngmL−1 level (n =5) for diazinon and fenitrothion, respectively. Determination of OPPs can be easily carried out with this fast, accurate, sensitive and simple method procedure.
Highlights
► C18–SiO2–Fe3O4 NPs as sorbent can be easily synthesized. ► These NPs were applied for extraction trace amount of organophosphorus pesticides. ► This method is fast, accurate, sensitive and simple.Development of a non-triangular separation region for improving the performance of a three-zone simulated moving bed chromatography for binary separation with linear isotherms
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Sungyong Mun
For a three-zone simulated moving bed (SMB) chromatography with linear isotherms, the feasible set of operating parameters for complete separation is known to exist within a triangular region of the triangle theory that is formed in the operating parameter plane spanned by the flow-rate-ratios in the separation zones (II and III), which are commonly denoted as m 2 and m 3. Such an operating region for complete separation region, however, has been established only in the first quadrant (m 2, m 3) plane, where m 2 >0 and m 3 >0, until now. In this study, a new complete-separation region was developed in the third quadrant (m 2, m 3) plane, where m 2 <0 and m 3 <0, regarding a three-zone SMB process for the first time. The results showed that the new separation region created in the third quadrant (m 2, m 3) plane took a non-triangular shape. The operating parameters within such a non-triangular separation region were capable of guaranteeing complete separation for an ideal system with no mass-transfer effects. For a non-ideal system with considerable mass-transfer effects, the operating parameters that were selected with a sufficient margin from the boundaries of the non-triangular separation region led to high purities. One of the noteworthy features in the pattern of solute migration for such case was that both low-affinity and high-affinity solutes reached their corresponding product ports after taking a turn around the SMB bed once. Finally, it was confirmed from the results of SMB optimization based on genetic algorithm and detailed model that the operating parameters in the third quadrant (m 2, m 3) plane, if chosen properly, could ensure higher purities or higher throughput than the optimal operating parameters in the first quadrant (m 2, m 3) plane.
Source:Journal of Chromatography A, Volume 1256
Sungyong Mun
For a three-zone simulated moving bed (SMB) chromatography with linear isotherms, the feasible set of operating parameters for complete separation is known to exist within a triangular region of the triangle theory that is formed in the operating parameter plane spanned by the flow-rate-ratios in the separation zones (II and III), which are commonly denoted as m 2 and m 3. Such an operating region for complete separation region, however, has been established only in the first quadrant (m 2, m 3) plane, where m 2 >0 and m 3 >0, until now. In this study, a new complete-separation region was developed in the third quadrant (m 2, m 3) plane, where m 2 <0 and m 3 <0, regarding a three-zone SMB process for the first time. The results showed that the new separation region created in the third quadrant (m 2, m 3) plane took a non-triangular shape. The operating parameters within such a non-triangular separation region were capable of guaranteeing complete separation for an ideal system with no mass-transfer effects. For a non-ideal system with considerable mass-transfer effects, the operating parameters that were selected with a sufficient margin from the boundaries of the non-triangular separation region led to high purities. One of the noteworthy features in the pattern of solute migration for such case was that both low-affinity and high-affinity solutes reached their corresponding product ports after taking a turn around the SMB bed once. Finally, it was confirmed from the results of SMB optimization based on genetic algorithm and detailed model that the operating parameters in the third quadrant (m 2, m 3) plane, if chosen properly, could ensure higher purities or higher throughput than the optimal operating parameters in the first quadrant (m 2, m 3) plane.
Highlights
► A new separation region was developed for a three-zone SMB chromatographic process. ► The new separation region was created in the third quadrant (m 2, m 3) plane. ► It was compared with the previous triangular region in the first quadrant plane. ► The new region could surpass the previous triangular region in terms of purities. ► The new region could surpass the previous triangular region in terms of throughput.On-matrix derivatization for dynamic headspace sampling of nonvolatile surface residues
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Scott D. Harvey, Jon H. Wahl
The goal of this study is to extend sampling by the field and laboratory emission cell (FLEC) dynamic headspace technique to applications that target nonvolatile residues. On-matrix derivatization of residues to render analytes stable and more volatile is explored to achieve this goal. Results show that on-matrix derivatizations of nerve agent hydrolysis products (monoalkyl methylphosphonic acids and methylphosphonic acid [MPA]) with diazomethane were successful on glass and painted wallboard (at the 10-μg level). It also was successful on the more difficult concrete (at the 500-μg level) and carpet (at the 20-μg level), substrates that cannot be successfully sampled using swipe techniques. Analysis of additional chemical warfare (CW)-associated residues can be approached by on-matrix derivatization with trifluoroacetic anhydride (TFAA). For example, amines (used as stabilizers or present as decomposition products of the nerve agent VX) or thiodiglycol (hydrolysis product of sulfur mustard) could be sampled as their TFAA derivatives from glass, painted wallboard, and concrete (at the 40-μg level), as well as carpet (at the 80-μg level) surfaces. Although the amine and thiodiglycol are semi-volatile and could be sampled directly, derivatization improves the recovery and chromatographic behavior of these analytes.
Source:Journal of Chromatography A, Volume 1256
Scott D. Harvey, Jon H. Wahl
The goal of this study is to extend sampling by the field and laboratory emission cell (FLEC) dynamic headspace technique to applications that target nonvolatile residues. On-matrix derivatization of residues to render analytes stable and more volatile is explored to achieve this goal. Results show that on-matrix derivatizations of nerve agent hydrolysis products (monoalkyl methylphosphonic acids and methylphosphonic acid [MPA]) with diazomethane were successful on glass and painted wallboard (at the 10-μg level). It also was successful on the more difficult concrete (at the 500-μg level) and carpet (at the 20-μg level), substrates that cannot be successfully sampled using swipe techniques. Analysis of additional chemical warfare (CW)-associated residues can be approached by on-matrix derivatization with trifluoroacetic anhydride (TFAA). For example, amines (used as stabilizers or present as decomposition products of the nerve agent VX) or thiodiglycol (hydrolysis product of sulfur mustard) could be sampled as their TFAA derivatives from glass, painted wallboard, and concrete (at the 40-μg level), as well as carpet (at the 80-μg level) surfaces. Although the amine and thiodiglycol are semi-volatile and could be sampled directly, derivatization improves the recovery and chromatographic behavior of these analytes.
Highlights
► On-matrix derivatization developed for dynamic headspace sampling. ► Targeted analytes were chemical warfare hydrolysis products and amines. ► Substrates included glass, painted wallboard, carpet, and concrete. ► Technique was successful for all analytes on all substrates. ► Recoveries reasonable, except low for half-acid methylphosphonic acids on concrete.Strong cation exchange column allow for symmetrical peak shape and increased sample loading in the separation of basic compounds
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Zhen Long, Chaoran Wang, Zhimou Guo, Xiuli Zhang, Lilly Nordahl, Xinmiao Liang
Strong cation exchange (SCX) mode, an alternative to reversed-phase (RP) mode, was described in this paper to obtain symmetrical peak shape and high sample loading for the separation of basic compounds. The retention mechanisms on SCX modified silica sorbents have been demonstrated including electrostatic and hydrophobic interactions. The effects of eluent ionic strength, apparent pH on retention were investigated and the cation-exchange capacity was also characterized. Good efficiency (>56,000platem−1) and excellent peak shape (Tf<1.2) for various basic probes were obtained on the SCX column. Furthermore, good peak shapes and separation can be maintained under high concentration injections, indicating good potential in preparative use. These results were also compared with those obtained on two conventional RP stationary phases. The overall results demonstrated that SCX stationary phases can be used as alternatives to RP stationary phases in the separation of basic compounds, especially in the purification of basic compounds.
Source:Journal of Chromatography A, Volume 1256
Zhen Long, Chaoran Wang, Zhimou Guo, Xiuli Zhang, Lilly Nordahl, Xinmiao Liang
Strong cation exchange (SCX) mode, an alternative to reversed-phase (RP) mode, was described in this paper to obtain symmetrical peak shape and high sample loading for the separation of basic compounds. The retention mechanisms on SCX modified silica sorbents have been demonstrated including electrostatic and hydrophobic interactions. The effects of eluent ionic strength, apparent pH on retention were investigated and the cation-exchange capacity was also characterized. Good efficiency (>56,000platem−1) and excellent peak shape (Tf<1.2) for various basic probes were obtained on the SCX column. Furthermore, good peak shapes and separation can be maintained under high concentration injections, indicating good potential in preparative use. These results were also compared with those obtained on two conventional RP stationary phases. The overall results demonstrated that SCX stationary phases can be used as alternatives to RP stationary phases in the separation of basic compounds, especially in the purification of basic compounds.
Highlights
► Symmetric peaks can be obtained even with high amount of bases injected. ► Significant peak tailing or broadening is negative on SCX column. ► Good column efficiency can be obtained on SCX column.Maximizing the peak capacity using coupled columns packed with 2.6μm core–shell particles operated at 1200bar
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Axel Vaast, Jelle De Vos, Ken Broeckhoven, Matthias Verstraeten, Sebastiaan Eeltink, Gert Desmet
We report on the peak capacity that can be produced by operating a state-of-the-art core–shell particle type (d p =2.6μm) at its kinetic optimum at ultra-high pressures of 600 and 1200bar. The column-length optimization needed to arrive at this kinetic optimum was realized using column coupling. Whereas the traditional operating mode (using a single 15cm column operated at its optimum flow rate of 0.4mL/min) offered a peak capacity of 162 in 10.8min, a fully optimized train of 60cm (4×15cm) columns offered a peak capacity of 325 in 61min when operated at 1200bar. Even though the particles have a reputed low flow resistance and a relatively large size (>2μm), it was found that the increase in performance that can be generated when switching from a fully optimized 600bar operation to a fully optimized 1200bar operation is significant (roughly 50% reduction of the analysis time for the same peak capacity and approximately a 20% increase in peak capacity if compared for the same analysis time). This has been quantified in a generic way using the kinetic plot method and is illustrated by showing the chromatograms corresponding to some of the data points of the kinetic plot curve.
Source:Journal of Chromatography A, Volume 1256
Axel Vaast, Jelle De Vos, Ken Broeckhoven, Matthias Verstraeten, Sebastiaan Eeltink, Gert Desmet
We report on the peak capacity that can be produced by operating a state-of-the-art core–shell particle type (d p =2.6μm) at its kinetic optimum at ultra-high pressures of 600 and 1200bar. The column-length optimization needed to arrive at this kinetic optimum was realized using column coupling. Whereas the traditional operating mode (using a single 15cm column operated at its optimum flow rate of 0.4mL/min) offered a peak capacity of 162 in 10.8min, a fully optimized train of 60cm (4×15cm) columns offered a peak capacity of 325 in 61min when operated at 1200bar. Even though the particles have a reputed low flow resistance and a relatively large size (>2μm), it was found that the increase in performance that can be generated when switching from a fully optimized 600bar operation to a fully optimized 1200bar operation is significant (roughly 50% reduction of the analysis time for the same peak capacity and approximately a 20% increase in peak capacity if compared for the same analysis time). This has been quantified in a generic way using the kinetic plot method and is illustrated by showing the chromatograms corresponding to some of the data points of the kinetic plot curve.
Highlights
► Use of 2.6μm core–shell columns operated at 1200bar in gradient UHPLC. ► Coupling columns are needed to operate at the kinetic optimum at this pressure. ► Increased pressure results in a substantial gain in performance or analysis time. ► Even 2μm particles can benefit from a 1200bar operation limit.Simultaneous measurement in mass and mass/mass mode for accurate qualitative and quantitative screening analysis of pharmaceuticals in river water
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
M.J. Martínez Bueno, Maria M. Ulaszewska, M.J. Gomez, M.D. Hernando, A.R. Fernández-Alba
A new approach for the analysis of pharmaceuticals (target and non-target) in water by LC–QTOF-MS is described in this work. The study has been designed to assess the performance of the simultaneous quantitative screening of target compounds, and the qualitative analysis of non-target analytes, in just one run. The features of accurate mass full scan mass spectrometry together with high MS/MS spectral acquisition rates – by means of information dependent acquisition (IDA) – have demonstrated their potential application in this work. Applying this analytical strategy, an identification procedure is presented based on library searching for compounds which were not included a priori in the analytical method as target compounds, thus allowing their characterization by data processing of accurate mass measurements in MS and MS/MS mode. The non-target compounds identified in river water samples were ketorolac, trazodone, fluconazole, metformin and venlafaxine. Simultaneously, this strategy allowed for the identification of other compounds which were not included in the library by screening the highest intensity peaks detected in the samples and by analysis of the full scan TOF-MS, isotope pattern and MS/MS spectra – the example of loratadine (histaminergic) is described. The group of drugs of abuse selected as target compounds for evaluation included analgesics, opioids and psychostimulants. Satisfactory results regarding sensitivity and linearity of the developed method were obtained. Limits of detection for the selected target compounds were from 0.003 to 0.01μg/L and 0.01 to 0.5μg/L, in MS and MS/MS mode, respectively – by direct sample injection of 100μL.
Source:Journal of Chromatography A, Volume 1256
M.J. Martínez Bueno, Maria M. Ulaszewska, M.J. Gomez, M.D. Hernando, A.R. Fernández-Alba
A new approach for the analysis of pharmaceuticals (target and non-target) in water by LC–QTOF-MS is described in this work. The study has been designed to assess the performance of the simultaneous quantitative screening of target compounds, and the qualitative analysis of non-target analytes, in just one run. The features of accurate mass full scan mass spectrometry together with high MS/MS spectral acquisition rates – by means of information dependent acquisition (IDA) – have demonstrated their potential application in this work. Applying this analytical strategy, an identification procedure is presented based on library searching for compounds which were not included a priori in the analytical method as target compounds, thus allowing their characterization by data processing of accurate mass measurements in MS and MS/MS mode. The non-target compounds identified in river water samples were ketorolac, trazodone, fluconazole, metformin and venlafaxine. Simultaneously, this strategy allowed for the identification of other compounds which were not included in the library by screening the highest intensity peaks detected in the samples and by analysis of the full scan TOF-MS, isotope pattern and MS/MS spectra – the example of loratadine (histaminergic) is described. The group of drugs of abuse selected as target compounds for evaluation included analgesics, opioids and psychostimulants. Satisfactory results regarding sensitivity and linearity of the developed method were obtained. Limits of detection for the selected target compounds were from 0.003 to 0.01μg/L and 0.01 to 0.5μg/L, in MS and MS/MS mode, respectively – by direct sample injection of 100μL.
Highlights
► A strategy for qualitative/quantitative screening of PPCPs in water is proposed. ► Simultaneous screening of target and non-target analytes by accurate MS and MS/MS. ► An elucidation strategy for identification of unexpected compounds is described. ► By injecting large sample volumes (100μL) satisfactory results are obtained.Identification and quantification of 3-iodothyronamine metabolites in mouse serum using liquid chromatography–tandem mass spectrometry
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Sarah A. Hackenmueller, Thomas S. Scanlan
3-Iodothyronamine (T1AM) is an endogenous derivative of thyroxine. Recently there have been numerous reports of analytical methods to quantify endogenous T1AM levels, but substantial discrepancies in concentration depending on the method of analysis (LC–MS/MS or immunoassay) suggest endogenous T1AM may be covalently modified in vivo. Using information dependent acquisition methods to perform unbiased scans for T1AM metabolites following a single IP injection in mice, we have identified O-sulfonate-T1AM, N-acetyl-T1AM and T1AM-glucuronide as conjugates occurring in vivo, as well as the oxidatively deaminated 3-iodothyroacetic acid and non-iodinated thyroacetic acid. 3-iodothyroacetic acid, O-sulfonate-T1AM and T1AM-glucuronide are present in serum at greater concentrations that unmodified T1AM and all metabolites are extensively distributed to tissues. These results suggest covalent modifications of T1AM may play a critical role in regulating distribution and biological activity of T1AM, and analytical methods to quantify endogenous T1AM should be able to account for these metabolites as well.
Source:Journal of Chromatography A, Volume 1256
Sarah A. Hackenmueller, Thomas S. Scanlan
3-Iodothyronamine (T1AM) is an endogenous derivative of thyroxine. Recently there have been numerous reports of analytical methods to quantify endogenous T1AM levels, but substantial discrepancies in concentration depending on the method of analysis (LC–MS/MS or immunoassay) suggest endogenous T1AM may be covalently modified in vivo. Using information dependent acquisition methods to perform unbiased scans for T1AM metabolites following a single IP injection in mice, we have identified O-sulfonate-T1AM, N-acetyl-T1AM and T1AM-glucuronide as conjugates occurring in vivo, as well as the oxidatively deaminated 3-iodothyroacetic acid and non-iodinated thyroacetic acid. 3-iodothyroacetic acid, O-sulfonate-T1AM and T1AM-glucuronide are present in serum at greater concentrations that unmodified T1AM and all metabolites are extensively distributed to tissues. These results suggest covalent modifications of T1AM may play a critical role in regulating distribution and biological activity of T1AM, and analytical methods to quantify endogenous T1AM should be able to account for these metabolites as well.
Highlights
► T1AM metabolites were identified using information dependent acquisition methods. ► T1AM is extensively metabolized in mouse serum following a single IP injection. ► MRM LC–MS/MS methods were validated to quantify T1AM metabolites in serum. ► T1AM-glucuronide and Ac-T1AM were identified as novel compounds.Interaction of dodecaborate cluster compounds on hydrophilic column materials in water
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Ping Fan, Jennifer Neumann, Stefan Stolte, Jürgen Arning, Denise Ferreira, Katarina Edwards, Detlef Gabel
The interaction of a series of dodecaborate cluster compounds B12X12 2− and B12X11Y2− (X=H, Cl, Br, I and Y=SH, OH, NR3) with hydrophilic column materials (Superdex 200, Sepharose 4B, Sephadex G-50, Sephadex G-100, alumina, silica gel and anion exchange material) was studied. Almost all the dodecaborate cluster compounds were retained strongly on Superdex 200. The halogenated cluster compounds interacted with Sepharose 4B, Sephadex G-50, Sephadex G-100 and alumina; on alumina, also the non-halogenated clusters were retained. Silica gel showed the least interaction with all compounds. The thermodynamic parameters were investigated for a selection of compounds on Superdex 200 and Sephadex G-100. Values for ΔH° were found to be negative on both gels. As the change in entropy ΔS° was also negative, it compensated ΔH° to a large extent. The clusters interacted also strongly with anion exchange material in ion chromatography; the interaction decreased with increasing acetonitrile concentration, implying a large contribution from solvent effects.
Source:Journal of Chromatography A, Volume 1256
Ping Fan, Jennifer Neumann, Stefan Stolte, Jürgen Arning, Denise Ferreira, Katarina Edwards, Detlef Gabel
The interaction of a series of dodecaborate cluster compounds B12X12 2− and B12X11Y2− (X=H, Cl, Br, I and Y=SH, OH, NR3) with hydrophilic column materials (Superdex 200, Sepharose 4B, Sephadex G-50, Sephadex G-100, alumina, silica gel and anion exchange material) was studied. Almost all the dodecaborate cluster compounds were retained strongly on Superdex 200. The halogenated cluster compounds interacted with Sepharose 4B, Sephadex G-50, Sephadex G-100 and alumina; on alumina, also the non-halogenated clusters were retained. Silica gel showed the least interaction with all compounds. The thermodynamic parameters were investigated for a selection of compounds on Superdex 200 and Sephadex G-100. Values for ΔH° were found to be negative on both gels. As the change in entropy ΔS° was also negative, it compensated ΔH° to a large extent. The clusters interacted also strongly with anion exchange material in ion chromatography; the interaction decreased with increasing acetonitrile concentration, implying a large contribution from solvent effects.
Highlights
► Dodecaborate clusters are retained on hydrophilic matrices used for gel filtration. ► Interaction is driven by enthalpy, with entropy partly counter-acting the affinity. ► With alumina as matrix, retention is observed for some of the clusters. ► Silica retains the clusters the least, Superdex 200 the strongest. ► The phenomenon might be used to separate different dodecaborate clusters.Three-channel column-switching high-performance liquid chromatography with electrochemical detection for determining bioactive redox components in Salvia miltiorrhiza
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Xianchun Chen, Akira Kotani, Hideki Hakamata, Jie Wang, Shouying Du, Fumiyo Kusu
Three-channel column-switching high-performance liquid chromatography with electrochemical detection (3LC-3ED), which consists of three flow ways, two switching valves, four columns, and three electrochemical detectors, was developed for determining various redox components in Salvia miltiorrhiza with high sensitivity. In this study, the analytes were divided into three groups as follow: Group I [salvianic acid A (Danshensu) sodium salt (DSS), protocatechuic acid (PA), protocatechuic aldehyde (PAD), and caffeic acid (CA)], Group II [rosmarinic acid (RA), lithospermic acid (LA), and salvianolic acid B (SAB)], and Group III [cryptotanshinone (Cry), tanshinone I (Tan I), and tanshinone IIA (Tan IIA)]. By rotating each switching valve to change the elute flow way, the components in Groups I, II, and III were directed into the oxidative (+0.7V), another oxidative (+0.7V), and reductive (−0.2V) detection channels, respectively. Chromatographic peaks of components in Groups I, II, and III appeared within 69, 53, and 60min, respectively, in each channel. The detection limits of DSS, PA, PAD, CA, RA, LA, SAB, Cry, Tan I, and Tan IIA were 4.2, 2.8, 10, 10, 3.9, 3.8, 3.0, 132, 119, and 109fmol, respectively, thus the sensitivity by the present 3LC-3ED is superior to those of previously reported gradient LC-ED and LC with UV detection. As an application, the phenolic acid contents and tanshinones in nine batches of S. miltiorrhiza were successfully determined.
Source:Journal of Chromatography A, Volume 1256
Xianchun Chen, Akira Kotani, Hideki Hakamata, Jie Wang, Shouying Du, Fumiyo Kusu
Three-channel column-switching high-performance liquid chromatography with electrochemical detection (3LC-3ED), which consists of three flow ways, two switching valves, four columns, and three electrochemical detectors, was developed for determining various redox components in Salvia miltiorrhiza with high sensitivity. In this study, the analytes were divided into three groups as follow: Group I [salvianic acid A (Danshensu) sodium salt (DSS), protocatechuic acid (PA), protocatechuic aldehyde (PAD), and caffeic acid (CA)], Group II [rosmarinic acid (RA), lithospermic acid (LA), and salvianolic acid B (SAB)], and Group III [cryptotanshinone (Cry), tanshinone I (Tan I), and tanshinone IIA (Tan IIA)]. By rotating each switching valve to change the elute flow way, the components in Groups I, II, and III were directed into the oxidative (+0.7V), another oxidative (+0.7V), and reductive (−0.2V) detection channels, respectively. Chromatographic peaks of components in Groups I, II, and III appeared within 69, 53, and 60min, respectively, in each channel. The detection limits of DSS, PA, PAD, CA, RA, LA, SAB, Cry, Tan I, and Tan IIA were 4.2, 2.8, 10, 10, 3.9, 3.8, 3.0, 132, 119, and 109fmol, respectively, thus the sensitivity by the present 3LC-3ED is superior to those of previously reported gradient LC-ED and LC with UV detection. As an application, the phenolic acid contents and tanshinones in nine batches of S. miltiorrhiza were successfully determined.
Highlights
► A novel three-channel HPLC with electrochemical detection (3LC-3ED) was developed. ► The 3LC-3ED has oxidative and reductive detection channels in an isocratic run. ► The seven phenolic acids (PHAs) and three tanshinones (TANs) are analytes. ► Femtomole level determination of PHAs and TANs were performed within 70min. ► The 3LC-3ED was applied to the analysis of Salvia miltiorrhiza.Preparation of organic-silica hybrid boronate affinity monolithic column for the specific capture and separation of cis-diol containing compounds
28 August 2012,
09:53:23
Publication year:
2012
Source:Journal of Chromatography A, Volume 1256
Qianjin Li, Chenchen Lü, Hengye Li, Yunchun Liu, Heye Wang, Xin Wang, Zhen Liu
A new boronate-silica hybrid monolithic column was prepared using a one-pot approach with 3-acrylamidophenylboronic acid (AAPBA) as the boronate affinity ligand. The AAPBA-silica monolith exhibited several attractive advantages. First, it is highly hydrophilic, providing excellent specificity and avoiding the presence of organic solvent in the mobile phase. Second, due to its large surface area, it exhibited a high binding capacity, 49.5μmol/mL, the highest among the boronate affinity monolithic columns appeared in the literature. Third, the monolith can bind with cis-diol containing compounds at pH as low as 6.5, which not only avoids the use of basic pH conditions at which the silica monolith may hydrolysis but also facilitates the applications to wider sample range. Finally, the hybrid monolithic column exhibited apparent secondary separation capability, which allows for two-dimensional (2D) separation of cis-diol compounds in a single column. Due to these merits, the AAPBA-silica hybrid monolithic column can be a promising separation medium for the analysis of cis-diol containing compounds.
Source:Journal of Chromatography A, Volume 1256
Qianjin Li, Chenchen Lü, Hengye Li, Yunchun Liu, Heye Wang, Xin Wang, Zhen Liu
A new boronate-silica hybrid monolithic column was prepared using a one-pot approach with 3-acrylamidophenylboronic acid (AAPBA) as the boronate affinity ligand. The AAPBA-silica monolith exhibited several attractive advantages. First, it is highly hydrophilic, providing excellent specificity and avoiding the presence of organic solvent in the mobile phase. Second, due to its large surface area, it exhibited a high binding capacity, 49.5μmol/mL, the highest among the boronate affinity monolithic columns appeared in the literature. Third, the monolith can bind with cis-diol containing compounds at pH as low as 6.5, which not only avoids the use of basic pH conditions at which the silica monolith may hydrolysis but also facilitates the applications to wider sample range. Finally, the hybrid monolithic column exhibited apparent secondary separation capability, which allows for two-dimensional (2D) separation of cis-diol compounds in a single column. Due to these merits, the AAPBA-silica hybrid monolithic column can be a promising separation medium for the analysis of cis-diol containing compounds.
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