Determination of homogentisic acid in urine for diagnosis of alcaptonuria: Capillary electrophoretic method optimization using experimental design

Homogentisic acid (HGA) is a diagnostic metabolite that accumulates in the urine and tissues of patients with alkaptonuria which is a rare autosomal recessive disease. HGA is a specific metabolite in urine and serum, which is used for diagnosis of alkaptonuria. This study presents an inexpensive and easy capillary electrophoretic (CE) method for the quantitative determination of HGA in urine samples. CE method were optimized using full factorial experimental design. The optimal separation electrolyte and separation voltage were revealed as 45 mmol/L phosphate buffer at pH 7.0 and 22 kV, respectively. Under these conditions the presence of HGA is detected in 6 min. Repeatability of migration times and corrected peak areas of HGA (as R.S.D.%) were found as 0.37 and 1.99, respectively. The detection limit (LOD) was 0.56 μg/mL as 3 times of the average noise and the quantification limit (LOQ) was 1.85 μg/mL as 10 times of the average noise for HGA. Urine samples were directly injected to the capillary without any pretreatment step.

Abstract

Homogentisic acid (HGA) is a diagnostic metabolite that accumulates in the urine and tissues of patients with alkaptonuria which is a rare autosomal recessive disease. HGA is a specific metabolite in urine and serum, which is used for diagnosis of alkaptonuria. This study presents an inexpensive and easy capillary electrophoretic (CE) method for the quantitative determination of HGA in urine samples. CE method were optimized using full factorial experimental design. The optimal separation electrolyte and separation voltage were revealed as 45 mmol/L phosphate buffer at pH 7.0 and 22 kV, respectively. Under these conditions the presence of HGA is detected in 6 min. Repeatability of migration times and corrected peak areas of HGA (as R.S.D.%) were found as 0.37 and 1.99, respectively. The detection limit (LOD) was 0.56 μg/mL as 3 times of the average noise and the quantification limit (LOQ) was 1.85 μg/mL as 10 times of the average noise for HGA. Urine samples were directly injected to the capillary without any pretreatment step.

Colloidal lithography-based fabrication of highly-ordered nanofluidic channels with an ultra-high surface-to-volume ratio

Lab Chip, 2018, Accepted ManuscriptDOI: 10.1039/C7LC01326D, PaperShuli Wang, Yongshun Liu, Peng Ge, Qiqi Kan, Nianzuo Yu, Jing Wang, Jingjie Nan, Shunsheng Ye, Junhu Zhang, Weiqing Xu, Bai YangThis article shows a new strategy for the fabrication of na…

Lab Chip, 2018, Accepted Manuscript
DOI: 10.1039/C7LC01326D, Paper
Shuli Wang, Yongshun Liu, Peng Ge, Qiqi Kan, Nianzuo Yu, Jing Wang, Jingjie Nan, Shunsheng Ye, Junhu Zhang, Weiqing Xu, Bai Yang
This article shows a new strategy for the fabrication of nanofluidics based on nanoscale gaps in nanopillar arrays. Silicon nanopillar arrays are prepared in designed position by combining conventional photolithography...
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Analysis of new psychoactive substances in human urine by ultra high performance supercritical fluid and liquid chromatography: Validation and comparison

New psychoactive substances represent serious social and health problem as tens of new compounds are detected in Europe annually. They often show structural proximity or even isomerism which complicates their analysis. Two methods based on ultra high performance supercritical fluid chromatography and ultra high performance liquid chromatography with mass spectrometric detection were validated and compared. A simple dilute-filter-and-shoot protocol utilizing propan-2-ol or methanol for supercritical fluid or liquid chromatography, respectively, was proposed to detect and quantify 15 cathinones and phenethylamines in human urine. Both methods offered fast separation (<3 min) and short total analysis time. Precision was well below 15% with a few exceptions in liquid chromatography. Limits of detection in urine ranged from 0.01 to 2.3 ng/mL, except for cathinone (5 ng/mL) in supercritical fluid chromatography. Nevertheless, this technique distinguished all analytes including four pairs of isomers, while liquid chromatography was unable to resolve fluoromethcathinone regioisomers. Concerning matrix effects and recoveries, supercritical fluid chromatography produced more uniform results for different compounds and at different concentration levels. This work demonstrates the performance and reliability of supercritical fluid chromatography and corroborates its applicability as an alternative tool for analysis of new psychoactive substances in biological matrixes.
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Abstract

New psychoactive substances represent serious social and health problem as tens of new compounds are detected in Europe annually. They often show structural proximity or even isomerism which complicates their analysis. Two methods based on ultra high performance supercritical fluid chromatography and ultra high performance liquid chromatography with mass spectrometric detection were validated and compared. A simple dilute-filter-and-shoot protocol utilizing propan-2-ol or methanol for supercritical fluid or liquid chromatography, respectively, was proposed to detect and quantify 15 cathinones and phenethylamines in human urine. Both methods offered fast separation (<3 min) and short total analysis time. Precision was well below 15% with a few exceptions in liquid chromatography. Limits of detection in urine ranged from 0.01 to 2.3 ng/mL, except for cathinone (5 ng/mL) in supercritical fluid chromatography. Nevertheless, this technique distinguished all analytes including four pairs of isomers, while liquid chromatography was unable to resolve fluoromethcathinone regioisomers. Concerning matrix effects and recoveries, supercritical fluid chromatography produced more uniform results for different compounds and at different concentration levels. This work demonstrates the performance and reliability of supercritical fluid chromatography and corroborates its applicability as an alternative tool for analysis of new psychoactive substances in biological matrixes.

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Amino acid racemization and its relation to geochronology and archaeometry

Amino acid racemization, used as a method of relative and quantitative dating of fossils, evaluates the degree of postmortem conversion of l to d amino acid enantiomers. While extensively utilized, this method has garnered confusion due to controversial age estimates for human fossils in North America in the 1970s. This paper explains the age controversy and aftermath, current chromatographic methods used in research, mathematical calibration models, and a short synopsis of other dating techniques in geochronology and archaeometry.
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Abstract

Amino acid racemization, used as a method of relative and quantitative dating of fossils, evaluates the degree of postmortem conversion of l to d amino acid enantiomers. While extensively utilized, this method has garnered confusion due to controversial age estimates for human fossils in North America in the 1970s. This paper explains the age controversy and aftermath, current chromatographic methods used in research, mathematical calibration models, and a short synopsis of other dating techniques in geochronology and archaeometry.

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A novel technique for determination of the fructose, glucose and sucrose distribution in nectar from orchids by HPLC-ELSD

Publication date: Available online 18 February 2018
Source:Journal of Chromatography B
Author(s): Dan Nybro Lindqvist, Henrik Ærenlund Pedersen, Lars Holm Rasmussen
The dominant components in floral nectar is fructose, glucose and sucrose. The concentration and the ratio between the sugars are indicative for plant species and play an important part in the interplay between plants and pollinators. In this paper we present a novel HPLC-ELSD based analytical method for sugar characterization of nectar from orchids. Nectar was collected on Whatman No. 1 paper and preserved in the field by 70 v/v% ethanol. The analytical method had a linear range up to at least 3000 mg L−1 for all 3 sugars with a precision of 1.5–1.7%. Correlation coefficients were 0.9999 to 1.0000. The LOD of all sugars were 5–7 mg L−1 and the LOQ were 17–19 mg L−1. Field samples were stable for min. 7 weeks at −18 °C. The technique was applied to two species of Platanthera (Orchidaceae) in order to test whether species-related differences in sugar composition could be observed. No differences were found between the two species, which were sucrose-dominant (53.5–100%) though with high variation within species and between individual flowers.

Publication date: Available online 18 February 2018
Source:Journal of Chromatography B

Author(s): Dan Nybro Lindqvist, Henrik Ærenlund Pedersen, Lars Holm Rasmussen

The dominant components in floral nectar is fructose, glucose and sucrose. The concentration and the ratio between the sugars are indicative for plant species and play an important part in the interplay between plants and pollinators. In this paper we present a novel HPLC-ELSD based analytical method for sugar characterization of nectar from orchids. Nectar was collected on Whatman No. 1 paper and preserved in the field by 70 v/v% ethanol. The analytical method had a linear range up to at least 3000 mg L−1 for all 3 sugars with a precision of 1.5–1.7%. Correlation coefficients were 0.9999 to 1.0000. The LOD of all sugars were 5–7 mg L−1 and the LOQ were 17–19 mg L−1. Field samples were stable for min. 7 weeks at −18 °C. The technique was applied to two species of Platanthera (Orchidaceae) in order to test whether species-related differences in sugar composition could be observed. No differences were found between the two species, which were sucrose-dominant (53.5–100%) though with high variation within species and between individual flowers.





Synthesis and characterization of Ag+-decorated poly(glycidyl methacrylate) microparticle design for the adsorption of nucleic acids

Publication date: Available online 18 February 2018
Source:Journal of Chromatography B
Author(s): Kadir Erol, Aytekin Uzunoglu, Kazım Köse, Büşra Sarıca, Emre Avcı, Dursun A. Köse
In this study, we report on the adsorption of RNA and DNA molecules by exploiting the high binding affinity of these nucleic acids to Ag+ ions anchored on magnetic poly(glycidyl methacrylate) (PGMA) microparticles. PGMA microparticles were synthesized and modified with nicotinamide which enabled to anchor Ag+ ions on the surface. The successful preparation of PGMA was confirmed by the presence of characteristic FTIR peaks. The ESR results showed that the incorporation of FeNi salt to the polymeric structure provided a magnetic property to the microparticles. The amount of nicotinamide and Ag+ ions used to modify the surface of the particles were found to be 1.79 wt% and 52.6 mg Ag/g microparticle, respectively. The high affinity of nucleic acids to Ag+ ions were exploited for the adsorption studies. At the optimum working conditions, the adsorption capacity of microparticles was found to be 40.1 and 11.48 mg nucleic acid/g microparticle for RNA and DNA, respectively. Our study indicated that the use of novel Ag+-decorated magnetic PGMA particles can be successfully employed as adsorbents for fast, easy, and cost-friendly adsorption of nucleic acids with high purity as well as high in quantity.

Publication date: Available online 18 February 2018
Source:Journal of Chromatography B

Author(s): Kadir Erol, Aytekin Uzunoglu, Kazım Köse, Büşra Sarıca, Emre Avcı, Dursun A. Köse

In this study, we report on the adsorption of RNA and DNA molecules by exploiting the high binding affinity of these nucleic acids to Ag+ ions anchored on magnetic poly(glycidyl methacrylate) (PGMA) microparticles. PGMA microparticles were synthesized and modified with nicotinamide which enabled to anchor Ag+ ions on the surface. The successful preparation of PGMA was confirmed by the presence of characteristic FTIR peaks. The ESR results showed that the incorporation of FeNi salt to the polymeric structure provided a magnetic property to the microparticles. The amount of nicotinamide and Ag+ ions used to modify the surface of the particles were found to be 1.79 wt% and 52.6 mg Ag/g microparticle, respectively. The high affinity of nucleic acids to Ag+ ions were exploited for the adsorption studies. At the optimum working conditions, the adsorption capacity of microparticles was found to be 40.1 and 11.48 mg nucleic acid/g microparticle for RNA and DNA, respectively. Our study indicated that the use of novel Ag+-decorated magnetic PGMA particles can be successfully employed as adsorbents for fast, easy, and cost-friendly adsorption of nucleic acids with high purity as well as high in quantity.





Simple method for the determination of personal care product ingredients in lettuce by ultrasound-assisted extraction combined with solid-phase microextraction followed by GC–MS

A simple method for the simultaneous determination of personal care product ingredients: galaxolide, tonalide, oxybenzone, 4-methylbenzyliden camphor, padimate-o, 2-ethylhexyl methoxycinnamate, octocrylene, triclosan and methyl triclosan in lettuce by ultrasound-assisted extraction combined with solid-phase microextraction followed by gas chromatography with mass spectrometry was developed. Lettuce was directly extracted by ultrasound-assisted extraction with methanol, this extract was combined with water, extracted by solid-phase microextraction in immersion mode and analyzed by gas chromatography with mass spectrometry. Good linear relationships (25–250 ng g−1, R2 > 0.9702) and low detection limits (1.0–25 ng g−1) were obtained for analytes along with acceptable precision for almost all analytes (RSDs < 20%). The validated method was applied for the determination of personal care product ingredients in commercial lettuce and lettuces grown in soil and irrigated with the analytes, identifying the target analytes in leaves and roots of the latter. This procedure is a miniaturized and environmentally friendly proposal which can be a useful tool for quality analysis in lettuce.
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Abstract

A simple method for the simultaneous determination of personal care product ingredients: galaxolide, tonalide, oxybenzone, 4-methylbenzyliden camphor, padimate-o, 2-ethylhexyl methoxycinnamate, octocrylene, triclosan and methyl triclosan in lettuce by ultrasound-assisted extraction combined with solid-phase microextraction followed by gas chromatography with mass spectrometry was developed. Lettuce was directly extracted by ultrasound-assisted extraction with methanol, this extract was combined with water, extracted by solid-phase microextraction in immersion mode and analyzed by gas chromatography with mass spectrometry. Good linear relationships (25–250 ng g−1, R> 0.9702) and low detection limits (1.0–25 ng g−1) were obtained for analytes along with acceptable precision for almost all analytes (RSDs < 20%). The validated method was applied for the determination of personal care product ingredients in commercial lettuce and lettuces grown in soil and irrigated with the analytes, identifying the target analytes in leaves and roots of the latter. This procedure is a miniaturized and environmentally friendly proposal which can be a useful tool for quality analysis in lettuce.

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Effect of the flow profile on separation efficiency in pressure-assisted reversed-polarity capillary zone electrophoresis of anions: Simulation and experimental evaluation

Capillary electrophoresis connected to electrospray ionization mass spectrometry is a promising combination to analyze complex biological samples. The use of sheathless electrospray ionization interfaces, such as a porous nanoelectrospray capillary emitter, requires the application of forward flow (either by pressure or electroosmosis) to maintain the electrospray process. The analysis of solute molecules with strong negative charges (e.g., aminopyrenetrisulfonate labeled glycans) necessitates a reversed-polarity capillary electrophoresis separation mode, in which case the electroosmotic flow is counter current, thus pressure assistance is necessary. In this study, we compared the effect of forced convection with and without counter electroosmotic flow on the resulting separation efficiency in capillary electrophoresis based on flow profile simulations by computational fluid dynamics technique and by actual experiments. The efficiencies of the detected peaks were calculated from the resulting electropherograms and found approximately 790 000 plates/m for electrophoresis with counter electroosmotic flow, 16 000 plates/m with pressure only (such as would be in open tubular liquid chromatography) and 400 000 plates/m for electrophoresis with simultaneous counter electroosmotic flow and forward pressure assistance, which validates the simulation data.
This article is protected by copyright. All rights reserved

Abstract

Capillary electrophoresis connected to electrospray ionization mass spectrometry is a promising combination to analyze complex biological samples. The use of sheathless electrospray ionization interfaces, such as a porous nanoelectrospray capillary emitter, requires the application of forward flow (either by pressure or electroosmosis) to maintain the electrospray process. The analysis of solute molecules with strong negative charges (e.g., aminopyrenetrisulfonate labeled glycans) necessitates a reversed-polarity capillary electrophoresis separation mode, in which case the electroosmotic flow is counter current, thus pressure assistance is necessary. In this study, we compared the effect of forced convection with and without counter electroosmotic flow on the resulting separation efficiency in capillary electrophoresis based on flow profile simulations by computational fluid dynamics technique and by actual experiments. The efficiencies of the detected peaks were calculated from the resulting electropherograms and found approximately 790 000 plates/m for electrophoresis with counter electroosmotic flow, 16 000 plates/m with pressure only (such as would be in open tubular liquid chromatography) and 400 000 plates/m for electrophoresis with simultaneous counter electroosmotic flow and forward pressure assistance, which validates the simulation data.

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Comparisons of the pharmacokinetic and tissue distribution profiles of withanolide B after intragastric administration of the effective part of Datura metel L. in normal and psoriasis guinea pigs

Publication date: Available online 17 February 2018
Source:Journal of Chromatography B
Author(s): Lianrong Yang, Xin Meng, HaixueKuang
A simple, highly sensitive ultra-performance liquid chromatography- electrospray ionization-mass spectrometry (LC-ESI-MS) method has been developed to quantify of withanolide B and obakunone (IS) in guinea pig plasma and tissues, and to compare the pharmacokinetics and tissue distribution of withanolide B in normal and psoriasis guinea pigs. After mixing with IS, plasma and tissues were pretreated by protein precipitation with methanol. Chromatographic separation was performed on a C18 column using aqueous (0.1% formic acid) and acetonitrile (0.1% formic acid) solutions at 0.4 mL/min as the mobile phase. The gradient program was selected (0–4.0 min, 2–98% B; 4.0–4.5 min, 98–2% B; and 4.5–5 min, 2% B). Detection was performed on a 4000 QTRAP UPLC–ESI-MS/MS system from AB Sciex in the multiple reaction monitoring (MRM) mode. Withanolide B and obakunone (IS) were monitored under positive ionization conditions. The optimized mass transition ion-pairs (m/z) for quantitation were 455.1/109.4 for withanolide B and 455.1/161.1 for obakunone.

Publication date: Available online 17 February 2018
Source:Journal of Chromatography B

Author(s): Lianrong Yang, Xin Meng, HaixueKuang

A simple, highly sensitive ultra-performance liquid chromatography- electrospray ionization-mass spectrometry (LC-ESI-MS) method has been developed to quantify of withanolide B and obakunone (IS) in guinea pig plasma and tissues, and to compare the pharmacokinetics and tissue distribution of withanolide B in normal and psoriasis guinea pigs. After mixing with IS, plasma and tissues were pretreated by protein precipitation with methanol. Chromatographic separation was performed on a C18 column using aqueous (0.1% formic acid) and acetonitrile (0.1% formic acid) solutions at 0.4 mL/min as the mobile phase. The gradient program was selected (0–4.0 min, 2–98% B; 4.0–4.5 min, 98–2% B; and 4.5–5 min, 2% B). Detection was performed on a 4000 QTRAP UPLC–ESI-MS/MS system from AB Sciex in the multiple reaction monitoring (MRM) mode. Withanolide B and obakunone (IS) were monitored under positive ionization conditions. The optimized mass transition ion-pairs (m/z) for quantitation were 455.1/109.4 for withanolide B and 455.1/161.1 for obakunone.





A UPLC-ESI-Q-TOF method for rapid and reliable identification and quantification of major indole alkaloids in Catharanthus roseus

Publication date: Available online 17 February 2018
Source:Journal of Chromatography B
Author(s): Won Tae Jeong, Heung Bin Lim
We developed a novel ultra performance liquid chromatography-quadrupole time-of-flight (UPLC-Q-TOF) mass spectrometry method that allows sensitive, rapid, and reliable detection and identification of six representative indole alkaloids (vincristine, vinblastine, ajmalicine, catharanthine, serpentine, and vindoline) that exhibit physiological activity in Catharanthus roseus (C. roseus). The alkaloids were eluted on a C18 column with acetonitrile and water containing 0.1% formic acid and 10 mM ammonium acetate, and separated with good resolution within 13 min. Electrospray ionization-Q-TOF (ESI-Q-TOF) analysis was performed to characterize the molecules and their fragment ions, and the characteristic ions and fragmentation patterns were used as to identify the alkaloids. The proposed analytical method was verified in reference to the ICH guidelines and the results showed excellent linearity (R2 &gt; 0.9988), limit of detection (1 ng/mL to 10 ng/mL), limit of quantification (3 ng/mL to 30 ng/mL), intra-day and inter-day precisions, and extraction recovery rates (92.8% to 104.1%) for all components. The validated UPLC-Q-TOF method was applied to the analysis of extracts from the root, stem, and leaves of C. roseus, allowing the identification of six alkaloids by comparison of retention times, molecular ions, and fragmentation patterns with those of reference compounds. Sixteen additional indole alkaloids were tentatively identified by comparison of chromatograms to chemical databases and literature reports. The contents of bis-indole alkaloids (vincristine and vinblastine) were high in the aerial parts, while the contents of mono-indole alkaloids (ajmalicine, catharanthine, serpentine, and vindoline) were high in the roots. The present results demonstrate that the proposed UPLC-Q-TOF method can be useful for the investigation of phytochemical constituents of medicinal plants.

Publication date: Available online 17 February 2018
Source:Journal of Chromatography B

Author(s): Won Tae Jeong, Heung Bin Lim

We developed a novel ultra performance liquid chromatography-quadrupole time-of-flight (UPLC-Q-TOF) mass spectrometry method that allows sensitive, rapid, and reliable detection and identification of six representative indole alkaloids (vincristine, vinblastine, ajmalicine, catharanthine, serpentine, and vindoline) that exhibit physiological activity in Catharanthus roseus (C. roseus). The alkaloids were eluted on a C18 column with acetonitrile and water containing 0.1% formic acid and 10 mM ammonium acetate, and separated with good resolution within 13 min. Electrospray ionization-Q-TOF (ESI-Q-TOF) analysis was performed to characterize the molecules and their fragment ions, and the characteristic ions and fragmentation patterns were used as to identify the alkaloids. The proposed analytical method was verified in reference to the ICH guidelines and the results showed excellent linearity (R2 &gt; 0.9988), limit of detection (1 ng/mL to 10 ng/mL), limit of quantification (3 ng/mL to 30 ng/mL), intra-day and inter-day precisions, and extraction recovery rates (92.8% to 104.1%) for all components. The validated UPLC-Q-TOF method was applied to the analysis of extracts from the root, stem, and leaves of C. roseus, allowing the identification of six alkaloids by comparison of retention times, molecular ions, and fragmentation patterns with those of reference compounds. Sixteen additional indole alkaloids were tentatively identified by comparison of chromatograms to chemical databases and literature reports. The contents of bis-indole alkaloids (vincristine and vinblastine) were high in the aerial parts, while the contents of mono-indole alkaloids (ajmalicine, catharanthine, serpentine, and vindoline) were high in the roots. The present results demonstrate that the proposed UPLC-Q-TOF method can be useful for the investigation of phytochemical constituents of medicinal plants.





Supercritical fluid chromatographic-tandem mass spectrometry method for monitoring dissipation of thiacloprid in greenhouse vegetables and soil under different application modes

Publication date: Available online 16 February 2018
Source:Journal of Chromatography B
Author(s): Runan Li, Zenglong Chen, Fengshou Dong, Jun Xu, Xingang Liu, Xiaohu Wu, Xinglu Pan, Yan Tao, Yongquan Zheng
A rapid, sensitive and effective supercritical fluid chromatographic-tandem mass spectrometry (SFC-MS/MS) method was developed to analyze thiacloprid for the first time. The SFC-MS/MS conditions were optimized with the ultra-performance convergence chromatography (UPC2) BEH column (100 mm × 3.0 mm, 1.7 μm particle size) and thiacloprid was eluted at 1.22 min in gradient mode with CO2/methanol as mobile phase. The 0.1% formic acid in methanol (v/v) was used as postcolumn compensation solution to improve sensitivity. The ABPR pressure, flow rate of mobile phase and flow rate of compensation pump were set at 1800 psi, 1.8 mL/min, and 0.1 mL/min, respectively. The average recoveries of thiacloprid in soil at four spiking levels (5, 10, 100, 1000 μg/kg) ranged between 78.8% and 107.1% with relative standard deviations (RSDs) lower than 12.2% and the limit of quantitation (LOQ) was 5 μg/kg. The proposed method can distinctly improve the analysis efficiency by 2–12 times and reduce the solvent consumption by 5%–95% compared with reported methods. It was applied to investigate the dissipation rates of thiacloprid in greenhouse vegetables and soil under different application modes. The half-lives of thiacloprid in cucumber and soil were 9.55–20.44 days and 3.74–9.14 days separately under different application modes, 10.60 days in tomato under foliar spraying. The residues in vegetables under root irrigation were all less than that under foliar spraying. The results could offer useful data for risk assessment of thiacloprid in agricultural production.

Publication date: Available online 16 February 2018
Source:Journal of Chromatography B

Author(s): Runan Li, Zenglong Chen, Fengshou Dong, Jun Xu, Xingang Liu, Xiaohu Wu, Xinglu Pan, Yan Tao, Yongquan Zheng

A rapid, sensitive and effective supercritical fluid chromatographic-tandem mass spectrometry (SFC-MS/MS) method was developed to analyze thiacloprid for the first time. The SFC-MS/MS conditions were optimized with the ultra-performance convergence chromatography (UPC2) BEH column (100 mm × 3.0 mm, 1.7 μm particle size) and thiacloprid was eluted at 1.22 min in gradient mode with CO2/methanol as mobile phase. The 0.1% formic acid in methanol (v/v) was used as postcolumn compensation solution to improve sensitivity. The ABPR pressure, flow rate of mobile phase and flow rate of compensation pump were set at 1800 psi, 1.8 mL/min, and 0.1 mL/min, respectively. The average recoveries of thiacloprid in soil at four spiking levels (5, 10, 100, 1000 μg/kg) ranged between 78.8% and 107.1% with relative standard deviations (RSDs) lower than 12.2% and the limit of quantitation (LOQ) was 5 μg/kg. The proposed method can distinctly improve the analysis efficiency by 2–12 times and reduce the solvent consumption by 5%–95% compared with reported methods. It was applied to investigate the dissipation rates of thiacloprid in greenhouse vegetables and soil under different application modes. The half-lives of thiacloprid in cucumber and soil were 9.55–20.44 days and 3.74–9.14 days separately under different application modes, 10.60 days in tomato under foliar spraying. The residues in vegetables under root irrigation were all less than that under foliar spraying. The results could offer useful data for risk assessment of thiacloprid in agricultural production.





Entropic trap purification of long DNA

Lab Chip, 2018, Accepted ManuscriptDOI: 10.1039/C7LC01355H, PaperPranav Agrawal, Zsofia Bognar, Kevin DorfmanLong-read genomic applications, such as genome mapping in nanochannels, require long DNA that is free of small-DNA impurities. We have develope…

Lab Chip, 2018, Accepted Manuscript
DOI: 10.1039/C7LC01355H, Paper
Pranav Agrawal, Zsofia Bognar, Kevin Dorfman
Long-read genomic applications, such as genome mapping in nanochannels, require long DNA that is free of small-DNA impurities. We have developed a chip-based system based on entropic trapping that can...
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Lateral Flow Assay with Pressure Meter Readout for Rapid Point-of-care Detection of Disease-associated Protein

Lab Chip, 2018, Accepted ManuscriptDOI: 10.1039/C8LC00010G, PaperBingqian Lin, Zhichao Guan, Yanling Song, Eunyeong Song, Zifei Lu, Dan Liu, Yuan An, Zhi Zhu, Leiji Zhou, Chaoyong James YangPaper-based assays such as lateral flow assays are good cand…

Lab Chip, 2018, Accepted Manuscript
DOI: 10.1039/C8LC00010G, Paper
Bingqian Lin, Zhichao Guan, Yanling Song, Eunyeong Song, Zifei Lu, Dan Liu, Yuan An, Zhi Zhu, Leiji Zhou, Chaoyong James Yang
Paper-based assays such as lateral flow assays are good candidates for portable diagnostic owing to their user-friendly format and low cost. In terms of analytical detection, the lateral flow assays...
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Molecular imprinted polymers based on magnetic chitosan with different deep eutectic solvent monomers for the selective separation of catechins in black tea

Two types of molecular-imprinted polymers-based magnetic chitosan with facile deep eutectic solvent-functional monomers (Fe3O4-CTS@DES-MIPs) were synthesized and applied as adsorbents in magnetic solid-phase extraction (MSPE) for the selective recognition and separation of (+)-catechin, (−)-epicatechin, and (−)-epigallocatechin gallate in black tea. The obtained Fe3O4-CTS@DES-MIPs were characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The selective recognition ability was examined by adsorption experiments. The actual amounts of (+)-catechin, (−)-epicatechin, and (−)-epigallocatechin gallate extracted from black tea using Fe3O4-CTS@DES-MIPs by the MSPE method were 13.10 mg g−1, 6.32 mg g−1, and 8.76 mg g−1, respectively. In addition, the magnetic Fe3O4-CTS@DES-MIPs showed outstanding recognition and selectivity. Therefore, it can be used to separate bioactive compounds from black tea. The new-type of DES adopted as the functional monomer in this paper provides a new perspective for the recognition and separation of bioactive compounds.
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Abstract

Two types of molecular-imprinted polymers-based magnetic chitosan with facile deep eutectic solvent-functional monomers (Fe3O4-CTS@DES-MIPs) were synthesized and applied as adsorbents in magnetic solid-phase extraction (MSPE) for the selective recognition and separation of (+)-catechin, (−)-epicatechin, and (−)-epigallocatechin gallate in black tea. The obtained Fe3O4-CTS@DES-MIPs were characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The selective recognition ability was examined by adsorption experiments. The actual amounts of (+)-catechin, (−)-epicatechin, and (−)-epigallocatechin gallate extracted from black tea using Fe3O4-CTS@DES-MIPs by the MSPE method were 13.10 mg g−1, 6.32 mg g−1, and 8.76 mg g−1, respectively. In addition, the magnetic Fe3O4-CTS@DES-MIPs showed outstanding recognition and selectivity. Therefore, it can be used to separate bioactive compounds from black tea. The new-type of DES adopted as the functional monomer in this paper provides a new perspective for the recognition and separation of bioactive compounds.

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Application of off-line two-dimensional high-performance countercurrent chromatography on the chloroform-soluble extract of Cuscuta auralis seeds

In this study, the chloroform-soluble extract of C. auralis was separated successfully using off-line two-dimensional high-performance countercurrent chromatography, yielding a γ-pyrone, two alkaloids, a flavonoid and four lignans. The first-dimensional countercurrent separation using a methylene chloride/methanol/water (11:6:5, v/v/v) system yielded three sub-fractions (fractions I–III). The second-dimensional countercurrent separations, conducted on fractions I–III using n-hexane/ethyl and acetate/methanol/acetic acid (5:5:5:5:0, 3:7:3:7:0 and 1:9:1:9:0.01, v/v/v/v/v) systems, gave maltol (1), (−)-(13S)-cuscutamine (2), (+)-(13R)-cuscutamine (3), (+)-pinoresinol (4), (+)-epipinoresinol (5), kaempferol (6), piperitol (7) and (9R)-hydroxy-d-sesamin (8). To the best of our knowledge, maltol was identified for the first time in Cuscuta species. Furthermore, this report details the first full assignment of spectroscopic data of two cuscutamine epimers, (−)-(13S)-cuscutamine and (+)-(13R)-cuscutamine.
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Abstract

In this study, the chloroform-soluble extract of C. auralis was separated successfully using off-line two-dimensional high-performance countercurrent chromatography, yielding a γ-pyrone, two alkaloids, a flavonoid and four lignans. The first-dimensional countercurrent separation using a methylene chloride/methanol/water (11:6:5, v/v/v) system yielded three sub-fractions (fractions I–III). The second-dimensional countercurrent separations, conducted on fractions I–III using n-hexane/ethyl and acetate/methanol/acetic acid (5:5:5:5:0, 3:7:3:7:0 and 1:9:1:9:0.01, v/v/v/v/v) systems, gave maltol (1), (−)-(13S)-cuscutamine (2), (+)-(13R)-cuscutamine (3), (+)-pinoresinol (4), (+)-epipinoresinol (5), kaempferol (6), piperitol (7) and (9R)-hydroxy-d-sesamin (8). To the best of our knowledge, maltol was identified for the first time in Cuscuta species. Furthermore, this report details the first full assignment of spectroscopic data of two cuscutamine epimers, (−)-(13S)-cuscutamine and (+)-(13R)-cuscutamine.

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