## Carbon Nanodots-Based Fluorescent Turn-On Sensor Array for Biothiols

Analytical ChemistryDOI: 10.1021/acs.analchem.7b00956

Analytical Chemistry
DOI: 10.1021/acs.analchem.7b00956

## Characterization of Complex Polymer Self-Assemblies and Large Aggregates by Multidetector Thermal Field-Flow Fractionation

Analytical ChemistryDOI: 10.1021/acs.analchem.7b01445

Analytical Chemistry
DOI: 10.1021/acs.analchem.7b01445

## Resonant-Gravimetric Identification of Competitive Adsorption of Environmental Molecules

Analytical ChemistryDOI: 10.1021/acs.analchem.7b00723

Analytical Chemistry
DOI: 10.1021/acs.analchem.7b00723

## Gel-seq: Whole-Genome and Transcriptome Sequencing by Simultaneous Low-Input DNA and RNA Library Preparation Using Semi-Permeable Hydrogel Barriers

Lab Chip, 2017, Accepted ManuscriptDOI: 10.1039/C7LC00430C, PaperGordon D Hoople, Andrew Richards, Yan Wu, Kota Kaneko, Xiaolin Luo, Gen-Sheng Feng, Kun Zhang, Albert P PisanoThe advent of next generation sequencing has fundamentally changed genomics r…

Lab Chip, 2017, Accepted Manuscript
DOI: 10.1039/C7LC00430C, Paper
Gordon D Hoople, Andrew Richards, Yan Wu, Kota Kaneko, Xiaolin Luo, Gen-Sheng Feng, Kun Zhang, Albert P Pisano
The advent of next generation sequencing has fundamentally changed genomics research. Unfortunately, standard protocols for sequencing the genome and the transcriptome are incompatible. This forces researchers to choose between examining...
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## Doxycycline as a new chiral selector in capillary electrophoresis

Publication date: 28 July 2017 Source:Journal of Chromatography A, Volume 1508 Author(s): Min Gyeong Jang, Myung Duk Jang, Jung Hag Park Doxycycline (DOX) is one of the tetracycline class of antibiotics and has not been examined …

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Min Gyeong Jang, Myung Duk Jang, Jung Hag Park

Doxycycline (DOX) is one of the tetracycline class of antibiotics and has not been examined for its enantioseparation abilities previously. The purpose of the present work was to evaluate DOX as a chiral selector (CS) using capillary electrophoresis (CE) in nonaqueous mode. Systematic experiments were performed to investigate the effects of concentration of CS, compositions of organic solvents and background electrolytes, applied voltage on chiral separation of a set of acidic chiral compounds. Excellent resolutions of enantiomers of acidic chiral compounds were attained in a background electrolytes composed of 50:50 acetonitrile/methanol+214mM acetic acid+ 63mM triethylamine and 38mM DOX. The results show that DOX is a viable chiral selector in CE for the enantioseparation of the type of chiral compounds investigated.

## Continuous protein concentration via free-flow moving reaction boundary electrophoresis

Publication date: 28 July 2017 Source:Journal of Chromatography A, Volume 1508 Author(s): Fanzhi Kong, Min Zhang, Jingjing Chen, Liuyin Fan, Hua Xiao, Shaorong Liu, Chengxi Cao In this work, we developed the model and the…

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Fanzhi Kong, Min Zhang, Jingjing Chen, Liuyin Fan, Hua Xiao, Shaorong Liu, Chengxi Cao

In this work, we developed the model and theory of free-flow moving reaction boundary electrophoresis (FFMRB) for continuous protein concentration for the first time. The theoretical results indicated that (i) the moving reaction boundary (MRB) can be quantitatively designed in free-flow electrophoresis (FFE) system; (ii) charge-to-mass ratio (Z/M) analysis could provide guidance for protein concentration optimization; and (iii) the maximum processing capacity could be predicted. To demonstrate the model and theory, three model proteins of hemoglobin (Hb), cytochrome C (Cyt C) and C-phycocyanin (C-PC) were chosen for the experiments. The experimental results verified that (i) stable MRBs with different velocities could be established in FFE apparatus with weak acid/weak base neutralization reaction system; (ii) proteins of Hb, Cyt C and C-PC were well concentrated with FFMRB; and (iii) a maximum processing capacity and recovery ratio of Cyt C enrichment were 126mL/h and 95.5% respectively, and a maximum enrichment factor was achieved 12.6 times for Hb. All of the experiments demonstrated the protein concentration model and theory. In contrast to other methods, the continuous processing ability enables FFMRB to efficiently enrich diluted protein or peptide in large volume solution.

## Sensitivity enhancement by chromatographic peak concentration with ultra-high performance liquid chromatography–nuclear magnetic resonance spectroscopy for minor impurity analysis

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): Takashi Tokunaga, Ken-ichi Akagi, Masahiko Okamoto
High performance liquid chromatography can be coupled with nuclear magnetic resonance (NMR) spectroscopy to give a powerful analytical method known as liquid chromatography-nuclear magnetic resonance (LC-NMR) spectroscopy, which can be used to determine the chemical structures of the components of complex mixtures. However, intrinsic limitations in the sensitivity of NMR spectroscopy have restricted the scope of this procedure, and resolving these limitations remains a critical problem for analysis. In this study, we coupled ultra-high performance liquid chromatography (UHPLC) with NMR to give a simple and versatile analytical method with higher sensitivity than conventional LC-NMR. UHPLC separation enabled the concentration of individual peaks to give a volume similar to that of the NMR flow cell, thereby maximizing the sensitivity to the theoretical upper limit. The UHPLC concentration of compound peaks present at typical impurity levels (5.0–13.1 nmol) in a mixture led to at most three-fold increase in the signal-to-noise ratio compared with LC-NMR. Furthermore, we demonstrated the use of UHPLC-NMR for obtaining structural information of a minor impurity in a reaction mixture in actual laboratory-scale development of a synthetic process. Using UHPLC-NMR, the experimental run times for chromatography and NMR were greatly reduced compared with LC-NMR. UHPLC-NMR successfully overcomes the difficulties associated with analyses of minor components in a complex mixture by LC-NMR, which are problematic even when an ultra-high field magnet and cryogenic probe are used.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Takashi Tokunaga, Ken-ichi Akagi, Masahiko Okamoto

High performance liquid chromatography can be coupled with nuclear magnetic resonance (NMR) spectroscopy to give a powerful analytical method known as liquid chromatography-nuclear magnetic resonance (LC-NMR) spectroscopy, which can be used to determine the chemical structures of the components of complex mixtures. However, intrinsic limitations in the sensitivity of NMR spectroscopy have restricted the scope of this procedure, and resolving these limitations remains a critical problem for analysis. In this study, we coupled ultra-high performance liquid chromatography (UHPLC) with NMR to give a simple and versatile analytical method with higher sensitivity than conventional LC-NMR. UHPLC separation enabled the concentration of individual peaks to give a volume similar to that of the NMR flow cell, thereby maximizing the sensitivity to the theoretical upper limit. The UHPLC concentration of compound peaks present at typical impurity levels (5.0–13.1 nmol) in a mixture led to at most three-fold increase in the signal-to-noise ratio compared with LC-NMR. Furthermore, we demonstrated the use of UHPLC-NMR for obtaining structural information of a minor impurity in a reaction mixture in actual laboratory-scale development of a synthetic process. Using UHPLC-NMR, the experimental run times for chromatography and NMR were greatly reduced compared with LC-NMR. UHPLC-NMR successfully overcomes the difficulties associated with analyses of minor components in a complex mixture by LC-NMR, which are problematic even when an ultra-high field magnet and cryogenic probe are used.

## A simple and sensitive approach to quantify methyl farnesoate in whole arthropods by matrix-solid phase dispersion and gas chromatography–mass spectrometry

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): Rosa Montes, Rosario Rodil, Teresa Neuparth, Miguel M. Santos, Rafael Cela, José Benito Quintana
Methyl farnesoate (MF) is an arthropod hormone that plays a key role in the physiology of several arthropods’ classes being implicated in biological processes such as molting and reproduction. The development of an analytical technique to quantify the levels of this compound in biological tissues can be of major importance for the field of aquaculture/apiculture conservation and in endocrine disruption studies. Therefore, the aim of this study was to develop a simple and sensitive method to measure native levels of MF in the tissue of three representative species from different arthropods classes with environmental and/or economic importance. Thus, a new approach using whole organisms and the combination of matrix solid-phase dispersion with gas chromatography coupled to mass spectrometry was developed. This method allows quantifying endogenous MF at low levels (LOQs in the 1.2–3.1ng/g range) in three arthropod species, and could be expanded to additional arthropod classes. The found levels ranged between 2 and 12ng/g depending on the studied species and gender. The overall recovery of the method was evaluated and ranged between 69 and 96%.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Rosa Montes, Rosario Rodil, Teresa Neuparth, Miguel M. Santos, Rafael Cela, José Benito Quintana

Methyl farnesoate (MF) is an arthropod hormone that plays a key role in the physiology of several arthropods’ classes being implicated in biological processes such as molting and reproduction. The development of an analytical technique to quantify the levels of this compound in biological tissues can be of major importance for the field of aquaculture/apiculture conservation and in endocrine disruption studies. Therefore, the aim of this study was to develop a simple and sensitive method to measure native levels of MF in the tissue of three representative species from different arthropods classes with environmental and/or economic importance. Thus, a new approach using whole organisms and the combination of matrix solid-phase dispersion with gas chromatography coupled to mass spectrometry was developed. This method allows quantifying endogenous MF at low levels (LOQs in the 1.2–3.1ng/g range) in three arthropod species, and could be expanded to additional arthropod classes. The found levels ranged between 2 and 12ng/g depending on the studied species and gender. The overall recovery of the method was evaluated and ranged between 69 and 96%.

## Determination of acidity constants and prediction of electrophoretic separation of amyloid beta peptides

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): Roger Peró-Gascón, Fernando Benavente, José Barbosa, Victoria Sanz-Nebot
In this paper we describe a strategy to estimate by CE the acidity constants (pKa) of complex polyprotic peptides from their building peptide fragments. CE has been used for the determination of the pKas of five short polyprotic peptides that cover all the sequence of amyloid beta (Aβ) peptides 1–40 and 1–42 (Aβ fragments 1–15, 10–20, 20-29, 25–35 and 33–42). First, the electrophoretic mobility (me) was measured as a function of pH of the background electrolyte (BGE) in the pH range 2–12 (bare fused silica capillary, I=25mM and T=25°C). Second, the mes were fitted to equations modelling the ionisable behaviour of the different fragments as a function of pH to determine their pKas. The accuracy of the pKas was demonstrated predicting the electrophoretic behaviour of the studied fragments using the classical semiempirical relationships between me and peptide charge-to-mass ratio (me vs. q/Mr1/2, classical polymer model, q=charge and Mr=relative molecular mass). Separation selectivity in a mixture of the fragments as a function of pH was evaluated, taking into account the influence of the electroosmotic flow (EOF) at each pH value, and a method for the simple and rapid simulation of the electropherograms at the optimum separation pH was described. Finally, the pKas of the fragments were used to estimate the pKas of the Aβ peptides 1–40 and 1–42 (tC and D 3.1, E 4.6 and Y 10.8 for acidic amino acids and tN-D 8.6, H 6.0, K 10.6 and R 12.5 for basic amino acids), which were used to predict their behaviour and simulate their electropherograms with excellent results. However, as expected due to the very small differences on q/Mr1/2 values, separation resolution of their mixtures was poor over the whole pH range. The use of poly(vinyl alcohol) (PVA) coated capillaries allowed reducing the EOF and a slight improvement of resolution.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Roger Peró-Gascón, Fernando Benavente, José Barbosa, Victoria Sanz-Nebot

In this paper we describe a strategy to estimate by CE the acidity constants (pKa) of complex polyprotic peptides from their building peptide fragments. CE has been used for the determination of the pKas of five short polyprotic peptides that cover all the sequence of amyloid beta (Aβ) peptides 1–40 and 1–42 (Aβ fragments 1–15, 10–20, 20-29, 25–35 and 33–42). First, the electrophoretic mobility (me) was measured as a function of pH of the background electrolyte (BGE) in the pH range 2–12 (bare fused silica capillary, I=25mM and T=25°C). Second, the mes were fitted to equations modelling the ionisable behaviour of the different fragments as a function of pH to determine their pKas. The accuracy of the pKas was demonstrated predicting the electrophoretic behaviour of the studied fragments using the classical semiempirical relationships between me and peptide charge-to-mass ratio (me vs. q/Mr 1/2, classical polymer model, q=charge and Mr =relative molecular mass). Separation selectivity in a mixture of the fragments as a function of pH was evaluated, taking into account the influence of the electroosmotic flow (EOF) at each pH value, and a method for the simple and rapid simulation of the electropherograms at the optimum separation pH was described. Finally, the pKas of the fragments were used to estimate the pKas of the Aβ peptides 1–40 and 1–42 (tC and D 3.1, E 4.6 and Y 10.8 for acidic amino acids and tN-D 8.6, H 6.0, K 10.6 and R 12.5 for basic amino acids), which were used to predict their behaviour and simulate their electropherograms with excellent results. However, as expected due to the very small differences on q/Mr 1/2 values, separation resolution of their mixtures was poor over the whole pH range. The use of poly(vinyl alcohol) (PVA) coated capillaries allowed reducing the EOF and a slight improvement of resolution.

## Importance of optimizing chromatographic conditions and mass spectrometric parameters for supercritical fluid chromatography/mass spectrometry

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): Yuka Fujito, Yoshihiro Hayakawa, Yoshihiro Izumi, Takeshi Bamba
Supercritical fluid chromatography/mass spectrometry (SFC/MS) has great potential in high-throughput and the simultaneous analysis of a wide variety of compounds, and it has been widely used in recent years. The use of MS for detection provides the advantages of high sensitivity and high selectivity. However, the sensitivity of MS detection depends on the chromatographic conditions and MS parameters. Thus, optimization of MS parameters corresponding to the SFC condition is mandatory for maximizing performance when connecting SFC to MS. The aim of this study was to reveal a way to decide the optimum composition of the mobile phase and the flow rate of the make-up solvent for MS detection in a wide range of compounds. Additionally, we also showed the basic concept for determination of the optimum values of the MS parameters focusing on the MS detection sensitivity in SFC/MS analysis. To verify the versatility of these findings, a total of 441 pesticides with a wide polarity range (logPow from −4.21 to 7.70) and pKa (acidic, neutral and basic). In this study, a new SFC-MS interface was used, which can transfer the entire volume of eluate into the MS by directly coupling the SFC with the MS. This enabled us to compare the sensitivity or optimum MS parameters for MS detection between LC/MS and SFC/MS for the same sample volume introduced into the MS. As a result, it was found that the optimum values of some MS parameters were completely different from those of LC/MS, and that SFC/MS-specific optimization of the analytical conditions is required. Lastly, we evaluated the sensitivity of SFC/MS using fully optimized analytical conditions. As a result, we confirmed that SFC/MS showed much higher sensitivity than LC/MS when the analytical conditions were fully optimized for SFC/MS; and the high sensitivity also increase the number of the compounds that can be detected with good repeatability in real sample analysis. This result indicates that SFC/MS has potential for practical use in the multiresidue analysis of a wide range of compounds that requires high sensitivity.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Yuka Fujito, Yoshihiro Hayakawa, Yoshihiro Izumi, Takeshi Bamba

Supercritical fluid chromatography/mass spectrometry (SFC/MS) has great potential in high-throughput and the simultaneous analysis of a wide variety of compounds, and it has been widely used in recent years. The use of MS for detection provides the advantages of high sensitivity and high selectivity. However, the sensitivity of MS detection depends on the chromatographic conditions and MS parameters. Thus, optimization of MS parameters corresponding to the SFC condition is mandatory for maximizing performance when connecting SFC to MS. The aim of this study was to reveal a way to decide the optimum composition of the mobile phase and the flow rate of the make-up solvent for MS detection in a wide range of compounds. Additionally, we also showed the basic concept for determination of the optimum values of the MS parameters focusing on the MS detection sensitivity in SFC/MS analysis. To verify the versatility of these findings, a total of 441 pesticides with a wide polarity range (logPow from −4.21 to 7.70) and pKa (acidic, neutral and basic). In this study, a new SFC-MS interface was used, which can transfer the entire volume of eluate into the MS by directly coupling the SFC with the MS. This enabled us to compare the sensitivity or optimum MS parameters for MS detection between LC/MS and SFC/MS for the same sample volume introduced into the MS. As a result, it was found that the optimum values of some MS parameters were completely different from those of LC/MS, and that SFC/MS-specific optimization of the analytical conditions is required. Lastly, we evaluated the sensitivity of SFC/MS using fully optimized analytical conditions. As a result, we confirmed that SFC/MS showed much higher sensitivity than LC/MS when the analytical conditions were fully optimized for SFC/MS; and the high sensitivity also increase the number of the compounds that can be detected with good repeatability in real sample analysis. This result indicates that SFC/MS has potential for practical use in the multiresidue analysis of a wide range of compounds that requires high sensitivity.

## The diversity of methoxyphenols released by pyrolysis-gas chromatography as predictor of soil carbon storage

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): Marco A. Jiménez-González, Ana M. Álvarez, Pilar Carral, Francisco J. González-Vila, Gonzalo Almendros
The variable extent to which environmental factors are involved in soil carbon storage is currently a subject of controversy. In fact, justifying why some soils accumulate more organic matter than others is not trivial. Some abiotic factors such as organo-mineral associations have classically been invoked as the main drivers for soil C stabilization. However, in this research indirect evidences based on correlations between soil C storage and compositional descriptors of the soil organic matter are presented. It is assumed that the intrinsic structure of soil organic matter should have a bearing in the soil carbon storage. This is examined here by focusing on the methoxyphenols released by direct pyrolysis from a wide variety of topsoil samples from continental Mediterranean ecosystems from Spain with different properties and carbon content. Methoxyphenols are typical signature compounds presumptively informing on the occurrence and degree of alteration of lignin in soils. The methoxyphenol assemblages (12 major guaiacyl- and syringyl-type compounds) were analyzed by pyrolysis-gas chromatography-mass spectrometry. The Shannon-Wiener diversity index was chosen to describe the complexity of this phenolic signature. A series of exploratory statistical analyses (simple regression, partial least squares regression, multidimensional scaling) were applied to analyze the relationships existing between chemical and spectroscopic characteristics and the carbon content in the soils. These treatments coincided in pointing out that significant correlations exist between the progressive molecular diversity of the methoxyphenol assemblages and the concentration of organic carbon stored in the corresponding soils. This potential of the diversity in the phenolic signature as a surrogate index of the carbon storage in soils is tentatively interpreted as the accumulation of plant macromolecules altered into microbially reworked structures not readily recognized by soil enzymes. From a quantitative viewpoint, the partial least squares regression models exclusively based on total abundances of the 12 major methoxyphenols were especially successful in forecasting soil carbon storage.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Marco A. Jiménez-González, Ana M. Álvarez, Pilar Carral, Francisco J. González-Vila, Gonzalo Almendros

The variable extent to which environmental factors are involved in soil carbon storage is currently a subject of controversy. In fact, justifying why some soils accumulate more organic matter than others is not trivial. Some abiotic factors such as organo-mineral associations have classically been invoked as the main drivers for soil C stabilization. However, in this research indirect evidences based on correlations between soil C storage and compositional descriptors of the soil organic matter are presented. It is assumed that the intrinsic structure of soil organic matter should have a bearing in the soil carbon storage. This is examined here by focusing on the methoxyphenols released by direct pyrolysis from a wide variety of topsoil samples from continental Mediterranean ecosystems from Spain with different properties and carbon content. Methoxyphenols are typical signature compounds presumptively informing on the occurrence and degree of alteration of lignin in soils. The methoxyphenol assemblages (12 major guaiacyl- and syringyl-type compounds) were analyzed by pyrolysis-gas chromatography-mass spectrometry. The Shannon-Wiener diversity index was chosen to describe the complexity of this phenolic signature. A series of exploratory statistical analyses (simple regression, partial least squares regression, multidimensional scaling) were applied to analyze the relationships existing between chemical and spectroscopic characteristics and the carbon content in the soils. These treatments coincided in pointing out that significant correlations exist between the progressive molecular diversity of the methoxyphenol assemblages and the concentration of organic carbon stored in the corresponding soils. This potential of the diversity in the phenolic signature as a surrogate index of the carbon storage in soils is tentatively interpreted as the accumulation of plant macromolecules altered into microbially reworked structures not readily recognized by soil enzymes. From a quantitative viewpoint, the partial least squares regression models exclusively based on total abundances of the 12 major methoxyphenols were especially successful in forecasting soil carbon storage.

## Pixel-by-pixel correction of retention time shifts in chromatograms from comprehensive two-dimensional gas chromatography coupled to high resolution time-of-flight mass spectrometry

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): Yasuyuki Zushi, Jonas Gros, Qingping Tao, Stephen E. Reichenbach, Shunji Hashimoto, J.Samuel Arey
A pixel-by-pixel method for correcting retention time (RT) shifts in whole chromatograms from comprehensive two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC×GC-HRTOFMS) is introduced. A previously developed robust algorithm for correcting RT shifts was extended to high-resolution mass-spectral data. The performance of the new method in terms of decreasing RT shifts and peak volume changes was tested on GC×GC-HRTOFMS data. The RT shift correction algorithm, using linear interpolation for the 1st dimension and Sibson natural neighbor interpolation for the 2nd dimension, performed well for systematically shifted data acquired using two different temperature programs in terms of decreasing RT differences and alterations to the peak volumes and mass spectra. A modified RT shift correction algorithm, using Sibson natural neighbor for both dimensions, performed better for RT shifts caused by column damage, for which the original interpolation method did not appropriately correct RT shifts. Although further investigation would be required for more types of severe shifts, this study shows that the developed method is useful for correcting RT shifts with GC×GC-HRTOFMS.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Yasuyuki Zushi, Jonas Gros, Qingping Tao, Stephen E. Reichenbach, Shunji Hashimoto, J.Samuel Arey

A pixel-by-pixel method for correcting retention time (RT) shifts in whole chromatograms from comprehensive two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC×GC-HRTOFMS) is introduced. A previously developed robust algorithm for correcting RT shifts was extended to high-resolution mass-spectral data. The performance of the new method in terms of decreasing RT shifts and peak volume changes was tested on GC×GC-HRTOFMS data. The RT shift correction algorithm, using linear interpolation for the 1st dimension and Sibson natural neighbor interpolation for the 2nd dimension, performed well for systematically shifted data acquired using two different temperature programs in terms of decreasing RT differences and alterations to the peak volumes and mass spectra. A modified RT shift correction algorithm, using Sibson natural neighbor for both dimensions, performed better for RT shifts caused by column damage, for which the original interpolation method did not appropriately correct RT shifts. Although further investigation would be required for more types of severe shifts, this study shows that the developed method is useful for correcting RT shifts with GC×GC-HRTOFMS.

## Chemicalome and metabolome profiling of polymethoxylated flavonoids in Citri Reticulatae Pericarpium based on an integrated strategy combining background subtraction and modified mass defect filter in a Microsoft Excel Platform

Publication date: 28 July 2017 Source:Journal of Chromatography A, Volume 1508 Author(s): Su-Ling Zeng, Li Duan, Bai-Zhong Chen, Ping Li, E-Hu Liu Detection of metabolites in complex biological matrixes is a great challenge b…

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Su-Ling Zeng, Li Duan, Bai-Zhong Chen, Ping Li, E-Hu Liu

Detection of metabolites in complex biological matrixes is a great challenge because of the background noise and endogenous components. Herein, we proposed an integrated strategy that combined background subtraction program and modified mass defect filter (MMDF) data mining in a Microsoft Excel platform for chemicalome and metabolome profiling of the polymethoxylated flavonoids (PMFs) in Citri Reticulatae Pericarpium (CRP). The exogenously-sourced ions were firstly filtered out by the developed Visual Basic for Applications (VBA) program incorporated in the Microsoft Office. The novel MMDF strategy was proposed for detecting both target and untarget constituents and metabolites based on narrow, well-defined mass defect ranges. The approach was validated to be powerful, and potentially useful for the metabolite identification of both single compound and homologous compound mixture. We successfully identified 30 and 31 metabolites from rat biosamples after oral administration of nobiletin and tangeretin, respectively. A total of 56 PMFs compounds were chemically characterized and 125 metabolites were captured. This work demonstrated the feasibility of the integrated approach for reliable characterization of the constituents and metabolites in herbal medicines.

## Proposal of 5-methoxy-N-methyl-N-isopropyltryptamine consumption biomarkers through identification of in vivo metabolites from mice

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): D. Fabregat-Safont, M. Barneo-Muñoz, F. Martinez-Garcia, J.V. Sancho, F. Hernández, M. Ibáñez
New psychoactive substances (NPS) are a new breed of synthetically produced substances designed to mimic the effects of traditional illegal drugs. Synthetic cannabinoids and synthetic cathinones are the two most common groups, which try to mimic the effects of the natural compounds 9Δ-tetrahydrocannabinol and cathinone, respectively. Similarly, synthetic tryptamines are designer compounds which are based on the compounds psilocin, N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine found in some mushrooms. One of the most important tryptamine compounds found in seizures is 5-methoxy-N,N-diisopropyltryptamine, which has been placed as controlled substance in USA and some European countries. The control of this compound has promoted the rising of another tryptamine, the 5-methoxy-N-methyl-N-isopropyltryptamine, which at the time of writing this article has not been banned yet. So, it is undeniable that this new substance should be monitored.5-methoxy-N-methyl-N-isopropyltryptamine has been reported by the Spanish Early Warning System and detected in our laboratory in two pill samples purchased in a local smart shop. This has promoted the need of stablishing consumption markers for this compound in consumers’ urine. In the present work, the metabolism and pharmacokinetic of 5-methoxy-N-methyl-N-isopropyltryptamine has been studied by an in vivo approach, using adult male mice of the inbred strain C57BLJ/6. The use of ultra-high performance liquid chromatography coupled to high resolution mass spectrometry allowed the identification of four metabolites. After the pharmacokinetic study in serum and urine, the O-demethylated metabolite and the non-metabolised parent compound are proposed as consumption markers in hydrolysed urine. Data reported in this work will help hospitals and forensic laboratories to monitor the consumption and potential intoxication cases related to this tryptamine.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): D. Fabregat-Safont, M. Barneo-Muñoz, F. Martinez-Garcia, J.V. Sancho, F. Hernández, M. Ibáñez

New psychoactive substances (NPS) are a new breed of synthetically produced substances designed to mimic the effects of traditional illegal drugs. Synthetic cannabinoids and synthetic cathinones are the two most common groups, which try to mimic the effects of the natural compounds 9Δ-tetrahydrocannabinol and cathinone, respectively. Similarly, synthetic tryptamines are designer compounds which are based on the compounds psilocin, N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine found in some mushrooms. One of the most important tryptamine compounds found in seizures is 5-methoxy-N,N-diisopropyltryptamine, which has been placed as controlled substance in USA and some European countries. The control of this compound has promoted the rising of another tryptamine, the 5-methoxy-N-methyl-N-isopropyltryptamine, which at the time of writing this article has not been banned yet. So, it is undeniable that this new substance should be monitored. 5-methoxy-N-methyl-N-isopropyltryptamine has been reported by the Spanish Early Warning System and detected in our laboratory in two pill samples purchased in a local smart shop. This has promoted the need of stablishing consumption markers for this compound in consumers’ urine. In the present work, the metabolism and pharmacokinetic of 5-methoxy-N-methyl-N-isopropyltryptamine has been studied by an in vivo approach, using adult male mice of the inbred strain C57BLJ/6. The use of ultra-high performance liquid chromatography coupled to high resolution mass spectrometry allowed the identification of four metabolites. After the pharmacokinetic study in serum and urine, the O-demethylated metabolite and the non-metabolised parent compound are proposed as consumption markers in hydrolysed urine. Data reported in this work will help hospitals and forensic laboratories to monitor the consumption and potential intoxication cases related to this tryptamine.

## Ideal versus real automated twin column recycling chromatography process

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): Fabrice Gritti, Mike Leal, Thomas McDonald, Martin Gilar
The full baseline separation of two compounds (selectivity factors α&lt;1.03) is either impractical (too long analysis times) or even impossible when using a single column of any length given the pressure limitations of current LC instruments. The maximum efficiency is that of an infinitely long column operated at infinitely small flow rates. It is determined by the maximum allowable system pressure, the column permeability (particle size), the viscosity of the eluent, and the intensity of the effective diffusivity of the analytes along the column.Alternatively, the twin-column recycling separation process (TCRSP) can overcome the efficiency limit of the single-column approach. In the TCRSP, the sample mixture may be transferred from one to a second (twin) column until its band has spread over one column length. Basic theory of chromatography is used to confirm that the speed-resolution performance of the TCRSP is intrinsically superior to that of the single-column process. This advantage is illustrated in this work by developing an automated TCRSP for the challenging separation of two polycyclic aromatic hydrocarbon (PAH) isomers (benzo[a]anthracene and chrysene) in the reversed-phase retention mode at pressure smaller than 5000psi. The columns used are the 3.0mm×150mm column packed with 3.5μm XBridge BEH-C18 material (α=1.010) and the 3.0mm or 4.6mm×150mm columns packed with the same 3.5μm XSelect HSST3 material (α=1.025). The isocratic mobile phase is an acetonitrile–water mixture (80/20, v/v). Remarkably, significant differences are observed between the predicted retention times and efficiencies of the ideal TCRSP (given by the number of cycles multiplied by the retention time and efficiency of one column) and those of the real TCRSP. The fundamental explanation lies in the pressure-dependent retention of these PAHs or in the change of their partial molar volume as they are transferred from the mobile to the stationary phase. A revisited retention and efficiency model is then built to predict the actual performance of real TCRSPs. The experimental and calculated resolution data are found in very good agreement for a change, Δvm=−10cm3/mol, of the partial molar volume of the two PAH isomers upon transfer from the acetonitrile–water eluent mixture to the silica-C18 stationary phase.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Fabrice Gritti, Mike Leal, Thomas McDonald, Martin Gilar

The full baseline separation of two compounds (selectivity factors α &lt;1.03) is either impractical (too long analysis times) or even impossible when using a single column of any length given the pressure limitations of current LC instruments. The maximum efficiency is that of an infinitely long column operated at infinitely small flow rates. It is determined by the maximum allowable system pressure, the column permeability (particle size), the viscosity of the eluent, and the intensity of the effective diffusivity of the analytes along the column. Alternatively, the twin-column recycling separation process (TCRSP) can overcome the efficiency limit of the single-column approach. In the TCRSP, the sample mixture may be transferred from one to a second (twin) column until its band has spread over one column length. Basic theory of chromatography is used to confirm that the speed-resolution performance of the TCRSP is intrinsically superior to that of the single-column process. This advantage is illustrated in this work by developing an automated TCRSP for the challenging separation of two polycyclic aromatic hydrocarbon (PAH) isomers (benzo[a]anthracene and chrysene) in the reversed-phase retention mode at pressure smaller than 5000psi. The columns used are the 3.0mm×150mm column packed with 3.5μm XBridge BEH-C18 material (α =1.010) and the 3.0mm or 4.6mm×150mm columns packed with the same 3.5μm XSelect HSST3 material (α =1.025). The isocratic mobile phase is an acetonitrile–water mixture (80/20, v/v). Remarkably, significant differences are observed between the predicted retention times and efficiencies of the ideal TCRSP (given by the number of cycles multiplied by the retention time and efficiency of one column) and those of the real TCRSP. The fundamental explanation lies in the pressure-dependent retention of these PAHs or in the change of their partial molar volume as they are transferred from the mobile to the stationary phase. A revisited retention and efficiency model is then built to predict the actual performance of real TCRSPs. The experimental and calculated resolution data are found in very good agreement for a change, $Δ v m = − 10$ cm3/mol, of the partial molar volume of the two PAH isomers upon transfer from the acetonitrile–water eluent mixture to the silica-C18 stationary phase.

## Evaluation of uncertainty sources in the determination of testosterone in urine by calibration-based and isotope dilution quantification using ultra high performance liquid chromatography tandem mass spectrometry

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): J. Pitarch-Motellón, A.F. Roig-Navarro, J.V. Sancho, M. Ibáñez, N. Fabregat-Cabello, O.J. Pozo, Rosa Ventura, J.I. García Alonso, Pablo Rodríguez-González, Adriana González Gago, Amaia Ereño Artabe, Peter Van Eenoo, Koen Deventer, Yvette Dehnes, Sebastian Rzeppa
Three quantification methodologies, namely calibration with internal standard (Cal-IS, non-weighted), weighted calibration with internal standard (wCal-IS) and isotope pattern deconvolution (IPD) have been used for the determination of testosterone in urine by LC–MS/MS. Uncertainty has been calculated and compared for the three methodologies through intra- and inter-laboratory reproducibility assays. IPD showed the best performance for the intra-laboratory reproducibility, with RSD and combined uncertainty values below 4% and 9% respectively. wCal-IS showed similar performance, while Cal-IS where not constant and clearly worse at the lowest concentration assayed (2ng/mL) reaching RSD values up to 16%. The inter-laboratory assay indicated similar results although wCal-IS RSD (20%) was higher than IPD (10%) and Cal-IS get worse with RSD higher than 40% for the lowest concentration level. Uncertainty budgets calculated for the three procedures revealed that intercept and slope were the most important factors contributing to uncertainty for Cal-IS. The main factors for wCal-IS and IPD were the volumes of sample and/or standard measured.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): J. Pitarch-Motellón, A.F. Roig-Navarro, J.V. Sancho, M. Ibáñez, N. Fabregat-Cabello, O.J. Pozo, Rosa Ventura, J.I. García Alonso, Pablo Rodríguez-González, Adriana González Gago, Amaia Ereño Artabe, Peter Van Eenoo, Koen Deventer, Yvette Dehnes, Sebastian Rzeppa

Three quantification methodologies, namely calibration with internal standard (Cal-IS, non-weighted), weighted calibration with internal standard (wCal-IS) and isotope pattern deconvolution (IPD) have been used for the determination of testosterone in urine by LC–MS/MS. Uncertainty has been calculated and compared for the three methodologies through intra- and inter-laboratory reproducibility assays. IPD showed the best performance for the intra-laboratory reproducibility, with RSD and combined uncertainty values below 4% and 9% respectively. wCal-IS showed similar performance, while Cal-IS where not constant and clearly worse at the lowest concentration assayed (2ng/mL) reaching RSD values up to 16%. The inter-laboratory assay indicated similar results although wCal-IS RSD (20%) was higher than IPD (10%) and Cal-IS get worse with RSD higher than 40% for the lowest concentration level. Uncertainty budgets calculated for the three procedures revealed that intercept and slope were the most important factors contributing to uncertainty for Cal-IS. The main factors for wCal-IS and IPD were the volumes of sample and/or standard measured.

## Application of C8 liquid chromatography-tandem mass spectrometry for the analysis of enniatins and bassianolides

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): Justin B. Renaud, Megan J. Kelman, David R. McMullin, Ken K.-C. Yeung, Mark W. Sumarah
Several moderately pathogenic Fusarium species produce enniatins, a family of cyclohexadepsipeptides with insecticidal and phytotoxic activities. A semi-targeted LC–MS/MS approach utilizing reversed-phase C8 UHPLC column chromatography that combines both product ion and neutral loss filtering was developed to detect enniatins and structurally-related compounds in a sample. Using this methodology, resolution of all major enniatins was achieved with a 6-min LC run. From extracts of F. avenaceum, F. acuminatum and F. subglutinans, 23 enniatins and 16 previously unreported bassianolide-like cyclooctadepsipeptides were detected. Enniatins B, B1, A1 and A were the most frequently detected enniatins from silage and inoculated maize. The newly discovered bassianolide compounds were also detected, in lesser amounts on inoculated maize and in naturally contaminated silage.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Justin B. Renaud, Megan J. Kelman, David R. McMullin, Ken K.-C. Yeung, Mark W. Sumarah

Several moderately pathogenic Fusarium species produce enniatins, a family of cyclohexadepsipeptides with insecticidal and phytotoxic activities. A semi-targeted LC–MS/MS approach utilizing reversed-phase C8 UHPLC column chromatography that combines both product ion and neutral loss filtering was developed to detect enniatins and structurally-related compounds in a sample. Using this methodology, resolution of all major enniatins was achieved with a 6-min LC run. From extracts of F. avenaceum, F. acuminatum and F. subglutinans, 23 enniatins and 16 previously unreported bassianolide-like cyclooctadepsipeptides were detected. Enniatins B, B1, A1 and A were the most frequently detected enniatins from silage and inoculated maize. The newly discovered bassianolide compounds were also detected, in lesser amounts on inoculated maize and in naturally contaminated silage.

## Molecularly imprinted nanoparticles grafted to porous silica as chiral selectors in liquid chromatography

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508
Author(s): Raquel Gutierrez-Climente, Alberto Gomez-Caballero, Antonio Guerreiro, Deiene Garcia-Mutio, Nora Unceta, M. Aránzazu Goicolea, Ramon J. Barrio
The work presented here explores the grafting of molecularly imprinted nanoparticles (MIN) on silica beads for the development of new chiral stationary phases (CSP). Both solid-phase imprinting and precipitation polymerisation were tested for MIN synthesis though the latter approach was the only one that provided efficient chiral selectors. MIN particles were prepared by iniferter polymerisation initiated by UV radiation, using itaconic acid as functional monomer and ethylene dimethacrylate as cross-linker. This resulted in particles with an average size of 249.0±4.0nm which were covalently immobilised onto chromatographic silica beads. The resultant CSP based on the composite silica beads-MIN was capable of resolving the racemate of the antidepressant drug citalopram and also separating its major metabolites by liquid chromatography, with better efficiency and peak symmetry than other MIP based CSP. The methodology presented here allowed for the quantification of the pharmacologically active enantiomer (+)-(S)-citalopram (SCIT) and its main metabolites (+)-(S)-desmethylcitalopram (SDCIT) and (+)-(S)-didesmethylcitalopram (SDDCIT) in urine, registering mean recoveries that ranged from 91.5 to 103.7% with RSD values that were below 10% in all tested concentration levels (0.1, 0.75 and 5μgmL−1), which confirmed method suitability for the intended application.

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Raquel Gutierrez-Climente, Alberto Gomez-Caballero, Antonio Guerreiro, Deiene Garcia-Mutio, Nora Unceta, M. Aránzazu Goicolea, Ramon J. Barrio

The work presented here explores the grafting of molecularly imprinted nanoparticles (MIN) on silica beads for the development of new chiral stationary phases (CSP). Both solid-phase imprinting and precipitation polymerisation were tested for MIN synthesis though the latter approach was the only one that provided efficient chiral selectors. MIN particles were prepared by iniferter polymerisation initiated by UV radiation, using itaconic acid as functional monomer and ethylene dimethacrylate as cross-linker. This resulted in particles with an average size of 249.0±4.0nm which were covalently immobilised onto chromatographic silica beads. The resultant CSP based on the composite silica beads-MIN was capable of resolving the racemate of the antidepressant drug citalopram and also separating its major metabolites by liquid chromatography, with better efficiency and peak symmetry than other MIP based CSP. The methodology presented here allowed for the quantification of the pharmacologically active enantiomer (+)-(S)-citalopram (SCIT) and its main metabolites (+)-(S)-desmethylcitalopram (SDCIT) and (+)-(S)-didesmethylcitalopram (SDDCIT) in urine, registering mean recoveries that ranged from 91.5 to 103.7% with RSD values that were below 10% in all tested concentration levels (0.1, 0.75 and 5μgmL−1), which confirmed method suitability for the intended application.

## Magnetic nanoparticles and high-speed countercurrent chromatography coupled in-line and using the same solvent system for separation of quercetin-3-O-rutinoside, luteoloside and astragalin from a Mikania micrantha extract

Publication date: 28 July 2017 Source:Journal of Chromatography A, Volume 1508 Author(s): Juanqiang Wang, Shan Geng, Binghai Wang, Qian Shao, Yingtong Fang, Yun Wei A new in-line method of magnetic nanoparticles (MNPs) coup…

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508

Author(s): Juanqiang Wang, Shan Geng, Binghai Wang, Qian Shao, Yingtong Fang, Yun Wei

A new in-line method of magnetic nanoparticles (MNPs) coupled with high-speed countercurrent chromatography (HSCCC) using a same solvent system during the whole separation process was established to achieve the rapid separation of flavonoids from Mikania micrantha. The adsorption and desorption capacities of five different MNPs for flavonoid standards and Mikania micrantha crude extract were compared and the most suitable magnetic nanoparticle Fe3O4@SiO2@DIH@EMIMLpro was selected as the in-line MNP column. An in-line separation system was established by combining this MNP column with HSCCC through a six-way valve. The comparison between two solvent systems n-hexane-ethyl acetate-methanol-water (3:5:3:5, v/v) and ethyl acetate-methanol-water (25:1:25, v/v) showed that the latter solvent system was more suitable for simultaneously in-line separating three flavonoids quercetin-3-O-rutinoside, luteoloside and astragalin from Mikania micrantha. The purities of these three compounds with the ethyl acetate-methanol-water solvent system were 95.13%, 98.54% and 98.19% respectively. Results showed the established in-line separation system of MNP-HSCCC was efficient, recyclable and served to isolate potential flavonoids with similar polarities from natural complex mixtures. The in-line combination of magnetic nanoparticles with high-speed countercurrent chromatography eluting with the same solvent system during the whole separation process was established for the first time.

## Editorial Board

Publication date: 28 July 2017 Source:Journal of Chromatography A, Volume 1508

Publication date: 28 July 2017
Source:Journal of Chromatography A, Volume 1508