Journal of chromatography. B, Analytical technologies in the biomedical and life sciences (J Chrom B )

Publisher: Elsevier

Description

The Journal of Chromatography B. addresses advancements in and applications of analytical methodologies related to drugs, other pharmacologically active compounds, metabolites, as well as to bio-polymers such as proteins and nucleic acids. The areas considered include: clinical analysis, therapeutic drug monitoring, pharmaceutical analysis and novel approaches to sample preparation in bioanalysis; the qualitative and quantitative analysis of proteins, peptides and their post-translational modifications as well as nucleic acids; the screening and profiling of body fluids and tissues related to monitoring the level of active substances, including metabolites, biomarkers and toxicants; the comparative analysis of biological systems and proteomics and genomics including novel ways of data handling and interpretation; analytical techniques covered include the various facets of chromatography, electrophoresis and related methods, including mass spectrometry and affinity-based methodologies.

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Elsevier

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Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: In the present study, for the first time, a new extraction method based on "ultrasound assisted microextraction-nanomaterial solid phase dispersion (UAME-NMSPD)" was developed to preconcentrate the low quantity of thymol and carvacrol in pharmaceutical samples prior to their HPLC-UV separation/determination. The analytes were accumulated on nickel sulfide nanomaterial loaded on activated carbon (NiS-NP-AC) that with more detail identified by XRD, FESEM and UV-vis technique. Central composite design (CCD) combined with desirability function (DF) was used to search for optimum operational conditions. Working under optimum conditions specified as: 10min ultrasonic time, pH 3, 0.011g of adsorbent and 600μL extraction solvent) permit achievement of high and reasonable linear range over 0.005-2.0μgmL(-1) (r(2)>0.9993) with LOD of thymol and carvacrol as 0.23 and 0.21μgL(-1), respectively. The relative standard deviations (RSDs) were less than 4.93% (n=3). Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 01/2015; 975:34-9.
  • Xiao-Li Feng, Zeng-Shan Liu, Xi-Lin Liu, Shi-Ying Lu, Yan-Song Li, Pan Hu, Dong-Ming Yan, Wei-Hua Tong, Quan Wang, Yu Zhou, Wen Jin, Yan-Xia Ding, Dong-Xue Gai, Hong-Lin Ren
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    ABSTRACT: A protein with high purity has become an essential pre-requisite for investigating its bioactivity, molecular structure and characteristics. Therefore, the development of technologies for efficient purification of protein is urgently necessary. The objective of this study was to establish a purification protocol for a recombinant protein rG17PE38. Different forms of chromatography such as hydrophobic interaction and ion exchange chromatography were chosen as the core purification steps. The performance of each technique was optimized to meet the requirements and the purification steps were arranged in a logical way of facilitating to operate in next step. In addition, some characteristics of the protein such as stability, bioactivity and cellular location were determined. Finally, whether the protein could induce cell apoptosis was also explored. The results showed the protein purified via the suggested three-step purification scheme could obtain a purity of 95%, and its bioactivity in the form of IC50 was 17.6ng/mL, furthermore it could keep stable at 4°C for at least 10 days. The protein could bind on its target cell membrane specifically, and inducing cell apoptosis was demonstrated to be one of the cytotoxicity mechanisms of the protein. Results obtained in our study may provide useful information on strategies of protein purification and lay a substantial foundation for the followed animal or clinical experiments on rG17PE38. Copyright © 2015. Published by Elsevier B.V.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 01/2015; 981-982C:48-56.
  • Rick W Fedeniuk, Del McKenzie, Massey Mizuno, Connie Neiser, Collin O'Byrne, Bryn Shurmer
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    ABSTRACT: Separate methods for the quantitation and confirmation of regulatory relevant residue concentrations of total florfenicol and tulathromycin residues in multiple tissue matrices were developed and validated. Total florfenicol residues, determined and expressed as florfenicol amine (FFA) equivalents, were quantified and confirmed over a concentration range of 100-4000ng/g, with an LOD of 33ng/g, while total tulathromyicn residues, determined as CP-60,300 and expressed as tulathromycin equivalents, were quantified and confirmed over a concentration range of 500-10,000ng/g, with an LOD of 300ng/g. A 2 or 1h acid digestion for the FFA and tulathromycin methods, respectively, followed by extraction, cleanup, and concentration using mixed-mode strong cation-exchange SPE cartridges was used. Quantitation and confirmation were accomplished using commercially available tri-deuterated FFA (FFA-D3) as internal standard and multiple reaction monitoring (MRM) of three transitions per target analyte. Mean recoveries and matrix effects were 60% and 25%; and 100% and 110%, respectively for the target analytes florfenicol amine and CP-60,300. Intra-lab method reproducibilities ranged from 7 to 11% RSD, which are within the AOAC recommended HORRATr guidelines for method reproducibilities estimated from single laboratory validation studies. Blind spikes showed that method bias was generally less than 15% for both methods within the calibration range. Both methods have been shown to meet requirements for use in national chemical residue monitoring programs. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 01/2015; 983-984C:1-9.
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    ABSTRACT: This study establishes a novel calibration method for pre-equilibrium hollow-fiber liquid-phase microextraction (PE-HF-LPME), where the time constant of the extraction of the analyte from sample matrix to the extraction phase (organic solvent) is obtained from a simple concentration curve. Comparing to the traditional kinetic calibration method, where the time constant was obtained from the extraction time profile, the new calibration approach shows improved accuracy and precision. More importantly, deuterated standards are not required in the new method, thus significantly improving its cost-effectiveness and extending its applicability to a wide range of analytes lack of deuterated analogs serving as internal standards. In addition, mass spectrometry is not necessary for the quantification of analytes with the new calibration method, which may further extend the applicability of PE-HF-LPME to some laboratories without mass spectrometers. This study has been substantiated with both theoretical and experimental evidences. Further, the feasibility of the method for real biological samples was demonstrated by measuring the free concentration of flunitrazepam in urine and plasma samples and its drug-protein binding ratio in plasma. The results showed that the method had a short analysis time and was easily implemented with high accuracy and good reproducibility. Copyright © 2015. Published by Elsevier B.V.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 980C:28-33.
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    ABSTRACT: An accelerated solvent extraction (ASE)-solid-phase extraction (SPE)-liquid chromatography with electrospray ionization-tandem mass spectrometry (ASE-SPE-LC-ESI-MS/MS) methodology was developed for the extraction, cleanup and quantification of ultra-trace organic acids in Masson pine (Pinus massoniana L.) tissues. The separation was carried out on a Bio-Rad Aminex HPX-87H sulfonic column with an eluent containing 5mmolL(-1) H2SO4 at a flow rate of 0.5mLmin(-1). A linear ion trap mass spectrometer equipped with electrospray ionization (ESI) source was operated in negative ion mode, and the six organic acids were eluted within 20min. ASE extraction, SPE cleanup and LC-ESI-MS/MS analysis conditions were optimized to obtain reliable information about plant organic acid composition. Selective reaction monitoring (SRM) was employed for quantitative measurement. Intra-day precisions averaged 6.7%, and inter-day precisions were 2.1-10.7% for organic acid measurements in the pine samples. External standard calibration curves were linear over the range of 16.5-5000ngL(-1), and detection limits based on a signal-to-noise ratio of three were at 0.5-5.0ngL(-1). The results obtained showed the sensibility of the method was better than that of previously described HPLC methodology, and had no significant matrix effect. The proposed ASE-SPE-LC-ESI-MS/MS method is sensitive and reliable for the determination of ultra-trace organic acids in plant samples, despite the presence of the particularly complex matrix. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 981-982C:1-8.
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    ABSTRACT: Optimization of supramolecular solvent-based microextraction (SSME) of Loratadine and its determination with high-performance liquid chromatography (HPLC) with ultra violet (UV) detection were investigated. A factorial design (FD) and a central composite face-centered (CCF) were applied to evaluate the SSME procedure. The effect of four parameters on extraction efficiency was investigated. The factors studied were decanoic acid amount, percentage of tetrahydrofuran (THF) (v/v), pH and extraction time. According to half factorial design results, the effective parameters were decanoic acid amount, THF percentage (v/v) and pH. Then, a CCF was applied to obtain optimal condition. The optimized conditions were obtained at 110mg of decanoic acid, 10% of THF and pH=3. The limits of detection were in the range of 0.3-0.4ng/ml. Linearity of the method was determined to be in the range of 1.0-400.0ng/ml for distilled water and 1.3-400.0ng/ml for plasma. The extraction recovery was >92%. RSD for intra and inter day (n=5) of extraction of Loratadine were 3.1% and 6.2%, respectively. The developed method was successfully applied for the determination of Loratadine in distilled water and plasma samples. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 980C:41-47.
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    ABSTRACT: A sensitive and rapid ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed to determine glimepiride (GPD) and fluoxetine (FLU) in human plasma using diazepam as the internal standard (IS) simultaneously. The presented method used an Acquity UPLC BEH C18 column for chromatographic separation with tandem mass spectrometric detection on a QTrap5500 mass spectrometer operated in positive ESI mode. The mobile phase is a mixture of acetonitrile and 1% formic acid in water with gradient elution at a flow rate of 0.40mL/min. The GPD, FLU and IS were eluted at 1.46, 1.27 and 1.39min, respectively. The MRM transitions of m/z 491.3→126.3 and m/z 310.5→148.1 were used to quantify for GPD and FLU, respectively. The linearity of this method was found to be within the concentration range of 2.5-300ng/mL and 0.1-20ng/mL for GPD and FLU in human plasma, respectively. The intra- and inter-day precision (RSD%) were less than 10.3% and accuracy (RE%) was within ±7.3%. The matrix effect were 95.3-100.7% for GPD and FLU. GPD and FLU were sufficiently stable under all relevant analytical conditions. The method was also successfully applied to the clinical samples after a single oral dose of 2mg GLP and 40mg FLU in patients. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 980C:16-19.
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    ABSTRACT: Glutamic acid (Glu) and aspartic acid (Asp), as two important neurotransmitters, have been the focus of increasingly intense research over the past several years. Glu and Asp are present in biological fluids such as serum at trace levels, but complex components in biological matrices make it difficult to determine them in biological samples. In this paper, a sensitive and simple method coupled with indirect UV detection, using benzoic acid (BA) as the UV-absorbing probe, was developed and validated for the quantitative determination of Glu and Asp in human serum and Compound Amino Acid Injection-18 AA. The method combines a dynamic pH junction with a sweeping technique using β-cyclodextrin (β-CD) as the complexing agent for sweeping. Employing this proposed method, low detection limits of 0.061μg/mL for Glu and 0.032μg/mL for Asp were obtained. The sensitivity was improved 30- and 55-fold for Glu and Asp compared to conventional CE method. Standard curves were linear (r>0.999) over the concentration range of 0.1-8.0μg/mL. To further improve the resolution of Asp from interfering substances in human serum, 6% (v/v) methanol was added to the sample matrix, and resulted in the detection limits of 0.125μg/mL for Glu and 0.057μg/mL for Asp. With a simple precipitation of protein, the method has been successfully applied to the analysis of human serum, and the recoveries (82% for Glu and 87% for Asp) were achieved with relative standard deviations of 1.9% and 2.0%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 980C:20-27.
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    ABSTRACT: Bile acids (BAs) have recently gained more attention because of their diverse roles from digestion to signaling. Simultaneous analyses of various BAs in biological samples are challenging due to their structural similarity, relatively low concentrations, and the presence of isomeric forms. In this study, we report a simple and sensitive UPLC-MS/MS method for simultaneous quantifications of 13 BAs including four unique sea lamprey BAs in sea lamprey plasma, liver, intestine, and gills. A straightforward protein precipitation (PPT) method was used to extract BAs from the biological samples. Separation of all target analytes was achieved on a reverse-phase UPLC column in 15min, and detection was carried out on MS/MS with ESI in the negative ionization mode. This method was validated regarding its linearity, limits of detection (LOD), recovery, matrix effect, reproducibility, accuracy and precision. Significant improvements compared to previous LC-MS/MS methods were observed as a result of the application of UPLC and extensive optimization of experimental conditions. The method showed excellent linearity with high regression coefficients (>0.99) over a range of 0.5-1000ng/mL and LODs ranged from 0.009 to 0.11ng/mL. The applications of the developed method demonstrated that it simultaneously determined all target BAs in different biological sample matrices with excellent sensitivity, selectivity and reproducibility. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 980C:72-78.
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    ABSTRACT: Analysis of blood proteins holds critical promise for in depth understanding of physiological states. Protein content of hemolymph from Drosophila melanogaster is of particular analytical interest because the insect open circulatory system involves chemical signaling through the hemolymph. The challenge of working with this sample, however, is the nanoliter volumes of solution available for analysis. In this study, we developed a novel hyphenated Agilent nano-HPLC chip column-MS method to obtain proteomic information from individual fruit fly hemolymph, using a low-volume sample collection technique established previously. The total amount of individual Drosophila hemolymph protein is determined around 0.798±0.251μg/100nL based upon a Bradford assay with BSA. Hemolymph samples around 50nL were collected from single flies and digested using a customized micro-scale digestion protocol. Mass spectral analysis shows a total of 19 proteins were identified from the hemolymph of individual flies. Of these findings, 6 novel proteins have been identified for the first time with evidence at the translation level. Detection of 13 proteins well-known in the literature speaks to the method's validity and demonstrates the ability to reproducibly analyze volume-limited samples from individual fruit flies for protein content. This nano-scale analysis method will facilitate future study of Drosophila and lead to a more complete understanding of the physiology of the fly model system. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 981-982C:33-39.
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    ABSTRACT: Arachidonic acid, the origin of the eicosanoids family, occurs in biological samples as free acid and as ester in lipids. Free arachidonic acid is oxidized to numerous metabolites by means of enzymes including cyclooxygenase (COX). Arachidonic acid esterified to lipids is attacked by reactive oxygen species (ROS) to generate numerous oxidized arachidonic acid derivatives. Generally, it is assumed that ROS-derived arachidonic acid derivatives are distinct from those generated by enzymes such as COX. Therefore, ROS-generated eicosanoids are considered specific biomarkers of oxidative stress. However, there are serious doubts concerning a strict distinction between the enzyme-derived eicosanoids and the ROS-derived iso-eicosanoids. Prominent examples are prostaglandin F2α (PGF2α) and 15(S)-8-iso-prostaglandin F2α (15(S)-8-iso-PGF2α) which have been originally considered to exclusively derive from COX and ROS, respectively. There is convincing evidence that both COX and ROS can oxidize arachidonic acid to PGF2α and 15(S)-8-iso-PGF2α. Thus, many results previously reported for 15(S)-8-iso-PGF2α as exclusive ROS-dependent reaction product, and consequently as a specific biomarker of oxidative stress, require a careful re-examination which should also consider the analytical methods used to measure 15(S)-8-iso-PGF2α. This prominent but certainly not the only example underlines more than ever the importance of the analytical chemistry in basic and clinical research areas of oxidative stress. In the present work, we report analytical protocols for the reliable quantitative determination of 15(S)-8-iso-PGF2α in human biological samples including plasma and urine by mass spectrometry coupled to gas chromatography (GC-MS, GC-MS/MS) after specific isolation of endogenous 15(S)-8-iso-PGF2α and the externally added internal standard [3,3',4,4'-(2)H4]-15(S)-8-iso-PGF2α by immunoaffinity column chromatography (IAC). 15(S)-8-iso-PGF2α esterified to plasma lipids is hydrolysed by KOH. 15(S)-8-iso-PGF2α and [3,3',4,4'-(2)H4]-15(S)-8-iso-PGF2α are analyzed as pentafluorobenzyl ester trimethylsilyl ether derivatives in the electron-capture negative-ion chemical ionization mode. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014;
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    ABSTRACT: Antibody-drug conjugates (ADCs) are becoming a major class of oncology therapeutics. Because ADCs combine the monoclonal antibody specificity with the high toxicity of a drug, they can selectively kill tumor cells while minimizing toxicity to normal cells. Most of the current ADCs in clinical trials are controlled, but heterogeneous mixtures of isomers and isoforms. Very few protocols on ADC characterization at the peptide level have been published to date. Here, we report on the improvement of an ADC peptide mapping protocol to characterize the drug-loaded peptides by LC-MS analysis. These methods were developed on brentuximab vedotin (Adcetris(®)), a commercial ADC with an average of four drugs linked to interchain cysteine residues of its antibody component. Because of the drug hydrophobicity, all the steps of this protocol including enzymatic digestion were improved to maintain the hydrophobic drug-loaded peptides in solution, allowing their unambiguous identification by LC-MS. For the first time, the payloads positional isomers observed by RP-HPLC after IdeS-digestion and reduction of the ADC were also characterized. Copyright © 2015 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 981-982C:9-13.
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    ABSTRACT: Recently, colistin has become one of the most important drugs for treating infections caused by multidrug-resistant Gram-negative bacteria. Therapeutic drug monitoring is recommended to ensure the safety and efficacy of colistin and to improve clinical outcomes. This study developed an accurate and sensitive high-performance liquid chromatography-fluorescence detection (HPLC-FLD) method for the quantification of colistin in human plasma. The sample preparation included protein precipitation using trichloroacetic acid (TCA) and methanol, followed by in-solid phase extraction (In-SPE) derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). A Poroshell 120 EC-C18 2.1×100mm (2.7μm) column was used in the HPLC method with a mobile phase composed of acetonitrile (ACN), tetrahydrofuran (THF), and deionized (DI) water (82%, 2%, 16% (v/v), respectively). Polymyxin B1 was used as the internal standard. The total analysis time was 22min under optimal separation conditions. The HPLC-FLD method was validated over a therapeutic range of 0.3-6.0μgmL(-1). The intra-day and inter-day precisions for colistin A and colistin B were below 9.9% and 4.5% relative standard deviations, respectively. The accuracy test results were between 100.2 and 118.4%. The extraction recoveries were between 81.6 and 94.1%. The method was linear over the test range, with a 0.9991 coefficient of determination. The limit of detection was 0.1μgmL(-1). The validated HPLC-FLD method was successfully applied to quantify the colistin concentrations in 2 patient samples for therapeutic drug monitoring. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 980C:48-54.
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    ABSTRACT: The determination of morphine and its isobaric metabolites morphine-3-beta-d-glucuronide (M3G) and morphine-6-beta-d-glucuronide (M6G) is useful for therapeutic drug monitoring and forensic identification of drug use. In particular, capillary electrophoresis with mass spectrometry (CE-MS) represents an attractive tool for opioid analysis. Whereas volatile background electrolytes in CE often improve electrospray ionization for coupled MS detection, such electrolytes may reduce CE separation efficiency and resolution. To better understand the effects of background electrolyte (BGE) composition on separation efficiency and detection sensitivity, this work compares and contrasts method development for both volatile (ammonium formate and acetate) and nonvolatile (ammonium phosphate and borate) buffers. Peak efficiencies and migration times for morphine and morphine metabolites were optimal with a 25mM ammonium borate buffer (pH=9.5) although greater sensitivities were achieved in the ammonium formate buffer. Optimized CE methods allowed for the resolution of the isobaric morphine metabolites prior to high mass accuracy, electrospray ionization quadrupole time-of-flight (ESI-QTOF) MS detection applicable to the analysis of urine samples in under seven minutes. Urine sample preparation required only a 10-fold dilution with BGE prior to analysis. Limits of detection (LOD) in normal human urine were found to be 1.0μg/mL for morphine and 2.5μg/mL for each of M3G and M6G by CE-ESI-QTOF-MS. These LODs were comparable to those for CE-UV analysis of opioid standards in buffer, whereas CE-ESI-QTOF-MS analysis of opioid standards in buffer yielded LODs an order of magnitude lower. Patient urine samples (N=12) were analyzed by this new CE-ESI-QTOF-MS method and no significant difference in total morphine content relative to prior liquid chromatography-mass spectrometry (LC-MS) results was found as per a paired-t test at the 99% confidence level. Whereas the LC-MS method applied to these samples determined only total morphine content, this new CE-ESI-QTOF-MS method allowed for species differentiation in addition to total morphine determination. By this method, it was found that M3G and M6G metabolites were present in a 5:1 concentration ratio, on average, in patient samples. Therefore, the CE-ESI-QTOF-MS method not only allows for total morphine concentration determination comparable to established LC-MS methods, but also allows for differentiation between morphine and its trace glucuronides, yielding additional biochemical information about drug metabolism. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 980C:65-71.
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    ABSTRACT: An LC–MS/MS method for the determination of BMS-791325 and its metabolite in plasma.•A systematic method optimization strategy was applied during method development.•The results demonstrate that the method is accurate, precise, and reproducible.•The validated method was used to support multiple preclinical toxicokinetic studies.•The first reference for measuring the drug concentration in biological matrices.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 973:1-8.
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    ABSTRACT: The progress of DNA vaccines is dependent on the development of suitable chromatographic procedures to successfully purify genetic vectors, such as plasmid DNA. Human Papillomavirus is associated with the development of tumours due to the oncogenic power of E6 and E7 proteins, produced by this virus. The supercoiled HPV-16 E6/E7 plasmid-based vaccine was recently purified with the arginine monolith, with 100% of purity, but only 39% of recovery was achieved. Therefore, the present study describes the application of experimental design tools, a newly explored methodology in preparative chromatography, in order to improve the supercoiled plasmid DNA recovery with the arginine monolith, maintaining the high purity degree. In addition, the importance and influence of pH in the pDNA retention to the arginine ligand was also demonstrated. The Composite Central Face design was validated and the recovery of the target molecule was successfully improved from 39% to 83.5%, with an outstanding increase of more than double, while maintaining 100% of purity. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 978-979C:145-150.
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    ABSTRACT: A simple, rapid and solvent-free multi-residue method has been developed and applied to confirm and quantify a series of volatile compounds in five cherry wines by gas chromatography coupled with mass spectrometry (GC-MS). Four parameters (e.g., coating material of fiber, temperature and time of extraction, and addition of sodium chloride in the solution) of headspace solid-phase micro-extraction (HS-SPME) were optimized, resulting in the best extraction condition including 50/30μm DVB/CAR/PDMS fiber, 45min and 50°C of SPME, and 2g of sodium chloride addition in the wine during the extraction. The SPME had LODs and LOQs ranging from 0.03 to 7.27μgL(-1) and 0.10 to 24.24μgL(-1) for analytic compounds, respectively. Repeatability and reproducibility values were all below 19.8%, with mean values of 12.7% and 10.5%, respectively. Regression coefficients (R(2)) of detective linearity of the standard curves was higher than 0.9852. Moreover, relative recoveries of analytical targets were achieved in a range of 60.7-125.6% with good relative standard deviation values (≤20.6%). In addition, a principal component analysis (PCA) was used to analyze the aroma profiles of the wines, which indicated that five samples were distinctly divided into two groups based on their different geographical origins and volatile compounds. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 978-979C:122-130.
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    ABSTRACT: A sensitive and rapid method based on formate-adduct ion detection was developed and fully validated for digoxin determination in rat plasma. For LC/MS/MS detection with formate-adducts as precursor ions, transitions of m/z 825.5→779.9 for digoxin and m/z 809.5→763.4 for the internal standard (digitoxin) were monitored in negative mode. To investigate the impact of formic acid on the mass response and method sensitivity, a formic acid concentration range of 0-0.1% (0, 0.0005%, 0.002%, 0.01%, 0.1%, v/v) was evaluated. A concentration of 0.002% gave the highest sensitivity, which was 16- to 18-fold higher than deprotonated ions, and was designated as the contribution giving the strongest ionization enhancement and adduction. A number of parameters were then varied in order to optimize the method, and a limit of quantitation (LOQ) at 0.2ng/mL was reached with an injection volume of 5μL, a total run time of 3min, and 0.1mL of rat plasma. A calibration curve was plotted over the range 0.2-50ng/mL (R(2)=0.9998), and the method was successfully applied to study pharmacokinetics in rat following a single oral administration of digoxin (0.05mg/kg). Four additional steroid saponins (digitoxin, deslanoside, ginsenoside Rg1 and Rb1) were investigated to assess the impact of formic acid on the mass response of steroid saponins. Compounds with a conjugated lactonic ring in their structures such as digoxin, digitoxin and deslanoside tended to form stable formate-adduct ions more easily. The LC/MS/MS method developed here is therefore well suited for the quantification of steroid saponins that are difficult to deprotonate using other MS approaches. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 978-979C:138-144.
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    ABSTRACT: Icaritin (ICT), a bioactive metabolite of prenylflavonoids from genus Epimedium, has displayed potential benefits for the treatment of osteoporosis, prostate cancer, liver cancer, renal cancer and breast cancer. To investigate the quantity of ICT in bones in vivo, a simple and sensitive ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed. After a rapid one-step liquid-liquid extraction using ethyl acetate with recovery more than 87.2% at four levels (0.1, 0.2, 8 and 15ng/mL), ICT and internal standard coumestrol were analyzed on a C18 column using a gradient elution of acetonitrile and water containing ammonium formate and formic acid at a flow rate of 0.3mL/min. Quantification was performed using selected reaction monitoring mode to monitor precursor-product ion transitions of m/z 367.1→297.1 for ICT and of 267.0→211.1 for coumestrol in the negative ionization mode. A calibration curve with good linearity (r>0.99) within the concentration range of 0.1-20ng/mL for ICT was obtained with the lower limit of quantification of 0.1ng/mL. Matrix effect did not interfere with ICT analysis and ICT was stable under three freeze-thaw cycles, short-term temperature, post-preparative and long-term temperature conditions. The method was successfully applied to a dynamic distribution of ICT in mouse bone after a single intraperitoneal administration to ICT to mice. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 12/2014; 978-979C:24-28.