bluuebunny/crossref_metadata_2025_split huggingface dataset:
A fully automated HPLC method for the determination of catecholamines in biological samples utilizing ethylenediamine condensation and peroxyoxalate chemiluminescence detection
Authors: Prados Pablo , Higashidate Sakae , Imai Kazuhiro 
Published: May 2005

AbstractA fully automated in‐line extraction reversed‐phase high‐performance liquid chromatography (HPLC) method with chemiluminescence detection was developed for the analysis of human and rat plasma catecholamines (CAs), norepinephrine (NE), epinephrine (E) and dopamine (DA). N‐Methyldopamine (N‐MeDA) was used as an internal standard. The method involves collection of plasma samples, which are first diluted with a sample dilution buffer containing N‐MeDA, and in‐line extraction of CAs using a carboxylic acid small resin precolumn (SERUMOUT‐CEX). This pre‐extraction process was coupled with an HPLC system including reversed‐phase mode separation on an analytical column (TSK gel ODS‐80Ts), fluorogenic derivatization with ethylenediamine (ED) and finally postcolumn peroxyoxalate chemiluminescence reaction detection using bis [4‐nitro‐2‐(3,6,9‐trioxadecyloxycarbonyl)phenyl]oxalate (TDPO) and hydrogen peroxide. The optimized mobile phase compositions, flow rates, operation timing for the adsorption and desorption of CAs in the precolumn, the separation in the analytical column and the optimum fluorogenic and chemiluminogenic reaction conditions were investigated.The detection limit for all the CAs was about 1 fmol (signal‐to‐noise ratio is 2). Excellent linearity of the calibration curves for CAs was observed in the range from 5 to 500 fmol for each CA using the internal standard. The relative standard deviations of the method for determining NE (183 fmol), E (23.6 fmol) and DA (6.1 fmol) in 50 μL of human plasma (n = 3) were 2.8, 2.7 and 3.1%, respectively, for the within‐day assay and 5.0, 3.8 and 4.0%, respectively, for the between‐day assay. The method was applicable to the determination of CAs in 25–50 μL of human or rat plasma.
Experimental models for optimization of insulin separation on reversed phase columns
Authors: Dimov N. , Simeonov S. 
Published: May 2005

AbstractExperimentally defined relationships have been found to describe adequately the retention and separation of bovine and porcine insulins as well as their desamido products on reversed phases C4 30 nm and C18 10 nm pore diameter. The equations are valid for a region of initial acetonitrile concentrations from 16 to 31% and gradient rates from 0.04 to 0.60%/min. The peak heights showed an exact non‐linear relationship with the time interval between the first and last peak of interest, independent of their retention time.The number of experiments required for obtaining the parametric estimates of the models depends on the particular task, but in all cases is less than eight.The relationships found permit the correct choice to be made in advance both for analysis conditions for a particular column and for different requirements of insulin analysis.
Direct determination of mitoxantrone in plasma by high performance liquid chromatography using an automatic precolumn‐switching system as sample clean‐up procedure
Authors: Catalin Jacques , Peloux Anne F. , Coloma Fabrice , Payet Brigitte , Lacarelle Bruno , Cano Jean P. , Just‐Landi Sylvaine 
Published: May 2005

AbstractA high‐performance liquid chromatography method which uses direct injection and a column‐switching valve for determination of mitoxantrone in plasma is described. After addition of internal standard, plasma was deproteinized by adding 5‐sulphosalicylic acid reagent. The supernatant was injected onto an enrichment precolumn flushed with washing solvent (methanol and water 5:95).Absorbed mitoxantrone was backflushed from the precolumn into an analytical column C18 Nucleosil 250 × 4 mm with a gradient elution (solvent A, ammonium formate buffer 1.6 M, pH 4.3; solvent B, acetonitrile and water 40:60; linear gradient from 45 to 55% of B for 30 min was programmed) at a flow rate of 1.3 mL/min. Detection was carried out at 665 nm.This method showed obvious advantages over conventional extraction procedures in terms of speed and facility of sample handling.
Quantitative analysis of neuroactive amino acids in brain tissue by liquid chromatography using fluorescent pre‐column labelling with o‐phthalaldehyde and N‐acetyl‐L‐cysteine
Authors: Soto‐Otero R. , Méndez‐Alvarez E. , Galán‐Valiente J. , Aguilar‐Veiga E. , Sierra‐Marcuño G. 
Published: May 2005

AbstractA high‐performance liquid chromatographic method for the determination of aspartic acid, glutamic acid, glutamine, glycine, taurine, and γ‐aminobutyric acid in brain tissue is described. Amino acids were derivatized with o‐phthalaldehyde/N‐acetyl‐L‐cysteine, a fluorescent labelling mixture, in the presence of 0.1 M borate buffer pH 9.5. The derivatization reaction was sensitive to the pH and concentration of borate buffer. A drift in the fluorescent response less than 4% was obtained with the reported conditions after 4 h of reaction. The resolution of the amino acid derivatives was accomplished in a reversed‐phase column with a methanol gradient in 50 mM acetate buffer pH 5.5. These conditions also allowed the separation of the major tissue free physiological amino acids. L‐Norvaline was used as an internal standard for both peak identification and quantification. Within‐day and between‐day precision were less than 6.2%, and the accuracy ranged from 99.1 to 104%. The applicability of the method was demonstrated in a study in rats in which the levels of the assayed amino acids in discrete areas of brain were examined.
Glutathione and cysteine measurement in biological samples by HPLC with a glassy carbon working detector
Authors: Carvalho F. D. , Remião F. , Valet P. , Timbrell J. A. , Bastos M. L. , Ferreira M. A. 
Published: May 2005

AbstractAn HPLC method using a glassy carbon working detector for measuring cysteine and reduced glutathione (GSH) in biological samples was developed. Oxidized glutathione (GSSG) was also measured after reduction with glutathione reductase. This study was conducted in human plasma. Cysteine and GSH standard curves were linear in the physiological range, presenting detection limits of 22.0 pmol and 6.0 pmol respectively. Plasmatic results found were 43.92 ± 4.15, 4.50 ± 0.65, and 0.19 ± 0.12 mM (means ± SE), for cysteine, GSH and GSSG, respectively. Peak specificity for cysteine and reduced glutathione was certified by their disappearance after treatment with N‐ethylmaleimide.
Simultaneous determination of antidepressant drugs and metabolites by HPLC. Design and validation of a simple and reliable analytical procedure
Authors: Joron S. , Robert H. 
Published: May 2005

AbstractAn analytical procedure suitable for routine use has been developed and validated for the simultaneous separation and quantification of most of the antidepressant drugs (bicyclic, tricyclic and tetracyclic) and their metabolites in human serum by reversed‐phase high performance liquid chromatography with ultraviolet detection. The method has good sensitivity and specificity, without the need for long and complex extraction procedures. The results obtained with three different analytical columns were compared and an improvement in specificity by selection of column and detection wavelength used was achieved.
Measurement of theophylline metabolites produced by reaction with hepatic microsome by high performance liquid chromatography following solid phase extraction
Authors: Konishi Hiroki , Yamaji Akira 
Published: May 2005

AbstractAn analytical method has been developed with which to measure the microsomal enzyme activities responsible for oxidative theophylline metabolism. Three metabolites: 3‐Methylxanthine (3‐MX); 1‐methylxanthine (1‐MX); 1,3‐dimethyluric acid (1,3‐DMU), with acetaminophen as an internal standard (IS), were separated by solid phase extraction using a Sep‐Pak C18 cartridge, followed by high performance liquid chromatography on a reversed‐phase column with isocratic elution using 25 mM acetate buffer containing 4% acetonitrile and 2.5 mM tetra‐n‐butylammonium hydrogen sulphate (pH 5.25) as the mobile phase. The analytes were clearly resolved and no interference with foreign peaks was observed. A linear relationship was obtained for the metabolites over the concentration range of 0.5–5.0 μg/mL, and their analytical recovery was almost 100%. This method can be used to assess drug interactions involving alterations in the biotransformation of theophylline.
A comparison of fluorescence versus chemiluminescence detection for analysis of the fluorescamine derivative of histamine by HPLC
Authors: Walters Denise Lowe , James John E. , Vest Floyd B. , Karnes H. Thomas 
Published: May 2005

AbstractFluorescence and chemiluminescence detection were compared for HPLC analysis of the fluorescamine derivative of histamine. The kinetic behaviour of the chemiluminescent response for the derivative was characterized in a static system. An HPLC method was optimized for the derivative using fluorescence detection. Fluorescence detection was linear over the range of 166–1666 pg on column for the fluorescamine–histamine derivative with a limit of detection of 13 pg on column. Using a detector designed for optimal use with chemiluminescence, the chemiluminescence response of the fluorescamine derivative was linear over a range of 1.66–16.6 ng on column with a limit of detection of 1.0 ng on column. These results exemplify a case in which superior detectibility is provided by fluorescence over chemiluminescence, and contradicts many reports comparing fluorescence to chemiluminescence. The authors conclude that chemiluminescence should be considered when indicated by conditions established for separation that are favourable for the observation of chemiluminescence. These conditions include sufficiently low excitation energies corresponding to an excitation maximum greater than 400 nm, favourable dipole character of analytes, mobile phases of high organic content, and an appropriate pH of the mobile phase.
Fluidized‐bed receptor‐affinity chromatography
Authors: Spence Cheryl , Schaffer Carol Ann , Kessler Stephen , Bailon Pascal 
Published: May 2005

AbstractA multipurpose fluidized‐bed receptor‐affinity purification system based upon the biological recognition between an immobilized receptor and its soluble protein ligands is described. The fluidized affinity sorbent consists of a soluble form of interleukin‐2 receptor chemically bonded to an aldehyde derivative of controlled pore glass beads, which have a pore diameter of 1000 Å and a particle density of 1.2–1.3 g/mL. The fluidized‐bed separation device used in this study consists of a specially designed column fitted at the inlet end with a perforated distributor plate covered with a screen and the top outlet with an adjustable piston. The fluidized‐bed consisting of a loose gel matrix permits the unimpeded passage of cell debris and particulate matter, while the target protein is captured by the affinity beads. Purification of the humanized‐anti‐Tac monoclonal antibody is used as a model system to determine the operational parameters. Also, fluidized‐bed receptor‐affinity chromatography has been successfully employed in the purification of recombinant interleukin‐2 and single chain anti‐Tac(Fv)‐Pseudomonas exotoxin immunotoxin from unclarified inclusion body extracts. Overall, fluidized‐bed receptor‐affinity chromatography is found to be a productive affinity method suitable for the purification of recombinant human interleukin‐2 and related molecules.
HPLC separation of pentazocine enantiomers in serum using an ovomucoid chiral stationary phase
Authors: Kelly J. W. , Stewart J. T. , Blanton C. D. 
Published: May 2005

AbstractA stereospecific HPLC method was developed for the analysis of (−) and (+) pentazocine in human serum. Each enantiomer and the internal standard nalophine were isolated from serum using a liquid–liquid extraction procedure. Recoveries of 99.05 ± 5.37 and 97.42 ± 2.78% were obtained for (−) and (+) pentazocine, respectively. Resolution of the enantiomers was obtained by using an ovomucoid chiral stationary phase with a mobile phase of methanol: acetonitrile: 10 mM phosphate buffer, pH 5.8 (20:5.3:74.7 v/v/v). A resolution (Rs) value of 1.80 was obtained for the pentazocine enantiomers. Linear calibration curves were obtained in the 10–100 ng/mL range for each enantiomer in serum. The detection limit based on a signal‐to‐noise ratio of 3 was 5 ng/mL for each enantiomer in serum using fluorescence detection with excitation at 275 nm and emission set at 335 nm. The lowest quantifiable level was found to be 10 ng for each enantiomer. Precision and accuracy of the method were in the 3.8–4.8% and 1.3–4.2% ranges, respectively.
Comparison of standard chromatographic procedures for the optimal purification of soluble human brain acetylcholinesterase
Authors: Novales‐Li Philipp 
Published: May 2005

AbstractWith the view of purifying soluble human brain acetylcholinesterse (AChE) into its separate isoforms, various preparative chromatographic procedures were compared. Chromatofocusing of cerebrospinal fluid (CSF) AChE revealed two major activity peaks, whilst that of caudate nucleus AChE showed one major peak, Both CSF and caudate nucleus AChE eluted at isoelectric points (pI) of between 5.5 and 5.2 Chromatofocusing failed to separate AChE into its individual isoforms, based on qualitative isoelectric focusing. Preparative purification by affinity chromatography showed a better AChE yield with the use of procainamide as a ligand, vis‐à‐vis acridinium. Maximum recovery for CSF and caudate nucleus AChE was 10 and 43% using acridinium and procainamide, respectively. Qualitative analysis by SDS‐PAGE of affinity‐purified AChE revealed four major bands between 50 and 62kDa, corresponding to the catalytic subunits of AChE as verified by an anti‐AChE polyclonal antibody. A size‐exclusion column also allowed brain AChE purification, with the latter eluting at a putative molecular mass of 310 kDa. Unfortunately, cation‐exchange using the state‐of‐the‐art SMART system failed to separate AChE into its isoforms. AChE aggregation is given as one major obstacle precluding good resolution of isoforms.
Interaction of carboxymethyl‐γ‐cyclodextrin with anticancer drugs studied by charge‐transfer thin‐layer chromatography
Authors: Cserháti Tibor 
Published: May 2005

AbstractThe interaction between 22 anticancer drugs and carboxymethyl‐γ‐cyclodextrin (CM‐γ‐CD) was studied by reversed‐phase charge‐transfer thin‐layer chromatography and the relative strenth of interaction was calculated. CM‐γCD formed inclusion complexes with 11 compounds, the complex always being more hydrophilic than the uncomplexed drug. The inclusion forming capacity of drugs differed considerably according to their chemical structure. Both principal component analysis and cluster analysis found a relationship between the inclusion complex forming capacity and hydrophobicity parameters of anticancer drugs. This result suggests that the preponderant role of hydrophobic interactions is in inclusion complex formation.
High‐resolution separation of PCR product and gene diagnosis by capillary gel electrophoresis
Authors: Baba Yoshinobu , Tomisaki Riyo , Sumita Chinuyo , Tsuhako Mitsutomo , Miki Tetsuro , Ogihara Toshio 
Published: May 2005

AbstractHigh‐resolution separation of a PCR product from a mixture of DNA restriction fragments was achieved using capillary gel electrophoresis. The capillary gel electrophoretic separation gives an excellent resolution of two fragments of the 500‐bp PCR product and the 506‐bp DNA fragment, which differs by only 6 bp, and the complete separation of a broader chain lenght range of DNA fragments up to 12kbp within 20min. The plate number of gel‐filled capillary was achieved to be 2 million plates per meter. Capillary gel electrophoresis is applied to the gene diagnosis for heart disease through apolipoprotein E genotyping. The advantages and limitations of capillary gel electrophoresis in the application to PCR analysis and DNA diagnosis are discussed.
Simple determination of formaldehyde in dimedone adduct form in biological samples by high performance liquid chromatography
Authors: Sárdi Éva , Tyihák Ernö 
Published: May 2005

AbstractA high performance liquid chromatographic method for the determination of endogenous formaldehyde in dimedone adduct form in biological samples is described. The simple procedure involves extraction of the formaldehyde of different binding force in biological samples with methanol containing dimedone as the capture molecule and separation on a C18 reversed phase column with methanol as eluent.
TLC studies on certain aminoglycoside antibiotics
Authors: Bhushan R. , Joshi Shalini 
Published: May 2005

AbstractAminoglycoside antibiotics were separated by thin layer chromatography. Separation was achieved on untreated silica gel layers using various combinations of solvent systems, dioxane:ammonia, methanol:ammonia and propanol:ammonia. These antibiotics were visualized with the help of iodine vapours.
Effect of column temperature and nitrogen flow rate on the separation of cis‐permethrinic acid isomers on a (2, 3, 6‐Tri‐O‐methyl)‐β‐cyclodextrin coated capillary column
Authors: Payer Károly , Forgács Esther , Cserhàti Tibor 
Published: May 2005

AbstractThe separation efficiency of a capillary column coated with (2, 3, 6‐tri‐O‐methyl)‐β‐cyclodextrin was determined at the temperature and flow rate ranges of 80–120°C and 0.3–1.5 mL/min respectively using (+) and (−) cis‐permethrinic acid methylesters as test compounds. The dependence of the retention differences, sum of peak widths and separation factor on the temperature and flow rate was calculated with step regression analysis. The column exhibited acceptble isomer separation capacity at each temperature and flow rate proving the excellent separation power of the cyclodextrin coating. The differences between the retention times of isomers depended on the logarithm and on the reciprocal value of temperature, the effect of flow rate was negligible. The sum of their peak widths depended reciprocally on the temperature and logarithmically on the flow rate, the impact of temperature being higher than that of flow rate. The significant impact of the reciprocal value of temperature can be explained by the inclusion complex formation between cyclodextrin and cis‐permethrinic acid methylester isomers. The resolution depended on the square of column temperature and flow rate, indicating local optimums at each temperature and flow rate.
Simultaneous determination of catecholamines, their basic metabolites and serotonin in urine by high‐performance liquid chromatography using A mixed‐mode column and an eight‐channel electrochemical detector
Authors: Mashige Fumiko , Matsushima Yoshikazu , Miyata Chizuko , Yamada Rika , Kanazawa Hideko , Sakuma Ichiro , Takai Nobuharu , Shinozuka Noriko , Ohkubo Akiyuki , Nakahara Kazuhiko 
Published: May 2005

AbstractA high‐performance liquid chromatographic method for simultaneous determination of free catecholamines, their basic metabolites and serotonin in human urine was developed. The compounds were separated on a precolumn of cation‐exchange resin and a mixed‐mode (C18/cation‐exchange) column and determined by an eight‐channel electrochemical detector. By this method, free norepinephrine (NE), epinephrine (E), dopamine (DA), normetanephrine (NMN), metanephrine (MN), 3‐methoxy‐tyramine (3‐MT) and serotonin (5‐HT) were determined in 40 min with inter‐assay precision of 1.9, 3.2, 1.2, 1.6, 1.6, 5.5 and 3.2%, respectively. Detection limits were between 0.05 (E) and 0.3 (3‐MT) pmol. The mean values of analytical recovery for NE, E, DA, NMN, MN, 3‐MT, 5‐HT were 99, 104, 104, 99, 102, 109 and 99% respectively.
BioCARS—a novel nonlinear optical technique to study vibrational spectra of chiral biological molecules in solution
Authors: Koroteev Nikolai I. 
Published: May 2005

AbstractA description is given of a novel coherent nonlinear optical technique, acronymed as BioCARS, which can be considered as a nonlinear variant of vibrational optical activity with no background (unlike spontaneous Raman optical activity) and with the capability of studying the whole vibrational spectra of biomolecules in water solutions (unlike vibrational circular dichroism). The BioCARS technique is based on a coherent five‐wave mixing process in macroscopically noncentrosymmetric liquid solutions of chiral biomolecules. It is the generalization for chiral (optically‐active) liquids of the well‐known CARS (Coherent Anti‐Stokes Raman Spectroscopy) technique. The theoretical background of the BioCARS technique is developed, the calculation of the relevant material parameter, which describes the BioCARS process,—a fourth‐order nonlinear susceptibility—is given for a simple model chiral medium, and selection rules for BioCARS spectra are discussed. © 1995 John Wiley & Sons, Inc.
Taking a risk and playing it safe: the use of actors in interagency child protection training
Authors: Lexton Ann , Smith Martin , Olufemi David , Poole Gaye 
Published: May 2005

AbstractInteragency training in child protection is an important part of engaging professionals in a common approach to their collective responsibility for safeguarding children. Training is a key method for empowering professionals to carry out their complex role in child protection with appropriate knowledge, skills and confidence. In Buckinghamshire, experiential learning involving actors has met with some success as part of the interagency child protection training programme. The following paper proposes the argument for using actors, describes how this is done and evaluates its effectiveness for participants, trainers and actors. It is suggested that this method has ample rewards if properly planned, particularly for practitioners in lessons for practice. A close working relationship must be developed between actors and trainers. Scenarios that seem real can be portrayed and skills can then be practised in the knowledge that no one is really being harmed but valuable lessons for real‐life situations can be learned. A central aspect is learning together in a supportive environment away from a blame culture. Copyright © 2005 John Wiley & Sons, Ltd.
Correlations between common tests for assessment of liver damage: Indices of the hepatoprotective activity of promethazine in carbon tetrachloride hepatotoxicity
Authors: Reddrop Colin J. , Cheeseman Kevin H. , Slater T. F. 
Published: May 2005

AbstractThe effects of promethazine (PM) on different aspects of the hepatotoxic action of CCl4 in the rat were investigated with the objective of finding rapid and reliable indicators of hepatoprotective effects. The study was based on definitive histological assessment of liver damage caused by CCl4 in the presence and absence of PM: PM (78 μmol kg−1, i.p.) protected against CCl4‐induced hepatic necrosis 24 h after a low dose of CCl4 (1.3 mmol kg−1) but not against a higher dose (13.0 mmol kg−1). The large increases in plasma activities of GOT, GPT and LDH produced by dosing with CCl4 were partially inhibited by the administration of PM. PM and CCl4 caused a synergistic and long‐lasting decrease in body temperature (2–3°C for 8–10 h). Modifying the toxicity with PM, together with a low dose of CCl4, helped to minimize secondary effects of CCl4, to clarify the sequence of toxic events, and to assess the sensitivity of some standard tests of hepatotoxicity. Simultaneous measurement of over 20 commonly used biochemical screening tests in individual animals 3 or 6 h after treatment permitted direct correlation of a wide variety of concentrations, activities and effects. For example, liver CHCl3 concentrations (as a measure of CCl4 metabolism) correlate strongly with increases in diene conjugation of microsomal lipids (as a measure of CCl4‐induced lipid peroxidation); malonaldehyde production appears to be less sensitive as a measure of lipid peroxidation in vivo than diene conjugation. The changes induced in each parameter and the correlations between them are discussed with reference to the overall nature of the hepatotoxic reaction and its modification by PM.