bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of ascorbic acid and dehydroascorbic acid in gastric juice by HPLC
Authors: Sanderson M. J. , Schorah C. J. 
Published: May 2005

AbstractNew methods are presented for measuring total vitamin C and the ascorbic acid/dehydroascorbic acid ratio in gastric juice. Extracts are prepared from a gastric juice which are suitable for direct injection onto a Waters Nova‐pak C18 Radial‐pak cartridge for high performance liquid chromatography (HPLC) using ultraviolet absorbance at 270 nm for detection. Both enable removal of interfering mucus and mucopolysaccharide breakdown products in a novel way. The first uses mini‐columns of Sephadex G‐50, run in acidic conditions to remove large molecular weight material while maintaining the ascorbic acid/dehydroascorbic acid ratio as it was in the fresh sample. Addition of dithiothreitol converts the dehydroascorbic acid quantitatively to ascorbic acid, thus enabling measurement of both components. The second method converts all the dehydroascorbic acid to ascorbic acid at the outset. A perchloric acid extract is neutralized and passed through a Sep‐Pak C18. A new internal standard, reductic acid, is introduced for ascorbic acid analysis which behaves identically on Sep‐Pak C18. Samples are analysed by ion‐pair chromatography using 0.02 M NH4H2PO4 buffer (pH 7.1): methanol (80:20 v/v) containing 0.62 g/L tetrapentylammonium bromide. The detection limit was 1 ng ascorbic acid, and chromatography was completed in 5 min. The values obtained by the two independent HPLC methods were in good agreement with each other and with those obtained by the 2,4‐dinitrophenylhydrazine colorimetric method.
Direct concurrent measurement of urinary vanillylmandelic acid, 5‐hydroxyindoleacetic acid and homovanillic acid by HPLC. Three methodologies compared
Authors: van Haard P. M. M. , Wielders J. P. M. , Wikkerink J. B. W. 
Published: May 2005

AbstractThree different direct HPLC methods for the determination of 3‐methoxy‐4‐hydroxymandelic acid (VMA, vanillylmandelic acid), 5‐hydroxyindoleacetic acid (5‐HIAA) and 3‐methoxy‐4‐hydroxyphenylacetic acid (HVA, homovanillic acid) in urine were compared: two spectrofluorometric methods, applying discontinuous gradients, and one serial coulometric linear gradient method. The imprecision study (n = 6) revealed comparable coefficients of variation (CV), intra‐assay ranging 1.4–11.1%, and inter‐assay ranging 5.9–11.8% for physiological and moderately elevated levels of VMA, 5‐HIAA and HVA. All methods showed good linearities up to 100 μmol/L for each of the three compounds studied. Analytical recoveries were 97–114% for VMA, 87–103% for 5‐HIAA, and 80–95% for HVA. Recoveries were not dependent on urinary relative densities in the range 1.010–1.030 kg/L or on protein content (prior to acidification) in the range 0.1–3 g/L, or on the pH of conservation in the range 2–5 or on storage temperature in the range −20–+22°C for three weeks.The distributed‐sample comparison revealed acceptable correlations and clinically unimportant accuracy differences between the methods. It is concluded that direct fluoro netric and electrochemical HPLC methods can be used in the determination of major catecholamine and serotonin metabolites in human urine for clinical diagnosis and follow‐up of neural crest and carcinoid tumours.
Selective purification of reduced oligosaccharides using a phenylboronic acid bond elut column: Potential application in HPLC, mass spectrometry, reductive amination procedures and antigenic/serum analysis
Authors: Stoll Mark S. , Hounsell Elizabeth F. 
Published: May 2005

AbstractA phenylboronic acid (PBA) derivatized Bond Elut column has been investigated for the selective purification of oligosaccharide alditols and of oligosaccharide derivatives formed by reductive amination reactions. These compounds are specifically retained by the column via interaction of sterically unhindered vicinal hydroxyl groups, hence achieving their separation from glycopeptides, unreduced oligosaccharides and non‐carbohydrate reactants. This purification procedure has widespread application for the clean‐up of derivatives prior to HPLC, mass spectrometry and antigenic/serum analysis.
HPLC analysis of polyamines and their acetylated derivatives in the picomole range using benzoyl chloride and 3,5‐dinitrobenzoyl chloride as derivatizing agent
Authors: Wongyai Surapote , Oefner Peter , Bonn Günther 
Published: May 2005

AbstractAnalytical methods are described for the quantitative determination of putrescine, cadaverine, spermidine, spermine and the acetylated derivatives of spermidine and spermine in biological fluids using pre‐column derivatization with either benzoyl chloride or 3,5‐dinitrobenzoyl chloride, which were added to each sample as solutions in diethyl ether. Putrescine, spermidine and spermine can be analysed in seminal plasma at nanogram levels when benzoyl chloride is used as derivatizing agent. In the analysis of putrescine, cadaverine, spermidine and acetyl derivatives of spermidine and spermine, higher sensitivity is obtained with 3,5‐dinitrobenzoyl‐chloride. This method can readily be used in the determination of acetylated polyamines in urine samples.
MicroHLPC determination of amygdalin in Semen pruni armeniacae and Semen pruni persicae
Authors: He Li‐Yi , Li Bao‐Ming 
Published: May 2005

AbstractThe application of micro HPLC to the determination of amygdalin in Semen pruni armeniacae and Semen pruni persicae is described. Amygdalin is separated at ambient temperature on a reversed phase column of U‐Finepak SIL C18(150×0.5 mm) with methanol + water (25: 75 v/v) as the mobile phase at a flow rate of 10 μL/min. The results are calculated by the internal standard method. The linear range is 1–7 μg. The CV and recovery of pure amygdalin are 1.47% (n = 10) and 98.13%, respectively. The results of analysis are lower than those obtained by TLC, but microHPLC is much simpler, faster, and more sensitive and reproducible than TLC.
Compositional analysis of the three main gangliosides from adult human myometrium by a rapid capillary gas chromatographic method
Authors: Zhu Zhengmei , Li Ruixiang , Cui Zhaochun , Zhou Liangmo , Huang Mingxian 
Published: May 2005

AbstractA new capillary GC method is described for the compositional analysis of the three main gangliosides isolated from adult human myometrium. The sample was subjected to methanolysis, acetylation and trimethylsilylation which allows all the constituents to be analyzed simultaneously. The predominant ganglioside was found to be GD3, with GM3 and GT1b the next most abundant.
Determination of catechol‐O‐methyltransferase activity in erythrocytes by high performance liquid chromatography with electrochemical detection
Authors: Schultz Eija , Nissinen Erkki , Kaakkola Seppo 
Published: May 2005

AbstractA rapid assay employing HPLC with electrochemical detection for catechol‐O‐methyltransferase (COMT) activity in red blood cells is described. Enzyme activity is determined from erythrocyte lysates using S‐adenosyl‐L‐methionine as methyl donor and 3,4‐dihydroxybenzoic acid as substrate. The 3‐O‐ and 4‐O‐methylated reaction products are measured by high‐performance liquid chromatography with electrochemical detection. Human erythrocyte soluble form of COMT had Km values of 6.1 μM and 26.0 μM for S‐adenosyl‐L‐methionine and dihydroxybenzoic acid, respectively. The mean O‐methylation ratio for the soluble form of COMT was 5.3. An O‐methylation ratio of 15.5 was estimated in the membrane fraction of an erythrocyte pool from three samples. The activities of soluble COMT in erythrocytes of some animal species are also reported. The procedure is easily automated, and a large number of samples can be processed during one working day.
Determination of polyol profiles in human urine by capillary gas chromatography
Authors: Haga Hidehiko , Nakajima Terumi 
Published: May 2005

AbstractA new rapid capillary gas chromatographic method is described for the profile analysis of urinary polyols as their trifluoroacetyl derivatives. Ten urinary polyols: erythritol, threitol, fucitol, ribitol, arabinitol, xylitol, mannitol, glucitol, galactitol and myo‐inositol were completely determined for the first time. Iditol was newly found in normal urine. Urinary polyols were verified by gas chromatography/mass spectrometry.
High performance liquid chromatographic measurement of lignocaine in tissue samples following transabdominal placental biopsy
Authors: Monkman S. C. , Armstrong R. , Flanagan R. J. , Holt D. W. , Rosevear S. 
Published: May 2005

AbstractA method is described for the measurement of lignocaine in small samples of fetal and placental tissue. Tissue samples (ca 100 mg) are digested using a preteolytic enzyme. Lignocaine and an internal standard are extracted into methyl tert‐butyl ether and analysed by high‐performance liquid chromatography with electrochemical detection (+1.0 V vs Ag/AgCl). The limit of accurate measurement is better than 0.1 mg/kg wet weight for a 100 mg sample. This method has been used to assess fetal exposure to the drug when used as a local anaesthetic during transabdominal placental biopsy (chorionic villus sampling). The range of lignocaine concentrations found in the tissue samples was large (from <0.04 mg/kg wet weight to 15.4 mg/kg wet weight) although most samples contained less than 1.0 mg lignocaine/kg wet weight.
A high performance liquid chromatography/electrochemical assay for glutamatergic neurotransmitters in the rat brain
Authors: Harsing L. G. , Lajtha A. , Vizi E. S. 
Published: May 2005

AbstractThe release and content of the excitatory amino acid neurotransmitters glutamate and aspartate in rat striatum were determined by liquid chromatography/electrochemistry. This determination was based on precolumn off‐line derivatization of the amino acids with o‐phthaldialdehyde and 2‐mercaptoethanol (OPT/2‐MCE), and the adducts formed were separated under isocratic conditions and oxidized on a glassy carbon electrode at moderate potential (+0.6 V). The standard and the extracted glutamate when derivatized with OPT/2‐MCE produced similar electrochemical and chromatographic characteristics. The detection limit of glutamate was 0.5 pmol. Depolarization induced by the high potassium medium (40 mmol/L) enhanced the release of glutamate and aspartate from superfused rat striatum, whereas the efflux of glutamine remained unchanged. Perfusion (for 60 – 70 min) removed 50 – 80% of the free amino acid content of striatal tissue. The method described here is useful in neurochemical investigations of the brain amino acid neurotransmitters.
Application of high performance liquid chromatography combined with diode‐array detection for analysis of proteins and peptides in human cerebrospinal fluid
Authors: Silberring Jerzy , Nyberg Fred , Lyrenäs Sven 
Published: May 2005

AbstractDifferent strategies for HPLC separation, including molecular sieving, ion‐exchange, and hydrophobic interaction as well as reversed phase chromatography, were used to study molecular components in human cerebrospinal fluid (CSF). The separations were followed by photodiode‐array UV detection, which is a recently developed technique allowing a direct and rapid discrimination between peptides and proteins differing in their content of aromatic amino acids. By the various HPLC techniques in conjunction with diode‐array detection it was possible to identify and characterize several protein and peptide components present in CSF. The procedure also allowed quantitative analysis of CSF proteins using minute amounts of the fluid.
High performance liquid chromatography stability study of malonyl‐coenzyme A, using statistical experimental designs
Authors: De Spiegeleer Bart M. J. , Sintobin Karel , Desmet Jan 
Published: May 2005

AbstractMalonyl‐CoA is a biochemically important compound, formed by an acetyl‐coenzyme A carboxylase catalysed reaction. The stability of this short‐chain coenzyme A derivative under various experimental conditions is discussed in this article. High‐performance liquid chromatography was used for the analysis of the reaction mixture because of its excellent selectivity and sufficient sensitivity. Several variables were investigated as possible stability‐influencing factors: pH, magnesium and buffer concentration, reaction temperature and time. The Plackett‐Burman screening design was first used for selecting the most important variables, with which a central composite design was constructed. In this way, a response surface was obtained with the percentage remaining malonyl‐CoA as a function of magnesium concentration, reaction temperature and time. The usefulness of this approach is demonstrated by obtaining kinetic data from the mathematical function and by the evaluation of the stopping of reaction procedure in the activity assay of acetyl‐coenzyme A carboxylase.
Thin layer chromatography of dansyl and dinitrophenyl derivatives of amino acids. A review
Authors: Bhushan R. , Reddy G. P. 
Published: May 2005

AbstractThe dinitrophenyl (DNP) derivatives of amino acids have found continual application in protein sequencing since Sanger used them for the first time for the sequencing of insulin. Dansyl derivatives of amino acids have been widely used in protein sequencing because of their fluorescent nature. The success of protein sequencing largely depends upon correct identification of such derivatives. The choice for the method of identification is related to cost, the availability of instrumentation and to the sensitivity needed for the analysis. Thin layer chromatography (TLC) is simple and has several advantages over other chromatographic methods. Therefore the literature after 1972 is reviewed for TLC analysis of dansyl‐ and DNP‐amino acids, the two important amino acid derivatives required for identifying protein sequences. Additionally, the literature on the TLC resolution of enantiomeric mixtures of dansyl amino acids is reviewed. Application of various adsorbents, composition of solvent systems and other experimental conditions together with successful resolution data have been discussed. TLC provides a direct and inexpensive method for the resolution of enantiomers, and is fast becoming a sensitive instrumentalized quantitative analytical technique.
High resolution chromatography of ribonucleosides and its application to RNA analysis
Authors: Tanaka Kouji , Yazawa Kouhei , Nakajima Terumi 
Published: May 2005

AbstractA simple and precise method was developed for the separation of nucleosides including modified nucleosides and oligonucleotides. Nineteen kinds of nucleosides were completely separated by HPLC using an ODS column (TSK‐gel ODS 80TM) and aqueous mobile phases. The RNA molecule was digested by base restrictive RNase (RNase A, RNase T1) and the digests were separated chromatographically into each oligonucleotide. The nucleoside composition of an oligonucleotide was then determined by this analytical system. It is thus possible to fit the oligonucleotide in the original RNA molecule by using modified bases as markers. The reaction site of quinacrine mustard for tRNAPhe (from yeast) could be determined by this analytical system.
Rapid quantitative determination of epirubicin and its metabolites in plasma using high performance liquid chromatography and fluorescence detection
Authors: Dine T. , Brunet C. , Luyckx M. , Cazin M. , Gosselin P. , Cazin J. L. 
Published: May 2005

AbstractA rapid sensitive and selective isocratic technique was developed for the analysis of plasma epirubicin and three of its known fluorescent metabolites epirubicinol, 4′‐O‐β‐D‐glucuronyl‐4′‐epidoxorubicin and 4′‐O‐β‐D‐glucuronyl 1,3‐dihydro‐4′‐epidoxorubicin, with daunorubicin as an internal standard, by using high performance liquid chromatography (HPLC) with fluorescence detection and a ‘Hypersil ODS’ column. The drugs were easily and efficiently extracted with a Sep‐Pak C18 cartridge and the mean recoveries were greater than 85%. Intraassay and Interassay coefficients of variation (plasma samples) were better than 8.25%. An example of pharmacokinetic study obtained in a cancer patient after intravenous injection of epirubicine is described.
Application of reversed phase high performance liquid chromatography to the analysis of sulphidopeptide leukotrienes in pig bile
Authors: Tagari Philip , Ethier Diane , Ford‐Hutchinson Anthony , Cirino Maria 
Published: May 2005

AbstractReversed phase HPLC methodology has been developed for separation of peptide leukotrienes and indomethacin in porcine bile. Reproducible recoveries were obtained using radioactive leukotrienes ([3H]LTC4, 57.1 ± 2.5%; [3H]LTE4, 62.7 ± 1.9%; [3H]LTD4, 54.3 ± 2.7%). Radioimmunoassay of column eluant demonstrated that as little as 300 pg of exogenous leukotrienes could be measured in bile fluids, with similar recoveries. Analysis of bile sampled 60–90 min after initiation of experimental endotoxic shock in indomethacin treated pigs revealed a leukotriene concentration of 5.24 ± 1.16 ng/mL(LTD4). This was significantly greater (p < 0.05, n = 3) than that observed in samples collected prior to endotoxin (0.42 ± 0.23 ng/mL), or from untreated animals (0.85 ± 0.51 ng/mL). This method is thus applicable to investigation of the role of 5‐lipoxygenase products in porcine models of human disease, including shock conditions such as endotoxaemia, during cyclooxygenase inhibition by indomethacin.
Removal of sodium dodecyl sulphate from proteins isolated by sodium dodecyl sulphate polyacrylamide gel electrophoresis
Authors: Kaplan Batia , Pras Mordechai 
Published: May 2005

AbstractA procedure is described for the removal of sodium dodecyl sulphate (SDS) from proteins isolated by SDS‐polyacrylamide gel electrophoresis (SDS‐PAGE). The proteins separated by SDS‐PAGE were stained with Coomassie Blue and extracted with Tris‐HCI buffer containing SDS. The obtained extracts were subjected to gel permeation chromatography in an acidic aqueous acetonitrile solution. The procedure allows purification of the isolated proteins not only from SDS, but also from Coomassie Blue, buffer salts and other small molecular weight contaminants.
Low‐level interferences in peroxyoxalate chemiluminescence
Authors: Gooijer C. , Velthorst N. H. 
Published: May 2005

AbstractThe role of interferences at concentrations lower than 10−3 M in peroxyoxalate chemiluminescence is examined based on experimental results available in the literature. Implications for fluorophore and for hydrogen peroxide determinations are discussed. An interpretation in terms of the reaction mechanism is proposed.
A chemiluminometric method for NADPH and NADH using a two‐enzyme bioreactor and its application to the determination of magnesium in serum
Authors: Tabata Masayoshi , Totani Masayuki , Murachi Takashi 
Published: May 2005

AbstractChemiluminometric methods are described for the automated flow injection analysis of NADPH and NADH using an immobilized enzyme column reactor and serum magnesium. This application is for the clinical analysis of NADPH and NADH. The reactor for NADPH and NADH contains immobilized L‐glutamate dehydrogenase and L‐glutamate oxidase, and that for serum magnesium immobilized hexokinase, glucose‐6‐phosphate dehydrogenase, L‐glutamate dehydrogenase and L‐glutamate oxidase. When the sample is introduced into the four‐enzyme bioreactor, hydrogen peroxide is produced in proportion to the concentration of serum magnesium by the successive reactions. A co‐immobilized hexokinase/glucose‐6‐phosphate dehydrogenase/glutamate dehydrogenase column reactor gave better efficiency compared with an enzyme column which was prepared by packing co‐immobilized hexokinase/glucose‐6‐phosphate dehydrogenase and immobilized glutamate dehydrogenase to make two layers. Magnesium in serum was determined with 1μ L of the sample without carry‐over and for an assay time of approximately 15 s. The present method is sensitive (detection limit 0.1 nmol) because Mg2+ is recycled in a column, and gives perfect linearity of the data up to 3.0 mmol/L with satisfactory precision, reproducibility, and accurate reaction recoveries.
High performance liquid chromatography determination of doxorubicin and daunorubicin in plasma using UV detection and column switching
Authors: Mikan A. , Lanao J. Martinez , Lopez F. Gonzalez , Hurle A. Dominguez‐Gil 
Published: May 2005

AbstractA method for the determination of doxorubicin and daunorubicin in plasma is described. The plasma is injected directly into a loop column and then washed with water. After switching the injection valve, the sample is separated on a phenyl column using detection at 254 nm. The detection limit is 10 ng/mL, the coefficient of variation is 7% for 100 ng/mL of doxorubicin and 4% for 200 ng/mL of daunorubicin.
A new method for the high performance liquid chromatographic determination of TA‐870, a dopamine prodrug (catechol ester compound)
Authors: Yoshikawa Masayoshi , Endo Hiroshi , Hoshino Kumiko , Sugawara Yoichi , Takaiti Osasi , Kanda Susumu , Imai Kazuhiro 
Published: May 2005

AbstractA new method for the high performance liquid chromatographic (HPLC) determination of N(N‐acetyl‐L‐methionyl)‐O,O‐bis(ethoxycarbonyl)dopamine (TA‐870), a dopamine prodrug, in biological fluid has been developed. In order to measure with an electrochemical detector (ECD), TA‐870 was passed first through an immobilized carboxylesterase column to be converted to the electrochemically active deethoxycarbonylated TA‐870 (DEC‐TA‐870). The properties of this carboxylesterase immobilized on Sepharose 4B were examined by this flow injection system. Hydrolysis of TA‐870 with this immobilized carboxylesterase was a maximum at pH 7 – 8 and 50 °C, and the activity decreased in the presence of organic solvent such as acetonitrile. For the determination of TA‐870 in biological fluids, an HPLC‐immobilized enzyme‐ECD system using a column‐switching technique was developed. The blood was deproteinized with ethanol, and TA‐870 in the ethanol extracts was adsorbed in Bond Elut C18. The dichloromethane eluate from Bond Elut C18 was injected into the HPLC system. The HPLC apparatus was composed of three pumps, two separation columns (LiChrosorb Si 60 and μ Bondasphere), a trap column (Bond Elut), an enzyme column, ECD and the column‐switching system. The calibration curve for TA‐870 in blood was linear in the range from 2 to 200 ng/mL. This new assay method might be useful also for the determination of other catechol ester compounds.
High performance liquid chromatographic studies of erythrocyte haem biosynthetic enzyme activities in alcoholic macrocytosis
Authors: Wright D. J. , Lim C. K. , Peters T. J. 
Published: May 2005

AbstractThe activities of 5‐aminolaevulinate dehydrase (ALA‐D), hydroxymethylbilane synthase (HMB‐S), uroporphyrinogen III synthase (URO‐S) and uroporphyrinogen decarboxylase (URO‐D) in the erythrocytes of alcoholics were assayed and compared with those in controls and abstaining alcoholics. The HMB‐S and URO‐S activities in alcoholics were significantly higher than the controls and there were significant correlations between enzyme activities and mean corpuscular volume (MCV). Alcoholics abstaining from alcohol over a nine‐month period showed a return to normal enzyme activities in parallel with the normalization of their MCV. Abstaining alcoholics thus all had normal HMB‐S and URO‐S activities. The ALA‐D and URO‐D activities of alcoholics were not significantly different from controls or from abstaining alcoholics. Alcohol appears to have a selective effect on the haem biosynthetic enzymes in the erythron.