bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative determination of itazigrel in rodent diet by reversed‐phase HPLC and evaluation of its stability at 20°C
Authors: Bombardt Paul A. , Bothwell Brian E. , Closson Sharon K. , Adams Wade J. 
Published: May 2005

AbstractA simple, accurate and precise procedure for the quantitation of itazigrel (a potent lipophilic inhibitor of collagen and arachidonic acid‐induced aggregation being studied for its effects on peripheral vascular disease) from granulated rodent diet is presented. The drug was extracted from rodent diet using methanol + water (80:20) following dissolution of the diet in water. Samples of the supernatant were injected into the HPLC and the eluent was monitored with a fluorescent detector (λex = 320 and λem = 430) to achieve analytical specificity. Interday coefficients of variation of the calibration curve slope were ±6% on standards between 0 and 1000 μg/g. Potency and homogeneity of the drug spiked diet prepared over a 1 year interval at 70,200 and 600 μg/g was 99.3 ± 2.5%, 100 ± 1.8%, and 101 ± 1.9% of label, respectively. Samples prepared for chromatography were stable for 24 h at 20°C, and drug in diet was stable for 102 days when protected from light and stored at 20°C.
High performance liquid chromatography of biological polyamines using immobilized enzyme as post‐column reactor followed by electrochemical detection
Authors: Watanabe Noriyuki , Asano Masao , Yamamoto Katsunobu , Nagatsu Toshiharu , Matsumoto Takatoshi , Fujita Keisuke 
Published: May 2005

AbstractA novel analytical method for biological polyamines (putrescine, spermidine and spermine) was developed. Polyamines were separated by ion‐pair reversed phase chromatography using a polymer‐based octadecyl bonded column. A polyamine oxidase immobilized column worked effectively as a post‐column reactor to convert polyamines to hydrogen peroxide which was eventually detected by electrochemical oxidation on platinum electrode. This method required neither tedious derivatization nor gradient elution, permitting us to perform simple and rapid analysis of polyamines. The detection limits were 0.3, 0.6, and 4 pmol injected for putrescine, spermidine, and spermine, respectively with a linear range of two to three orders of magnitude. Chromatograms obtained with samples from human urine and rat brain homogenates demonstrated the high sensitivity and selectivity of the method.
Analysis of drug in tissue homogenates by high performance liquid chromatography with direct injection and column switching
Authors: Imai Hideo , Tamai Gen 
Published: May 2005

AbstractAn HPLC method with direct sample injections and column switching was investigated for the analysis of drugs in tissue homogenates. The appropriate precolumn packings and analytical column packings were surveyed in order to obtain quantitative recovery. The use of a large bore end‐fitting filter for the precolumn avoided the interference due to minute tissue particles. A minicolumn was used to trap the analyte or clean up the sample. The method was applicable to hydrophilic as well as hydrophobic drugs in liver, kidney or heart tissues, and has been extensively used in the determination of drugs in centrifugal cell fractions such as the nucleus, mitochondria and microsome.
A rapid method for isolation of human hemoglobin benzo[a]pyrene diol epoxide derived adducts using high performance liquid chromatography
Authors: Naylor S. , Gan L.‐S. , Day B. W. , Skipper P. L. , Tannenbaum S. R. 
Published: May 2005

AbstractA method is described to isolate rapidly human hemoglobin‐benzo[a]pyrene diol epoxide adducts. A combination of 300 Å pore size C4 reversed phase HPLC to effect separation of adducted protein from native protein, and μ‐bore C18 reversed phase HPLC to isolate and partially characterize proteolytic peptide adducts (by UV), was used.
Simultaneous determination of some organophosphorus pesticides by high performance liquid chromatography
Authors: Kumar Reena 
Published: May 2005

AbstractAn HPLC method for the simultaneous detection of six organophosphorus pesticides (Dimethoate, Ethion, Malathion, Phorate, Phosalone and Parathion) on a Zorbex ODS column using methanol + water (80: 20) as solvent is described.
Optimization of an Isocratic Reversed Phase Liquid Chromatographic System for the Separation of Fourteen Steroids Using Factorial Design and Computer Simulation
Authors: Wei Ji‐Qing , Wei Ji‐Lu , Zhou Xian‐Teng 
Published: May 2005

AbstractAn optimization strategy for an isocratic reversed phase high performance liquid chromatographic system (RP‐HPLC) is described. Factorial design and a computer program are used to predict the retention time and resolution of fourteen steroids. An optimized rapid (<25 min) isocratic RP‐HPLC system for the satisfactory separation of cortisone, cortisol, corticosterone, 11‐deoxycortisol, 11‐deoxycorticosterone, 17α‐hydroxyprogesterone, progesterone, androstenedione, testosterone, estrone, estradiol, estriol, prednisone acetate and dexamethasone acetate has been developed using this strategy through eight experiments.
High performance liquid chromatographic separation of cisplatin and its hydrolysis products on alumina and application to studies of their interaction with cysteine
Authors: Shearan Paula , Alvarez José M. Fernández , Zayed Nihal , Smyth Malcolm R. 
Published: May 2005

AbstractAn alumina stationary phase has been assessed in the study of the retention behaviour of the anticancer drug cisplatin and its major hydrolysis products. Parameters such as buffer concentration in the mobile phase, pH, organic modifier and competing ion have been investigated in order to optimize chromatographic separation with ultraviolet detection. The separation scheme developed has been used to monitor the hydrolysis of cisplatin in aqueous and saline media, and to monitor the interaction of hydrolysed solutions of cisplatin with the amino acid cysteine. A new peak was observed in the chromatograms of such mixtures when they had been allowed to stand for periods of greater than 16 h and, from analysis of the data obtained, it was concluded that this new peak was due to a complex formed between the mono‐aquo hydrolysis product of cisplatin and the amino acid.
Studies on the effects of imidazole on the peroxyoxalate chemiluminescence detection system for high performance liquid chromatography
Authors: Imai Kazuhiro , Nishitani Atsuhiko , Tsukamoto Yukie , Wang Wei‐Hong , Kanda Susumu , Hayakawa Kazuichi , Miyazaki Motoichi 
Published: May 2005

AbstractThe catalytic effect of bases (imidazole, pyridine, Tris and triethylamine) on the peroxyoxalate chemiluminescence (PO‐CL) reaction for high performance liquid chromatography (HPLC) was investigated. Imidazole increased PO‐CL intensity extraordinarily, whereas the other bases (pyridine, Tris and triethylamine) did not. The peak heights of dipyridamole (coronary vasodilator) obtained using the eluents containing buffers were largest at pH 7.0, a few times less at pH 6.0 and pH 5.0, 100 times less at pH 4.0 and a few hundred times less at pH 3.0. The eluents containing buffers at pH 3, 4, 5, 6 or 7 each with imidazole increased the peak heights by a few to ten times as compared with those without imidazole, and those peak heights were within one order of magnitude. On the other hand, the eluent containing buffer at pH 2 did not affect the peak heights with or without imidazole. Bis(4‐nitro‐2‐(3,6,9‐trioxadecyloxycarbonyl)phenyl) oxalate (TDPO) alone and bis(2,4‐dinitrophenyl)oxalate (DNPO) plus TDPO were recommended to be used against eluents containing buffers of pH 5 – 7 and pH 3 – 4, respectively. Dipyridamole and benzydamine hydrochloride (anti‐inflamatory drug) were separated on the ODS column and detected by the present system. The detection limits of dipyridamole and benzydamine hydrochloride were 40 amol and 270 fmol, respectively.
Continuous flow determination of nitrite with membrane separation/chemiluminescence detection
Authors: Aoki Toyoaki 
Published: May 2005

AbstractA method for the determination of nitrite in water utilizing a membrane separation process and a chemiluminescence detector, with the addition of air‐stripping and air‐carrier, is proposed. The microporous poly(tetrafluoroethylene) tube was used as separator to transfer nitric oxide (reduced by iodine in acidic media) into a gas phase. Air‐stripping was used to enhance the separation. Chemiluminescence signals produced from the reaction of nitric oxide with ozone were linearly proportional to the concentration of nitrite from 10 ppb (μg as N/L) to 5 ppm (mg N/L). The relative standard deviation (n = 5) was 0.7% at 0.1 ppm. The time elapse from starting the sample flow until the signal reached a stable level was 1.5 min.
Isolation and characterization of β‐hydroxypropionic acid‐ and hydroxyacetic acid‐uroporphyrin I in the urine of a patient with congenital erythropoietic porphyria by high performance liquid chromatography and liquid secondary ion mass spectrometry
Authors: Guo Rong , Chaim W. , Rideout J. M. , Lawson A. M. , Lim C. K. 
Published: May 2005

Abstractβ‐Hydroxypropionic acid‐ and hydroxyacetic acid‐uroporphyrin I have been isolated from the urine of a patient with congenital erythropoietic porphyria by reversed phase high performance liquid chromatography. The compounds were characterized by their chemical behaviour and confirmed by liquid secondary ion mass spectrometry.
Determination of 6‐mercaptopurine and its metabolites in plasma or serum by high performance liquid chromatography
Authors: Sahnoun Z. , Serre‐Debeauvais F. , Lang J. , Faucon G. , Gavend M. 
Published: May 2005

AbstractA sensitive and accurate reversed phase liquid chromatographic assay was developed for the determination of 6‐mercaptopurine (6MP) (the active metabolite of azathioprine) in human plasma. The assay involved extraction into acetonitrile and dichloromethane from plasma pretreated with 0.038 M of dithiothreitol solution. The residue was analyzed by isocratic chromatography on a C18 analytical column with UV detection at 326 nm. The average extraction recovery of 6MP was 85%.The method has been applied successfully to the determination of 6MP and its metabolites in pharmacokinetic studies.
Chiral separation and determination of propranolol enantiomers in rat or mouse blood and tissue by column switching high performance liquid chromatography with ovomucoid bonded stationary phase
Authors: Tamai Gen , Edani Masami , Imai Hideo 
Published: May 2005

AbstractResolution of propranolol (PL) enantiomers in biological samples was accomplished by column switching high performance liquid chromatography using a short precolumn and an analytical column of ovomucoid chiral phase. Plasma, whole blood or tissue homogenate sample was directly injected into the precolumn, and PL was adsorbed on Butyl Toyopearl 650‐M. After column switching, the PL was backflushed and transferred to the analytical column (Ultron ES‐OVM) by the eluant. Fluorometric detection was carried out at λex = 297 nm and λem = 340 nm with a detection limit of 0.5 pmol (signal to noise ratio = 2). The recovery 98.8–103%), reproducibility (coefficient of variance less than 3%) and enantiomer resolution (separation factor 1.15) were satisfactory using as eluant 50 mM sodium dihydrogenphosphate (pH 4.6) containing 12% ethanol. The time course of elimination of PL enantiomers in rat or mouse blood and tissues was also studied.
Isocratic reversed phase high performance liquid chromatography determination of twelve natural corticosteroids in serum with on‐line ultraviolet and fluorescence detection
Authors: Wei Ji‐qing , Wei Ji‐lu , Zhou Xian‐teng , Cheng Ji‐ping 
Published: May 2005

AbstractAn isocratic reversed phase high performance liquid chromatography procedure utilizing ultraviolet and fluorescence detectors linked in series is described for the analysis of cortisone (E), cortisol (F), corticosterone (B), 11‐deoxycortisol (S), 11‐deoxycorticosterone (DOC), androstenedione (A), testosterone (T), 17‐hydroxyprogesterone (17‐OHP), progesterone (P), estriol, estradiol, estrone, prednisone acetate and dexamethasone acetate in serum. Serum specimens were extracted with ethyl ether. The optimized mobile phase was methanol + tetrahydrofuran + water 26:18:56, v/v/v). A Shim‐pack ODS column was used. The recoveries were 80 to 103%. lntra‐ and inter‐day coefficient of variance were less than 8%. The detection limit is 0.5 pmol per injection volume for estriol, estradiol, E, F and B; 1 pmol for S, A, DOC and estrone; 2 pmol for T and 17‐OHP; and 4 pmol for P. Serum from normal subjects and patients with congenital adrenal hyperplasia due to 21‐ or l7‐hydroxylase deficiency were measured, as well as samples of maternal and umbilical cord serum.
High performance liquid chromatographic determination of methylxanthines in canine serum, gastric and pancreatic juices
Authors: Casoli Philippe , Vérine Henri 
Published: May 2005

AbstractA convenient high performance liquid chromatographic method for the determination of methylxanthines in biological samples is described. Separation was achieved by reversed phase chromatography using a mobile phase consisting of tetrahydrofuran + methanol + 0.01M potassium dihydrogen phosphate, pH 3.5 (1:20:79, v/v/v), on a 7 μm C18 column and a C18 Lichrosorb precolumn at a flow rate of 0.8 mL/min. Levels varying from 0.25 – 16 mg/L could be detected by UV at 280 nm. In this range, standard curves were established for 4 methylxanthines: theobromine, paraxanthine, theophylline and caffeine in 4 media: mobile phase, serum, gastric and pancreatic juices, and were found to be linear (r ≥ 0.9975). Overall characteristics of the method were determined as: percent recovery (89.54%), accuracy (≥99.4%) and reproducibility (≥95%). Retention times ranged from 4.21 ± 0.01 (1‐methyluric acid) to 10.8 ± 0.03 min (caffeine). Animal experiments (5 and 10 mg/kg boluses) were used to determine caffeine half life in dog's blood (310 ± 46 and 453 ± 59 min, respectively) and its secretion into pentagastrin stimulated gastric juice (mean concentrations 2.51 and 6.04 mg/L; mean outputs 351 and 1206 μg/2.25 h; both statistically different at p < 0.001 level).
Separation and quantification of histamine and Nτ‐methylhistamine in brain extracts
Authors: Pastó Manel , Sabria Josefa 
Published: May 2005

AbstractHistamine and its Nτ‐methyl derivative can be separated from perchloric acid extracts of rat brain by high performance liquid chromatography on a C18 column under isocratic conditions eluting with 0.1 M sodium phosphate buffer containing 0.19 mM sodium dodecyl sulphate and 25% methanol. Using electrochemical detection, histamine and Nτ‐methylhistamine can be detected at levels of less than 40 pg/μL tissue extract (<1 pmol). The retention times for histamine and Nτ‐methylhistamine were 15 min and 23 min, respectively, at a flow rate of 1.2 mL/min, and both compounds eluted as acceptably sharp peaks. The concentrations of histamine and Nτ‐methylhistamine in brain from seven‐day‐old rats were found to be very similar to those obtained by other analytical procedures.
Separation of proteins by consecutive sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis and reversed phase high performance liquid chromatography
Authors: Kaplan Batia , Pras Mordechai 
Published: May 2005

AbstractA procedure for the preparative separation of proteins was developed by using consecutively sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis (SDS‐PAGE) and reversed phase high performance liquid chromatography (HPLC). The proteins were separated by SDS‐PAGE and afterwards extracted from the gel. The extracted proteins were separated from SDS and other small molecular weight contaminants on a Fractogel TSK HW‐40 (F) column in acidic aqueous acetonitrile. The proteins eluted from the Fractogel column were fractionated by HPLC. The identity and purity of the recovered proteins was confirmed by SDS‐PAGE analysis.
Application of ion pair high performance liquid chromatography to the analysis of porphyrins in clinical samples
Authors: Jacob K. , Luppa P. 
Published: May 2005

AbstractReversed phase ion pair chromatography is a highly selective separation technique for the determination of free porphyrin carboxylic acids from human materials. Isocratic and gradient elution methods can be used to analyse porphyrin isomers and to establish porphyrin profiles for the biochemical diagnosis of porphyrias. Ion pair high performance liquid chromatography led to the discovery of the atypical isomers II and IV of uroporphyrin and coproporphyrin in human urine. Advantages and limitations of the ion pair technique are discussed.
Field flow fractionation in biomedical analysis
Authors: Levin Shulamit 
Published: May 2005

AbstractSamples of biomedical interest which have been analysed by field‐flow fractionation techniques are surveyed. The list begins with whole cells and microorganisms, going through viruses, nucleic acids, cell fragments and organelles, down to proteins and their aggregates. The principles of separation in the normal and steric mode of retention are illustrated, and instrumentation and techniques are described. The review concentrates mainly on the two systems of choice for biomedical applications: sedimentation and flow field‐flow fractionation.
Analysis of vitamin D and its metabolites using thermospray liquid chromatography/mass spectrometry
Authors: Watson David , Setchell Kenneth D. R. , Ross Richardus 
Published: May 2005

AbstractA new method is described for the analysis of vitamin D and its metabolites utilizing thermospray (TSP) mass spectrometry as an on‐line detector for high performance liquid chromatogrpahy. Ionization conditions were optimized for use with isocratic reversed phase chromatography. TSP mass spectrometry was employed in series with a UV absorbance detector to facilitate comparisons between the two methods of detection. Positive ion TSP mass spectra were recorded for vitamin D2, vitamin D3, 25‐hydroxyvitamin D3 (25(OH)D3), 1,25‐dihydroxyvitamin D3 (1,25(OH)2D3) and 24,25‐dihydroxyvitamin D3 (24,25(OH)2D3). The spectra contained protonated molecular ions, ammonium adduct ions and fragment ions due to the loss of one or more molecules of water. A comparison of quantitative precision was made by determining UV absorbance and TSP standard curves for vitamin D3 using two different methods: (1) External standard method with post‐column (post UV detector) addition of ammonium acetate. (2) As (1) but using the method of internal standards with a closely eluting internal standard (vitamin D2). In each case the quantitative precision (correlation coefficient) for UV absorbance detection was superior owing to intrinsic instability of the TSP ion beam. A stable isotopically labelled internal standard was employed in the development of an assay for 1,25(OH)2D3. The assay was used to quantify in vitro enzymic conversion of 25(OH)D3 to 1,25(OH)2D3 in guinea pig and sheep renal mitochondrial incubations. TSP LC/MS was also applied to analysis of an extract of human blood plasma in which D3 and each of its principal metabolites were identified in a single analysis.
Medium‐ and long‐chain 3‐hydroxymonocarboxylic acids: Analysis by gas chromatography combined with mass spectrometry
Authors: Dorland L. , Ketting D. , Bruinvis L. , Duran M. 
Published: May 2005

AbstractMedium‐ and long‐chain 3‐hydroxymonocarboxylic acids represent intermediates in the β‐oxidation of fatty acids: they accumulate in the plasma of patients with an inherited deficiency of long‐chain 3‐hydroxyacylcoenzyme A dehydrogenase. 3‐Hydroxy acids with chain lengths varying from 6 to 16 were synthesized by a Reformatzky reaction. Capillary gas chromatography of the pertrimethylsilyl derivatives was performed on a CP‐Sil 19 CB column, coupled to a quadrupole mass spectrometer in the electron impact mode. Calculation of the retention indices showed that the separation of the 3‐hydroxy acids from the homologous straight‐chain fatty acids may be troublesome, stressing the need for mass spectrometric identification.
High performance liquid chromatography of glucose using a post‐column reactor of immobilized enzyme followed by electrochemical detection (glucose‐LCEC)
Authors: Watanabe Noriyuki 
Published: May 2005

AbstractA sensitive and selective, reasonably fast method for the determination of glucose content has been developed. A glucose oxidase immobilized column was coupled to a small‐size anion exchange column/borate buffer chromatograph. The hydrogen peroxide produced in the enzyme reaction was detected directly by an amperometric detector using a platinum working electrode. The detection limit was 0.03 ppm (1.5 × 10−7 M, 3 pmol/injection). The linear dynamic range was three orders of magnitude at least. The system was stable and reproducible both in short‐and long‐term operation. The proposed method is suitable for analysis of complicated matrices of biological samples because of its good selectivity and sensitivity.
4‐(N,N‐Dimethylaminosulphonyl)‐7‐Fluoro‐2,1,3‐Benzoxadiazole as chemilumigenic reagent for high performance liquid chromatographic peroxyoxalate chemiluminescence detection
Authors: Uzu Sonoko , Imai Kazuhiro , Nakashima Kenichiro , Akiyama Shuzo 
Published: May 2005

Abstract4‐(N,N‐Dimethylaminosulphonyl)‐7‐fluoro‐2,1,3‐benzoxadiazole (DBD‐F), presented as a fluorogenic labelling reagent for amines and amino acids, is preferred for peroyoxalate chemiluminescence (PO‐CL) detection in high performance liquid chromatography. Amino acids and epinephrine derivatized with DBD‐F were separated on a reversed phase column and detected at the femtomole level by the PO‐CL detection system.
Solid phase extraction of oxcarbazepine and its metabolites from plasma for analysis by high performance liquid chromatography
Authors: Hartley R. , Green M. , Lucock M. D. , Ryan S. , Forsythe W. I. 
Published: May 2005

AbstractA rapid, sensitive and simple‐to‐operate high performance liquid chromatographic method for the simultaneous determination of oxcarbazepine, 10‐hydroxycarbazepine and 10,11‐dihydro‐10,11‐trans‐dihydroxy‐carbamazepine in plasma is described. The drug and its metabolites were extracted from plasma using commercially available reversed phase octadecylsilane bonded‐silica columns (Bond Elut C18, 1 mL capacity). Chromatographic separation of oxcarbazepine and its metabolites was achieved using a mobile phase consisting of acetonitrile/methanol/water (13:25:62 by volume) at a flow rate of 1.2 mL/min in conjunction with a Waters Associates Nova‐Pak C18 column. The analytical column, in Radial‐Pak cartridge form, was used in combination with a LiChrospher 5 μm C18 guard column. By measuring the UV absorbance at 214 nm, plasma levels in the region of 50–100 ng/mL for the drug and its metabolites can be detected with only 100 μL of plasma. The method has been applied to pharmacokinetic studies of oxcarbazepine and its metabolites in children with epilepsy; preliminary pharmacokinetic findings in two patients at steady‐state are presented.