bluuebunny/crossref_metadata_2025_split huggingface dataset:
High performance liquid chromatographic analysis of six conjugated and unconjugated estrogens in serum
Authors: Su Syang Y. , Shiu Gerald K. , Simmons John , Viswanathan C. T. , Skelly Jerome P. 
Published: May 2005

AbstractSix estrogens—estrone, equilin, estradiol, sodium estrone sulphate, sodium equilin sulphate and sodium 17‐α‐dihydroequilin sulphate in dog serum were successfully separated and quantified by a high performance liquid chromatographic method developed in our laboratories. The mobile phase was optimized by studying the effects of an organic modifier (acetonitrile) and an ion pairing reagent (tetrabutylammonium hydroxide). The serum sample work‐up procedure was designed to recover both conjugated and unconjugated estrogens. The optimum method involved acetonitrile to precipitate serum proteins/peptides and extract estrogens. Residues were reconstituted in 50% acetonitrile in water for injection. The detection limits for these six estrogens via UV detection ranged from 0.5 to 5 ng on‐column with a signal‐to‐noise ratio (S/N) of 10 for a 20 μL injection and via fluorescence 0.1 ng on‐column for 17‐β‐estradiol. Validation data are included for all six estrogens.
Mixed‐bed polymeric o‐nitrobenzophenone reagents for the on‐line derivatization of amines in high performance liquid chromatography
Authors: Szulc Michael E. , Krull Ira S. 
Published: May 2005

AbstractSeveral polymer‐bound o‐nitrobenzophenone reagents containing different detector‐sensitive tags have been combined in the same reactor for the on‐line derivatization of amine samples. The formation of multiple derivatives allows numerous opportunities for quantitation from the same injection, and also allows improved identification from the retention times of the multiple derivatives. Changing the reaction conditions changes the ratio of the products formed, so that changes in the ratio of peak heights and areas can also be used for analyte identification. In this work, propylamine was derivatized in acetonitrile on‐line, precolumn. Changing the reaction conditions, of reaction time, temperature, solvent, presence of catalyst and the components of the reactor, changed the ratio of the derivatives formed. These changes in product formation with changing reaction conditions were applied to the identification and quantitation of amphetamine and methamphetamine in urine. The drugs were identified by the retention times of their derivatives, the ratio of te peak areas of the derivatives and the change in the ratios after changing reaction conditions. Each derivative was also used for quantitation of levels of spiked concentrations of amphetamine and methamphetamine, with relative errors less than 8%.
An automated method for the determination of a new potential antiepileptic agent (CGP 33101) in human plasma using high performance liquid chromatography
Authors: Brunner Linda A. , Powell Mark L. 
Published: May 2005

AbstractAn automated analytical method utilizing laboratory robotics has been developed and validated for quantifying concentrations of a new antiepileptic drug candidate (CGP 33101) in human plasma. The robotic system aliquots the biological sample, adds the internal standard (CGP 23901) and pH 12 buffer, extracts the compounds from the basified matrix into an organic phase (methyl‐t‐butyl ether:dichloromethane, 2:1) and concentrates the extracts for reversed‐phase, high performance liquid chromatographic (HPLC) analysis. The robotic system is directly interfaced with the HPLC system. Separation is achieved on a Hypersil 3 μm C18 column (4.6 × 50 mm) with ultraviolet detection of the analytes at 230 nm. Specificity was demonstrated by the lack of interfering peaks at the retention times for both the drug and internal standard. Recovery and reproducibility assessments indicated good accuracy (overall mean relative recovery of 102.7%) and precision (coefficient of variation of 4.4 to 7.7%) for CGP 33101 over the concentration range of 50–4000 ng/mL. The limit of quantification (LOQ) is 50 ng/mL. The method has been successfully applied to a clinical study in which normal volunteers received single oral doses of 400‐‐1200 mg of this new drug candidate.
Solid phase extraction and simultaneous high performance liquid chromatographic determination of antipyrine and its major metabolites in urine
Authors: Sarkar Mohamadi A. , March Clark , Karnes H. Thomas 
Published: May 2005

AbstractA reversed phase gradient high performance liquid chromatographic method utilizing solid phase extraction has been described for the simultaneous determination of antipyrine (AP), 4‐hydroxyantipyrine (4‐OHAP), norantipyrine (NorAP) and 3‐hydroxymethylantipyrine (3‐OHMAP) in human urine after hydrolysis with β‐glucuronidase. The C‐18 sorbent cartridges were conditioned and urine samples were applied, washed with 1 × 4 mL of phosphate buffer and eluted with 3 × 100 μL of 20% v/v of acetonitrile in methylene chloride. The eluent was evaporated to dryness, reconstituted in 100 μL phosphate buffer and injected. The calibration ranges were 2.0–250 μg/mL (AP), 2.5–250 μg/mL (NorAP), 2.0–250 μg/mL (3‐OHMAP) and 5.0–500 μg/mL (4‐OHAP) with regression coefficients of 0.998 or greater. Specificity was indicated by the absence of interferences in chromatogram of blank urine from normal as well as cirrhotic patients. The average recovery was 86.7% for AP, 90.5% for NorAP, 85.2% for 4‐OHAP and 74.2% for 3‐OHMAP. The within‐assay precision as indicated by the reproducibility of the assayed spiked urine was less than 9% in all cases and the between‐assay precision was less than 12%. The method was applied to studies on antipyrine metabolism in stable cirrhotic patients. Following administration of a single oral dose of about 1000 mg to nine stable cirrhotic patients and eigh age‐matched healthy volunteers, the cumulative account excreted in the urine up to 48 h for AP and the three metabolites was comparable to other literature reports.
Robotic solid phase extraction and high performance liquid chromatographic analysis of ranitidine in serum or plasma
Authors: Lloyd Thomas L. , Perschy Teresa Benedetti , Gooding Ann E. , Tomlinson Julie J. 
Published: May 2005

AbstractA fully automated assay for the analysis of ranitidine in serum and plasma, with and without an internal standard, was validated. It utilizes robotic solid phase extraction with on‐line high performance liquid chromatographic (HPLC) analysis. The ruggedness of the assay was demonstrated over a three‐year period. A Zymark Py Technology II® robotic system was used for serial processing from initial aspiration of samples from original collection containers, to final direct injection onto the on‐line HPLC system. Automated serial processing with on‐line analysis provided uniform sample history and increased productivity by freeing the chemist to analyse data and perform other tasks. The solid phase extraction efficiency was 94% throughout the assay range of 10–250 ng/mL. The coefficients of variation for within‐ and between‐day quality control samples ranged from 1 to 6% and 1 to 5%, respectively. Mean accuracy for between‐day standards and quality control results ranged from 97 to 102% of the respective theoretical concentrations.
Determination of 1,5‐Anhydroglucitol in urine by high performance liquid chromatography and an enzyme sensor
Authors: Tajima Shigeru , Hashiba Masashi , Suzuki Takayuki , Akanuma Hiroshi , Yabuuchi Masahiko 
Published: May 2005

AbstractA simple high performance liquid chromatographic method combined with an enzyme sensor has been developed to measure 1,5‐anhydroglucitol in urine. The enzyme sensor consists of a hydrogen peroxide electrode and a chitosan membrane of an immobilized pyranose oxidase. As the system does not resist interfering substances, urine samples are first purified by passing them through a two‐layer column packed with (1) strongly basic anion (OH− form, the upper layer) and (2) strongly acidic (H+ form, the lower layer) exchange resins. 1,5‐Anhydroglucitol is efficiently recovered in the flow‐through fraction of the column. In this system, the minimum detectable concentration of 1,5‐anhydroglucitol is 0.1 mg/L, and the measurable range extends from 0.1 to 60 mg/L. The coefficient of variation values of the within‐day and day‐to‐day precisions are 3.0‐6.5% and and 4.4‐6.7% respectively, and there is good agreement between the results measured by our method and those obtained by the gas‐liquid chromatographic/mass spectrometric method (r=0.994). The method we have described here has been successfully used to elucidate a mechanism for the reducing 1,5‐anhydroglucitol level in the serum and plasma of patients.
High performance gel filtration using monodisperse highly cross‐linked agarose as a one‐step system for mucin purification
Authors: Parker N. , Finnie I. A. , Raouf A. H. , Ryder S. D. , Campbell B. J. , Tsai H. H. , Iddon D. , Milton J. D. , Rhodes J. M. 
Published: May 2005

AbstractHigh performance gel filtration on monodisperse cross‐linked agarose (Superose 6) has been assessed as a system for purification of mucus glycoproteins. Comparison with the conventional two‐step purification of mucus glycoprotein by Sepharose CL4B gel filtration followed by caesium chloride density gradient centrifugation shows that purification by high performance gel filtration is at least as thorough, yielding mucin that is free from non‐mucin glycoproteins as defined by buoyant density, mobility on sodium dodecyl sulphate‐polyacrylamide gel electrophoresis and absence of Concanavalin A binding (mannose‐containing) material. This technique allows mucus glycoprotein to be purified from lyophilized crude mucin in 120 min compared with approximately 72 h using the conventional techniques. This makes the comparative study of mucus glycoprotein changes in disease states much more feasible.
Free‐solution capillary electrophoretic separation of small hydrophilic peptides
Authors: Zhang Y. K. , Chen N. , Wang L. 
Published: May 2005

AbstractSmall hydrophilic peptides differing in only one glycine amino acid group have been successfully separated by free‐solution capillary electrophoresis (FSCE) using phosphate buffer at acid pH. The effects of column temperature and operating current on the migration times of these small peptides have been investigated. The results from FSCE have been compared with those from reversed phase high performance liquid chromatography.
Thermal desorption‐gas chromatographic determination of ethane and pentane in breath as potential markers of lipid peroxidation
Authors: Massias L. , Postaire E. , Regnault C. , Hazebroucq G. 
Published: May 2005

AbstractFormation of free radicals and lipoperoxidation occur at the onset of cellular damage. These effects are produced during normal metabolism and in pathological states. The peroxidation of polyunsaturated fatty acids, i.e. linoleic acid and linolenic acid, which are both cellular membrane compounds, induces ethane and pentane formation in pulmonary air exhalation. These two volatile hydrocarbons can be considered as potential lipoperoxidation markers. Methodological difficulties limit the use of these gases for assessment of free oxygen radical activity but we have developed and validated a non‐invasive technique. A study was performed with ten healthy volunteers.
Determination of free and total proline and hydroxyproline in plasma and tissue samples by gas chromatography with flame photometric detection
Authors: Kataoka Hiroyuki , Nagao Katsuyuki , Makita Masami 
Published: May 2005

AbstractA selective and sensitive method for the determination of free and total proline (Pro) and 4‐hydroxyproline (Hyp) by gas chromatography (GC) was developed. For free Pro and Hyp analysis, plasma and tissue homogenate were extracted with methanol. For total Pro and Hyp analysis, these samples were hydrolysed in 6 M HCI. After removal of primary amino compounds by the reaction with o‐phthaldialdehyde, Pro and Hyp in methanol extract and acid hydrolysate were converted into their N‐dimethylthiophosphoryl methyl ester derivatives and then determined by GC with flame photometric detection using a DB‐5 capillary column. This method was successfully applied to small samples without prior clean‐up, and Pro and Hyp in these samples could be analysed without any influence from coexisting substances. Overall recoveries of Pro and Hyp added to plasma and tissue samples were 92–106%. The analytical results of free and total Pro and Hyp in human plasma and mouse tissue samples are presented.
Metabolic fate of fenitrothion in liver, kidney and brain of rat
Authors: Kumar Reena , Roy Shalini , Rishi Ritu , Sharma C. B. 
Published: May 2005

AbstractThe metabolic fate of fenitrothion, O,O‐dimethyl‐O‐(3‐methyl‐4‐nitro phenyl) phosphorothioate, was investigated in rat tissues during the first 24 hours following the intramusculer administration of the pesticide in the animal. High performance liquid chromatography (HPLC) of the pesticide and its metabolites formed in liver, kidney and brain showed the time‐dependent sequential conversion of the pesticide into three major metabolites. These metabolites were separated and purified to homogeneity by HPLC and characterized by IR spectroscopy as O,O‐dimethyl‐O‐)3‐methyl‐4‐aminophenyl) phosphorothioate (metabolite I), O,O‐dimethyl phosphorothioate (metabolite II), and O,O‐dimethylphosphate (metabolite III). These results indicated reduction of the nitro group in fenitrothion aas the first step, followed by the hydrolytic cleavage of the P‐O‐aryl bond in metabolite I and the oxidative desulphurylation of metabolite II. Fenitrothion was found to induce ultrastructural changes in liver cells especially after 12 h exposure nuclear membrane was completely distorted, nuclear intactness was totally lost and smooth endoplasmic reticulum and Golgi apparatus were abnormally enlarged. In 24 h, however, the regeneration of the nuclear material was observed.
Determination of nitrite by high‐performance liquid chromatography system with electrochemical detector: Measurement of nitric oxide synthase activity in rat cerebellum cytosol
Authors: Kaku Shinsuke , Tanaka Makoto , Muramatsu Makoto , Otomo Susumu 
Published: May 2005

AbstractA simple and sensitive assay method for NO synthase activity is described. Using glassy carbon as electrode and 30% methanol solution with 10 mM NH4Cl as mobile phase, NO can be measured without disturbing ECD‐detectable substance in NO synthase assay mixture. The NO production in the assay mixture of rat cerebellum NO synthase increased with protein and in a time‐dependent manner. The Km value for the substrate, L‐arginine, was 1.25 μM. The enzyme activity was inhibited in a concentration‐dependent manner by a NO synthase inhibitor, NNA. The Ki value for NNA was 0.166 ± 0.060 μM. This ECD–HPLC method for determining NO synthase activity has advantages compared with the diazo‐coupling method of the Greiss reagent and the isotopic method in which the conversion of the substrate, [14C]L‐arginine, to the product, [14C]L‐citrulline is measured; it is simple, sensitive and is convenient for studying the NO synthase activity with various compounds as the substrate.
Sensitive determination of (−)‐isoproterenol and (−)‐(R)‐1‐(3,4‐dihydroxyphenyl)‐2‐[(3,4‐dimethoxyphenethyl)amino] ethanol (T‐0509), a cardiotonic agent, in rat plasma utilizing a fully automated catecholamine analyser
Authors: Prados Pablo , Higashidate Sakae , Imai Kazuhiro , Sato Yoji , Nagao Taku 
Published: May 2005

Abstract(−)‐Isoproterenol (ISO), used as bronchodilator, and (−)‐(R)‐1‐(3,4‐dihydroxyphenyl)‐2‐ [(3,4‐dimethoxyphenethyl)amino]ethanol (T‐0509), a new cardiotonic agent, were determined in rat plasma (only 25 μL) using a fully automated catecholamine (CA) analyser that includes in‐line pre‐extraction of CAs, coupled with an HPLC–ethylenediamine condensation reaction and a peroxyoxalate chemiluminescence detection system (HPLC–ED–PO‐CL). The chromatographic conditions were: precolumn, SERUMOUT‐CEX; buffer for delivering CAs in the precolumn, 10 mM potassium phosphate buffer (pH 7.5)/ethanol (92 + 8, v/v) (1 mL/min); precolumn clean‐up solution, 4% phosphoric acid/acetonitrile (50 + 50, v/v) (1 mL/min); analytical column, TSKgel ODS‐80Ts, 250 × 4.6 mm i.d.; eluent, 75 mM potassium acetate buffer (pH 3.2)/50 mM potassium phosphate buffer (pH 3.2)/acetonitrile (83.6 + 4.4 + 12, v/v/v for ISO and 76 + 4 + 20 v/v/v for T‐0509) (1 mL/min); fluorogenic reagent solution, 105 mM ED and 175 mM imidazole in acetonitrile/ethanol (90 + 10, v/v) (0.25 mL/min); chemiluminogenic reaction solution, 0.25 mM TDPO, 150 mM hydrogen peroxide and 110 mM TFA in dioxane/ethyl acetate (50 + 50, v/v) (1.4 mL/min). Colterol, (±)‐1‐(3,4‐dihydroxyphenyl)‐2‐[(1,1‐dimethyl)ethylamino]ethanol, (±)‐N‐t‐butylnorepinephrine was used as an internal standard (IS) for ISO, and (±)‐1‐(3,4‐dihydroxyphenyl)‐2‐ [(3,4,5‐trimethoxyphenethyl)amino]ethanol, (±)‐(3,4,5‐trimethoxyphenethylaminomethyl)‐3,4‐dihydroxybenzylalcohol (T‐1583) for T‐0509. The detection limits for ISO and T‐0509 were 1.3 and 0.9 fmol on injection, respectively.
Isolation and purification of three glucuronides of antipyrine. Proposal for an original analytical method for quantitation of sulpho‐ and glucuroconjugated metabolites
Authors: Palette C. , Cordonnier P. , Tillequin F. , Koch M. , Advenier C. , Pays M. 
Published: May 2005

AbstractThe determination of the concentrations of antipyrine metabolites in biological fluids is hampered by the difficulty in obtaining pure conjugated compounds to be used as standards. Most authors have proposed determination of total forms by high performance liquid chromatography (HPLC) after deconjugation of these metabolites using chemical or enzymatic hydrolysis. Up to now there is no satisfactory hydrolysis method for the study of all antipyrine metabolites. The situation is further complicated by the fact that the deconjugated metabolites are highly unstable whichever technique is being used. Because of the lack of stability of all these molecules it has been necessary to isolate the glucuroconjugated compounds from urine. We describe a method which allows us to obtain highly purified glucuroconjugated metabolites of antipyrine. Sulphoconjugated compounds have been synthesized previously. We are thus able to propose a chromatographic procedure which allows us to determine simultaneously all stable phase I and phase II metabolites of antipyrine in biological fluids without any step of extraction. This analytical technique allows us to study the activity of the different isoenzymes implicated in the metabolism of antipyrine.
Human hemofiltrate as a source of circulating bioactive peptides: Determination of amino acids, peptides and proteins
Authors: Schepky Andreas G. , Bensch Klaus W. , Schulz‐Knappe Peter , Forssmann Wolf‐Georg 
Published: May 2005

AbstractHuman hemofiltrate (HF) was evaluated regarding its content of free amino acids, proteins, and regulatory peptides. Human HF was obtained from patients with end stage renal disease (ESRD). In contrast to plasma it mainly contains low and middle weight molecules ⩽45 kDa. The content of free amino acids, peptides, and proteins in pooled filtrate was determined by amino acid analysis using ortho‐phtaldialdehyde/fluorenyl methyl chloroformate (OPA/FMOC) precolumn derivatization. The total amount of peptides and proteins in human HF is 49.4 mg/L (n = 8). The levels of all free amino acids (230 mg/L) and the concentration of some regulatory peptides like insulin, endothelin, gastrin, vasopressin and angiotensin II were similar compared with blood plasma. The amount of peptides and proteins detected in the filtrate was around 0.07% of total plasma proteins, and consisted mainly of smaller proteins and peptides as shown by size exclusion chromatography (SEC). The presence of large proteins in plasma is reduced by a factor of 1500 after filtration. We conclude that human hemofiltrate is a valuable source for the large‐scale extraction of regulatory peptides.
Determination of sulphur amino acids by gas chromatography with flame photometric detection
Authors: Kataoka Hiroyuki , Tanaka Hirofumi , Fujimoto Ayumi , Noguchi Ikuko , Makita Masami 
Published: May 2005

AbstractA selective and sensitive method has been developed for the determination of sulphur amino acids by gas chromatography (GC). Sulphur amino acids were converted into their N(S)‐isopropoxycarbonyl methyl ester derivatives and measured by GC with flame photometric detection using a DB‐17 capillary column. The derivatives were sufficiently volatile and stable to give single symmetrical peaks. The detection limits of sulphur amino acids were ca. 0.5–1 pmol per injection, and the calibration curves were linear in the range 0.5–1 nmol for each sulphur amino acid. This method was successfully applied to small urine samples without prior cleanup, and sulphur amino acids in these samples could be analysed without any influence from coexisting substances. Overall recoveries of sulphur amino acids added to urine samples were 85–113%. The analytical results of free sulphur amino acid contents in urine samples of normal subjects are presented.
Carbonic anhydrase‐immobilized precolumn for selective on‐line sample pretreatment in high‐performance liquid chromatographic determination of certain sulphonamide drugs
Authors: Ohta Takafumi , Takamiya Ittetsu , Takitani Shoji 
Published: May 2005

AbstractCarbonic anhydrase (CA)‐immobilized aminopropyl silica precolumn was developed for direct injection determination of certain sulphonamide drugs in biological fluids by column‐switching (CS) high‐performance liquid chromatography. Under the optimized conditions, only the sulphonamide drugs with an unsubstituted sulphonamide group were retained on the CA precolumn and separated on a reversed‐phase analytical column. Of these, the retention of hydrochlorothiazide (HCT), chlorothiazide, acetazolamide, furosemide (FS) and chlorthalidone was almost quantitative. The peak area of HCT was proportional to the concentration in the range of 1–100 nmol/mL with relative standard deviations of 3.7% (5 nmol/mL) and 0.7% (100 nmol/mL).This CS system was applied to urine and plasma samples spiked with HCT and FS. Endogenous components of these were effectively removed, and HCT and FS were selectively retained on the CA precolumn. Almost quantitative recoveries and reproducibility were obtained.
Quantitative determination of 21‐hydroxy‐deflazacort in human plasma using gradient semi‐microbore liquid chromatography
Authors: Reynolds Donald L. , Burmaster Steve D. , Eichmeier Larry S. 
Published: May 2005

AbstractA sensitive and selective liquid chromatographic procedure to quantitate the deflazacort metabolite 21‐hydroxy‐deflazacort (DF‐21OH) in human plasma was developed and validated. DF‐21OH and fludrocortisone acetate (internal standard, IS) were isolated from human plasma (2 mL) by solid‐phase extraction onto C‐18 cartridges. Potential interferences were selectively removed and analytes were eluted with ethyl acetate. Following evaporation, the residue was reconstituted for HPLC analysis. Separation was achieved by gradient elution using a 5 μm YMC Basic column (2.0 × 100 mm) with mobile phases consisting of 20% methanol and 50% acetonitrile in 50 mM phosphate buffer (pH 3) at a temperature of 50°C. Flow rate was maintained at 0.3 mL/min., and analytes were quantified spectrophotometrically at 246 nm.The assay was validated over the range 1.0 to 500 ng/mL DF‐21OH. Calibration curves were prepared using a weighted (1/concentration) nonlinear quadratic regression algorithm. Peak‐height ratios were proportional to the amount of DF‐21OH added to plasma. Assay precision (%RSD) ranged from 4.2 to 11%, with a corresponding assay accuracy (% relative error) of ±2.8%. Absolute recovery of DF‐21OH from plasma was 78–86% over the concentration range. The minimum quantitation limit was 1.0 ng/mL.