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Journal of Chromatography

R K Keller, R Thompson
A rapid procedure for the preparation of short-chain (C s-C.) isoprenoid diphosphates is described . It is based on the method of Cornforth and Popjak [Methods Enzymol., 15 (1969) 359-390] which utilizes bis-triethylammonium phosphate in trichioroacetonitriie as the phosphorylating reagent . The reaction takes place in 15 min, and product isolation, previously requiring several steps, is done in a single step using either preparative thin-layer chromatography or flash chromatography on silica . From a single TLC plate, up to 50 μ mol of pure farnesyl diphosphate (i ...
August 13, 1993: Journal of Chromatography
Y Tani, T Ohno
A rapid and sensitive reversed-phase ion-pair liquid chromatographic system with fluorimetric detection by post-column sodium nitrite oxidation was established for measuring six pterin compounds (6R-5,6,7,8-tetrahydrobiopterin, 6S,5,6,7,8-tetrahydrobiopterin, 7,8-dihydrobiopterin, biopterin, pterin and D-neopterin). The coefficients of variation for these pterins were 0.705-3.714%, and the minimum detectable amount was ca. 10-20 pg at a signal-to-noise ratio of 3. A linear detector response was also verified...
August 11, 1993: Journal of Chromatography
A Guerrieri, F Palmisano, P G Zambonin, M De Lena, V Lorusso
A copper-modified strong cation exchange stationary phase was used for the solid phase extraction of the antineoplastic drug doxifluridine (5'-deoxy-5-fluorouridine) and some of its main metabolites from human serum. Sorption of fluoropyrimidine derivatives due to complex formation with copper(II) was maximal at pH values around neutrality. Analytes were eluted by ligand exchange with ammonia. The average recoveries ranged from 70% to 108%. Reversed-phase chromatography with ultraviolet detection was used for the separation and quantitation of the analytes...
July 23, 1993: Journal of Chromatography
L H Leenheers, R Engel, W E Spruit, W J Meuling, M J Jongen
A high-performance liquid chromatographic (HPLC) assay for methyl 5-hydroxy-2-benzimidazole carbamate (5-HBC) in urine was developed in order to assess the exposure of workers to the pesticide carbendazim. 5-HBC is measured in urine after hydrolysis, sample clean-up through a strong cation-exchange (SCX) column and extraction with ethyl acetate. HPLC with electrochemical detection provides selective and sensitive determination of 5-HBC with a detection limit of 5 micrograms/l. A C18 reversed-phase column was used with 0...
March 5, 1993: Journal of Chromatography
M Kajita, T Niwa, N Takeda, H Yoshizumi, A Tatematsu, K Watanabe, T Nagatsu
N-Methyldopamine (epinine) has been identified for the first time in parkinsonian and normal human brains by gas chromatography-mass spectrometry. N-Methylsalsolinol and N-methylnorsalsolinol, which are analogues of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, which produces parkinsonism in humans, may be synthesized from N-methyldopamine by the Pictet-Spengler condensation reaction as an alternative metabolic pathway.
March 5, 1993: Journal of Chromatography
J C Vergniol, R Bruno, G Montay, A Frydman
A rapid, selective and reproducible high-performance liquid chromatographic (HPLC) method with ultraviolet detection was developed for the determination of the anti-cancer agent Taxotere in biological fluids. The method involves a solid-phase extraction step (C2 ethyl microcolumns) using a Varian Advanced Automated Sample Processor (AASP) followed by reversed-phase HPLC. The validated quantitation range of the method is 10-2500 ng/ml in plasma with coefficients of variation < or = 11%. The method is also suitable for the determination of Taxotere in urine samples under the same conditions...
November 6, 1992: Journal of Chromatography
V Debal, H Morjani, J M Millot, J F Angiboust, B Gourdier, M Manfait
A high-performance liquid chromatographic method has been developed for the determination within tumour cells of a new vinca alkaloid, vinorelbine. Extractions of vinorelbine from cells were carried out using absolute ethanol. The extracts were injected into a reversed-phase system consisting of two Novapak C18 columns connected in series. The mobile phase was acetonitrile-phosphate buffer, pH 2.7 (60:40, v/v). Using a fluorescence detection, the limit of determination was 8 pmol injected. This method would be suitable for studying the cellular pharmacokinetics of vinorelbine in patients...
October 2, 1992: Journal of Chromatography
G Flesch, E Francotte, F Hell, P H Degen
An enantioselective liquid chromatographic assay for the simultaneous determination of the S-(+) and R-(-) enantiomers of the monohydroxylated metabolite of oxcarbazepine in human plasma is described. The metabolite is the active principle. The method is based on the extraction of plasma with diethyl ether-dichloromethane (2:1, v/v), separation of the organic phase, evaporation of the solvent and dissolution of the residue in the mobile phase. The two enantiomers were resolved on a Chiralcel OD (250 mm x 4...
October 2, 1992: Journal of Chromatography
K Borner, E Borner, H Lode
A specific and sensitive analytical method for the determination of sparfloxacin in serum and urine is described. Serum proteins are removed by precipitation with acetonitrile after the addition of ofloxacin as an internal standard. The supernatant solvent is evaporated in a vacuum concentrator and the dry residue is redissolved in the mobile phase. Separation is performed on a cation-exchange column (Nucleosil 100 5SA, 125 x 4.0 mm I.D., 5 microns particle size) protected by a guard column (Perisorb RP-18, 30 x 4...
September 2, 1992: Journal of Chromatography
T B Vree, E W van Ewijk-Beneken Kolmer, J F Nouws
A gradient high-performance liquid chromatographic analysis for the direct measurement of flumequine, with its acyl glucuronide, in plasma and urine of humans has been developed. In order to prevent hydrolysis and isomerization of flumequine acyl glucuronide, the samples were acidified by the oral intake of four 1.2-g amounts of ammonium chloride per day. In contrast to the acyl glucuronides of non-steroidal anti-inflammatory drugs, flumequine and its acyl glucuronide were stable in urine of pH 5.0-8.0. Flumequine acyl glucuronide is unstable at pH 1...
August 7, 1992: Journal of Chromatography
S B Johnson, R E Brown
A simple procedure for simultaneously derivatizing non-hydroxy and hydroxy fatty acids prior to GC analysis [I. Ciucanu and F. Kerek, J. Chromatogr., 284 (1984) 179] has been evaluated for its usefulness in determining sphingolipid acyl composition. The method uses methyl iodide in polar aprotic solvents to generate methyl esters of carboxyl groups and methyl ethers of hydroxyl groups. Methylation efficiency is examined as a function of hydroxyl group presence and location in free fatty acids as well as a function of 2-hydroxy fatty acid chain length...
July 17, 1992: Journal of Chromatography
T Niwa, W Maruyama, D Nakahara, N Takeda, H Yoshizumi, A Tatematsu, A Takahashi, P Dostert, M Naoi, T Nagatsu
N-Methylsalsolinol, an analogue of 1,2,3,6-tetrahydropyridine, is present in the brains of patients with Parkinson's disease. To determine the metabolic pathway for the synthesis of N-Methylsalsolinol in the brain, salsolinol was perfused through the striatum or the substantia nigra of the rat brain by in vivo microdialysis. N-Methylsalsolinol was detected in the brain dialysate samples during microdialysis with salsolinol using gas chromatography-mass spectrometry with selected-ion monitoring. These results demonstrate that endogenous N-methylation of salsolinol into N-methylsalsolinol occurs in the brain in vivo...
July 1, 1992: Journal of Chromatography
H Kastrissios, M F Hung, E J Triggs
A high-performance liquid chromatographic method with ultraviolet detection at 210 nm for quantitation of bupivacaine and two of its metabolites from plasma and urine is described. The compounds are extracted into n-hexane-isopropanol (5:1), evaporated and the reconstituted residue injected onto a reversed phase C18 column. Standard curves for all compounds were linear (r2 greater than 0.999) in the range 20-2000 ng/ml, with a limit of detection of 10 ng/ml. The inter-day coefficients of variation ranged between 2...
May 20, 1992: Journal of Chromatography
K Isosaki, N Seno, I Matsumoto, T Koyama, S Moriguchi
Methyl vinyl ether-maleic anhydride copolymer (MMAC) is a water-insoluble polymer with an acid anhydride group which reacts with amino groups of ligands to form stable amide bonds. MMAC was used to immobilize protein ligands on two kinds of supports, the wells of plastic microtitre plates for enzyme-linked immunosorbent assay and related methods, and gels for affinity adsorbents. The wells were first coated with MMAC and then allowed to react with proteins. The immobilization of proteins by this method was efficient and occurred in a dose-dependent manner...
April 24, 1992: Journal of Chromatography
E Pianezzola, V Bellotti, R La Croix, M Strolin Benedetti
A sensitive and selective high-performance liquid chromatographic method for the determination of cabergoline in plasma and urine has been developed. After buffering plasma and urine samples, cabergoline was extracted with a methylene chloride-isooctane mixture, back-extracted into 0.1 M phosphoric acid, then analysed by reversed-phase high-performance liquid chromatography. Quantitation was achieved by electrochemical detection of the eluate. The linearity, precision and accuracy of the method were evaluated...
February 7, 1992: Journal of Chromatography
R J Bushway, H L Hurst, J Kugabalasooriar, L B Perkins
A fluorescent reversed-phase high-performance liquid chromatographic method was developed for the analysis of carbendazim in blueberries. Recoveries of fortified blueberries at 27 and 810 ng/g were more than adequate with good precision. Forty commercial blueberry samples were analyzed and the amount of carbendazim ranged from none detected (detection limit of 15 ng/g) to 155 ng/g. Confirmation of carbendazim in the blueberry samples was made by enzyme immunoassay and UV photodiode array.
December 20, 1991: Journal of Chromatography
J W Russell, D Marrero, V J Whiterock, L J Klunk, J E Starrett
A high-performance liquid chromatographic (HPLC) method for the determination of 9-[(2-phosphonylmethoxy)ethyl]adenine (PMEA) in urine is described. The procedure includes treatment of the urine sample with chloroacetaldehyde to form the fluorescent 1,N6-ethenoadenosine derivative, which was analyzed by reversed-phase HPLC with fluorometric detection. Validation of the method showed good sensitivity, precision and reproducibility. The method is useful for the study of urinary excretion of PMEA in the rat.
December 6, 1991: Journal of Chromatography
M Cociglio, R Alric, O Bouvier
A reversed-phase column liquid chromatographic assay is described and validated for lamotrigine, a new anticonvulsant drug. The drug and its internal standard were extracted from plasma into acetonitrile according to a previously described solvent-demixing procedure, separated on LiChrospher 100CN, and measured by ultraviolet absorption at 280 nm. The assay performance was evaluated through analysis of variance and of regression with our usual validation design. The method detects ca. 2 ng (55 micrograms/l x 30 microliters) and shows a linear response with a constant 5% coefficient of variation from 1 to 10 mg/l...
December 6, 1991: Journal of Chromatography
M W Sinz, R P Remmel
Lamotrigine is an investigational anticonsulvant drug undergoing clinical trials. A simultaneous assay was developed to quantitate lamotrigine and its major metabolite, lamotrigine 2-N-glucuronide, from guinea pig whole blood. The extraction procedure and reversed-phase high-performance liquid chromatographic (HPLC) assay employed sodium dodecylsulfate (SDS) as an ion-pairing reagent to selectively separate lamotrigine and lamotrigine 2-N-glucuronide from endogenous blood components, other anti-convulsant drugs, and their metabolites...
November 15, 1991: Journal of Chromatography
F Karege, W Rudolph
This paper describes a high-performance liquid chromatographic method with ultraviolet detection for measuring plasma phenylacetic acid. This simple and reliable method consists of an acid hydrolysis of conjugated phenylacetic acid before extraction with an organic solvent: washed ethyl acetate saturated in sodium chloride. The recovery of extraction was estimated by internal standardization with phenylpropionic acid, and validated by addition of phenylacetic acid standards. A preliminary application to plasma phenylacetic acid in patients suffering from depression is described...
October 4, 1991: Journal of Chromatography
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