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L A Pachla

Publications and source records attributed to L A Pachla.

32 records · Page 2Linked to original sources
PubMed1984

Improved liquid chromatographic assay for the analysis of pirmenol in plasma and urine.

A sensitive, specific, and rapid high-performance liquid chromatographic procedure was developed for the determination of pirmenol in human biological fluids. Plasma or urine samples were alkalinized and extracted with cyclohexane. The organic extract was evaporated to dryness, reconstituted with the mobile phase, and then chromatographed on a microparticulate spherical trimethylsilane stationary phase with UV detection at 254 nm. The procedure for the assay of pirmenol in plasma was linear from 0.125 to 5.0 micrograms/mL. The reproducibility of the peak area ratios of the standard curves had relative standard deviations between 7.7 and 1.8% and a relative error of 0-4.6% over the linear range. The accuracy for the determination of pirmenol in human plasma containing 0.5, 2.5, and 4.0 micrograms/mL had relative errors of 9.0, 3.8, and 3.6%, respectively. Thirty compounds were tested and found not to interfere in the assay of the drug in plasma, and the method was found to be suitable for clinical samples. The urine procedure was linear between 1.0 and 30.0 micrograms/mL. The reproducibility of the peak areas of the standard curves had relative standard deviations that ranged from 1.9 to 6.2% over the linear range. The accuracy for the determination of pirmenol in human urine containing 5.0, 17.5, and 25.0 micrograms/mL had relative errors of 1.4, 0.5, and 2.8%, respectively.

Anti-Arrhythmia Agents↗
PubMed1975

Estimation of serum uric acid by high performance liquid chromatography with electrochemical detection.

A precise method for serum uric acid is described based on direct electrochemical oxidation in the eluate from high performance liquid chromatography. The detection limit for uric acid was found to be approximately 1 pg and accurate measurements were possible at the 100 pg level. Detailed procedures are outlined for 0.5 ml and 25 mul serum samples, the relative standard deviations being 1.7% and 1.8%, respectively, for a 6.2 ml/dl serum pool. Samples were normally deproteinized, however, the analysis can be carried out by injection of 2 mul of serum diluted 10-fold with distilled water. The proposed micro method is highly selective and eliminates the need for the enzyme preparation and/or nonspecific colorimetric reagents in common use.

Autoanalysis↗
PubMed1975

Colorimetric, enzymatic, and liquid-chromatographic methods for serum uric acid compared.

We describe high-performance liquid chromatography in conjunction with electrochemical detection as a possible reference method for serum uric acid. Separation was effected on a column packed with "Vydac" strong anion-exchange resin, with use of a detection potential of +0.80 V vs. an Ag/AgCl reference electrode. Results were linearly related to concentration up to 1.0 g/liter, and no interferences were seen. Assay of human sera gave within-run and day-to-day coefficients of variation of 0.83% and 1.1%, respectively; analytical recoveries averaged 100%. Comparison of the new procedure (x) with the phosphotungstate and uricase methods (y) showed the following linear regression and correlation coefficients for results: y equal 0.963x + 0.219 (r = 0.995), and y = 0.991x + 0.165 (r = 0.999), respectively. As compared to these methods, the procedure we describe is more accurate, because of the selective detection system based on retention time and redox potential. Samples can be analyzed at the rate of 20/h. No deproteinization is required.

Chromatography, Ion Exchange↗
PubMedDate not supplied

Bioanalytic considerations for pharmacokinetic and biopharmaceutic studies.

The correct evaluation of pharmacokinetic and biopharmaceutic data can only be achieved if accurate analytic data are obtained. The accuracy of analytic data depends on the criteria used to validate the method. Consequently, careful scrutiny of drug stability, assay sensitivity, selectivity, recovery, linearity, precision, and accuracy is necessary for the proper interpretation of data. The importance of method validation and its influence on pharmacokinetic and biopharmaceutic data evaluation and interpretation will be discussed.

Biopharmaceutics↗
PubMedDate not supplied

Analytical methods for measuring uric acid in biological samples and food products.

During the last 7 decades, uric acid methodology has kept pace with the introduction of state-of-the-art technology (e.g., spectroscopy, electrochemistry, chromatography) or the discovery of unique chemical processes (e.g., redox, enzymatic). We envision this practice will continue in the future. There never will be a single analytical method applicable for biofluids or foodstuffs. Therefore, it is imperative that the analyst not only understand the advantages and disadvantages of a procedure, but also thoroughly understand its underlying chemical and technological principles. Since many procedures available for analysis of biofluids and foodstuffs rely on identical chemical or technological principles, this report shall review both sample types and the available spectroscopic, electroanalytical, and chromatographic methods.

Animals↗
PubMedDate not supplied

Analytical methods for determining ascorbic acid in biological samples, food products, and pharmaceuticals.

Over the last decade, numerous publications have appeared describing analyses for ascorbic acid in food products, pharmaceuticals, and biological samples. This review focuses on the chemistry associated with many of these procedures. The papers discussed have historical importance, are important to understanding the method, or have significantly advanced ascorbic acid analysis. The review has 4 major sections: spectroscopic, electrochemical, enzymatic, and chromatographic methods of analysis.

Animals↗