High pressure liquid chromatographic determination of sorbitol in bulk sorbitol

An HPLC procedure for determining sorbitol in bulk sorbitol is described. An Aminex HPX-87 column (Bio-Rad) is used with water as a mobile phase and with a refractive index detector to monitor column eluate. Sorbitol is separated from pentaerythritol, erythritol, ribitol, ethylene glycol, propylene glycol, arabitol, galactitol, mannitol, iditol, and other carbohydrates. The precision of the sorbitol determination, characterized by a 95% confidence interval, corresponds to +/- 1.22%.     

High pressure liquid chromatographic determination of cyclosporin-A in human plasma

Periodic monitoring of plasma drug concentrations has been suggested as a means whereby the toxicity of Cyclosporin A (CyA) can be reduced in patients undergoing bone marrow transplantation. We have developed a sensitive and specific method for the determination of CyA in plasma using reverse phase high pressure liquid chromatography (HPLC). Cyclosporin D was used as the internal standard. The lower limits of detection are 100 ng/ml in biological fluids and 20 ng per injection onto the column. We have analyzed plasma samples from patients who received CyA at doses which ranged from 8 to 15 mg/kg/day. Although all patients experienced toxic or therapeutic effects, plasma concentrations of CyA were consistently less than 100 ng/ml when analyzed by this method. We conclude that analytical methods currently available for the detection of CyA are unsuitable for the monitoring of patients who receive this agent.     

High pressure liquid chromatographic determination of aflatoxins in wines and other liquid products

A previously developed high pressure liquid chromatographic (HPLC) method was evaluated by an extensive recovery study of aflatoxins from wines and other liquid products. The HPLC column and the preliminary cleanup procedures were both modified for this study. Four aflatoxins (B1, B2, and G2) were recovered at 80-116% from 28 samples of various liquid commodities spiked at the 1 microgram/L (1 ppb) level. The detection limit of the proposed method for wines and fruit juices was about 0.02 ppb. A total of 53 samples were analyzed for aflatoxins during this study.     

High pressure liquid chromatographic determination of baicalin in lung-cleaning and diarrhoea-relieving infusion

The baicalin in the compound recipe of traditional Chinese medicine Lung-cleaning and Diarrhoea-relieving Infusion was determined by reverse phase high pressure liquid chromatographic method. Methanol-water-tetrahydrofuran (200: 300: 50) was used as the mobile phase at ODS C-18 column with ultraviolet detection. The result showed that baicalin was separated well from other components. External standard method was used for quantitative determination. The recovery rate was 101.4% and RSD 0.83%.     

High performance liquid chromatographic analysis of selected sulfonamides in plasma

Informative microsatellites associated with two genes on HSA12 (lysozyme, LYZ; tumour necrosis factor receptor, TNFR) and one gene on HSA2 (glutamic acid decarboxylase 1, GAD1) were mapped in the US Meat Animal Research Center (MARC) swine reference population and the physical assignment of a-lactalbumin (LALBA) was determined. A comparative map for HSA2 and HSA12 with SSC15 and SSC5, respectively, was developed by combining the results from this study with published type I loci mapped in both species. One rearrangement between HSA2 and SSC15 was detected while the number of rearrangements between HSA12 and SSC5 were numerous. These results indicated that conservation of synteny does not imply a conservation of gene order and that additional type I markers need to be mapped in the pig to fully understand the chromosomal rearrangements that occurred during the evolution of mammals.     

High-performance liquid chromatographic analysis of aminoglycoside antibiotics

The Category Test (CT) and the Wisconsin Card Sort Test (WCST) have long been the major instruments used for the assessment of "frontal lobe" brain damage. These tests have often been used interchangeably by clinicians. However, research to date has disagreed on the extent to which these tests can be interpreted in a similar manner. The current paper examined the interrelationships between the tests in 112 mixed brain injured clients. The results showed relatively small correlations between the tests in the range of .4 to .6 which were eliminated when age, education, premorbid IQ (Vocabulary) and spatial skills (Block Design) were used as covariates. Regression analyses showed clear differences in which WAIS-R tests predicted each test, while factor analysis revealed little overlap between the tests except for a small relationship between the number of WCST categories completed and CT errors. The CT appeared to reflect spatial and spatial analysis skills while the WCST reflected verbal analysis and sequential skills. The results clearly indicate that the tests are not interchangeable and do not reflect the same underlying cognitive skills nor can they be interpreted in the same manner for neuropsychological purposes.     

High-pressure liquid chromatographic analysis of tolbutamide in serum

A high-pressure liquid chromatographic (HPLC) analysis of tolbutamide in serum is described. The assay requires only 1 ml of serum and is capable of measuring as little as 2 mug of tolbutamide. The metabolites of tolbutamide do not interfere in the assay. Human serum samples, taken after a 1-g oral dose of tolbutamide, were analyzed by the HPLC and an existing GLC procedure, and the results are compared.     

High-performance liquid chromatographic analysis of porphyrins in clinical materials

Methods for the isolation of porphyrins as their methyl esters from porphyric urine and faeces as well as other biological materials are described. Quantitative analyses can be carried out by high-performance liquid chromatography (HPLC), using appropriate internal standards; hence excretion patterns in the various types of porphyria can be obtained which may facilitate clinical diagnosis more effectively than the earlier qualitative thin-layer chromatographic methods. Use of the newer microparticulate column packing materials has improved the efficiency of the HPLC analyses, and enables the more convenient isochratic elution techniques to be used (rather than gradient elution). Separations of some porphyrin isomers on these columns are also described.     

High-performance liquid chromatographic analysis of isoniazid and its dosage forms

A high-performance liquid chromatographic analysis is described for isoniazid as a drug entity and in its tablet and injectable dosage forms. After incorporation of the drug or dosage form in a solvent mixture and addition of an internal standard, tribenzylamine, an aliquot is chromatographed using a pellicular silica gel medium followed by UV spectrophotometric detection at 254 nm. The response of the chromatographic system was linear over a concentration range corresponding to 20-200% of the labelled amount of isoniazid. Comparison of the results with those obtained by the official USP XIX method indicates similar accuracy and precision. The advantages of the proposed method are its simplicity and rapidity, its potential for automation, and its specificity. The specificity was demonstrated in the presence of potential degradation products of isoniazid, other drugs used with isoniazid in combination dosage forms, and an adduct formed by the reaction of isoniazid with lactose in the tablet.     

High-performance liquid chromatographic analysis of chlorhexidine in saliva after mouthrinsing

BACKGROUND: Neutrophils contribute to the host defense mechanism, but they can cause remote organ injury in peritonitis. The purpose of this study was to examine neutrophil adhesion to the peritoneum and remote organs simultaneously in peritonitis using a fluorescence microscopic method. STUDY DESIGN: Experiment 1: Sprague-Dawley rats (n = 16) were injected intraperitoneally (ip) with saline solution or 10(5), 10(7), or 10(9) Escherichia coli. Five hours after challenge, 1 x 10(6) fluorescein-labeled neutrophils were infused. Two minutes after neutrophil injection, five peritoneal samples (the greater omentum, mesentery, parietal peritoneum, colon, and ileum), both lungs, the liver, and the right kidney were harvested for counting of labeled neutrophils under epifluorescent microscopy. Lung myeloperoxidase (MPO) activity was also determined. Experiment 2: Rats (n = 23) were given 10(9) E. coli ip. Before challenge (0 h) or at 1, 5, or 10 h after challenge, labeled neutrophils were infused. Then, the labeled neutrophil numbers in organs and lung MPO activities were assessed as described for Experiment 1. Hemodynamic and arterial blood gas data were also obtained in another set of rats before and at 1, 5, 8 and 10 h after 10(9) E. coli ip challenge. RESULTS: Experiment 1: The labeled neutrophil numbers in the peritoneum, lungs, and kidney showed significant positive correlations with the injected bacterial numbers. Lung MPO also positively correlated with E. coli number and labeled neutrophil number in the lungs. Experiment 2: Labeled neutrophil numbers in the peritoneum and kidney peaked at 5 h. The pulmonary labeled neutrophil number rose, reaching a plateau at 5 h. No remarkable change was observed in the hepatic labeled neutrophil number. There was a positive correlation between lung MPO activity and pulmonary labeled neutrophil number. Hemodynamic and blood gas data reflected a hyperdynamic state. CONCLUSIONS: Concomitant dose-dependent increases in neutrophil adhesion in the peritoneum, lungs, and kidney were observed in this peritonitis model. Increased neutrophil adhesion was transient in the peritoneum and kidney but persistent in the lungs. Strategies modulating neutrophil adhesion in organs are anticipated to be useful for the treatment of peritonitis.     

High-performance liquid chromatographic determination of L-aspartyl-L-phenylalanine methyl ester in various food products and formulations

A simple, rapid, and specific high-performance liquid chromatographic (HPLC) procedure is described for the analysis of the chemical sweetener L-aspartyl-L-phenylalanine methyl ester (aspartame). Using a strong cation exchange column and pressures less than 1000 psig, an analysis can be performed in less than 15 min. The technique has been applied to a wide range of food products and formulations. No interferences were found in the samples studied. Recoveries are quantitative, and the coefficients of variation for replicate analyses are less than or equal to 2.5%.     

Examination of micro-tip reversed-phase liquid chromatographic extraction of peptide pools for mass spectrometric analysis

Cyclical neutropenia (CN) is an interesting dynamic hematological disease in which the neutrophils spontaneously oscillate from approximately normal levels to near zero with a period between 19 and 21 days. In the only known animal model for this disorder, the grey collie, the disease's single apparent difference from human CN is the smaller period of 11-15 days. CN can be treated using the cytokine G-CSF which decreases the period (to about 14 days in humans), increases the mean value, and elevates the amplitude of the oscillations. After reviewing the clinical and laboratory data on this disease, we examine the proposition that CN is due to a loss of stability in the peripheral negative feedback control of neutrophil production. This is accomplished by the development of a physiologically realist mathematical model for the system. We conclude that there is no consistent way in which such a destabilization can give rise to either the clinical or laboratory characteristics of CN. Rather it seems more likely that the oscillations of CN are generated within the pluripotential stem cell population.     

Rapid and sensitive high-performance liquid chromatographic analysis of halogenopyrimidines in plasma

Recent studies have stressed the need for individual adjustment of 5-fluorouracil (5-FU) dosage. Most of the techniques previously reported are not well adapted to routine application. We describe a sensitive, selective and simple HPLC technique under isocratic conditions for the quantitation of 5-FU and other halogenopyrimidines. The proportion of reagents and internal standard were optimised to allow the use of minitubes, particularly adapted to large series of plasma assays. High extraction yield, 75% for 5-FU and 90% for 5-bromouracil and 5-chlorouracil, was obtained using 1.2 ml isopropanol-ethyl acetate (15:85, v/v) following precipitation of plasma proteins with 300 mg ammonium sulfate. The mobile phase was 0.01 M phosphate buffer (pH 3.0). Uracil and 5-fluorouracil were fully resolved with Spherisorb ODS2 column. The limits of quantitation and detection in human plasma were 6 ng ml(-1) and 3 ng ml(-1), respectively, for all compounds studied. The total analysis time required for each run was 25 min. Final results could be given within 90 min of blood sampling. At least 50 plasma samples could be analysed per day. This method has been successfully used for monitoring 5-FU-based treatments.     

Coulometric detection in high-performance liquid chromatographic analysis of cholesteryl ester hydroperoxides

From the secretion of neurotransmitters via synaptic vesicles to the expulsion of cellular waste via contractile vacuoles, exocytosis and its sequel, endocytosis, are being explored with a variety of new optical tools. Fluorescent markers, especially styryl dyes such as FM1-43 (which reversibly labels endosomal membranes), have been used to follow exo- and endocytic events in many cell types. Even though the development of new dyes is still largely empirical, some theoretical principles have emerged to guide future dye chemistry. Moreover, advances in optical imaging technology that augment conventional fluorescence microscopy are appearing. For example, interference reflection microscopy (which requires no flurophore) and total internal reflection microscopy have recently been used to observe single exocytic events at the contact point between a glass coverslip and the plasma membrane.     

Solid-phase extraction followed by high-performance liquid chromatographic analysis for monitoring herbicides in drinking water

A multiresidue analytical method based on C18 solid-phase extraction and one-run HPLC determination has been developed for the analysis of eleven acidic, neutral and weak basic herbicides in drinking water. A 1-1 sample of water was preconcentrated by passage through a 500-mg C18 solid phase extraction column. The retained compounds were eluted from the column with 1 ml of methanol. After concentration of the extract the pesticides were separated and quantified by reversed-phase HPLC with UV detection. Bentazone, 2,4-D, MCPA, fluazifop-acid, metoxuron, monolinuron, metobromuron, diuron, linuron, atrazine and simazine were determined simultaneously in a single run on a C18 HPLC column. Reanalyses of the sample extracts on a second cyano column were used to confirm the identity of the neutral and basic compounds. The limit of determination, defined as four times the baseline noise, varied between 0.01 microgram/l and 0.1 microgram/l depending on the compound, the detection sensitivity of the instrument and the type of HPLC column used.     

High performance liquid chromatographic method for the determination of lobenzarit disodium in a sustained release tablet formulation

A rapid and simple high performance liquid chromatographic method is described and validated for the determination of lobenzarit disodium (CAS 64808-48-6) in a sustained release tablet formulation. The calibration graph was linear over the range 20-105 micrograms/ml. The sensitivity (discriminator capacity) was 2.079 micrograms/ml. The coefficient of variations for repeatability and reproducibility were less than 1.60% and 1.30%, respectively. The accuracy of the method did not depend on lobenzarit concentration in tablets. The mean recovery was found to be 100.62%. The method was selective, even when degradation products were present.     

High performance liquid chromatographic method fo pyrantel tartrate in swine feeds and supplements

A new method for the determination of pyrantel tartrate in swine feed an supplements has been developed because the current official AOAC method is not applicable to feeds co-medicated with tylosin. The new method involves: (a) leaching of drug from feed with methanolic NaCl solution, (b) removal of interfering substances by ion pair liquid-liquid extraction and high performance liquid chromatography, and (c) quantitation of pyrantel tartrate by monitoring the ultraviolet absorption of the effluent stream at 313nm. The method of standard addition is used to compensate for the effect of the feed matrix on drug recovery. No interference is encountered from tylosin, carbadox, lincomycin, non-drug components of feeds and supplements, or potential degradation products of pyrantel tartrate, i.e., cis isomer of pyrantel tartrate and (E)-N-(3-methylaminopropyl)-2-thiopheneacrylamide. Results for the assay of 3 lots each of feeds and supplements containing 0.0106 and 0.106% pyrantel tartrate, respectively, were within +/-4% of label claim. Coefficients of variation ranged from 1.6 to 1.8% for feeds and from 1.9 to 3.9% for supplements.     

High-performance liquid chromatographic methods for determination of marine biotoxins

Paralysing and diarrhetic shellfish poisonings (PSP and DSP) are important intoxications caused by the consumption of shellfish, mainly bivalve molluscs, contaminated by certain species of toxic dinoflagellates present in the marine phytoplankton. Their appearance and massive reproduction take place in some periods of the year, causing the phenomenon commonly known as 'red tide'. This causes significant problems to health and to the economy of the Galician region. The AOAC mouse bioassay is the most commonly used method of analysis for these toxic compounds, being the official method in most countries. Owing to the lack of sensitivity and selectivity of the biological assay, HPLC methods were developed as an alternative methodology. In this paper work carried out on the improvement of the chromatographic conditions in order to achieve accurate information about the PSP and DSP compounds present in the studied samples is reported.