Determination of serum creatinine by gas-liquid chromatography

The gas-liquid chromatographic measurement of serum creatinine is described in the present study. A preliminary concentration on cation exchange resin is used. The different steps of the operating procedure are analysed. A statistical comparison is undertaken between the results obtained with gas-liquid chromatography and kinetic colorimetry method using Jaffé assay.     

Determination of cellulose and apparent hemicellulose in plant tissue by gas-liquid chromatography

A GLC method is described by which the neutral aldoses and cellulose can be measured in whole and digested plant tissue. Apparent hemicellulose is measured by difference. Accuracy of the method is unaffected by protein in concentrations up to 75%.     

Determination of delta-aminolaevulinic acid in biological fluids by gas-liquid chromatography with electron-capture detection

A derivative of delta-aminolaevulinic acid (AmLev), 2-methyl-3-acetyl-4-(3-propionic acid pentafluorobenzyl ester)pyrrole, with favourable properties for g.l.c. with electron-capture detection, was synthesized. Less than 1 pg could be detected on the column. 6-Amino-5-oxohexanoic acid formed the analogous derivative under similar conditions and was used as the internal standard in the development of a highly sensitive and specific assay for AmLev. The method has been applied to peripheral-venous and umbilical-cord plasma and to cerebrospinal fluid of normal and porphyric subjects.     

Determination of vanilmandelic acid in pig urine and chicken feces by gas-liquid chromatography

A gas chromatography method for the determination of free and bound vanilmandelic acid (VMA) in pig urine and chicken feces has been developed. The method consisted of extraction of the free or bound acids by ethyl acetate under acidic conditions. The ethyl acetate extracts were dried under nitrogen, followed by complete silylation of the phenolic and carboxylic acid groups with BSA (N,O)-bis (trimethylsilyl) acetamid. The solution was distilled at 180°C in a sealed glass tube after which the sample was injected on a stainless steel column (6 ft × .125 in. o.d.) containing 4% SE-30 on $\text{80}\text{100}$ mesh chromosorb GHP. The recovery of the urinary VMA was 82%, and the fecal VMA was 84% through the outlined procedures. Pigs ranging in age from 8 to 12 weeks were found to excrete $\text{2–8 mg urinary VMA}\text{24 hr}$ with no significant difference between the free and bound. Commercial laying hens excreted bound VMA in a range of $\text{1–5 mg}\text{24 hr}$ with a $\text{F}\text{B}$ ratio of 1:3.     

Determination of glutathionyl-hemoglobin in human erythrocytes by cation-exchange high-performance liquid chromatography

Since glutathionyl-hemoglobin has been suggested to be a clinical marker of oxidative stress in human blood and given the growing biological relevance of oxidative stress as a pathogenic factor in several diseases, we describe a method to measure glutathionyl-hemoglobin concentration in erythrocytes, by using cation-exchange high-pressure liquid chromatography with UV detection. The glutathionyl-hemoglobin peak has been identified on the basis of the following findings: (a) the peak increased when the sample was incubated with oxidized glutathione; (b) the peak disappeared when the sample was reduced with dithiothreitol, with the simultaneous increase of that corresponding to hemoglobin A(0); (c) the peak could be detected by incubating hemoglobin A(0) with reduced glutathione; (e) deconvoluted mass spectrum of the glutathionyl-hemoglobin peak showed a 16172.0-Da molecular mass, corresponding to hemoglobin beta bound to glutathione. Glutathionyl-hemoglobin concentration has been determined in erythrocytes of 40 healthy subjects, with a mean value of 2.58+/-0.7%, calculated as the percentage of its peak area ratio to that of total hemoglobin (HbA(0)+HbA(2)+HbA(1C)+glutathionyl-hemoglobin). The availability of a simple and reproducible method to detect glutathionyl-hemoglobin concentration in blood could be useful in monitoring oxidative stress, and for investigating the efficacy of antioxidant therapies in clinical trials.     

Separation of triglycerides by gas-liquid chromatography

The parameters affecting the separation and quantification of triglycerides by gas-liquid chromatography have been investigated with the use of QF-1 and SE-30 as stationary phases and a flame ionization detector. The isothermal characteristics of a wide variety of triglycerides (carbon number 6 to 60) on both columns show that long retention volume is directly proportional to carbon number and inversely proportional to absolute temperature. Isothermal retention indices of some triglycerides are given, as are column efficiencies (in terms of theoretical plates and ability to separate closely related triglycerides). When various rates of programmed temperature rise are used, retention indices have been found to be less useful than absolute or relative elution temperatures. The elution temperatures of triglycerides of carbon number 6 to 54 have been determined relative to that of trilaurin. Under optimal separation conditions weight and molar correction factors can be obtained. Triolein and tristearin have been partially separated, as have certain triglycerides that have the same carbon number but widely different fatty acids. The natural triglycerides of human milk fat have been separated.     

Determination of fatty acid content and composition in ultramicro lipid samples by gas-liquid chromatography

Simplified quantitative manipulations of very small amounts (30 micrograms) of lipids for determination of fatty acid content and composition by gas-liquid chromatography after (a) methanolysis (b) reduction and acetylation are described.     

Microdetermination of monosaccharides in glycoproteins by gas-liquid chromatography

In a newly developed method for determining picomolar quantities of monosaccharides in glycoproteins, the methyl glycosides released by methanolysis of glycoproteins are separated as trifluoroacetates by gas-liquid chromatography and are detected with an electron capture detector. The application of the method has been demonstrated for the analysis of the carbohydrate moiety of secretory component isolated from human colostral immunoglobulin A.