Rapid HPLC determination of total homocysteine and other thiols in serum and plasma: sex differences and correlation with cobalamin and folate concentrations in healthy subjects.

High-performance liquid chromatography with fluorescence detection has been utilized for the rapid determination of total homocysteine, cysteine, and cysteinylglycine in human serum and plasma. Our earlier procedure (Anal Biochem 1989;178:208), which used monobromobimane to specifically derivatize thiols, has been extensively modified to allow for rapid processing of samples. As a result, > 80 samples a day can be assayed for total homocysteine, cysteine, and cysteinylglycine.

Determination of plasma homocysteine by high-performance liquid chromatography with fluorescence detection.

Severe homocystinemia is frequently associated with vascular disease while the pathological consequences of moderate or slightly elevated plasma homocysteine are unknown. Cobalamin and folate deficiencies may result in an elevation of plasma homocysteine. A sensitive and reproducible assay for total plasma homocysteine has been developed.

Separation of plasma carotenoids and quantitation of beta-carotene using HPLC.

A method was developed for the extraction and separation of human plasma carotenoids and quantitation of beta-carotene. Carotenoids were extracted from plasma with ethanol: hexane and separated by C18 reversed phase HPLC using spherical 3 micron packing. beta-Carotene was identified and quantitated using an external standard.

Liquid-chromatographic determination of urinary riboflavin.

We describe a method for determining urinary riboflavin by "high-pressure" liquid chromatography, with fluorometric detection. An aliquot of a 24-h urine specimen is injected directly into the chromatograph and the natural fluorescence of riboflavin is measured as the compound is eluted. Interference from other fluorophores is obviated because of differing retention times.