Determination of cysteine in plasma and urine and homocysteine in plasma by high-pressure liquid chromatography

✍ Scribed by Rolf Saetre; Dallas L. Rabenstein

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 515 KB
• Volume: 90
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(78)90161-6

✦ Synopsis

New methods are described for the determination of reduced and total cysteine in urine and the nonprotein fraction of plasma, and total homocysteine in the nonprotein fraction of plasma. The method for reduced cysteine involves separation by high performance liquid chromatography (hplc). followed by detection with a mercury-based electrochemical detector. The detector has a detection limit of ca. 10m6 M cysteine. and is selective for sulfhydryl components of the biological fluids analyzed. Sample preparation involves centrifugation and filtration, and the hplc analysis time is approximately 8 min. Total cysteine and homocysteine are determined by electrolytic reduction of their disulfides to the sulfhydryl form prior to the hplc analysis. Results are presented which suggest that cysteine disulfide exchange reactions are a source of error in methods which employ derivatization with iodoacetate for the determination of cysteine in plasma.