Spectrophotometric Determination of Cystine with O-Phthalaldehyde in the Absence of Thiol
- 1 September 1988
- journal article
- research article
- Published by Taylor & Francis in Analytical Letters
- Vol. 21 (9) , 1545-1559
- https://doi.org/10.1080/00032718808066511
Abstract
A spectrophotometric method for the determination of cystine with o-phthalaldehyde (OPA) in the absence of thiol is described. When cystine is heated at 60.degree. C for 30 min in a low excess of OPA (pH 9.5), a very stable derivative with 1:2 stoichiometry (cystine:OPA) and an absorption maximum at 335 nm (.epsilon. = 4600) is formed. At pH < 1 the derivative is protonated (protonation constants: log K1 = 5.88 and log K2 = 3.70 at I = 0.1 and 20.degree. C) and another absorption band at 440 nm (.epsilon. = 3800) appears, which allows the determination of cystine in the presence of other amino acids.This publication has 14 references indexed in Scilit:
- Analyses of cystine in human hair: Its level in women's hair of former times.Journal of Nutritional Science and Vitaminology, 1981
- The interaction of amino acids with o-phthaldialdehyde: A kinetic study and spectrophotometric assay of the reaction productAnalytical Biochemistry, 1980
- Reaction of o-phthalaldehyde and thiols with primary amines: Fluorescence properties of 1-alkyl(and aryl)thio-2-alkylisoindolesAnalytical Biochemistry, 1978
- Colorimetric screening assay for cystine plus cysteine in legume seed mealsAnalytical Biochemistry, 1978
- Estimation of methionine and cystine in compounded poultry rationsJournal of Agricultural and Food Chemistry, 1974
- Spectrophotometric cysteine analysisJournal of Agricultural and Food Chemistry, 1972
- Fluorescence reaction for amino acidsAnalytical Chemistry, 1971
- pH dependency of the cyanide-nitroprusside colour reaction of cystineClinica Chimica Acta; International Journal of Clinical Chemistry, 1970
- Cystine Content of WoolTextile Research Journal, 1970
- Microdosage colorimétrique de la cystéïne et de la cystineAnalytica Chimica Acta, 1962