Fluorometric Determination of Tyrosine

Journal/Book: Reprinted from CLINICAL CHEMISTRY Vol. 15 No. 7 July 1969. 1969;

Abstract: Copyright (c) by American Association of Clinical Chemists HOEBER MEDICAL DIVISION of Harper & Row. Publishers Printed in U.S.A. From the National Communicable Disease Center Health Services and Mental Health Administration US Department of Health Education and Welfare Atlanta Ga 30333. Supported in part by funds received from the Social and Rehabilitation Services Administration Division of Mental Retardation. Use of trade names is for identification only and does not constitute endorsement by the Health Services and Mental Health Administration or by the US Department of Health Education and Welfare. Received for publication Aug 27 1968; accepted for publication Nov 17 1968. Modifications were made in the fluorometric method far the determination of serum tyrosine. An accurate and precise procedure was developed which did not involve the usual extraction with ethylene dichloride. The instability of the reaction mixture containing nitrosonaphthol nitric acid and sodium nitrite was corrected by the use of a phosphoric acid reagent. THE FOLLOWING FLUOROMETRIC PROCEDURE for tyrosine determination was developed in response to the need for an accurate and precise manual method as a complementary test for the confirmation of phenylketonuria (PKU; 1 2) and also as an aid in the confirmation of tyrosinosis and tyrosinemia (3). A study of the Waalkes and Udenfriend (4) fluorometric method for estimating tyrosine and of the various published colorimetric procedures for tyrosine (5-11) resulted in a simplified procedure which eliminated the extraction step involving ethylene dichloride without a change in specificity. ... ___MH

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