An Automated System for the Fluorometric Determination of Serum Lactate Dehydrogenase: Its Adaptability to an Automated System for Simultaneous Determination of Both Serum Lactate Dehydrogenase and Serum Glutamic Oxaloacetic Transaminase

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Abstract
An automated fluorometric system for the determination of serum LDH [lactate dehydrogenase] is presented. The NADH [nicotinamide adenine dinucleotide (reduced form)] formed when lactate is oxidized to pyruvate is used as an index of LDH activity and is quantitated by measuring the intensity of its native fluorescence after it is excited with ultraviolet radiation. The system utilizes various Auto Analyzer Modules and a Turner Fluorometer, Model No. 111 with Technicon''s adapter kit. The reagents consist of Tris buffer, 0.05 M, pH 8.8; lactate substrate containing 0.0M sodium lactate, 2.8 g of hydroxylamine HCL/l and Tris buffer; and NAD, 0.01 M. The procedure offers certain advantages over previously presented methods. By dialyzing the NADH into a recipient stream of Tris buffer, substances in the serum which usually interfere with fluorescence are removed. This obviates the necessity of running a series of daily controls. The determination rate is 60/hr and the cost per test is most inexpensive. The accuracy and precision are good with the coefficient of variation being only 6.7%. The manifold for this procedure can be combined with the SGOT [serum glutamic oxylacetic transaminase] procedure of A. L. Bobson to construct a dual manifold. This will allow the simultaneous determination of both SGOT and LDH without sacrificing accuracy or precision.