The Direct Colorimetric Determination of Urea in Blood and Urine
نویسنده
چکیده
Methods for the determination of urea in biological fluids have passed through an interesting cycle (cf. Peters and Van Slyke (3) pp. 539-544). The earliest procedures were strictly chemical ones, involving precipitation of the urea as an insoluble mercury complex or decomposition of the urea by means of heat or hypobromite. The use of the highly specific enzyme urease occurring in the jack and soy bean, introduced in 1913 by Marshall, has been the foundation of all generally accepted procedures since that time, although heat and hypobromite are still occasionally employed clinically as being more convenient than urease. The most widely used mod&cation is that in which the ammonia formed by enzymatic action is aerated into acid and titrated or nesslerized. Many attempts have been made to work out a simpler procedure with direct nesslerization of the ureasetreated filtrate in order to avoid aeration; however, turbidity too often materializes to warrant the wide acceptance of direct nesslerization. Fosse introduced xanthydrol as a reagent for precipitating urea, but this method has not gained wide usage, principally because of its lack of dependability. In 1942, Ormsby reported a technique for the direct calorimetric determination of urea itself, using diacetyl monoxime, a reagent employed by Fearon for the estimation of citrulline (2). Thus, the determination of urea has turned away from enzymatic methods and back to more strictly chemical ones. This change certainly involves a decrease in specificity, but at the same time a tremendous increase in convenience. Urease methods will remain the standards of reference, but need not be required for many ordinary purposes. The present paper describes a further modification of the diacetyl monoxime procedure, rendering it more uniform and convenient .
منابع مشابه
A new colorimetric method for the determination of urea nitrogen in blood with diacetyl monoxime-glucuronolactone-glucosaccharodilactone reagent.
In a previous paper,3) a colorimetric method for the determination of urea nitrogen in blood and urine was presented on the basis of a color reaction of urea with diacetyl monoxime (DAM) in phosphoric acid solution in the presence of D-glucuronolactone (GL), which served to produce a photo-stable color and eliminate the sigmoidal nature of calibration curve observed usually in the DAM method.4)...
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