Titration-curve analysis of urine and its clinical application

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  • Nagasawa Syuichi
    Division of Environmental Pollution Research Central Research Laboratory, Fukushima Medical College Third Department of Internal Medicine, Fukushima Medical College

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Other Title
  • 尿の滴定曲線による分析と臨床的応用
  • ニョウ ノ テキテイ キョクセン ニヨル ブンセキ ト リンショウテキ オウヨ
  • I. Qualitative and quantitative analysis of urinary acids using the automatic recording titrator
  • 第1報　自動記録滴定装置を用いた尿中酸の定性および定量分析

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Abstract

In order to evaluate renal functions in maintaining the acid-base balance, independent determinations are now made of pH, titratable acid (TA), NH4+ and HCO3- of urine, with much trouble, Therfore, an attempt was made to simplify the procedure by using the automatic recording titrator. This recently-devised apparatus automatically draws a titration curve and its differential curve (opH/ov). In this study, a qualitative analysis of urinary acids was made by obtaining the dissociation exponents from the above titration curve on the basis of the Henderson-Hasselbalch equation and a quantitative analysis was made by reading the alkali consumption from the same curve. Tests were carried out on the urine collected from 50 healthy males and 4 females ranging in age from 16 to 55. The titration curves obtained were classified into three types, i. e. J-, JJ-, and JJJ-type, according to the number of pH-jumps, i. e. 1, 2 and 3. The pH-jump is the inflection point of the curve where the acid is neutralized completely with alkali and the differential curve indicates a peak at this point. The J-type showed the existence of NH4+; the JJ, NH4+ and H2PO4- ; and the JJJ, NH4+, H2PO4- and organic acids. There was a significant correlation between pH of the urine and the type of titration curve. Generally speaking, when pH of the urine was over 7, the type was J ; when 6-7, JJ ; and when under 6, JJJ. Quantitatively, TA was estimated by reading the alkali consumption at pH 7.40 in the available type of titration curve ; organic acids (in titratable form), at the first pH-jump in the JJJ-type curve ; H2PO4-, at the first pH-jump in the JJ, or between the first and second pH-jumps in the JJJ ; and NH4+, at the first pH-jump in the J, between the first and second pH-jumps in the JJ, or between the second and third pH-jumps in the JJJ. Since NH4+ and HCO3- are of much the same acid strength, they are neutralized almost simultaneously.In this study, HCO3- was removed as CO2 by adding HCl to the sample and boiling it for 30 seconds, and its amount was represented by the difference in alkali consumption between the non-treated and acid-and-heat-treated samples.

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