Abstract
A filter paper absorption method (FPM) for collecting and transporting urine samples was designed and used in a field survey.
Fifty samples of urine, 10μl and 40μl were absorbed with 3.5×1.5cm (Na and K) and 5.5×1.3cm (Creatinine) No. 6 Toyo filter papers (Toyo Roshi Co., Ltd.). Two weeks after absorption, Na and K were extracted from the filter paper by immersion in either 5ml distilled water or 5ml distilled water to which about 0.03ml of concentrated HCl had been added. The amounts were measured by flame photometry. Creatinine (Cr) was extracted from the filter paper by immersion in 10ml distilled water in a test tube and the amount measured by Jaffe's method. Cr, Na, and K concentrations and Na/K, NaCl/Cr, K/Cr ratios obtained by the FPM were compared with control results as obtained by directly diluting urine specimens.
Correlation coefficients of the above values between FPM and control ranged between 0.990 and 0.998. Cr concentrations obtained by the FPM decreased as storage time increased until they showed a 9.2% decrease over the control at 8 weeks after original absorption. Otherwise, the correlation of Cr between the control and FPM showed high degrees of significance at any point during storage. There were, however, no significant changes in the Na and K concentrations over storage time, and the same values for the control were obtained by the addition of HCl. Furthermore, no significant differences were observed between control and FPM where HCl had not been added in the ratios of Na/K, NaCl/Cr and K/Cr, although significantly higher values from the FPM than for the control were obtained when HCl had been added.
