Comparative Study of Chemical Cubstances in Urine With and Without Toluene Preservative.

Pensiri Choosongsang, Panudda Musigavon, Phattanapong Choosongsang, Bralee Chaiman, Pittaya Treerat, Apichart Musaw, Anothai Pocathikorn


Collection of 24-hour (h) urine mostly uses toluene as a preservative, but we found that toluene in the bottle of urine collection patient taken home will volatile in advance. Therefore we aimed  to study changes in the chemistry substances in urine  with and  without toluene preservative at 24, 48  and 72h time points. We pooled random urine without preservative and analyzed immediately. The results were designated as the original values at 0h time point. The pooled urine  was divided into 2x100 mL portions,  one with 5 ml toluene in a glass bottle and the other  without preservative in a plastic bottle. Both of the bottles were left at room temperature and 5 mL samples from each bottle were analyzed at 24, 48, and 72h time points  with Modular P800 automatic analyzer. From this study we found that when using toluene as a preservative the differences of all test results were in  an acceptable range of total allowable error (TEa) for 72 hours. However, without preservatives the results showed  acceptable range of TEa for creatinine, protein, amylase and sodium at 72 hours, for UN, phosphorus and potassium at 48 hours and for calcium, uric acid and chloride at 24 hours.

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