摘要：The present experiment was undertaken to apply the previously established method to biological samples. Interference of organic materials on the color reaction could be eliminated by burning the ether extract with potassium carbonate in a crucible. Standard method A was as follows : The ether extract of a biological sample, acidified with sulfuric acid, is warmed with 1 ml of 15% potassium carbonate solution and a few milliliter of distilled water in a porcelain crucible (3.4 cmφ, 4.5 cmh) and heated on a boiling water bath to dryness. The organic material is completely carbonized by heating the crucible over an open flame. The residual ash is washed into a 20 ml conical flask through a filter paper, using a small volume of distilled water. This aqueous filtrate is evaporated to dryness and the residue is added with 1 ml of acetic acid, 1 ml of 2', 7'-dichlorofluorescein solution (250 mg/liter acetic acid), and 3 drops of 30% hydrogen peroxide. The flask is sealed with a parafilm and the solution is warmed at 45°for 70 min, shaking for a few seconds every 20 min. After addition of 3 ml of pyridine to this solution, its absorption is determined by spectrophotometer at 530 mμ. As a more simplified method B, all the reactions can be carried out in the same crucible but the final solution must be filtered through a filter paper to remove the carbon. Recovery test of bromvalerylurea in the urine extract by methods A and B showed that the values were not greatly different between these two methods.
