抄録
Determination of the arsenic compounds in urine is described. We have pursued the development of the analytical method of total, hydrolytic, and unhydrolytic arsenic in urine by flameless atomic absorption spectrometry using a carbon tube atomizer. a) Total arsenic was determined after the dried urine was burnt in the oxygen flask and the arsenic was isolated with extraction and back extraction. As a result, total arsenic in urine could be determined by as low as 0.5 ml of the sample volume, recoveries were higher than 92% and variation coefficients were about 9%. b) Hydrolytic arsenic was determined after the hydrolytic arsenic was hydrolyzed in 10N HCl solution and extraction and back extraction of arsenic were done by the same procedure as the determination of total arsenic. As a result, hydrolytic arsenic in urine could be determined by as low as 2 ml of the sample volume, recoveryies were about 100% and variation coeffients were about 10%. c) Unhydrolytic arsenic was calculated by subtraction of hydrolytlc arsenic value from the total arsenic value. Procedure (1) Total arsenic: 0.5-1 ml of urine was added to 70 mg of absorbent cotton which was hung with thread and dried for 2-3 days at room temperature. Then the dried sample was burnt in the oxygen flask. Arsenic was taken up in 25 ml of 10N HCl, and was transferred to a separatory funnel. Added 1 ml of 40% potassium iodide to reduce As (V) to As (III). Then arsenic was extracted with 20 ml of chloroform and back extracted with 2 ml of aqueous solution of magnesium salt (0.26% Mg (NO3)2·6H2O). The back extractant (20 μl) was injected into the carbon tube and the arsenic was determined according to the operating condition shown in Table 1. (2) Hydrolytic arsenic: 2 ml of urine was added into the separatory funnel, then added 25 ml of 10N HCl and 1 ml of 40% potassium iodjde and stand for 15 min. Arsenic was extracted with 5-10 ml of chloroform, and this was repeated twice. These extracted solutions were combined. Then arsenic was back extracted with 1 ml of aqueous solution of magnesium salt. The arsenic in the back extractant was determined by the same procedure as the total arsenic. Under these conditions, total arsenic and hydrolytic arsenic in human urine were determined, and the concentration of total arsenic was found to be 67 ppb (n=70) and hydrolytic arsenic was 5 ppb on the average.
