Rapid determination of trace metals in foods by using the microwave oven-digestion method. I. Determination of arsenic.

Wet digestion in a microwave oven for rapid determination of total arsenic was examined. Organic matter in samples was digested very rapidly in comparison with other heating methods. We then investigated Hirayama's method, in which nickel is added to samples to prevent loss of arsenic due to volatilization, and confirmed the effectiveness of nickel ion. Thus loss, of arsenic during wet digestion can be prevented by addition of nickel and by shortening the digestion time by the use of a microwave oven. By this method, arsenic contents in various foods could be determined with a recovery of 85.9-104% and a coefficient of variation of 1.8-5.7%. This microwave oven-digestion (MOD) method might also be applicable to the determination of other metals in foods.