Determination of mercury in urine.

THE LOSS OF MERCURY due to volatilization and incomplete removal of oxidizing agents which destroy dithizone are among the major problems in determining mercury in urine. This paper describes a method by which these difficulties are reduced to a minimum. In actual use, this method has been found efficient in screening large numbers of workers exposed to a mercury hazard. Most methods require a preliminary heating of the urine with strong oxidizing agents and concentrated acids. After the decomposition of organic matter, the mercury is either extracted directly (1-3), or initially isolated as the sulfide (4) or the volatile chloride (5). The final colorimetric estimation depends on the formation of the dithizone mercuric complex (2, 4, 5), the dithizone organic mercurial complex (3), or the di-beta-napthylthiocarbazone mercuric complex (1). The present method is based on the reduction of mercury in urine to metallic mercury by a hydrazine-copper system. Microgram concentrations of mercuric ion, sodium meralluride, and phenyl mercuric chloride are rapidly reduced to metallic mercury, both in aqueous solution and in urine. The finely divided metallic mercury is then oxidized to mercuric ion by the addition of sulfuric acid and potassium permanganate at room temperature. After the destruction of excess permanganate with hydroxylamine hydrochloride, the final estimation is made by a titrimetric dithizone technic adapted from the literature (6).