The effect of bacterial contamination and aging on the volatility of mercury in urine specimens.

The effect of specimen aging on the recovery of mercury from urine samples was investigated. It was found that in some aged specimens the addition of concentrated sulfuric acid to the urine without cooling resulted in a large loss of mercury. This phenomenon is presumed to be due to enhanced volatility of the mercury caused by bacterial action. This loss can be avoided by adding a suitable preservative to the urine, by chilling the urine while the concentrated sulfuric acid is being added, or, most conveniently, by using 50% (V/V) sulfuric acid in place of the concentrated acid. It was also found that the use of a reflux condenser is unnecessary when urine is being oxidized by heating with sulfuric acid and potassium permanganate.