INCREASED MERCURY CONTAMINATION OF DISTILLED AND NATURAL-WATER SAMPLES CAUSED BY OXIDIZING PRESERVATIVES

The passage of mercury vapor from ambient air through the walls of conventional polyethylene (CPE), linear polyethylene (LPE), and Teflon (FEP) containers can seriously contaminate solutions of distilled and natural water stored in these containers. The rate of mercury contamination is dramatically increased when the sample solution contains oxidizing agents such as nitric acid or potassium permanganate, which are commonly used as preservatives to prevent loss of mercury(II) ion. The rate of contamination also depends on container material and decreases in the order CPE > LPE > FEP > glass. Freezing the samples in plastic containers is an effective way to prevent mercury contamination. When freezing is not practical, storage in glass containers minimizes sample contamination from ambient mercury vapor. © 1979.