The use of silylation of glassware in mercury analytics was investigated. By treating the glassware with 5% (v/v) dichlorodimethylsilane in toluene, the surfaces of the vessels were inactivated. Method development proved that silylation can extend the range of stabile, contamination-free area as low as 1 ng/L mercury without any significant investments in laboratory clean-room facilities. The resilylation had to be done once a month.