Elimination of the memory effects of gold, mercury and silver in inductively coupled plasma atomic emission spectroscopy

The memory effects of mercury, gold and silver are eliminated by the use of sulfur containing complexing agents. In low concentrations (1 µg ml−1) of mercury and gold, the addition of 2% L-cysteine gives wash-out times of less than 1 min for both elements. At higher concentrations of gold and mercury, and at low concentrations of silver, the reagent is less effective. Thiourea, at a concentration of 1%, eliminates the memory effects of silver, also giving wash-out times of approximately 1.5 min. The use of thiourea with higher concentrations (100 µg ml−1) of mercury and gold delivers wash-out times of 1 min and 2 min, respectively. In a matrix similar to that found in many samples, the wash-out time for gold is less than 3.5 min and less than 2 min for mercury.