The effect of ammonium thiocyanate and sodium chloride on loss and recovery of mercury from water during storage

The effect of inorganic complexing agents such as thiocyanate and chloride on the stability of distilled water and natural waters spiked with 1 μg Hg l^-1 in polyethylene containers is reported. Distilled water solutions can be stored for several months without significant losses of mercury if they contain HNO₃(0.05–0.1 M) + NH₄SCN(0.001–0.01 M) or HNO₃(0.1 M) + NaCl(higher than 0.01 M). For river and pond waters, addition of HNO₃(0.1 M) + NH₄SCN(0.01 M) not only has a pronounced effect on preventing mercury losses, but also gives quantitative recoveries from spiked sample solutions from which mercury has been “lost”. Thiocyanate ion-favors desorption of mercury from solid phases; chloride is less effective in this respect.