Sampling and storage of natural waters for trace metal analysis

Methods for the collection, preservation and storage of natural water samples for the analysis of trace levels of heavy metals have been critically reviewed, with particular reference to the analysis of zinc, copper, lead, cadmium and mercury. Recommended prodecures are given which minimise the problems of sample contamination and adsorption losses. Carefully cleaned high-density polythene or Teflon containers are recommended for both sampling and storage, with a storage temperature of 4°C. Acidification to 0.05 M H⁺ with nitric acid is desirable, except in speciation studies. For mercury analysis the addition of an oxidant or complexing agent is also necessary.