Environmental mercury: rapid determination in water at nanogram levels.

Mercury compounds and free mercury are determined by emission spectrophotometry in a radiofrequency helium plasma. The method is simple, rapid, directly applicable to environmental water samples, and subject to few interferences. The useful working range is 10 nanograms to 10 micrograms, or 1 part per billion to 1 part per million in 10 milliliters of sample. The limit of detection is about 2 nanograms.