Inorganic mercury (Hg2+) stock standard solution
(1000 mg/l) was prepared from mercuric chloride (Merck).
A methyl mercury (CH3Hg+) stock standard (100 mg/l, Hg
as CH3Hg+) was prepared from methyl mercury chloride
(Merck) by dissolving appropriate amount of the solid in
acetone and making up to volume with high purity water.
All the stock standards were stored in a refrigerator at 4 ◦C
and protected from light. Working standards were prepared
just before use by appropriate dilution of the stock standard
solutions.