STANDARD-REFERENCE WATER-SUSPENDED SEDIMENT SAMPLE FOR TOTAL RECOVERABLE METALS.

The U. S. Geological Survey has been preparing and maintaining a library of standard-reference water samples for dissolved inorganic constituents for 19 years. Recently, the reference-sample program was expanded to include a water-suspended sediment mixture for the determination of total recoverable metals. An interlaboratory round-robin study was conducted. Digestion procedures used by the U. S. Geological Survey and the U. S. Environmental Protection Agency were used to solubilize the metals before their measurement. The data indicate that both digestion procedures for total recoverable metals are essentially equivalent. Precision data are comparable to those data obtained in standard-reference water samples for dissolved metals.