In the study, three samples containing between 0.005 and 5.0 mg per liter of each of nine metals - zinc, chromium, copper, magnesium, manganese, silver, lead, cadmium, and iron - were provided. Each participant was requested to do a single analysis for each of the metals in each of the three samples by the provided atomic absorption spectrophotometric method. This method, depending upon the sensitivity of the instrument (burner, tube, etc.) available, gave the participant a choice of aspirating the sample directly into the flame or of chelating with ammonium pyrrolidine dithiocarbamate and extracting into methyl isobutyl ketone before aspirating. The results obtained were evaluated in terms of whether the sensitivity of the method was sufficient to permit the measurement of the metal with a reasonable degree of precision and accuracy at the concentration prescribed by the drinking water standards.