A comparison of methods for determining lead content in drinking water: A portable anodic stripping voltammetry instrument method versus the standardEPA 239.2 method

Lead levels in drinking water were measured by the standard U.S. Environmen tal Protection Agency (EPA)-approved atomic absorption spectroscopy-graphit e furnace Method 239.2 and compared with determinations made with a newly a vailable portable anodic stripping voltammetry (PASV) instrument. A standar d curve was prepared at 2, 5, 10, 15, 20, 25, and 30 mu g/L of lead. PASV i nstrument readings were lower than standard EPA method values, with a mean difference and standard error (SE) of the mean between the two of 1.538 +/- 0.588 mu g/L (n = 7, p = 0.040, significant at the 95% confidence interval [CI]). First-flush drinking water samples collected from 144 water fountai ns/coolers were preserved with nitric acid. Total lead content was tested t wice for 29 EPA method samples and 54 PASV instrument samples to determine the variation within each method; results were not significant at the 95% C I. Total lead content was determined for 144 samples by both methods. PASV instrument readings were lower than standard EPA method values (mean differ ence and SE of the mean 0.630 +/- 0.206 mu g/L; n = 144, p = 0.0027, signif icant at the 95% CI). Mean and standard deviation of the 144 samples for th e EPA method and the PASV instrument were 6.5 +/- 11.8 mu g/L and 5.9 +/- 1 1.6 mu g/L, respectively. Means were below the action level for lead of 15 ppb (mu g/L), but some values were above the action level (18 [13%] using t he EPA method; 20 [14%] using the PASV instrument). Retesting by EPA method showed two false positive PASV values. Results indicate that in some field situations the PASV instrument may prove useful due to its relatively low price, small size, ease of use, and quick readings.