AWWA JAW64988

Analytical techniques for measuring trace arsenic (As) concentrations, such as the method described in this article, have much lower detection limits than conventional As measurement methods, and broader adoption of such methods could potentially drive a revision of the practical quantitation limit (PQL) for As in the future. Arsenic detection is limited by chloride interference in transmission quadrupole inductively coupled plasma/ mass spectrometry (ICP/MS). However, high-resolution ICP/MS can measure As concentrations as low as 29 ng/L. The (nonenforceable) federal and California health standards for As are substantially lower than the PQL, so in the future a lower PQL could be a contributing factor when evaluating and reporting regulatory standards. These conclusions are likely to affect the decisions that water utility managers make about new and upgraded analytical equipment and treatment processes for As and other contaminants for which the PQL is currently greater than corresponding health standards. Water utility managers need to understand that the PQL is a moving target and incorporate that knowledge when planning for future analytical, reporting, and treatment operations. Includes 23 references, tables, figures.