AWWA WQTC60573

Atmospheric pressure ionization (API) LC/MS and LC/MS/MS technology has had a wide range of applications in environmental analysis. These include the identification, confirmation, and quantification of polar disinfection byproducts (DBPs), pesticides, herbicides and other contaminants in water samples. The improved LC/MS and LC/MS/MS techniques have made it possible to directly analyze aqueous samples with a sensitivity of subpart per billion to low part per billion levels for many organic chemicals. Direct aqueous analysis has four obvious advantages. These include: significantly reduced analytical costs associated with sample collection, shipping, storage, and extraction; improved accuracy and precision of analytical results; improved turn-around time of analytical results; and, reduction of matrix effects because the samples are not preconcentrated. This paper summarizes several applications of LC/MS and LC/MS/MS technology for direct aqueous analysis of polar regulated and unregulated contaminants in finished drinking water and source water. The contaminants studied include perchlorate, ethylenethiourea (ETU), 2,6-dichlorobenzamide (BAM), and a number of selected pesticides. The method detection limits (MDLs) were calculated as a product of the standard deviation of seven replicate analyses and the student's t value with a 99% confidence level and n-1 degrees of freedom. The method accuracy (mean recovery) and precision (relative standard deviation, RSD) were determined by measuring 4-7 replicate laboratory fortified blanks (LFBs). The two analytical systems used were a Waters 2690 LC equipped with a ZMD detector and a Waters 2695 LC equipped with a Quattro micro API detector (Waters, Milford, MA). Includes 12 references, tables.