Recent developments in perchlorate detection

Abstract

Perchlorate is highly soluble and non-reactive with soil sediments. As a result perchlorate is exceedingly mobile in aqueous systems. Because of its resistance to react with other available constituents, perchlorate can persist for many decades under typical ground and surface water conditions. In 2003, the US EPA1 compiled a list of potential perchlorate release sources. Sites from 25 states were listed. Table 1 summarizes the upper concentration range of perchlorate contamination found at these sites. Besides surface and groundwater, perchlorate has been found in food crops, such as lettuce, in the southwestern states. The uptake of perchlorate by crops is the result of irrigation using perchlorate contaminated water from the Colorado River. 2 There is a concern that perchlorate will be taken up by alfalfa, a major crop in the southwestern states. Some of this alfalfa is fed to dairy cows, which could conceivably result in perchlorate contamination of dairy products such as milk. In 2003, the presence of perchlorate in milk samples from Lubbock, TX was reported. 3 Considerable efforts are underway to develop perchlorate detection methods for monitoring purposes, compliance, quality control, and delineation of contaminant plumes. These methods need to detect perchlorate in a wide range of sample matrices - including water, soil, fertilizers, milk, etc. Detection of trace quantities of perchlorate in these samples remains a challenging task because of the interferences from other anions, whose concentrations are usually several orders of magnitude higher than that of perchlorate. A number of technologies have been developed to detect perchlorate and include chromatographic and spectroscopic methods, gravimetry, etc. In a number of instances, two of these methods have been coupled to improve detection of perchlorate. In this communication, these methods are reviewed with regard to specificity, sensitivity, and reliability. How these methods are implemented is also discussed. © 2006 Springer Science+Business Media, Inc.