A microchip capillary electrophoresis (MCE) system has been developed for the determination of perchlorate in drinking water. The United States Environmental Protection Agency (USEPA) recently proposed a health advisory limit for perchlorate in drinking water of 15 parts per billion (ppb), a level requiring large, sophisticated instrumentation, such as ion chromatography coupled with mass spectrometry (IC-MS), for detection. An inexpensive, portable system is desired for routine online monitoring applications of perchlorate in drinking water. Here, we present an MCE method using contact conductivity detection for perchlorate determination. The method has several advantages, including reduced analysis times relative to IC, inherent portability, high selectivity, and minimal sample pretreatment. Resolution of perchlorate from more abundant ions was achieved using zwitterionic, sulfobetaine surfactants, N-hexadecyl-N,N-dimethyl-3-ammonio-1-propane sulfonate (HDAPS) and N-tetradecyl-N,N-dimethyl-3-ammonio-1-propane sulfonate (TDAPS). The system performance and the optimization of the separation chemistry, including the use of these surfactants to resolve perchlorate from other anions, are discussed in this work. The system is capable of detection limits of 3.4 +/- 1.8 ppb (n = 6) in standards and 5.6 +/- 1.7 ppb (n = 6) in drinking water.

Perchlorate is a pervasive water contaminant that has drawn national attention as a public health concern. Although perchlorate contamination has both natural and anthropogenic origins, its recurrent use in military munitions makes perchlorate the highest-priority military pollutant. Currently, perchlorate detection at the critical parts-per-billion level requires large, sophisticated instrumentation in a centralized laboratory. This report describes a fieldable, microchip capillary electrophoresis (MCE) device that is selective for perchlorate and exhibits reduced analysis times and reagent consumption. The device employs contact conductivity detection and zwitterionic surfactant chemistry to selectively resolve perchlorate from abundant environmental species such as chloride, nitrate, and sulfate. The prototype MCE system is capable of detection limits of 3.4 ± 1.8 ppb in standards and 5.6 ± 1.7 ppb in drinking water. Additional work modified the microchip geometry and separation chemistry, to account for higher ionic strength sample matrices such as surface and ground water, which cause interferences with perchlorate detection. A novel extraction method, incorporating the fundamentals of electrostatic ion chromatography (EIC), is presented as a way to overcome this challenge. Two extraction formats, employing either a packed bed or a monolith, were also investigated and presented in this work.