(716e) Microfluidic Pre-Concentration, Separation and Detection of Perchlorate From Environmental Water Samples

The hazards of long-term perchlorate exposure, namely the disruption of thyroid hormone production, have caused the United States Environmental Protection Agency (EPA) to propose a health advisory limit of 15 parts per billion (ppb) for drinking water. Implementation of a widespread monitoring system for this level of perchlorate requires rapid and uncomplicated analysis with low limits of detection. This work describes the combination of perchlorate pre-concentration and segregation on a fabricated monolith structure with the rapid analysis and low limits of detection afforded by microchip capillary electrophoresis (MCE) with conductivity detection. While MCE alone has limits of detection in the 5 ppb range for drinking water analysis, these limits can be improved without the interference caused by the presence of high concentrations of other anions (e.g. chloride, sulfate, iodide, and fluoride) present in environmental samples. The current device employs an in situ generated monolith bearing a quaternary ammonium ion, which selectively retains perchlorate versus the other anions, for pre-concentration. The efficacy of two sources of the quaternary ammonium ion as pre-concentration media has been investigated, the coating of a glycidyl methacrylate-based monolith with a zwitterionic, sulfobetaine surfactant, N-tetradecyl-N,N-dimethyl-3-ammonio-1-propane sulfonate (TDAPS), and the substitution of glycidyl methacrylate with of 2-(Dimethylamino)ethyl methacrylate (DMAEMA) as the monomer in the monolith matrix. Additionally, the effects of pore size, monomer concentration, and channel size on pre-concentration capability are examined for both standard and environmental samples.