AWWA WQTC58857

This study developed an electrospray ionization (ESI) liquid chromatography/mass spectrometry (LC/MS) method for the analysis of polar turfgrass pesticides that are commonly used in North America. The water samples were first extracted by using a solid phase extraction (SPE) technique. The analysis was then carried out with a Waters 2690 LC equipped with a ZMD detector. The separation was performed on a reverse phase C18 column. Acetonitrile/5 mM ammonium acetate in water were used as the solvents for the gradient mobile phase profile. The flowrate was set to 0.25 mL/min. The injection volume was 20 uL. This method was effectively used for the analysis of a number of turfgrass pesticides of low volatility in finished drinking water, groundwater, and surface water. These contaminants included bensulide, clopyralid, halofenozide, imidacloprid, mecoprop, neburon, oryzalin, paclobutrazol, triadimefon, triadimenol, etc. Bisphenol A-d16 was used as the internal standard. 4-(4'-bromophenyl)phenol was used as the surrogate. The calibrations were in a range of 0.05-30 ug/L. The method detection limits (MDLs) were determined by measuring seven replicate laboratory fortified blanks spiked at the method reporting level (MRL) at 0.5 ug/L or less. The MDLs were calculated as a product of the standard deviation of the replicate analyses and the student's t value with a 99% confidence level and a n-1 degree of freedom. The method accuracy (mean recovery) and precision (relative standard deviation, RSD) were determined by measuring four replicate laboratory fortified blanks (LFBs) spiked at 5-10 ug/L. Includes 9 references, tables.