You are here:
DETERMINATION OF CARBAMATE, UREA, AND THIOUREA PESTICIDES AND HERBICIDES IN WATER
Citation:
Wang, N. AND W L. Budde. DETERMINATION OF CARBAMATE, UREA, AND THIOUREA PESTICIDES AND HERBICIDES IN WATER. Analytical Chemistry 73(5):997-1006, (2001).
Impact/Purpose:
The purpose of this research project is to develop a strong qualitative and quantitative "gold standard" laboratory reference analytical method for the simultaneous selective and sensitive identification and measurement of those cyanobacteria toxins that are of the highest priority to EPA and state and local drinking water authorities. These toxins are on the drinking water candidate contaminant list (CCL), but the specific toxins that are the most likely to occur, and which are the potentially most hazardous, are not defined on the CCL. Six toxins were recommended for highest consideration by an EPA workshop in May, 2001. These are the alkaloids anatoxin-a and cylindospermopsin, and the four microcystins abbreviated RR, LR, YR , and LA (these characters are the standard single-character designations for four natural aminoacids). There are no published analytical methods that have been demonstrated to have the ability to detect and reliably measure the concentrations of these six compounds in a single drinking or source water sample. The purpose of this research is to not only develop and demonstrate this capability with real environmental samples, but also to do it in a single economical laboratory analytical method that requires about one hour from initial sample preparation to obtaining the results. It is expected that some other toxins will be found in the real environmental samples tested, and perhaps even new toxins may be discovered in this work. The techniques employed in this work, have the capability of tentatively identifying known and unknown toxins even when standards are not available.
Description:
Microbe liquid chromatography and positive ion electrospray mass spectrometry are applied to the determination of 16 carbamate, urea, and thiourea pesticides and herbicides in water. The electrospray mass spectra of the analytes were measured and are discussed and mobile phase matrix effects were evaluated. Analyte positive ion abundances are generally inversely related to the concentration of acetic acid in the acetonitrile-water mobile phase in the range of 0.001% to 0.1% (V/V) acetic acid. Using an internal standard for quantitative analyses and no acid in the mobile phase, retention time precision, peak width precision, concentration measurement precision, mean recoveries, and instrument detection limits were determined in reagent water. The 16 analytes were also measured in fortified environmental water samples from a recreational lake, a ground water well, a cistern, a farm pond, and drinking water. These measurements were at 5ng/mL of each analyte which is within the range expected for environmental pesticide and herbicide contaminants. The analytes were separated from the environmental water matrices with an online extraction and concentration to provide rapid sample analyses without a slow off-line liquid-liquid or liquid-solid-liquid extraction and extract concentration. Recoveries of 12 of the analytes from four environmental water samples were in the range of 75-124% with relative standard deviations in the range of 11-16%.