Determination of Simazine and Atrazine in River Water by Cloud-Point Extraction and High-Performance Liquid Chromatography

Atrazine and simazine are endocrine-disrupting herbicides that may be transported to surface water, unbalancing ecosystems. Sensitive and low-cost methods are required for monitoring the residues of these compounds. Although several highly sensitive chromatographic methods coupled to tandem mass spectrometry are available, these methods use high-cost instrumentation. Ultraviolet detection usually does not provide the sensitivity and selectivity for monitoring these herbicide residues at the maximum concentrations levels permitted by regulatory agencies, so that extraction and concentration steps are required. Cloud-point extraction in Triton X-114 micelles was investigated to extract and preconcentrate atrazine and simazine. Treatment of 10mL of sample solutions with 5mL of 5% (m v(-1)) Triton X-114 in the presence of NaCl (0.3g) with heating at 60 degrees C for 30min led to phase separation and the transfer of herbicides to the surfactant-rich phase, which was dissolved in 90:10 methanol:water for liquid chromatography analysis with ultraviolet detection. The linear dynamic range was 1-50 mu gL(-1) for the herbicides. The limits of detection were 0.13 and 0.27 mu gL(-1) for simazine and atrazine, respectively. The methodology was applied to water samples fortified with 1, 5, 15, and 50 mu gL(-1) of the analytes, resulting in recoveries between 86 and 132% with relative standard deviations less than 6%. The method is low cost and uses small volumes of toxic solvents with useful application in trial studies.