Determination of atrazine in environmental and biological samples using solid phase extraction and spectrophotometry

An analytical method employing a combination of solid phase extraction and spectrophotometry is proposed for the determination of a widely used herbicide atrazine. This combination is very simple and cheaper than chromatography and mass spectrometry based methods. The proposed method also reduced the use of toxic solvents. The method is based on the reaction of atrazine with pyridine to form a quaternary halide, which forms a carbinol base in the presence of alkali. Carbinol undergoes cleavage of heterocyclic ring to form glutaconic aldehyde that is subsequently coupled with sulphanilic acid to give a yellow orange dye which is measured spectrophotometrically at 460 nm. Beer's law is obeyed in the range 0.07-0.7 mu g/mL of atrazine. Molar absorptivity and Sandell's sensitivity were found to be 2.2 x 10(5) L/mol cm and 0.0009 mu g/cm(2), respectively. Breakthrough volume is found to be more than 100 mL. The use of solid phase extraction increases the sensitivity ten times. The proposed method is sensitive and found to be free from the interference of a large number of foreign species and other pesticides. The developed method was applied to spiked environmental and biological samples, the recovery was in the range from 95.2 to 99.2% with RSD of 0.36%.