A selective and sensitive colorimetric method for semi-automated solid-phase extraction of atrazine in environmental water samples

A selective and sensitive procedure for the trace analysis of atrazine (ATZ) in surface water samples was developed using the semi-automated solid-phase extraction (SPE) coupled with a colorimetric method. In this work, we developed Konig's reaction using p-anisidine as a new coupling agent to form a red-colored dye product having lambda max 500 nm and tuned the reaction conditions to occur at 40 degrees C. The possible structure of the orange-red dye product was proposed based on HPLC-UV and UPLC-MS analyses. Under the optimized conditions, the method provided linearity range of 10-30 mu g/L with a good coefficient of determination (R2 > 0.99) in different sample matrices. The limit of detection and limit of quantification were 2.49 and 7.54 mu g/L, respectively. The method validity was evaluated by analyzing the ATZ spiked samples collected from paddy fields, fish farms, and natural canal waters with a recovery range of 104-119 %, and the results were in good agreement with those obtained using HPLC-UV. The developed method was able to reduce the requirement of high heating temperature for the conventional Konig's reaction and was expected to be used for the practical analysis of ATZ at the ppb levels in natural water.