To establish a method for the simultaneous determination of dichloroacetic acid (DCAA)and nitrite in water by suppressed ion chromatography, and optimize their separation conditions through response surface methodology.

Thermo Scientific Dionex IonPac™ AS19 anion exchange column was used. Taking the separation degree of DCAA and nitrite as the core evaluation index, the effects of 3 key factors (column temperature, DCAA concentration and eluent concentration) on the separation degree were investigated by single-factor experiments. Building upon this, a Box-Behnken central composite design was employed to construct a response surface model, thoroughly exploring the interactions between the factors and determining the optimal separation conditions.

The optimal separation conditions obtained by response surface methodology were as follows: column temperature 25 ℃, DCAA mass concentration 1000 μg/L and eluent mass concentration 6 mmol/L (with nitrite mass concentration fixed at 100 μg/L as the experimental background). Under the optimized conditions, the separation degree between DCAA and nitrite reached 2.71, meeting the requirement for effective separation of components during detection. Methodological validation results demonstrated good linearity within a certain concentration range(determination coefficient r²>0.999), the relative standard deviations were below 3.5%, and spike recovery rates were 95%-107%. These findings indicated that the method possessed high accuracy and stability.

The detection method optimized in this study can effectively achieve simultaneous and accurate determination of DCAA and nitrite in water. It is characterized by simple operation, high efficiency and reliability, making it suitable for the routine monitoring of these 2 kinds of substances in actual drinking water. This provides strong technical support for water quality safety assessment.