Impact of Acetate, Formate, and Lactate Background Electrolytes on Nitrate and Nitrite Separation by Capillary Electrophoresis

This study comparatively evaluated acetate, formate and lactate background electrolytes (30 mM, pH 4.0) for the determination of nitrate and nitrite by capillary electrophoresis. Standard solutions (5, 25 and 50 µg mL-1) were used to investigate the effects of electrolytes on migration time, theoretical plate number, peak symmetry and resolution. Acetate generated the highest electroosmotic flow mobility but resulted in the longest migration, the lowest theoretical plate numbers and pronounced peak fronting. Formate exhibited the highest separation efficiency and better peak symmetry, while lactate produced the shortest migration times at 25 and 50 µg mL-1. Based on these findings, formate and lactate were selected for calibration and accuracy experiments. Both electrolytes demonstrated good linearity (R²=0.9994 and =0.9999) over the concentration range of 6.25-100 µg mL-1. Lactate provided lower limits of detection, especially for nitrite. Formate revealed a better analytical accuracy, with recoveries of nitrate and nitrite (95.6% and 98.6%, respectively), compared to lactate (79.4% and 72.5%). In conclusion, the most suitable electrolyte is formate for capillary electrophoretic determination of nitrate and nitrite in processed meat products.