Determination of Major Anions in Human Serum by Capillary Zone Electrophoresis

This study presents an optimized method for determining major anions (chloride, sulfate, phosphate, citrate, and lactate) in human serum using capillary zone electrophoresis (CZE) with indirect photometric detection. A comparative analysis was conducted to evaluate the effectiveness of an electroosmotic flow (EOF) modifier (cetyltrimethylammonium hydroxide—CTAOH) and an ion-pairing reagent (tetrabutylammonium hydroxide—TBAOH). The optimal electrolyte composition (10 mM chromate, 16 mM DEA, 0.5 mM CTAOH) was determined, ensuring high separation quality and detection sensitivity. An improved sample preparation method, involving protein precipitation with acetonitrile, was implemented. Achieved limits of detection were 6 mg/L for sulfate, 12 mg/L for phosphate, 10 mg/L for citrate, and 16 mg/L for lactate. The method’s validation characteristics (spike-recovery of 90–111%, relative standard deviation (RSD) ≤ 10%) demonstrate high accuracy and reproducibility.