Determination of citalopram by capillary electrophoresis is described. Compounds were separated at 28 kV in 75 mu m i.d. fused silica capillary tubing (total length 85 cm, effective length 65 cm) with 10 mM borate buffer, pH 8.5, containing 10% (v/v) methanol as running buffer. Citalopram and propylparaben (IS) appeared at 3.5 and 5.5 min, respectively. Repeatable linear results were obtained. The limits of detection and quantification were 5.73 x 10(-6) and 1.72 x 10(-5) M, respectively. When citalopram was determined in a pharmaceutical tablet by capillary electrophoresis and by a UV-spectrophotometric method differences between the results were not significant. The citalopram content of tablets was 100.8 +/- 2.95% of the label claim. The amount found in serum was 26.7 +/- 0.1% of the free drug, indicating that 73.3% of the drug was bound to protein.