Analysis of nitrate and nitrite in water and urine by capillary zone electrophoresis

A capillary zone electrophoresis method for the separation and analysis of nitrate and nitrite in water and urine was developed. No interference in the electropherogram from other anions is observed by using a polyacrylamide-coated column with a modified phosphate buffer at pH 3 for the separation, and UV absorption at 214 nm for the detection. The method does not require sample pretreatment or the use of organic solvents. The limit of detection for each analyte (S/N = 3), using a 75 microns I.D. capillary, is 0.5 microgram/ml. Urine samples require 40-fold dilution in order to maintain migration time reproducibility to within 1% relative standard deviation.