The determination of nitrite and nitrate in human blood plasma by capillary zone electrophoresis

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Abstract
The determination of nitrite and nitrate in human blood plasma by capillary zone electrophoresis (CZE) is described. Electrophoresis was carried out in a 65 cm long, 75 μm wide silica capillary, using 750 mM sodium chloride containing 5% NICE-Pak OFM Anion-BT (an additive reversing the electroosmotic flow) as running buffer, at a potential of 20 kV, with on-column UV detection at 214 nm. Under these conditions, the two anions migrated in the order of nitrite and nitrate, completely resolved from each other. Forty-one samples of ultrafiltered blood plasma of healthy volunteers were analyzed. The concentrations of nitrite and nitrate were 0.15 ± 0.07 mg/L and 3.2 ± 1.6 mg/L (mean± SD), respectively, with a linear correlation in the range of 0.1–50 mg/L. The within-day and between-day coefficients of variation (CVs) for nitrite and nitrate were lower than 5% and 8%, respectively. The recovery was 97-114%. The estimated plasma volume needed for each determination was 108 nL.