Nitrite and nitrate measurements in human urine by capillary electrophoresis.

Nitrite and nitrate represent relatively stable nitric oxide (NO) end products in several biological fluids. The amounts of nitrite and/or nitrate in urine have been shown to reflect local and/or systemic involvement of NO in pathological conditions, including urinary tract infections and cardiac and renal allograft rejection. Capillary electrophoresis (CE) has been used in analysis of several ions and micromolecules. Electrokinetic and hydrodynamic sample injections are the main methods of injecting samples onto capillary columns. The urine sample matrix may widely vary depending on urine concentration, urine pH, and ion intake. This chapter illustrates the measurement of nitrite and nitrate in urine by CE and the comparison between electrokinetic and hydrodynamic sample injections.