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Nitrite and nitrate measurement in human urine by capillary electrophoresis
Author(s) -
Morcos Edward,
Wiklund N. Peter
Publication year - 2001
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200108)22:13<2763::aid-elps2763>3.0.co;2-g
Subject(s) - nitrite , nitrate , chemistry , urine , chromatography , capillary electrophoresis , sodium nitrate , electrokinetic phenomena , nitric oxide , chloride , inorganic chemistry , biochemistry , organic chemistry
Nitrite and nitrate have been widely used as markers for nitric oxide (NO) formation in vivo and represent the major NO oxidation products in biological fluids. In the present study, the use of capillary electrophoresis (CE) in the measurement of nitrite and nitrate in human urine is described. Urine samples were electrophoresed in an extended light path fused‐silica capillary (104 cm; 75 νm ID) at an applied negative potential of 30 kV, and UV detection at 214 nm. Using electrokinetic sample injection (–6 kV×20 s), we found that urine concentration, pH, sodium and chloride interfered with nitrite and nitrate detection. The detection of nitrite and nitrate was decreased when hydrodynamic sample injection was used (30 mbar×60 s). However, basal levels of urinary nitrite (0.25 ± 0.05 ν M ) and nitrate (591 ± 115 ν M ) were detected and no interference by variations in urine concentration and pH was noted when hydrodynamic sample injection was used. Thus, hydrodynamic sample injection is convenient for the measurement of urinary nitrite and nitrate and avoids the effect of variations in urine matrices and pH on nitrite and nitrate detection.