title: Comparison of high-pressure liquid chromatography (HPLC) and Griess reagent-spectroscopic methods for the measurement of nitrate in serum from healthy individuals in the Nordic countries.
abstract: OBJECTIVE
  Bioavailability of NO can be estimated by measuring the concentration of nitrate (NO(3)) in serum. However, the methods used for the measurement NO(3) in plasma or serum show a great degree of variation. Therefore, we compared two analytical methods for the measurement of NO(3) in serum.
  
  
  METHODS
  The concentration of NO(3) in 600 serum samples collected from healthy individuals was determined by the HPLC and by the Griess reagent-spectroscopic method.
  
  
  RESULTS
  The concentration of NO(3) in the samples was 29.4+/-16.1 micromol/L and 26.2+/-14.0 micromol/L (mean+/-SD) measured by HPLC and Griess reagent-spectroscopic method respectively (p<0.0001). We detected a significant correlation between the two methods (R=0.81, p<0.0001).
  
  
  CONCLUSIONS
  A significant correlation between the two methods may suggest that either method can be used for the measurement of NO(3) in serum, however the Griess reagent-spectroscopic method measures lower concentrations of NO(3) than the HPLC method.
authors.affiliation: Department of Natural Sciences, University of Agder, 25 J Gimlemoen, Service box 422, 4604 Kristiansand, Norway.
authors.forename: Tine Lise
authors.initials: TL
authors.lastname: Larsen
authors.forename: Valentina
authors.initials: V
authors.lastname: Nilsen
authors.forename: Dag Olav
authors.initials: DO
authors.lastname: Andersen
authors.forename: George
authors.initials: G
authors.lastname: Francis
authors.forename: Pål
authors.initials: P
authors.lastname: Rustad
authors.forename: Mohammad Azam
authors.initials: MA
authors.lastname: Mansoor
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005029:Ethylenediamines / Q000737:chemistry*; D006801:Humans; D008875:Middle Aged; D009566:Nitrates / Q000097:blood*; D012015:Reference Standards; D013057:Spectrum Analysis / Q000379:methods*; D013424:Sulfanilamides / Q000737:chemistry*; D055815:Young Adult
chemical_list: D005029:Ethylenediamines; C095000:Griess reagent; D009566:Nitrates; D013424:Sulfanilamides