title: A novel spectrophotometric method for indirect determination of nitric oxide (NO) in serum.
abstract: BACKGROUND
  It is essential in clinical medicine to develop a simple and accurate analytical method for detecting nitric oxide (NO) in blood or other body fluid. In order to overcome the shortcomings of previous methods, this experiment developed a novel indirect analytical method of NO in serum.
  
  
  METHODS
  After nitrate was reduced by copper-coated cadmium granules, the nitrite produced was determined by diazotization of fuchsin acid and coupling to resorcinol. The maximum absorption appeared at 436 nm, with which the concentration of NO can be determined indirectly.
  
  
  RESULTS
  NO concentration and absorbance were linearly correlated over the concentration ranging from 0 to 198 μmol/l, r=0.999. The CVs were 7.16% for within-run and 9.07% for between-run assays, respectively. The average recovery rate ranged from 90.6% to 105.2%. The mean concentration of NO3(-)/NO2(-) was 59.2±17.0 μmol/l in serum of 30 normal volunteers. The serum concentration of NO3(-)/NO2(-) decreased significantly in patients with congestive heart failure (CHF) compared to the normal volunteers, P<0.05.
  
  
  CONCLUSIONS
  This method offers a reliable, simple, reagent safe and inexpensive analytical platform for the determination of NO in serum. Using this approach, we determined that the synthesis of endogenous NO decreased in patients with CHF.
authors.affiliation: Department of Central Laboratory, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200120, PR China.
authors.forename: Da
authors.initials: D
authors.lastname: Wo
authors.forename: Ping
authors.initials: P
authors.lastname: Zhuang
authors.forename: Zeng-guang
authors.initials: ZG
authors.lastname: Xu
authors.forename: Shumin
authors.initials: S
authors.lastname: Xu
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: Hui-ming
authors.initials: HM
authors.lastname: Mao
mesh_terms: D000328:Adult; D000368:Aged; D002104:Cadmium / Q000737:chemistry; D016022:Case-Control Studies; D003300:Copper / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry; D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000175:diagnosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000097:blood*; D009569:Nitric Oxide / Q000097:blood*; D009573:Nitrites / Q000097:blood*; D010084:Oxidation-Reduction; D012118:Resorcinols / Q000737:chemistry; D012394:Rosaniline Dyes / Q000737:chemistry; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000379:methods*
chemical_list: D009566:Nitrates; D009573:Nitrites; D012118:Resorcinols; D012394:Rosaniline Dyes; C476677:Schiff's reagent; D002104:Cadmium; D009569:Nitric Oxide; D003300:Copper; D004492:Edetic Acid; C031389:resorcinol
keywords: Nitrate; Nitric oxide; Nitrite; Serum; Spectrophotometric method