EFFECTS OF REDUCING REAGENTS AND TEMPERATURE ON CONVERSION OF NITRITEAND NITRATE TO NITRIC-OXIDE AND DETECTION OF NO BY CHEMILUMINESCENCE

To measure the concentration of nitrites and nitrates by chemiluminesc ence, we examined the efficiency of five reducing agents [V(III), Mo(V I) + Fe(II), NaI, Ti(III), and Cr(III)] to reduce nitrite (NO2-) and ( or) nitrate (NO3-) to nitric oxide (NO). The effect of each reducing a gent on the conversion of different amounts of NO2- and (or) NO3- (100 -500 pmol, representing concentrations of 0.4 to 2 mu molar) to NO was determined at 20 degrees C for NO2- and at 80 degrees C for NO3-. The effect of temperature from 20 to 90 degrees C on the conversion of a fixed amount of NO2- or NO3- (400 pmol or 1.6 mu molar) to NO was also determined. These five reducing agents are similarly efficient for th e conversion of NO2- to NO at 20 degrees C. V(III) and Mo(VI) + Fe(II) can completely reduce NO3- to NO at 80 degrees C. NaI and Cr(III) wer e unable to convert NO3- to NO. Increased temperature facilitated the conversion of NO3- to NO, rather than that of N-2(-) to NO. We evaluat ed the recovery of NO2- and NO3- from plasmas of pig and of dog. Recov ery from plasma of both animals was reproducible and near quantitative .