MEASUREMENT OF NITRITE AND NITRATE IN PLASMA, SERUM AND URINE OF HUMANS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY, THE GRIESS ASSAY, CHEMILUMINESCENCE AND GAS-CHROMATOGRAPHY MASS-SPECTROMETRY - INTERFERENCES BY BIOGENIC-AMINES AND N-G-NITRO-L-ARGININE ANALOGS

In this paper, the HPLC method for the measurement of nitrite and nitr ate in serum of humans newly reported by Fl Menyawi et al. is discusse d, especially in regard to the extremely low nitrate levels measured i n serum of healthy humans. From the discussion, it is concluded that: (1) Biogenic amines at physiological concentrations do not significant ly interfere with the batch Griess assay. (2) The HPLC method of Fl Me nyawi et al. does not reveal accurate levels for serum nitrate. (3) In serum and plasma of healthy humans, nitrate ranges within 15-70 mu M. (4) Exogenous N-G-nitro-L-arginine analogs can interfere with the mea surement of nitrate in human plasma and urine by the batch Griess assa y, chemiluminescence and GC-MS; interferences can be effectively elimi nated by solid-phase extraction on cation-exchangers. (C) 1998 Elsevie r Science BN. All rights reserved.