Determination of nitric oxide in hydrophytes using poly(methacrylic acid-ethylene glycol dimethacrylate) monolith microextraction coupled to high-performance liquid chromatography with fluorescence detection

Nitric oxide (NO) is a bioactive molecule that has recently emerged as a cellular messenger in numerous physiological processes in plants. A novel high -performance liquid chromatography (HPLC) method combined with poly(methacrylic acid-ethylene glycol dimethacrylate) (MAAEGDMA) monolith microextraction (PMME) is developed for sensitive determination of NO in hydrophytes. NO is derivatized using a fluorescent probe, 1,3,5,7-tetramethyl-8-(3',4'-diaminophenyl)-difluoroboradiaza-s-indacene (DAMBO), and then the derivatives are extracted with PMME and analyzed by high-performance liquid chromatography (HPLC) with fluorescence detection. The conditions for the derivatization and the subsequent extraction of NO derivatives are optimized in detail. The detection limit (S/N = 3) of NO is determined to be 2 x 10(-12) mol L-1. Close correlation coefficient and excellent method reproducibility are obtained for the analyte over a linear range of 9 x 10(-11) -4.5 x 10(-8) mol L-1. The inter- and intraday relative standard deviations (R.S.D.s) are less than 5%. The proposed method is successfully applied to the determination of NO levels in hydrophytes samples. (C) 2007 Elsevier B.V. All rights reserved.