Fourier transform infrared spectroscopic determination of ammonium at sub-microgram level in waters and biological fluids following removal of nitrate from sample matrix by zerovalent iron nanoparticles

Experimental parameters were optimized for rapid and precise determination of ammonium ion by FTIR spectroscopy in presence of nitrate ion in water and in samples collected from humans. Nitrates, whose FTIR spectra strongly overlap with those of ammonium ion, were removed from the sample matrix by treating it with zero-valent iron nanoparticles in acidic medium. The infrared peak at 1,400 cm(-1) was selected for determination of ammonium ion. Diffuse reflectance FTIR gives both qualitative and quantitative information on ammonium in a KBr matrix. The limit of detection and the limit of quantification of the method are 0.15 ng per 20 A mu L-1, and 0.5 ng per 20 A mu L-1, respectively. The relative standard deviation is 6% (n = 8). The results were compared to those of ion chromatography and show a high degree of acceptability. The method can be applied over a wide concentration range using small sample volumes.