N-compounds speciation analysis in environmental samples using ultrasound-assisted solid-liquid extraction and non-chromatographic techniques.

A fast, efficient, and non-chromatographic method was presented in this study for nitrite, nitrate, and p-nitrophenol (N-compounds) extraction and speciation analysis of environmental samples. By applying ultrasound-assisted solid-liquid extraction (USLE), analytes were efficiently extracted from water, soil, or sediment collected in areas of environmental disaster. These analytes were selectively converted to NO(g) through UV photolysis (NO3-), H2O2/UV photocatalysis (PNP), and direct conversion (NO2-). Following conversion, NO(g) was separated from the liquid phase and determined by high-resolution continuum source molecular absorption spectrometry (HR-CS MAS). The LODs obtained were 0.097 ± 0.004 mg L-1 for nitrite, 0.119 ± 0.004 mg L-1 for nitrate, and 0.090 ± 0.006 mg L-1 for p-nitrophenol. On applying this speciation method to environmental samples, concentrations were found to be up to 0.99 ± 0.03 mg L-1 (NO2-), 49.80 ± 2.5 mg L-1 (NO3-), and 0.10 ± 0.02 mg L-1 (PNP). Finally, addition/recovery study of real water, soil, and sediment samples showed 101 ± 2% recovery for NO2-, 100 ± 1% for NO3-, and 96 ± 5% for PNP.