UV photochemical hydride generation using ZnO nanoparticles for arsenic speciation in waters, sediments, and soils samples

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.

Non-chromatographic Speciation of As by HG Technique-Analysis of Samples with Different Matrices

The applicability of the hydride generation (HG) sample introduction technique combined with different spectrochemical detection methods for non-chromatographic speciation of toxic As species, i.e., As(III), As(V), dimethylarsinate (DMA) and monomethylarsonate (MMA), in waters and other environmental, food and biological matrices is presented as a promising tool to speciate As by obviating chromatographic separation. Different non-chromatographic procedures along with speciation protocols reported in the literature over the past 20 year are summarized. Basic rules ensuring species selective generation of the corresponding hydrides are presented in detail. Common strategies and alternative approaches are highlighted. Aspects of proper sample preparation before analysis and the selection of adequate strategies for speciation purposes are emphasized.