Determination of Linear Alkylbenzenesulphonates and Alkylphenol Polyethoxylates in Commercial Products and Marine Waters by Reversed- and Normal-Phase Hplc

Octadecylsilica was employed as reversed-phase HPLC packing material for the simultaneous separation and determination of linear alkylbenzenesulphonates (LAS) and nonylphenol polyethoxylates (NPEO). The role of NaClO4 dissolved in the mobile phase on the separation of LAS and NPEO was investigated: it turned out to affect only the elution volumes of LAS. Alkylphenol polyethoxylates were exhaustively extracted from liquid commercial cleaning products with hexane-acetone mixtures. A procedure for the determination of all the NPEO oligomers enriched from marine waters is presented

Graphitized carbon black extraction cartridges for monitoring polar pesticides in water

Abstract: Our previously reported procedure for analyzing pesticides in aqueous samples involving liquid-solid extraction by graphitzed carbon black (GCB) followed by liquid chromatography was appropriately modified for extending the analysis to very polar pesticides and pesticide metabolites. For this purpose, a 1-g GCB reversible extraction cartridge was adopted. Pesticide reextraction was performed by back-flushing the cartridge with a suitable eluant phase. The advantages of back-flush over forward flush desorption are illustrated. On extracting 2 L of drinking water spiked with the pesticides considered, the performance of the GCB cartridge was compared to that of a 1-g C18 bonded silica cartridge as well as to those of discontinuous and continous liquid-liquid extraction (LLE) techniques. The influence of the presence of humic substances in water on the quality of the analysis of the pesticides considered was assessed. The limits of quantification (5 times the limit of detection) of this method for the pesticides considered by analyzing municipal waters were below 0.1 mug/L, except for vamidothion and cymoxanil. Quantitative recoveries of even the most polar pesticides were obtained by submitting to the analysis volumes of ground and surface water samples no greater than 1 and 0.5 L, respectively

Selected herbicides in treated and untreated surface water

Atrazine, simazine, propazine, alachlor, and molinate were determined in raw (Po river) and treated waters of an advanced water supply treatment plant (WSTP) equipped with a granular activated carbon (GAC) column. Continous liquid-liquid (LLE) and C18 solid-phase (SPE) extractions were used to isolate the herbicides before the gas Chromatographic analysis using nitrogen-phosphorus (HRGC-NPD) and mass spectrometry (HRGC-MS) detection. The concentrations of atrazine in the raw water, in contrast to those of alachlor and molinate, were rather constant over the one year monitoring. The final effluent of the WSTP showed concentrations of the herbicides considered undetectable or far below the EC prescriptions. Adsorption on the GAC columns was the main process responsible for the major removal of atrazine. © 1991 Publications Division Selper Ltd