Gas-Chromatographic Technique for the Analysis of Flocculant PRAESTOL Content in Surface Waters

摘要

The increasing amount of relatively new industrial reagents used is of concern especially when the Ml environmental fate of these chemical compounds is insufficiently documented. For some of these new reagents, the lack of analysis methods creates difficulties in the water quality monitoring of the discharged effluents. This paper covers the development and optimization of an analysis method for the PraestolA3040L content in water samples. Praestol A3040L is a moderately anionic polyelectrolyte containing acrylamide-sodium acrylate copolymers, ethoxylated alcohols and hydrotreated light petroleum distillates as an aqueous emulsion and it is industrially used in water treatment installations to promote the settling of suspended particles. Based on the reagent known constituents the method uses as analytical signal the GC-FID detection and quantification ol:its non-polar hydrocarbons, separated from the water sample by liquid-liquid extraction. The GC method optimization was primary focused at achieving adequate repeatability and detection limits and not for the individual chemical species separation, the method using the combined signal generated by the complex organic fraction. The best results were achieved with an injector temperature of 375 X in split-splitless mode, a N2 H2 and air flow rate of 25 mL/min, 30 mllmin and 300 mL/min, a ratio of air:H2of 10:1, a carrier gas flow rate of 2 mL/min with an initial column temperature of 50 °C, followed by an increase with 20 °C Imin up to 360 °C and a detector temperature of 360 °C. The method has a detection limit of 0.005 mg/ L, a quantification limit of 0.01 mg/L with a repeatability of approximately 20 % and a linear calibration range up to 5 mg/L with a linearity coefficient of 0.997 (all concentrations being express as A3040L mass per aqueous sample volume).