Application of LPME/GC-ECD for determination of PCP in water

Abstract

Liquid-phase microextraction (LPME) followed by gas chromatography (GC) coupled with an electron capture detector (ECD) was applied for the analysis of pentachlorophenol (PCP) in aqueous samples. After alkalization with Na 2 CO 3 solution, PCP was acetylated with acetic anhydride. The pentachlorophenyl acetate derivative was then extracted with n-hexane by LPME. 1.5 μL organic drop exposed to the aqueous sample solution at 15℃ for 5 min, stirring rate at 100 r/min was chosen as the optimum extraction condition. Under this condition, LPME provided a very simple, fast and solvent-less procedure to collect PCP from aqueous sample for GC determination. The linearity of LPME/GC-ECD for PCP in distilled water was investigated at the range of 2-200 μg/L with a coefficient of correlation 0.998. The repeatability of this method was determined at the level of 50 μg/L with the average of relative standard deviations (RSDs) 7%. Detection limit was obtained at less than 0.5 μg/L levels. When LPME/GC-ECD was applied to the determination of PCP in municipal sewage, the average of relative recoveries and RSDs were 70% and 6.5%, respectively.

Historical Evolution of Catalysts for Ammonia Synthesis

“…47 The relationship between the activity and the iron oxides (Fe 3 O 4 , FeO and Fe 2 O 3 ) and their mixtures in the precursor were studied systematically, and a hump type curve was found between the activity and the ratio (Fe 2+ /Fe 3+ ). It was speculated that the monophase of iron oxide phase in the precursor is an essential condition for high activity of the catalyst and a uniform distribution of iron oxide phase and promoters is a key to make a better performance of catalyst.…”