Determination of Organochlorine Pesticides in Commercial Fish by Gas Chromatography with Electron Capture Detector and Confirmation by Gas Chromatography-Mass Spectrometry

Abstract

A method has been studied for the analysis of 16 organochlorine pesticides (OCPs) in Fish. The method was based on ultrasonic extraction using n-hexane-acetone (90:10, v/v) for 30 min, three times. The extracts were fractionated and cleaned up with a 5 g Florisil column. Diethylether:n-hexane (6:94,v/v) and (50:50,v/v) were used as elute solvents. Two fractions were collected separately. The mean recoveries of the 15 compounds were in the range of 82% to 96% with 3% to 11% RSD, except for endosulfan II only 76% recovery with 6% RSD was obtained. The concentrations of analytes were determined by gas chromatography with electron capture detection. Positive results were confirmed by gas chromatography-mass spectrometry in selected ion mode (SIM). The limit of detection and quantitation were in the range 0.02 to 0.34 ng/mL and 0.10 to 1.0 ng/mL, respectively. The method has been applied for the analysis of organochlorine pesticides in the edible portion of 10 different kinds of fish, namely, striped snaked-head (channa striats), common silver barb (Barbodes gonionotus), tubtim (Oreochromis niloticus), nile tilapia (Oreochromis niloticus), sand goby (Oxyeleotris marmoratus), common carp (Cyprinus carpio), grey feather (Notopterus notopterus), common climbing perch (Anabas testudineus), snake skin gourami (Trichogaster pectoralis) and moonlight gourami (Trichogaster microlepis). Fat contents ranged from 2% to 9%. The OCPs alpha-BHC, gamma-BHC, delta-BHC, aldrin, endosulfan I, p,p -DDE and dieldrin were detected in 9 of 10 species. The highest concentration was delta-BHC, 35±1 ng/g wet weights in Channa striats.