Determination of Acrylamide in Aquatic Environmental Samples by GC/MS

Abstract

Objectives This study was conducted to improve the analysis method used for acrylamide (AA) and to investigate the occurrence of AA in influent and effluent from sewage treatment plants in Korea. A liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) is commonly used for AA analysis of complex samples because it is fast, simple and effective. However, the disadvantages of LC–MS/MS include its relatively high operational cost, low sample throughput, and low sensitivity. Therefore, this study was conducted to develop a novel analytical method for the determination of AA in complex environmental waters using gas chromatography-mass spectrometry (GC/MS) combined with the derivatization with bromine following solid-phase extraction (SPE). Methods This work describes the development of a novel SPE and GC/MS method for the analysis of AA in complex environmental waters. SPE parameters such as absorbent type, desorption solvent and volume were optimized by conducting a series of experiments. The best SPE cartridge was selected by conducting the recovery test with four different absorbents cartridge (SupelcleanTM Coconut Charcoal cartridge, SupelcleanTM ENVITM–Carb Tubes, Cleanert ODS C18 and Oasis HLB Cartridges). The brominated derivative, 2,3-dibromopropionamide (2,3-DBPA), was extracted with ethyl acetate (EA) and analyzed by GC/MS in selected ion monitoring (SIM), employing d3-acrylamide (d3-AA) as internal standard prior to extraction. Method validation was performed in terms of linearity of standard calibration curve, method detection limit (MDL), limit of quantification (LOQ), accuracy and precision of reaction product 2,3-DBPA. Results and Discussion Based on the SPE experimental results, the active carbon SPE was selected as it gave the best adsorption efficiency (98.8%). The effects of pH and optimum bromine reaction time were found to be important determining factors for acrylamide analysis in water. The experimental results showed that the optimal reaction conditions of pH were 1.5 and 3 h, respectively. The validation process consisted of assessing the following parameters: linearity of standard calibration curve, method detection limit (MDL), limit of quantification (LOQ), precision and accuracy. The coefficients of determination (R2) in laboratory conditions were: R2=0.9981 (2.5~100 µg/L). MDL and LOQ of acrylamide were 1.19 µg/L and 3.79 µg/L, respectively. The recovery studies were carried out at two different concentration levels (10 µg/L and 50 µg/L, n=3). The intraday accuracy and precision were in the range of 100.6~102.0% and 3.2~3.5%, respectively, and the interday accuracy and precision were in the range of 96.0~97.4% and 4.3~8.0%, respectively. The AA contents in effluents of sewage treatment plants were in the range of 0.008~0.017 µg/L for May, 0.009~0.14 µg/L for June and not detected (N.D.)~0.02 µg/L for July samples. Conclusions An efficient analytical method for the determination of AA has been developed. Activated carbon SPE cartridge (SupelcleanTM Coconut Charcoal) was selected for the sample purification. The validation study showed that this method was a reliable method with high sensitivity, linearity, precision, and accuracy. The interday accuracy and precision were in the range of 96.0~97.4% and 4.3~8.0%, respectively. This method was successfully applied to the determination of AA in effluent waters of sewage treatment plants. The AA contents in effluents of sewage treatment plants were in the range of 0.008~0.017 µg/L for May, 0.009~0.14 µg/L for June and not detected (N.D.)~0.02 µg/L for July samples. Key words: Acrylamide, Bromination, GC/MS, SPE