Polychlorinated Biphenyls in Groundwater of Grombalia: Optimization and Validation of Analytical Procedures Using Gas Chromatography with Electron Capture Detector

Abstract

Now-a-days, the management of water resources is one of the main global challenges, both at the level of agricultural and industrial activities as well as direct consumption and poses various problems of both qualitative and quantitative order. In the entire world, groundwater suffers from various sources of contamination principally due to overusing of chemical fertilizer in the agricultural sector. The contamination of groundwater by organochlorines and more precisely by polychlorinated biphenyls (PCBs) is a problem of global order. As we know that Tunisia is based on agriculture work like citrus, olive, wheat and cereal, the study of water pollution is a topical subject that remains unclear. Polychlorinated Biphenyls (PCBs) are one class of persistent organic pollutants. PCBs in recent decades have attracted the attention of scientific and policy maker communities due to their persistence, their high capacity to bioaccumulation in the food chain and their toxic properties. This work is aimed to develop an efficient method for the analysis of targeted PCBs in groundwater sample taken from the region of Grombalia. Optimization of PCBs extraction was performed with applied the experimental design of Dohlert with two factors, solvent and number of extractions. Analysis of PCBs was performed with gas chromatography coupled with electron capture detector (GC-ECD) with an optimization of temperature program. Results shows that the optimal temperature program was obtained with a starting temperature of 160°C up to 280°C during 10 min with a rate of 4°C min-1 and the optimal condition of extraction was obtained with a mixture of hexane/ether (75/25%) and a three time extractions. The optimized method has been applied to the analysis of the PCBs in nine groundwater samples collected from the Grombalia city. Results indicate that PCBs concentrations varied between 5.2 μgL-1 and 169 μgL-1. However, the maximum acceptable concentration (MAC) in drinking and surface water recommended by EPA is 0.5 μgL-1 with a detection limit (LD) ranged between 0.05 to 1.9 μg L-1.