Determination of polycyclic aromatic hydrocarbons in water using nanoporous material prepared from waste avian egg shell

For the first time a biocompatible calcium carbonate vateritic polymorph was recrystallized from eggshell waste and its application for the extraction of polycyclic aromatic hydrocarbons in water samples was demonstrated. This nanoporous calcium carbonate was used as sorbent in dispersive micro-solid-phase extraction method. In this approach 50 mg of the calcium carbonate material having about 25 nm pores was placed in a 5 mL of water sample and ultrasonicated for 30 min. The cloudy sample was centrifuged at 13500 rpm for 2 min. The aqueous layer was then discarded and the CaCO ₃ material was dabbed dry with a lint-free tissue. The analytes were then desorbed with 100 μ L of dichloromethane by ultrasonication for 5 min. Finally, the extract was analyzed by gas chromatography flame ionization detector. Experimental parameters affecting the extraction recoveries were optimized. Using optimum extraction conditions, calibration curves were linear with correlation coefficients of 0.9853 to 0.9973 over the concentration range of 0.05 to 30 ng/mL. This method showed a detection limit as low as 0.004 ng/mL (at signal-to-noise ratio of 3). Performance of the dispersive micro-solid-phase extraction was compared with a previously optimized solid-phase extraction technique. The developed method displayed good extraction recoveries (85 ± 8-110 ± 4%) with high enhancement factors (388-1433-fold) and good repeatability (% RSD <13) and involved the use of minimal solvents. Analysis of seawater from Dammam Port revealed the presence of the analytes at concentrations between 0.15 ± 0.01 and 13.43 ± 1.54 ng/mL.