Analysis of some phthalate esters in water by solid phase extraction

Abstract

Solid Phase extraction (SPE) is the sample preparation technique that has been developed for the determination of some phthalate esters, i.e., dimethylphthalate, diethylphthalate, dibutylphthalate, buthylbenzylphthalate, di (2-ethylhexyl) phthalate and di-n-octylphthalate. This technique involves exteraction of aqueous solutions by using C18 SPE cartridge and the small volume of extract. Is analyzed by a gas chromatograph equipped with flame ionization detector. Various factors having effect on the percent recovery, i.e., the pH of solution, the sorbent mass, the eluting solvents and the elution volume are studied and evaluated. The pH value of solution at 2.0, 500 mg of sorbent mass, toluene as eluting solvent and 3.0 mL of toluene are chosen as optimal conditions of solid phase extraction for the analysis of phthalate esters in water samples. The method detection limit of this technigue is in the range of 0.51 – 1.26 ppb for all studied compounds. The percent recoveries of the phthalate esters are in the range of 105.24-88.01% with ± 1.37 – 2.66 % RSD. The accuracy of this technique is also studied and the percent errors are in the range of 0.03 – 2.00 % at the ppb level of concentration. Ethyl acetate which is less toxic than toluene is an alternative for eluting solvent giving the percent recoveries of phthalate esters in the range of 87.42-95.75 % with ± 1.59 – 2.81 % RSD. Moreover, the developed technique is also applied to analyze these phthalate esters in real water samples.