Fast sequential injection determination of benzo[A]pyrene using variable angle fluorescence with on-line solid-phase extraction.

A methodology for the analysis of drinking water for one of the most potent carcinogenic agents known; benzo[a]pyrene (BaP), in the presence of other interfering PAHs is presented. The methodology described is based on the sequential injection analysis of the sample on to a microcolumn (containing 5 mg of C18) where extraction and preconcentration of BaP takes place, followed by elution of BaP with 1 ml of 1,4-dioxane and subsequent detection by using variable angle fluorescence. The advantages of the method include the small amount of stationary phase employed together with the possibility of re-using the phase in order to carry out a large number of injections without the need for column re-packing. Also noteworthy is the small volume of 1,4-dioxane used to elute the BaP retained on the column and the small sample volumes required (9-10 ml) for achieving detection limits at the ng l-1 level. Thus, a methodology for BaP determination is obtained which complies with the requirements of the 98/83/EC Directive which fixes a maximum admissible concentration for this pollutant in waters for public consumption of 10 ng l-1. The variable angle spectra obtained are further processed by means of the multiple linear regression technique. The detection limit for BaP is 2.5 ng l-1, and the linear range is between 7.5 and 280 ng l-1.