An improved method for BTEX extraction from charcoal

In this paper we propose a simple procedure for the extraction of BTEX (benzene, toluene, ethylbenzene and xylenes) from activated charcoal. For this purpose synthetic samples were prepared in a laboratory and real samples were collected in a polluted environment using passive sampling. The proposed extraction procedure is based on the use of an appositely designed Soxhlet apparatus, dimensions of which are as small as the cartridge of the passive samplers, in order to accommodate this latter and permit us to use a small amount of solvent. The selection of the solvent was based on the strong desire to substitute carbon disulfide, which is by far the solvent of choice, with a less hazardous substance in order to enhance operator protection. Among the solvents tested the best results were obtained by using dichloromethane that, under optimized conditions, led to a complete recovery (>97%) of each analyte (BTEX), both in the synthetic and the real samples. The extraction procedure with CH2Cl2 in the Soxhlet lasted for about 20 minutes which also resulted in a reduced operating time.