RAPID DETERMINATION OF POLYCHLORINATED BIPHENYLS IN SOIL USING DIRECT THERMAL DESORPTION-GAS CHROMATOGRAPHY WITH NOVEL μ-VIAL INSERTION

The objective of this work was to develop a solvent-free extraction technique coupled with gas chromatography to quantitatively determine polychlorinated biphenyls (PCBs) in soil samples; thus, direct thermal desorption-gas chromatography (DTD-GC) was used. A small container of quartz deactivated by silanization, named the mu-vial, was developed for thermal desorption of solid samples. The novel mu-vial was inserted into the liner to load the solid sample. The insertion method can affect thermal desorption and transference from vaporizing chamber to the column. A comparison between four mu-vials (b, c, d, and e) that are used to determine PCBs using DTD-GC showed that the d-shaped mu-vial with a side hole enhanced analysis sensitivity and reliability. Experimental analysis revealed the main methodologies required to determine 17 PCBs using DTD-GC, which are summarized as follows: a spiked soil sample (50 ng g(-1) and 200 ng g(-1)) with a particle size of 250 gm, the method detection limits (MDLs) of 2.89-9.69 mu g kg(-1) (relative standard deviation RSD<7.86%), and a recovery of 72.5% to 104.2%; a desorption temperature of 450 degrees C; a desorption time of 120 s; and a transfer time to head column of 90 s. A test of real environmental samples demonstrated that the results using DTD-GC were similar to those obtained by EPA8082.