Comparative studies of PAH in pitch by liquid chromatography/fluorescence and other methods

In order to evaluate the PAH toxicity potential of our Soderberg cell emiss ions, a first PAH HPLC/Fl method was developed in the early 1990's. A quali ty control of PAH measurements, based on the B[a]P Eq. Index of homogeneous , stable reference materials, was implemented to follow the pitches used in the fabrication of anode pastes. This technique employed megabore columns (4.6-mm o.d.) with twin fluorescence detectors. In the mid-1990's, this met hod was upgraded to minibore columns in order to increase the accuracy. Dat a for the same pitches was accumulated over a three-year period. This commu nication compares the results from the two HPLC/Fl approaches including the extraction procedures, the stability of the PAH extracts, the stability of the equipment, the temporal resolution, the wavelengths used, etc., which can affect the apparent PAH values. This new method has also been compared with the results from other laboratories using different protocols and tech niques including the presence of instrument specific interferences.