COAL TAR PITCH VOLATILES
Benzene soluble particulate matter should not be attributed to coal tar pitch volatiles unless polynuclear aromatic hydrocarbons (PNAHs) are present. OSHA Method 58 specifies the collection of particulates using a glass fibre filter (GFF) and the gravimetric determination of the benzene-soluble fraction (BSF). If the BSF exceeds 0.2 mg/m3, then the sample should be analyzed by high performance liquid chromatography (HPLC) to determine the presence of selected PNAHs. The detection limit of the gravimetric procedure is listed as 6 ug per sample; the detection limit of the HPLC procedure is significantly lower. In many cases, NIOSH Method 5506 is preferred, as this method specifies collection using a filter as well as an XAD tube and collects both particulate and vapor phase PNAHs; analyses of both is performed by HPLC. The NIOSH method eliminates possible interferences and inaccuracies produced by the tedious extraction specified in the OSHA method. You can request two different PNAH HPLC scans: 5 compounds or 17 compounds.