Interferences from Filters and Solvents in PNA Analysis by High Performance Liquid Chromatography

Abstract

The polynuclear aromatic hydrocarbon (PNA) content of participate matter emitted into the air from combustion or other processes is receiving increasing attention. The particulate matter is normally collected on a filter which is subsequently extracted with an organic solvent and then analyzed by various methods. The background levels (nanograms or lower) of PNA or other substances (i.e., phenols, nitrosamines, etc.) in the filters and solvents can be significant sources of error in analytical procedures. In this paper we report the presence of these compounds in most of the readily available filter media as well as in analytical grade solvents used to extract the filters. The presence of these compounds becomes apparent only upon concentration to a few milliliters volume of about 150 ml of the solvent itself or after use of the solvent in extracting an unused filter. The analysis is by means of high performance liquid chromatography (HPLC) using an ultraviolet fluorescence or absorption detector. Filters used in collection or in extraction were made of Teflon, glass fiber, cellulose, and organic polymers; and solvents investigated were benzene, CHCl₃, CH₂Cl ₂, hexane, and cyclohexane. The effects of heat treatment on glass fiber filters is also noted. Finally, a recommended procedure to purify and evaluate the solvent and to choose the filter media is offered.