Determination of polychlorinated biphenyls in silicone fluids

Abstract

Two independent methods, using gas chromatography (GC) and high performance liquid chromatography (HPLC), have been developed for the determination of polychlorinated biphenyls (PCB) in polydimethylsiloxane (PDMS) fluids. For low levels (<5 ppm) of PCB, charcoal column chromatography Is used to separate the PCB from the siloxane matrix for subsequent GC analysis. At higher levels, the sample may be diluted In hexane and analyzed directly by gas chromatography with electron capture detection. For HPLC with UV detection, the PCB are separated from the siloxane by an acetonitrile extraction and analyzed by reverse-phase chromatography. The GC method is preferred for low concentrations of PCB. HPLC is often convenient for higher PCB levels or when trichlorobenzene concentrations are to be determined. The lower detection limit for PCB by GC is 25 ppb (wt/wt). The lower detection limit for PCB by HPLC is 100 ppb. If interfering species are present, the detection limits may be higher.