INTERFERENCE OF TRANSFORMER OIL MATRICES TO THE INTERNAL STANDARDS ONPCB QUANTIFICATION

Polychlorinated biphenyls (PCBs) are toxic, persistent, global environ mental contaminants which were formulated as complex mixtures of conge ners. Many methods have been developed in the past to analyze PCB in t ransformer oil samples for regulatory purposes. The most important con sideration in the cleanup procedure is the ability to remove the oil f rom the sample matrix, since trace amount of oil will interfere with t he subsequent GC-MS analysis. Electron capture detection (ECD) has bee n the most common method for gas chromatographic analysis of PCBs beca use of its high sensitivity toward halogenated compounds. ECD can also respond to some non-PCB compound resulting in biased concentrations o f PCB. In this work, a two-stage cleanup method, using DMSO liquid/liq uid extraction and HPLC column chromatography, has been applied to two types of transformer oil. Five internal standards have been selected to show their performance in the presence of different oil matrices. T he comparison of the PCB quantification at different conditions for GC -MS and GC-ECD will be demonstrated.