Structural Identification and Quantification of Chlorinated Paraffins in Fish Samples Using Comprehensive Two-Dimensional Gas Chromatography with Negative Chemical Ionization Quadrupole Time-of-Flight Mass Spectrometry and Comparison to a Direct Injection-Atmospheric Pressure Chemical Ionization-Orbitrap/Mass Spectrometry Method.

Abstract

This study presents a comprehensive two-dimensional gas chromatography with negative chemical ionization quadrupole time-of-flight mass spectrometry (GC × GC-NCI-QTOF/MS) method, which allows for a precise chromatographic separation of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs). A new reversed-phase column setup was used, which allows for more accurate separation of MCCPs compared to known GC × GC methods. In a pilot study, 25 freshwater fish samples were analyzed with this method to characterize chlorinated paraffin (CP) compositions. The CP composition was similar in the samples, an observation that is important for the development of a suitable routine method. MCCP contamination was considerably higher than SCCP contamination, with concentrations of 1.3-410 ng/g of wet weight and 0.67-6.5 ng/g of wet weight, respectively. These results were compared to those obtained using a second method, direct injection-atmospheric pressure chemical ionization (APCI)-Orbitrap/mass spectrometry (MS). GC × GC separation was considered to be advantageous for accurate quantification of CP contamination.