Quantitative analysis of polychlorinated n-alkanes in environmental samples

Polychlorinated n-alkanes (PCAs) are persistent organic pollutants of concern due to their toxicological properties, their capability to bioaccumulate and their widespread, unrestricted use. PCAs are classified according to the length of the alkane chain as short-chain chlorinated paraffins (SCCPs), medium-chain CPs (MCCPs) and long-chain CPs (LCCPs). PCAs represent a difficult analytical problem because of the complexity inherent in industrial mixtures. The total number of possible congeners is unknown, but far exceeds 10,000. Many procedures for separation and quantification of these contaminants have been described. However, most relevant works refer to SCCPs, and some others also include MCCPs. But, methodologies for LCCPs are very rare.In this article, we discuss different aspects of current analytical methodology, such as sample preparation, extraction, purification and final determination. Most PCA analyses have been performed by gas chromatography (GC) coupled to electron capture negative ionization (ECNI) mass spectrometry (MS), although alternatives based on the use of electron ionization tandem MS (EI-MS)2 and metastable atom bombardment (MAB) have been reported. New methodologies based on the use of comprehensive two-dimensional GC have also been developed. We discuss the advantages and the disadvantages of the different instrumental techniques, and outline conclusions and perspectives for the future.