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The term, persistent organic pollutants (POPs), describes a broad range of anthropogenic compounds present in the environment. POPs can be grouped into subclasses based on their original intended uses or chemical properties. In this chapter, five such groups of compounds are considered: polycyclic aromatic hydrocarbons, chlorinated aromatic compounds, pesticides, brominated flame retardants, and perfluoroalkyl and polyfluoroalkyl substances. The chapter provides an overview of some of the measurement issues and liquid chromatography methods used in the determination of persistent organic contaminants in environmentally relevant samples. Emphasis has been placed on research carried out since 2000. Purely gas chromatography- based methods have been excluded from this discussion, as have reports that emphasize sample cleanup and processing research.

The term persistent organic pollutants (POPs) describes a broad range of anthropogenic compounds present in the environment. Persistent organic pollutants can be grouped into subclasses based on their original intended uses or chemical properties. In this chapter, five such groups of compounds are considered: polycyclic aromatic hydrocarbons (PAHs), chlorinated aromatic compounds, pesticides, brominated flame retardants (BFRs), and perfluoroalkyl and polyfluoroalkyl substances (PFASs). The chapter provides an overview of some of the measurement issues and liquid chromatography (LC) methods used in the determination of persistent organic contaminants in environmentally relevant samples. Emphasis has been placed on research carried out since 2000. Purely gas chromatography (GC)–based methods have been excluded from this discussion, as have reports that emphasize sample cleanup and processing research.

Publisher Summary This chapter describes retention and selectivity for polycyclic aromatic hydrocarbons (PAHs) in reversed-phase liquid chromatography (LC). PAHs are widespread environmental contaminants resulting from emissions from a variety of sources including: industrial combustion, discharge of fossil fuels, residential heating, and motor vehicle exhausts. PAHs are usually present in environmental samples as extremely complex mixtures which contain numerous alkylated and non-alkylated isomers that vary greatly in relative concentration and carcinogenic or mutagenic properties. Because of excellent separation and detection selectivity of reversed-phase LC, this technique has been specified as the method of choice by the US Environmental Protection Agency (EPA) for the determination of PAHs in aqueous effluent. The ability of a column to discriminate among PAH isomers (and other classes of compounds) on the basis of the molecular structure is described as “shape selectivity.” The single most important parameter affecting column shape selectivity towards PAHs is a property involving phase structure—namely, the phase type. Differences in column selectivity between monomeric and polymeric C 18 phases are readily apparent for separations of PAH isomers.

Publisher Summary This chapter describes the second generation of environmental standard reference materials (SRMs), particularly, the natural matrix materials, the improvements in the analytical approach used for value assignment, and an examination of various modes of value assignment of SRMs for chemical composition at NIST and illustrates with examples their use. Polycyclic aromatic hydrocarbons (PAHs) have been one of the primary groups of compounds measured in environmental matrix SRMs. However, their sulfur analogues, polycyclic aromatic sulfur heterocycles (PASHs) are neglected even though their occurrence in various fossil fuels and other environmental samples as well as their mutagenic and carcinogenic potential has been reported. Another class of chlorinated hydrocarbon analytes of interest are the polychlorinated biphenyl (PCB) congeners without ortho-substituted chlorines, because they are potentially the most toxic PCBs, and LC methods have been developed for isolating the nonortho PCBs from other interfering PCBs. Measurements of nonortho PCBs have now been reported in a variety of environmental matrices, including sediments, fish, and marine mammals. However, at present there are no SRMs or certified reference materials (CRMs) from other sources with certified concentrations for these important PCB congeners.

A method is described for the determination of hydrocarbons in marine biota. This method utilizes dynamic headspace sampling of an aqueous caustic tissue homogenate to extract and collect volatile organic components. Interfering polar biogenic (non-anthropogenic) components are removed by normal-phase high-performance liquid chromatography (HPLC) prior to quantitation and identification of the hydrocarbons by gas chromatography and gas chromatography-mass spectrometry. After headspace sampling the non-volatile polycyclic aromatic hydrocarbons are solvent extracted from the tissue homogenate, isolated using normal-phase HPLC, and analyzed by reversed-phase HPLC with ultraviolet (UV) and fluorescence detection. Results of an interlaboratory comparison of determinations of hydrocarbons in mussel tissue are also reported. KEY WORDS: aliphatic hydrocarbons, aromatic hydrocarbons, gas chromatography, headspace sampling, high-performance liquid chromatography, interlaboratory comparison, polycyclic aromatic hydrocarbons.