Extraction of organic contaminants from grab and composite water samples

The analysis of organic contaminants in environmental aqueous matrices is a key step aimed at monitoring the health status of water supplies and preventing or isolating sources of pollution. Water sampling is a central aspect since, depending on the required information, samples are taken at a specific point in the water body (grab sampling) or different grab samples are taken at different times and points within the water body (composite sampling). In both cases, analyte enrichment and clean-up are the major objectives to determine traces and ultratraces of contaminants in environmental waters. Solid-phase extraction (SPE) and liquid-phase extraction (LPE) are the two families of techniques widely used to isolate and concentrate pollutants from environmental waters. These methods offer different strengths and weaknesses. Some of them are very fast (for instance some miniaturised LPE techniques), allow high enrichment factors and low detection limits (for instance, conventional SPE and disk-SPE), and a significant reduction of the matrix effect caused by dissolved organic and inorganic matter. The versatility of sorbent materials, extraction solvents, and application modes makes these techniques suitable for highly specific determinations and for multi-residue multi-class analyses depending on the environmental requirements.