The Application Notebook
Horizon Technology, Inc.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants, yet can be a health hazard and are therefore measured and regulated. The traditional extraction solvents used for solid phase extraction (SPE) methods involving PAH compounds are dichloromethane (DCM) and acetone. DCM has been used in the past because of its excellent solvating properties and its low boiling point which results in higher yields after extraction, drying, and concentration. DCM however is dangerous to work with as it has been proven to be a carcinogen at very low exposure levels. As such, many laboratories have now mandated that solvent extractions in environmental methods not use any halogenated solvents, in particular DCM. Previous work, done by Frederick Werres (1), has demonstrated good extraction efficiencies using acetone as the eluting solvent. However; acetone creates a problem with residual water in the final extracts due to its miscibility with water and a more optimal non-halogenated, non-polar solvent would improve performance. This application note demonstrates an improved extraction of 16 PAH compounds listed by the US Environmental Protection Agency (EPA) as priority pollutants, including all PAHs listed in the content of the EU Water Framework Directive, using the Horizon Technology SPE-DEX® 4790 automated SPE extraction system with Atlantic® C18 disks and Fast Flow Sediment Disk Holder (FFSDH) setup which is optimized for use with highly particulated samples.
The data in Table I show very good recoveries for the PAH analytes from 79% to 92%. The light end PAH analytes are affected more than the heavy end components when air dry times are reduced from 2 min to 1 min. The 1-min air dry times gave a result with a low of 79% for naphthalene and a high of 92% for both dibenz(ah)anthracene and benzo(ghi)perylene (avg. RSD 4.69%). The 2-min air dry times gave a recovery range of 73% to 90% (avg. RSD 10.26%). For more information on method development please see reference 2.
Table I: Recovery data of 20 Î¼g PAH spike from clean aqueous extractions using FFSDH and C18 disks 2 and 1 min air dry times
This application note demonstrates an efficient SPE disk extraction scheme for PAH compounds in aqueous samples. The method demonstrated excellent recoveries for an extraction scheme which uses acetone and hexane in place of chlorinated solvents for clean or dirty samples.
(1) F. Werres, P. Balsaa, and T.C. Schmidt, J Chromatogr. A 1216, 2235–2240 (2009).
(2) J. Fenster, K. Dinnean, D. Gallagher, and M. Ebitson, "Determination of PAH Compounds from Aqueous Samples Using a Non-Halogenated Extraction Solvent and Atlantic C18 Disks," Horizon Technology, Inc., Salem, New Hampshire, Application Note AN072 (2012).
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