title: Headspace needle-trap analysis of priority volatile organic compounds from aqueous samples: application to the analysis of natural and waste waters.
abstract: Combining headspace (HS) sampling with a needle-trap device (NTD) to determine priority volatile organic compounds (VOCs) in water samples results in improved sensitivity and efficiency when compared to conventional static HS sampling. A 22 gauge stainless steel, 51-mm needle packed with Tenax TA and Carboxen 1000 particles is used as the NTD. Three different HS-NTD sampling methodologies are evaluated and all give limits of detection for the target VOCs in the ng L⁻¹ range. Active (purge-and-trap) HS-NTD sampling is found to give the best sensitivity but requires exhaustive control of the sampling conditions. The use of the NTD to collect the headspace gas sample results in a combined adsorption/desorption mechanism. The testing of different temperatures for the HS thermostating reveals a greater desorption effect when the sample is allowed to diffuse, whether passively or actively, through the sorbent particles. The limits of detection obtained in the simplest sampling methodology, static HS-NTD (5 mL aqueous sample in 20 mL HS vials, thermostating at 50 °C for 30 min with agitation), are sufficiently low as to permit its application to the analysis of 18 priority VOCs in natural and waste waters. In all cases compounds were detected below regulated levels.
authors.affiliation: Chemistry Dept., University of Girona, Campus Montilivi s/n, 17071 Girona, Spain.
authors.forename: Monica
authors.initials: M
authors.lastname: Alonso
authors.forename: Laura
authors.initials: L
authors.lastname: Cerdan
authors.forename: Anna
authors.initials: A
authors.lastname: Godayol
authors.forename: Enriqueta
authors.initials: E
authors.lastname: Anticó
authors.forename: Juan M
authors.initials: JM
authors.lastname: Sanchez
mesh_terms: D000327:Adsorption; D004867:Equipment Design; D008401:Gas Chromatography-Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D009339:Needles; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012722:Sewage / Q000737:chemistry; D013696:Temperature; D055549:Volatile Organic Compounds / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D012722:Sewage; D055549:Volatile Organic Compounds; D014874:Water Pollutants, Chemical