title: Use of experimental design for the purge-and-trap-gas chromatography-mass spectrometry determination of methyl tert.-butyl ether, tert.-butyl alcohol and BTEX in groundwater at trace level.
abstract: An efficient method for the simultaneous determination of methyl tert.-butyl ether, tert.-butyl alcohol, benzene, toluene, ethylbenzene and xylene isomers in groundwater by purge-and-trap-gas chromatography-mass spectrometry was developed and validated. Experimental design was used to investigate the effects of temperature of extraction, time of extraction and percentage of salt added to the water samples. Regression models and desirability functions were applied to find the experimental conditions providing the highest global extraction yield. Validation was carried out in terms of limits of detection (LOD), limits of quantitation (LOQ), linearity and precision. LOD values ranging from 2.6 to 23 ng l(-1) were achieved, whereas linearity was statistically verified over two orders of magnitude for each compound. Precision was evaluated testing two concentration levels. Good results were obtained both in terms of intra-day repeatability and intermediate precision: RSD% lower than 4.5% at the highest concentration and lower than 13% at the lowest one were calculated for intra-day repeatability. A groundwater sample suspected of contamination by leaking underground petroleum storage tanks was analysed and some of the analytes were detected and quantitated.
authors.affiliation: Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Università degli Studi di Parma, Parco Area delle Scienze 17/A, 43100 Parma, Italy. fbianchi@nemo.cce.unipr.it
authors.forename: F
authors.initials: F
authors.lastname: Bianchi
authors.forename: M
authors.initials: M
authors.lastname: Careri
authors.forename: E
authors.initials: E
authors.lastname: Marengo
authors.forename: M
authors.initials: M
authors.lastname: Musci
mesh_terms: D001555:Benzene Derivatives / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D008738:Methyl Ethers / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014874:Water Pollutants, Chemical / Q000032:analysis*; D020002:tert-Butyl Alcohol / Q000032:analysis*
chemical_list: D001555:Benzene Derivatives; D008738:Methyl Ethers; D014874:Water Pollutants, Chemical; C043243:methyl tert-butyl ether; D020002:tert-Butyl Alcohol