title: Coping with matrix effects in headspace solid phase microextraction gas chromatography using multivariate calibration strategies.
abstract: SPME is extremely sensitive to experimental parameters affecting liquid-gas and gas-solid distribution coefficients. Our aims were to measure the weights of these factors and to design a multivariate strategy based on the addition of a pool of internal standards, to minimize matrix effects. Synthetic but real-like wines containing selected analytes and variable amounts of ethanol, non-volatile constituents and major volatile compounds were prepared following a factorial design. The ANOVA study revealed that even using a strong matrix dilution, matrix effects are important and additive with non-significant interaction effects and that it is the presence of major volatile constituents the most dominant factor. A single internal standard provided a robust calibration for 15 out of 47 analytes. Then, two different multivariate calibration strategies based on Partial Least Square Regression were run in order to build calibration functions based on 13 different internal standards able to cope with matrix effects. The first one is based in the calculation of Multivariate Internal Standards (MIS), linear combinations of the normalized signals of the 13 internal standards, which provide the expected area of a given unit of analyte present in each sample. The second strategy is a direct calibration relating concentration to the 13 relative areas measured in each sample for each analyte. Overall, 47 different compounds can be reliably quantified in a single fully automated method with overall uncertainties better than 15%.
authors.affiliation: Laboratory for Aroma Analysis and Enology, Aragón Institute of Engineering Research (I3A), Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, 50009 Zaragoza, Spain.
authors.forename: Vicente
authors.initials: V
authors.lastname: Ferreira
authors.affiliation: Laboratory for Aroma Analysis and Enology, Aragón Institute of Engineering Research (I3A), Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, 50009 Zaragoza, Spain.
authors.forename: Paula
authors.initials: P
authors.lastname: Herrero
authors.affiliation: Instituto de Química, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Medellin, Colombia.
authors.forename: Julián
authors.initials: J
authors.lastname: Zapata
authors.affiliation: Laboratory for Aroma Analysis and Enology, Aragón Institute of Engineering Research (I3A), Department of Analytical Chemistry, Faculty of Sciences, University of Zaragoza, 50009 Zaragoza, Spain. Electronic address: escudero@unizar.es.
authors.forename: Ana
authors.initials: A
authors.lastname: Escudero
mesh_terms: D002138:Calibration; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002849:Chromatography, Gas; D000431:Ethanol / Q000032:analysis; D005504:Food Analysis / Q000379:methods*; D052617:Solid Phase Microextraction; D014920:Wine / Q000032:analysis
chemical_list: D000431:Ethanol
keywords: HS-SPME-GC–MS; Multivariate calibration; PLSR; Volatile compounds