title: Ad-hoc blocked design for the robustness study in the determination of dichlobenil and 2,6-dichlorobenzamide in onions by programmed temperature vaporization-gas chromatography-mass spectrometry.
abstract: An 'ad-hoc' experimental design to handle the robustness study for the simultaneous determination of dichlobenil and its main metabolite (2,6-dichlorobenzamide) in onions by programmed temperature vaporization-gas chromatography-mass spectrometry (PTV-GC-MS) is performed. Eighteen experimental factors were considered; 7 related with the extraction and clean up step, 8 with the PTV injection step and 3 factors related with the derivatization step. Therefore, a high number of experiments must be carried out that cannot be conducted in one experimental session and, as a consequence, the experiments of the robustness study must be performed in several sessions or blocks. The procedure to obtain an experimental design suitable for this task works by simultaneously minimizing the joint confidence region for the coefficient estimates and the correlation among them and with the block. In this way, the effect of the factors is not aliased with the block avoiding possible misinterpretations of the effects of the experimental factors on the analytical responses. The developed experimental design is coupled to the PARAFAC2 method, which allows solving some specific problems in chromatography when working with complex matrix such as co-elution of interferents (including silylation artifacts from the derivatization step) and small shifts in the retention time and, besides, the unequivocal identification of the target compounds according to document SANCO/12571/2013.
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, 09001 Burgos, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Herrero
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, 09001 Burgos, Spain.
authors.forename: Celia
authors.initials: C
authors.lastname: Reguera
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, 09001 Burgos, Spain. Electronic address: mcortiz@ubu.es.
authors.forename: M Cruz
authors.initials: MC
authors.lastname: Ortiz
authors.affiliation: Department of Mathematics and Computation, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, 09001 Burgos Spain.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Sarabia
authors.affiliation: Department of Mathematics and Computation, Faculty of Sciences, University of Burgos, Plaza Misael Bañuelos s/n, 09001 Burgos Spain.
authors.forename: M Sagrario
authors.initials: MS
authors.lastname: Sánchez
mesh_terms: D001549:Benzamides / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D009570:Nitriles / Q000032:analysis*; D019697:Onions / Q000737:chemistry*; D012984:Software; D013696:Temperature; D014835:Volatilization
chemical_list: D001549:Benzamides; D009570:Nitriles; C057454:2,6-dichlorobenzamide; C055869:dichlobanil
keywords: Ad-hoc blocked design; Dichlobenil, PTV-GC–MS; PARAFAC2; Robustness; Ruggedness