title: PTV-LV-GC/MS/MS as screening and complementary method to HRMS for the monitoring of dioxin levels in food and feed.
abstract: Recent developments in trapping efficiency inside ion trap mass spectrometer permitted to lower instrument detection limit (IDL). An IDL of 200fgmul(-1) injected with a signal-to-noise ratio of 5:1 for tetrachlorodibenzo-p-dioxin (TCDD) was obtained by gas chromatography coupled to a quadrupole ion storage mass spectrometer in tandem mode (GC/MS/MS). Coupling large volume programmable temperature vaporizer (PTV-LV) injection to GC/MS/MS provides an alternative and complementary method to classical splitless-GC injection connected to high-resolution mass spectrometry (splitless-GC/HRMS) method for dioxin monitoring in food and feed. An injection volume of 10mul was found to be the best compromise between the sensitivity requirements and the robustness required for a high throughput method. PTV-LV-GC/MS/MS and Splitless-GC/HRMS were compared by performing analysis on five different matrices such as beef fat, yolk eggs, milk powder, animal feed and serum samples covering a concentration range of two orders of magnitude (i.e. 0.2-25ng WHO-TEQkg(-1)). An analysis of variance (ANOVA) was carried out. Fisher tests pointed out that the method effect for all the 2,3,7,8 congeners was not significant, indicating that the null hypothesis (H(0): mu(1)=mu(2)=...=mu(n)) was not rejected. Moreover, the interaction effects between methods and matrices were not significant for most of the 2,3,7,8 congeners. However, three congeners (2,3,7,8-TCDF; 1,2,3,4,7,8-HxCDD and 1,2,3,4,6,7,8-HpCDD) were characterized by P-values lower than the significance level (alpha=0.05). In toxic equivalence (TEQ), the study showed that no significant bias was observed between the two methods. Consequently, PTV-LV-GC/MS/MS is an attractive technique and can be used as a cost effective complementary method to HRMS for dioxin levels monitoring in food and feed.
authors.affiliation: Mass Spectrometry Laboratory-C.A.R.T., University of Liège, Allée de la Chimie 3, B-6C Sart-Tilman B-4000, Belgium.
authors.forename: Gauthier
authors.initials: G
authors.lastname: Eppe
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Focant
authors.forename: Catherine
authors.initials: C
authors.lastname: Pirard
authors.forename: Edwin De
authors.initials: ED
authors.lastname: Pauw