title: Control of strobilurin fungicides in wheat using direct analysis in real time accurate time-of-flight and desorption electrospray ionization linear ion trap mass spectrometry.
abstract: Ambient mass spectrometry has been used for the analysis of strobilurin residues in wheat. The use of this novel, challenging technique, employing a direct analysis in a real time (DART) ion-source coupled with a time-of-flight mass spectrometer (TOF MS) and a desorption electrospray ionization (DESI) source coupled with a linear ion trap tandem MS (LIT MS(n)), permitted a direct screen of the occurrence of target fungicides in treated grains in less than 1 min. For quantification purpose by DART-TOF MS, an ethyl acetate extract had to be prepared. With the use of a prochloraz as an internal standard, the performance characteristics obtained by repeated analyses of extract, spiked at 50 microg kg(-1) with six strobilurins (azoxystrobin, picoxystrobin, dimoxystrobin, kresoxim-methyl, pyraclostrobin, and trifloxystrobin), were in the following range: recoveries 78-92%, repeatability (RSD) 8-15%, linearity (R(2)) 0.9900-0.9978. The analysis of wheat with incurred strobilurin residues demonstrated good trueness of data generated by the DART-TOF MS method; the results were in a good agreement with those obtained by the conventional approach, i.e., by the QuEChERS sample handling procedure followed by identification/quantification employing high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Tandem mass spectrometry using DESI-LIT MS(n) provided a sufficient number of product ions for confirmation of the identity of azoxystrobin and pyraclostrobin in incurred wheat samples.
authors.affiliation: Department of Food Chemistry and Analysis, Institute of Chemical Technology Prague, 6 Prague 16628, Czech Republic.
authors.forename: Jakub
authors.initials: J
authors.lastname: Schurek
authors.forename: Lukas
authors.initials: L
authors.lastname: Vaclavik
authors.forename: H Dick
authors.initials: HD
authors.lastname: Hooijerink
authors.forename: Ondrej
authors.initials: O
authors.lastname: Lacina
authors.forename: Jan
authors.initials: J
authors.lastname: Poustka
authors.forename: Matthew
authors.initials: M
authors.lastname: Sharman
authors.forename: Marianne
authors.initials: M
authors.lastname: Caldow
authors.forename: Michel W F
authors.initials: MW
authors.lastname: Nielen
authors.forename: Jana
authors.initials: J
authors.lastname: Hajslova