Development of a liquid chromatography-electrospray-tandem mass spectrometry method for the quantitative determination of benzoxazinone derivatives in plants

9 pages, 5 figures, 5 tables.-- PMID: 12964761 [PubMed].-- Printed version published Jul 1, 2003.

A new method for the quantification of benzoxazinone derivatives in extracts of wheat foliage and root samples using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) is described. Using this method, the characterization, separation, and quantitative detection of a mixture of six naturally occurring 1,4-benzoxazin-3(4H)-one derivatives, including the hydroxamic acids (DIMBOA, DIBOA), lactams (HBOA, and HMBOA), benzoxazilinones (BOA, MBOA), and two synthetic methoxylated variations of DIBOA and HBOA, was achieved. The application of a novel, highly modified reversed-phase LC column, the dodecyl (C12) TMS end-capped Synergi MAX-RP, enhanced the on-line chromatographic separation through improvements to component resolution, analyte stability and peak shape and also to the column lifetime. The complete ESI-MS-MS precursor−product ion fragmentation pathways for the benzoxazinone derivatives are described for the first time and used to deduce a generic fragmentation pattern for the compound class. Characteristic transitions for the benzoxazinones were thus used in the developed analytical method enabling reliable quantification with simultaneous screening for other potentially present derivatives, while eliminating interferences from other coeluting contaminants from the complex plant extract matrix. Quantitative analysis was done in the multiple reaction monitoring mode, using two specific combinations of a precursor−product ion transitions for each compound. The ESI-MS-MS detection method offered improvements to the sensitivity and selectivity, as compared with previously applied LC methods, with detection limits down to 0.002−0.023 ng/μL. The developed method was demonstrated by analyzing foliages and roots of six different wheat cultivars using pressurized liquid extraction-solid-phase extraction cleanup-LC-ESI-MS-MS. The analytes were detected in the range of 0.7−207 μg/g of dry weight.

This research project was made possible by funding provided by the European Commission (5th Framework programme) under sustainable agriculture initiatives of the Quality of Life and Management of Living Resources (fate and toxicity of allelochemicals (natural plant toxins) in relation to environment and consumer, Project QLK5-2001-01967). Financial support for L.B. from the Foundation of Research, Science and Technology, New Zealand (IQAB0101) and the Ministerio of Ciencia y Tecnologia for funding provided to IIQAB-CSIC (AGL2001-4952-E)

Peer reviewed