Multi Residue Methods are playing an important role to monitor pesticide residues in tobacco. In order to reduce costs of analysis and turn-around times the so-called QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) multi residue method, developed by M. Anastassiades, S.J. Lehotay and co-workers^[1], was adapted to tobacco. Extracts obtained from the QuEChERS sample preparation are injected into a LC-MS/MS system equipped with an electrospray ionization source (ESI).The sample work-up procedure consists of the following steps:

• after the addition of water the finely ground tobacco material is extracted with acetonitrile followed by a salt induced (magnesium sulfate and sodium acetate) phase separation.
• the organic phase, separated by centrifugation is further cleaned-up by dispersive-SPE with a combination of primary secondary amine adsorbent (PSA) and magnesium sulfate in order to remove organic acids, excess water and other matrix components.
• the final determination is done by LC-ESI/MS/MS.

Detailed validation results will be presented for pesticides, listed in the CORESTA ACAC guide and amenable to LC-MS/MS determination. Recovery experiments at the advised Guidance Residue Levels on three representative types of tobacco [flue-cured (Virginia), air-cured (Burley) and sun-cured (Oriental)] were performed. Furthermore, analyte-dependent matrix effects for each type of tobacco were evaluated and will be discussed. Attention will be drawn to those pesticides ( e.g. aldicarb sulfoxide, methamidophos) that showed a significant increase of recovery compared to well-established multi residue methods like DFG S19 method.

Reference: [1] Anastassiades, M., S.J. Lehotay, D. Stajnbaher and F.J. Schenck (2003). "Fast and easy multiresidue method employing acetonitrile extraction/partitioning and "dispersive solid-phase extraction" for the determination of pesticide residues in produce." Journal of AOAC International 86(2): 412-431