We will present two improved methods to determine Crop Protection Agent (CPA) residues in tobaccos and tobacco products and discuss their development and validation. The methods are applicable to 53 of the 118 CPA recommended in the CORESTA Guide No. 1^[1]. The previous methods used a solid phase extraction followed by GC-MS/MS and LC-MS/MS. The new methods use a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe)^[2] extraction followed by LC-MS/MS. The validation was performed with spiked tobaccos (mixture of Burley and Virginia) with increasing levels of analytes. Results indicate that the methods are in line with the recommendations of the CORESTA Guide No. 5^[3] in terms of recovery and relative standard deviation. The limits of quantification were below the respective ACAC Guidance Residue Limit for all substances. The main advantages of the new methods over the older methods are: reduced workload, lower consumption of solvents and supplies, good recovery rates obtained for a wide range of CPAs.

Method 1: Identification and measurement of 50 CPAs. Samples are prepared for analysis by 1) extraction of aqueous sample with acetonitrile; 2) a buffer salt induced phase separation; 3) a dispersive solid phase extraction in the acetonitrile phase. Quantitative analysis is performed by LC-MS/MS.

Method 2: Identification and measurement of three CPAs (2,4-D; Dicamba and 2,4,5-T). Due to their acidic nature the QuEChERS extraction is modified. Samples are prepared for analysis by 1) pH adjustment; 2) extraction of aqueous sample with acetonitrile; 3) a buffer salt induced phase separation. Quantitative analysis is performed by LC-MS/MS.

[1] CORESTA Guide No. 1: The Concept and Implementation of Agrochemical Guidance Residue Levels
[2] Anastassiades et al., Journal of AOAC International 2003 86(2):412-431
[3] CORESTA Guide No. 5, Technical Guideline for Pesticide Residues Analysis on Tobacco and Tobacco Products