Among all the parameters that can affect the MSPD extraction procedure the nature of the solid support, the nature of the sorbent used for sample clean-up, the use of sulphuric acid in the clean-up step, the dimensions and material of the MSPD column, the nature and volume of the elution solvent and the sample amount were studied. Sample extracts obtained after MSPD procedure during optimisation were analysed by GC–MS