. On the other hand, very fine particles may pose some technical problems; consequently, centrifugation or filtration is applied to prepare the matrix [ 13, 29 ] . In the preparation step the sample is grinded and homogenized to increase the contact area between the matrix and the solvent. The particle sizes are usually in the range of 100 m m to 2 mm [ 8 ] . In some cases soaking of the dried plant material in the extracting solvent before MAE has resulted in improved yield. This procedure is called pre-leaching extraction [ 13 ] .