We separated several pesticides (imidacloprid, deltametrin, bifentrin, fenilbutation oxide, captan prepaquizofos, benflutamid, amitraz, hexachlor benzene, metachlor 960, triflurex 400, stamp) on chromatographic plates with diatomitic earth modified chemically C-8, using as a mobile phase a mixture of methanol and water in different ratios. Identifying pesticides was done through UV light examination at 254 nm. The pesticide amitraz was added to the milk and we extracted it 24 h later with methylene hexanechloride (1:1, v/v) and the extract was applied on the plates together with the standards. Identification was done with the standards and through mass spectrometry.