Retention profiles of some commercial pesticides, pyrethroid and acaricide residues and their application to tomato and parsley plants.

This work deals with the preconcentration of some water soluble pesticides, pyrethroids and acaricides by polyurethane foams. The retention profiles of the tested species were found quickly and reached equilibrium in a few min. Various parameters--e.g. pH, extraction media, shaking time, salt effect, temperature and sample volume--affecting the preconcentration of the tested species by the unloaded foams and tri-n-octylamine and tri-n-methylphosphate treated foams were optimized. The unloaded foams were employed in a column mode to study the quantitative retention and recovery of the tested species. The sorption efficiency and recovery of the compounds by the unloaded foam column were found to be up to 99.5% +/- 2.1. The height equivalent of a theoretical plate for the unloaded foam column was found to be in the range 1.9-2 +/- 0.2 mm. The sorption mechanisms of the tested compounds by the foams are discussed. Analysis of N, P, Na, K, Cu, Zn, Mn, Fe, humidity, wet and dry mass of tomato and parsley untreated and sprayed for different time intervals--i.e. 24, 72 and 120 h--with Chlorpyrifos, was carried out.