Retention and Separation Behavior of Some Organophosphorus and Pyrethroid Insecticides on Polyurethane Foams

Abstract

The application of polyurethane foam for the preconcentration of Cypermethrin, Malathion and Parathion insecticides was examined by the static mode of extraction. The retention of the tested species from aqueous media with the polyether polyurethane foam suggests that the solvent extraction and the cation chelation mechanism might be operative. Quantitative retention and recovery of the tested insecticides by the foam column mode of separation were carried out and satisfactory recovery percentages (up to 99.10±3.12%) were obtained. The number and the height equivalent of the theoretical plate of the foam columns were found in the range of 165 -170±4 and 1.85 -1.93±0.26 mm, respectively at 10 cm3/ min flow rate. Separation of the binary mixtures of Malathion-Cypermethrin and Parathion-Cypermethrin insecticides from the aqueous media was achieved successfully. The helical structure of the foam sorbents offfers rapid, versatile and effective separations and preconcentration of different compounds from fluid samples over conventional bulk-type granular sorbents. KeywordsPolyurethane foam, organophosphorous insecticide, pyrethroid insecticide, Parathion, MalathionAs a consequence of the activities of modern industries and agriculture many man-made pollutants have found their way into the environment, without the availability of much knowledge on their possible harmful effect on the environment. 1'2 The insecticides can enter water systems from agriculture land, direct entry from crop spraying, industrial and sewage effluent, dust and rain fall. The presence of these compounds in the aquatic environment has been known to cause severe health problems to animals and humans.3The most common reported extraction procedures for the removal or reduction of these pollutants are limited and are too expensive for routine analysis where many large volume samples are concentrated on site prior to quantitative analysis.4-9 The classical paper of Bowen1° and the pioneering studies of Braun and Farag11,12 on the application of polyurethane foam (PuF) sorbents to trace elements led to revealing the potentialities of their geometrical form: spherical membrane-shaped geometry in extraction chromatography. [10][11][12][13][14][15][16][17][18][19][20][21][22] In this paper, the extraction of some insecticides by polyether based polyurethane foam from large volume water samples is reported.The influence of various parameters on the retention of the tested species was carried out to determine whether the sorption on the polyurethane foams takes place by solvent extraction mechanism or by other mechanisms. ExperimentalReagents and materials All of the chemicals used were of analytical reagent grade. Open-cell polyether based polyurethane foam was supplied by Greiner K. G. Schaum (Stoffwerk, Kremsmunster, Austria). Foam cubes of approximately 1 cm3 were cut from a polyurethane foam sheet. The foam cubes were washed with HCl (10%v/v) and distilled water. The acid-free foam cubes were then washed with acetone in a Soxhlet extractor for 6 h and...