Determination of Acephate and Methamidophos in Foods Using Super-absorbent Polymer

Abstract

The water-soluble pesticides acephate and methamidophos were extracted from comminuted vegetables after their juice was absorbed by super-absorbent polymer particles. Food homogenate (10 g) was mixed with 5 g of polymer, and the mixture was extracted with 75 ml of ethyl acetate using a high speed homogenizer. The extracts were cleaned up by a silica gel mini-column and determination was by GC–FPD. This extraction procedure was compared with the Japanese official method in which samples were dehydrated with 75 g of anhydrous Na₂SO₄ and extracted with ethyl acetate. Unlike that of anhydrous Na₂SO₄ our mixture of sample and polymer was not bulky, nor did it harden. Recovery tests in seven vegetables at the 0.1 ppm level showed that recovery rates with polymer dehydration were usually more than 80% for both pesticides with <10% precision. The two extraction procedures detected similar pesticide levels in pesticide-containing vegetables. These findings revealed that the inexpensive super-absorbent polymer can be used in residual analysis of acephate and methamidophos in foods in place of bulky anhydrous Na₂SO₄.

References

1. E. Neidert and P. W. Saschenbrecker, J. AOAC Int., 1996, 79, 549.
2. R. R. Roy, R. H. Albert, P. Wilson, R. R. Laski, J. I. Roberts, T. J. Hoffmann, R. L. Bong, B. O. Bohannon and N. J. Yess, J. AOAC Int., 1995, 78, 930.
3. Food and Drug Administration, J. AOAC Int., 1995, 78, 118A.
4. Pesticide Analytical Manual, Volume 1, US Food and Drug Administration, USA, 1994, p. 302.
5. Manual of pesticide residue analysis, VCHWeinheim, 1987, vol. 1, p. 81.
6. Official Methods of Analysis, ed. Sawyer, L. D., McMahon, B. M., and Harvey, W., AOAC International Gaithersburg, MD, 16th edn., 1995, 985.
7. Ordinance of Prime Minister's Office, Prime Minister's Office of Japan, 1993, No. 54.
8. Ministry of Health and Welfare of Japan 1993, Bulletin 200.
9. Pesticide Analytical Manual, US Food and Drug Administration, Washington, DC, 1993, vol. 2, p. 77.
10. S. J. Lehotay, N. Aharonson, E. Pfeil and M. A. Ibrahim, J. AOAC Int., 1995, 78, 831.
11. S. J. Lehotay and K. I. Eller, J. AOAC Int., 1995, 78, 821.
12. P. van Zoonen, Analytical methods for pesticide residues in foodstuffs, Part 1, Ministry of Public Health, Welfare and Sport, The Netherlands, Amsterdam, 1996, p. 1.
13. J. Fillion, R. Hindle, M. Lacroix and J. Selwyn, J. AOAC Int., 1995, 78, 1252.
14. Y. Akiyama, M. Yano, T. Mitsuhashi, N. Takeda and M. Tsuji, J. Food Hyg. Soc. Jpn., 1996, 37, 351.