Determination of methyl isocyanate in air by fluorimetry

Abstract

The fluorimetric determination of methyl isocyanate in air is described. Methyl isocyanate in air was absorbed with dimethyl sulfoxide and hydrolyzed to form methylamine. Methylamine was reacted with acetylacetone and formaldehyde in pH 5.6 HOAc–NaOAc buffer solution to form N-methyl-2,6-dimethyl-3,5-diacetyl- 1,4-dihydropyridine, which is a fluorescent substance. The measurement of relative fluorescence intensity was carried out at 474 nm with excitation at 404 nm. Effects of pH, heating time and foreign ions on the determination of methyl isocyanate were examined. The relationship between fluorescence intensity and concentration of methyl isocyanate was linear in the range 0.00–0.80 µg ml^–1. The linear regression equation was C = 0.001 I + 0.0092, with a linear regression correlation coefficient of 0.9994. The recovery was 98.3–104.5% and the relative standard deviation was 1.5%. The method is rapid, simple and highly sensitive, and can be used for the determination of methyl isocyanate in air. The results obtained agreed with those of an extraction-photometric method.

References

1. F. Yu, Environ. Prot. Chem. Ind., 1985, 4, 225.
2. Compile Group of Analytical Methods of Harmful Substance in Air for Enterprise of Chemical Industry, Analytical Methods of Harmful Substance in Air for Enterprise of Chemical Industry, Chemical Industry Press, Beijing, 1988, p. 573.
3. S. Q. Chai and H. Yuan, Chin. Environ. Monit., 1988, 4, 88.
4. State Environmental Protection Bureau and Compile Group of Monitoring and Analytical Methods of Air and Waste Gas, Monitoring and Analytical Methods of Air and Waste Gas, China Environment Science Press, Beijing, 1990, p. 222.
5. R. F. Walker and M. A. Pinches, Analyst, 1979, 104, 928.
6. M. Spanne, H. Tinnerberg, M. Dalene and G. Skarping, Analyst, 1996, 121, 1095.
7. K. L. Dunlap, R. L. Sandridge and J. Keller, Anal. Chem., 1976, 48, 497.
8. D. A. Bagon and C. J. Purnell, J. Chromatogr., 1980, 190, 75.
9. E. H. Nieminen, L. H. Saarine and J. T. Laakso, J. Liq. Chromatogr., 1983, 6, 453.
10. D. Karlsson, M. Delene and G. Skarping, Analyst, 1998, 123, 1507.
11. W. Wu, M. Nazar, V. S. Gaind and L. Calovini, Analyst, 1987, 112, 863.
12. G. Skarping, L. Renman, C. Sango, L. Mathiasson and M. Dalene, J. Chromatogr., 1985, 346, 191.
13. G. Skarping, B. E. F. Smith and M. Dalene, J. Chromatogr., 1985, 331, 331.
14. J. Keller, K. L. Dunlap and R. L. Sandridge, Anal. Chem., 1974, 46, 1845.
15. J. Keller and R. L. Sandridge, Anal. Chem., 1979, 51, 1868.
16. C. S. Harden and D. C. Shoff, Field. Anal. Chem. Technol., 1997, 1, 285.
17. A. Hantzsch, Justus Liebigs Ann. Chem., 1882, 215, 72.
18. M. Pesez and J. Bartos, Ann. Pharm. Fr., 1969, 27, 161.
19. ACS Committee on Environmental Improvement, Anal. Chem., 1980, 52, 2242.
20. Y. X. Zheng, The Method of Mathematical Statistics in Analytical Chemistry, Science Press, Beijing, 1986, pp. 122, 231 and 308.