Volatile organic compounds

2.1 Introduction

Because compounds like benzene, dichloromethane, haloforms and others are known carcinogens, the continuous environmental monitoring of volatile organic compounds is mandatory. Both, the US EPA and the EC have included volatile organics on their priority pollutants lists.

All volatile organic compounds are analysed by capillary gas chromatography (CGC) with various combinations of sample preparation (sample introduction) and detection techniques.

Volatile organic compounds2 45

2.2 Compounds

	31. 1,2-dibromoethane	EC
	32. chlorobenzene	EC
EC	33. 1,1,1,2-tetrachloroethane
	34. ethyl benzene	EC
	35. m-xylene	EC
	36. p-xylene	EC
EC	37. o-xylene	EC
EC	38. styrene
EC	39. isopropyl benzene (cumene)	EC
EC	40. bromoform
	41. 1,1,2,2-tetrachloroethane	EC
EC	42. 1,2,3-trichloropropane
EC	43. n.propyl benzene
	44. bromobenzene
EC	45. 1,3,5-trimethylbenzene (mesitylene)
	46. 2-chlorotoluene
EC	47. 4-chlorotoluene
EC	48. tert.butyl benzene
EC	49. 1,2,4-trimethylbenzene
EC	50. sec.butyl benzene
EC	51. p-isopropyl toluene (p.cymene)
	52. 1,3-dichlorobenzene	EC
	53. 1,4-dichlorobenzene	EC
EC	54. n.butyl benzene
EC	55. 1,2-dichlorobenzene	EC
EC	56. l,2-dibromo-3-chloropropane
EC	57. 1,2,4-trichlorobenzene	EC
EC	58. hexachlorobutadiene	EC
EC	59. naphthalene	EC
	60. 1,2,3-trichlorobenzene	EC

1. dichlorodifluoromethane

2. chloromethane

3. vinyl chloride

4. bromomethane

5. chloroethane

6. trichlorofluoromethane

7. 1,1-dichloroethene

8. dichloromethane (methylene chloride)

9. trans-1,2-dichloroethene

10. 1,1-dichloroethane

11. 2,2-dichloropropane

12. cis-1,2-dichloroethene

13. chloroform

14. bromochloromethane

15. 1,1,1-trichloroethane

16. 1,1-dichloropropene

17. carbon tetrachloride

18. 1,2-dichloroethane

19. benzene

20. trichloroethene

21. 1,2-dichloropropane

22. bromodichloromethane

23. dibromomethane

24. cis-l,3-dichloropropene

25. toluene

26. trans- 1,3-dichloropropene EC

27. 1,1,2-trichloroethane

28. 1,3-dichloropropane

29. tetrachloroethene

30. dibromochloromethane

(EC): Included on the European Community Priority Pollutants list.

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2 Volatile organic compounds

2.3 General Procedure

Volatile organic compounds are analysed mainly by purge and trap in combination with capillary GC and various detectors including ECD, FID, PID (photoionization detection), ELCD (electrolytic conductivity detection) and MSD (mass spectroscopic detection), the latter being strongly recommended for its ability to confirm compound identification by mass spectra. As an alternative to purge and trap sampling, static headspace or direct aqueous injection may be used for the analysis of volatile organic compounds in water samples. In this chapter, four techniques suitable for routine analysis are described, namely; purge and trap/capillary gas chromatography with photoionization and electro­lytic conductivity detectors in series (EPA method 502.2), purge and trap/ capillary gas chromatography with mass spectroscopic detection (EPA method 524.2), static headspace with mass spectroscopic detection and finally capillary gas chromatography with electron capture detection for direct aqueous injection.