12.2 Compounds

Names and structures of compounds that can be monitored with the described analytical techniques are given below.

1. 

   — CHj-CH

   a \н,

   \H,

   ыи—сссн,»,

   SCH,

   CH,

   <h,q,-

   Desisopropylatrazine

2. Metamitron

5 Desethylatrazine 9 Hexazinone

10. Simazine

11. Metribuzin

12. Cyanazine IS Atrazine

Oft-'

H f

^H)C\

н,с

_X

CjHj -

HC— HfT*N NH—С

22. Sebuthylazine

23. Propazine

н,с^/

C,H,-

h,c_n

HC-

н,с'

«3

. Jch 24 Terbuthylazine

P CH,

27 Prometryn

CH,

N N

SCH,

29 Terbutryn

C,H,-HN

..NH,

Other compounds that can be analyzed by the same method:

N^N CHi

11 Г

3. Fenuron 18 Isoproturon

4. Chloridazone 19 Metobromuron 6 Crimidin 20 Propham

NH-C<N

a ch,

8 Bromacil 21 Meuzachlor

13. Methabenzthiazuion 25 Iinuron

14. Chlortoluron 26 Chloroxuron

16. Monolinuron 28 Chlorprohara

17. Diuron 30 Metolachlor

^rfriazine herbicides 12

231

12.3 General Procedure

After solid phase extraction (SPE) of the water sample, triazines are analysed by high pressure liquid chromatography (HPLC) with UV detection, capillary gas chromatography/mass spectroscopy (CGC/MS) or capillary gas chromatography with nitrogen phosphorus detection (CGC/NPD).

12.4 Sensitivity

40 ppt in routine analysis.

12.5 Detailed Procedures

12.5.1 Procedure 1: Solid phase extraction/HPLC/DAD

Materials

• Chemicals

• triazine reference compounds

• methanol, p.a.

• acetonitrile, p.a.

• ethyl acetate, p.a.

• water, HPLC-grade

• Solutions

• triazine stock solutions in methanol (lg/1)

• Tools

• glass fibre filter paper

• 0.45 цт microfilters

• solid phase extraction cartridges containing lg of octadecyl silica

• solid phase extraction cartridges containing 500 mg of silica

• SPE vacuum system

• water-jet pump

• blow-drying equipment

• Instrumentation

• liquid chromatograph with UV absorbance detector

. ODS HPLC column

232 12 Triazine herbicides

Chloral hydrate

13.1 Introduction

Chloral hydrate is a polar chlorinated substance used in the manufacturing of DDT. Due to its toxicity it is included in the EC priority pollutants list.

13.2 Compounds

Chloral hydrate

CI3C CH OH

OH 2,2,2-trichloro-l, 1-ethanediol

13.3 General Procedure

Water samples are adjusted to pH13-14. Under alkaline conditions, the analyte is converted to chloroform, which can be analysed by purge and trap - capillary gas chromatography/mass spectrometry (CGC/MS).

13.4 Sensitivity

5-10ppb

Chloral hydrate 13 243

Trends and concerns

The most important developments in capillary GC and HPLC have been made within the last 10 years and the technological development of both techniques, based on known but as yet unexploited features, is proceeding unabated. Most notable are high speed capillary GC on ultra narrow bore columns, large volume injection in capillary GC, capillary GC/time-of-flight mass spectroscopy, electrospray micropacked LC/mass spectroscopy, LC/electrospray-collisional induced dissociation mass spectroscopy, an alternative to MS/MS and various multidimensional techniques including capillary GC/capillary GC, LC/capillary GC and LC/LC.

In Figure 14.1, the analysis of solvents on a 12.5m x 50|im i.d. capillary column with a 1 |xm film of methylsilicone demonstrates the current state-of-the-art in capillary GC.

This combination of high analysis speed and detectability, high resolution and an ability to accept conventional capillary column sample loads is waiting for the development of sample introduction systems suitable for routine analysis.

In a recent publication (1) the analysis of polychlorodibenzodioxins and polychlorobenzofurans was performed on a novel multidimensional CGC/CGC/MS system based on flow controlled column switching that allows the simultaneous isomeric separation of tetrachloro-, pentachloro- and hexachloro-substituted dibenzodioxins and dibenzofurans on a polar column and the analysis of heptachloro- and octachloro-substituted dibenzodioxins and dibenzofurans on an apolar column. Temperature programmed injection performed in the solvent venting mode allows the injection of sample volumes large enough to bring the sensitivity up to typical CGC/high resolution MS levels. On-line LC/CGC will provide environmental analysts with many new possibilities for sample preparation and trace enrichment, interested readers are referred to the excellent book on the subject by K. Grob (2).

Supercritical fluids have several characteristics which make them useful both as mobile phases for chromatography and for the selective extraction of organic components from different matrices. Far superior in terms of analysis times and

1. F. David, P. Sandra, A. Hoffmann and J. Gerstel, Chromatographia, 34 (1992), p. 259.

2. K.Grob, "On-Line Coupled LC-GC", Huthig Verlag GmbH, Heidelberg (1991)

Trends and concerns 14 249

efficiency as compared to HPLC, the recent introduction of coupled packed columns and reliable instrumentation has moved SFC into the realm of routine analysis. Moreover, exotic detectors are not required, the compounds separated by SFC can be detected using standard GC detectors such as NPD and ECD. The 6 minute separation of sixteen priority pollutant PAHs shown in Figure 14.2 and the high efficiency separation of herbicides and pesticides using coupled columns shown in Figure 14.3 demonstrate the current state-of-the-art in SFC.

16 11

3-12 14

17

18 20

22

24 2»

26

29

30

31

32

13

3.3

7min

1. Figure 14.1: Separation of a solvents mixture by capillary gas chromatography. Peaks:

   methanol

2. ethanol

3. aceton

4. diethylether

5. ethylformiate

6. dichloromethane

7. n-propanol

8. carbondisulfide

9. trans 1,2-dichloro- ethylene

10. methylethylketone

11. ethylacetate

12. cis 1,2-dichloroethylene

13. chloroform

14. tetrahydrofurane

15. n-butanol

16. 1,2-dichloroethane (17)benzene

18. isooctane

19. p-dioxane

20. isobutylmethyl- ketone

(21)toluene

22. ethylpropylketone

23. dimethylformamide

24. butylacetate

25. n-butylether + m-xylene

26. p-xylene

27. cyclohexanol

28. o-xylene

29. dimethylmalonate + cyclohexanone

30. anisol

31. fenetol

32. benzylalcohol

33. dibutyl ketone

250

14 Trends and concerns

ptAU