3.3 General Procedure

Semi-volatile organic compounds are extracted by solid phase extraction (SPE) or continuous liquid-liquid extraction. Analysis is done by capillary gas chromatography/mass spectroscopy (CGC/MS).

3.4 Sensitivity

0.1-lppb.

3.5 Detailed Procedures

3.5.1 Procedure 1: Solid phase extraction/cgc/ms

Materials

• Chemicals

• pure reference compounds or certified standard stock solutions

• isotope labeled internal standards l,4-dichlorobenzene-d4, naphthalene-dg, acenaphthene-dio, phenanthrene-dio, chrysene-di2 and perylene-di2. These standards are purchased as pure compounds or as a certified mixture Sigma-Aldrich cat. no. 38,513-1, semi-volatile internal standard mixture of

6 compounds at 4000ug/ml

• surrogate standard, p.terphenyl-di4

• dichloromethane, pesticide analysis grade

• sodium sulphate, anhydrous, p.a.

• sodium sulphite, p.a.

• acetone, p.a.

• methanol, p.a.

• water, HPLC-grade

• hydrochloric acid, p.a.

78 3 Semi-volatile organic compounds

Polycyclic aromatic hydrocarbons (PAHs)

4.1 Introduction

Polycyclic aromatic hydrocarbons (PAHs) originate from the incomplete combustion of organic material. Widespread in the environment, PAHs are priority pollutants on both the EC and EPA lists. Due to the carcinogenic properties of some polycyclic aromatic hydrocarbons, selective and sensitive analytical methods are required. PAH determination is mostly limited to the analysis of 16 compounds (EC, EPA) in drinking, surface and waste water by capillary GC/MS, HPLC/UV with diode-array detector, HPLC with fluorescence detection or HPLC/UV with diode-array and fluorescence detectors connected in series.

4.2 Compounds

Compound names, molecular weights and structures are listed in Figure 4.1.

2. Acenaphthylene 152

3. Acenaphthene 154

202

202

1. Naphthtalene

4. Fluorene

5. Phenanthrene

6. Anthracene

7. Fluoranthene

8. Pyrene

9. Benzo(a)anthracene 228

228

lO.Chrysene

ll.Benzo(b)nuoranthene 228

12.Benzo(k)fluoranthene 252

13.Benzo(a)pyrene 252

14. Dibenzo(a,h)anthracene 278

15. Benzo(g,h,i)perylene 276

16.1ndeno(l,2.3-cd)pyrene 276

Figure 4.1: Compound names, molecular weights and structures of 16 priority pollutant polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons 4

101

4.3 General Procedure

PAHs in water samples may be extracted by either liquid-liquid or solid phase extraction and cleaned up using silica column chromatography. The extract may be analysed by CGC with mass spectrometric detection in SIM mode or by HPLC. For HPLC analysis, a UV detector makes detection in the nanogram range possible, diode-array detectors adding supplementary qualitative information. Fluorescence detection is more specific and approximately 100 times more sensitive than UV, making detection in the picogram range possible.

4.4 Sensitivity

< 0.1 ppb in routine analysis.

4.5 Detailed Procedures

4.5.1 Procedure 1: pah analysis using hplc (epa 550.0)

Materials

• Chemicals

• hexane, pesticide grade

• dichloromethane, pesticide grade

• anhydrous sodium sulphate

. silica 3% H₂O (100/200 mesh silica is heated for 16 hours at 130° С and then 3% H₂O is added)

• water, HPLC grade

• acetonitrile, far UV

• polyaromatic hydrocarbon standard mixture containing the 16 PAHs of 10ng/ul concentration in acetonitrile

(Dr. Ehrenstorfer GmbH, Augsburg, Germany)

• polyaromatic hydrocarbon standard mixture 610 M, Supelco N" 4-8743 containing 100ug/ml of compounds 5, 6, 8, 9, 10, 12, 13 and 16, 200ug/ml of compounds 4, 7, 11, 14 and 15, 1000ug/ml of compounds 1 and 3 and 2000|ig/ml of compound 2 (numbers refer to Figure 4.1)

102 4 Polycyelic aromatic hydrocarbons

Organochloro, nitrogen and phosphorus pesticides, polychlorinated (PCBs) and polybrominated biphenyls (PBrBs)