THE SEPARATION OF POLYCYCLIC AROMATIC HYDROCARBONS

THE SEPARATION OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) BY HIGH RESOLUTION GAS CHROMATOGRAPHY

Z. Moldovan and Florina Tusa

National Institute of Research and Development of Isotopic and Molecular Technology, 3400 Cluj-Napoca, P.O.B. 700, Romania, e-mail:

Introduction

Environmental monitoring and analytical surveys indicate that appreciable amounts of dangerous chemicals are released in air, water and soil. Since a number of these compounds are known to posses carcinogenic or mutagenic activities, their presence in the environment has to be regularly monitored to ensure that the permitted levels are not exceeded.

Products of combustion such as Polycyclic Aromatic Hydrocarbons (PAHs) are found in polluted environments, workplaces and different smokes. Some PAHs are known mutagens and carcinogens: benzo[a]pyrene, benzo[a]antracene, dibenzo[a,b]antracene. They can form DNA adducts in man and animals. These adducts are through to probably increase the risk for lung cancer and possibly for kidney, bladder and other cancers/1,2/.

The purpose of this study was to develop a convenient analytical method for the simultaneous determination of a wide range PAHs in environmental samples. The complete separation of these compounds is very important due of the fact that some compounds are very dangerous for the man and animal health. A lot of analytical methods were developed in the last decade. many of them are expensive and time consuming/3/. The paper presents a simple cost efficient method for the analysis of PAH in environmental samples.

Results and discussions

The chromatographic separation of 17 compounds on a long capillary column and detection with Flame Ionization Detector (GC-FID) were performed. The temperature program for an optimum separation was used.

The relative response factor (with respect of naphthalene) for FID detector was calculated. The medium value for Detection Limit obtained for a signal of three times more high that noise signal was of 1 ng for every compound. A complete separation of all 17 compounds was obtained in a total time of 30 min.

In the Fig 1-17 the compounds structure as well as the characteristic mass spectra are shown. The absolute and relative response factors relative to FID detector are shown in the Table 1.

The separation was performed with at a resolution enough for a complete separation of all compounds. The complete GC separation is shown in the Fig 18.



Fig 1. Indene (M=116)


Fig 2. Naphtalene (M=128)

Fig 3. 2 Methyl naphtalene (M=142)


Fig 4. 1 Methyl naphtalene (M=142)


Fig 5. Acenaphtene (M=154)


Fig 6. Fluorene (M=166)



Fig 7. Phenantrene (M=178)

Fig 8. Antracene (M=178)

Fig 9. Pyrene (M=202)


Fig 10. 11H-Benzo--Fluorene (M=216)


Fig 11. 11H-Benzo--Fluorene (M=216)


Fig 12. Benz--Antracene (M=228)



Fig 13. 7,12 Dimethyl Benzo-A-Antracene (M=256)

Fig 14. Benzo--Pyrene (M=252)


Fig 15. 3-Methyl Cholantrene (M=268)


Fig 16. Dibenzo-AH-Antracene


Fig 17. Dibenzo-AC-Antracene

Experimental section

Sample preparation

The samples was prepared by introduction of known quantity from every compound in a solvent mixture (n-hexane+ethyl ether 3:1).

Experimental condition

A HP-5MS (30x0.25mm) with 0.25m film thickness) containing 5% phenyl methyl siloxane was programmed from 1250C(5min) to 3300C at 150C/min (keeping this temperature for 10 min.). The flow eluent was 6 ml/min (Helium). The used detector was FID.

Table 1.

The FID response factors for PAHs. Absolute (Fi) and relative (Fr) values

Nr.crt

/

Component

/ Fi=Ai/mi / Fr=Fi/FN
1 / Indene / 300.2 / 0.44
2 / Naphtaline / 682.5 / 1
3 / 2-Methyl-Naphtaline / 233.3 / 0.34
4 / 1-Methyl-Naphtaline / 510.6 / 0.75
5 / Acenaphtene / 552.8 / 0.84
6 / Fluorene / 467.7 / 0.69
7 / Fenantrene / 512.9 / 0.75
8 / Antracene / 388.3 / 0.57
9 / Pyrene / 455.5 / 0.67
10 / 11-H-Benzo [] Fluorene / 513.3 / 0.76
11 / 11-H-Benzo [] Fluorene / 445.7 / 0.65
12 / Benz [a] Antracene / 354.6 / 0.51
13 / 7,12M2 Benz [ ] Antracene / 37.5 / 0.05
14 / Benzo [a] Pyrene / 303.1 / 0.44
15 / 3-Methyl-Cholantrene / 234.3 / 0.34
16+17 / Dibenzo [a,h] Antracene+
Dibenzo [a,c] Antracene / 202.9 / 0.30


Fig 18. GC separation of compounds 1-17

References:

1.G. Vollmer, L. Gianoni, L. Olsen, B.Sokull-Klutgen and S.J. Munn, Risk assessment, Occupational Exposure, European Commission, Joint Research Centre, 2001

2.C. D. Simpson, W. R. Cullen, Kristine B. Quinlan and K. J. Reimer, Chemosphere, 31, 4143-4155, 1995

3. R. L. Grob, Chromatographic analysis of the Environment, Marcel Dekker, Inc., New York, 1983