COEI-2-HYDCAR Aromatic polycyclic hydrocarbons

Determination of benzo(a)pyrene in oenological charbons by HPLC

1. Principle

Polycyclic aromatic hydrocarbons including benzoapyrene are extracted by hexane; the solvent is evaporated and the residue is taken up by the methanol-tetrahydrofuran for analysis by HPLC.

2. Apparatus and reagents

2.1.    Reagents and calibrations

• Acetonitrile for HPLC
• Hexane for pesticide residues
• Tetrahydrofuran for HPLC (THF)
• Deionised and microfiltered water
• Benzo[a]pyrene for HPLC.
  2.     Apparatus and chromatographic conditions

• octadecyl type HPLC column
• fluorimetric detector adjusted to the following detection conditions:
• excitation wave length: 300 nm,
• emission wave length: 416 nm.

Mobile phase:

• solvent A: Deionised and microfiltered water
• solvent B: acetonitrile

Flow 1.0 ml/mn

2.3.    Preparation of reference solutions

Benzoapyrene reference solution at about 100 mg/l in a methanol/THF mixture (50/50) stored for 3 years maximum in cold conditions.

Daughter solution at about 20 μg/l, prepared extemporaneous (0.5 ml of reference solution in 50 ml of methanol/THF then 1 ml of this intermediate solution in 50 ml de methanol/THF).

2.4.    Preparation of samples

2 g of oenological charbon are mixed in a 50 ml volumetric flask with 30 ml of hexane.

The polycyclic aromatic hydrocarbons are extracted for 5 min using a magnetic stirrer. The organic phase recovered by filtration is gathered in a evaporating flask and evaporated. The extract is taken up by 2 ml of a methanol/THF mixture (1/1, v/v) and injected.

3. Results

The benzoapyrene content must not be higher than 1 μg/kg.

Remark: It is also possible to determine benzo[a]pyrene by chromatography in gaseous phase by an apolar capillary column with detection by mass spectrometry.