EURL PT 540

National Reference Laboratories (NRLs): Determination of the 15+1 EU priority PAHs in spiked olive oil

Proficiency Test on the determination of the 15+1 EU priority PAHs in olive oil

The European Union Reference Laboratory for Polycyclic Aromatic Hydrocarbons organised a proficiency test on the determination of the 15+1 EU priority PAHs in olive oil.

The objectives of this study were to evaluate the capabilities of official food control laboratories (OCLs) in the determination of the 15+1 EU priority PAHs in olive oil.

Only EU official food control laboratories (OCLs) could participate in the study.

Participation was admitted to maximum 80 offical food control laboratories, which were accepted in the order of registration.

The cost for this proficiency test was EUR 250 (two hundred fifty) per registration!

Test material and analytes

The test material was olive oil spiked with the target analytes (see Table 1). One ampoule of about 20 mL of spiked olive oil was sent to the participants in the second half of September 2010. In addition participants got an ampoule with a solution of the target PAHs with undisclosed analyte content, in, depending on their preference, either acetonitrile or toluene. A third ampoule with a solution of the target analytes in the preferred solvent, with disclosed analyte content, was supplied to the participants to allow the participants verifying instrument calibration against an independent standard.

The measurands were the 15+1 EU priority PAHs as listed in Table 1.

Results had to be reported at least for the contents of benzo[a]pyrene, benz[a]anthracene, benzo[b]fluoranthene, and chrysene.

Table 1: 15+1 EU priority PAHs

General outline

Participants were requested to perform three independent analyses of both the spiked olive oil material as well as of the standard solution with undisclosed analyte content using a method of their choice. The analyses should be performed on the same day.

Performance assessment:

The performance of the participants in the determination of PAHs in olive oil was rated by z-scores. The gravimetrical preparation concentrations were used as assigned values.

The standard deviations for proficiency assessment was derived:
- for benzo[a]pyrene from the fitness-for-purpose function given in Commission Regulation (EC) No 333/2007 assuming a value of 0.3 µg/kg for the limit of detection
- for the other measurands from the modified Horwitz equation, setting for content levels below 120 µg/kg a general level of precision, expressed as relative standard deviation, of 22 %.

Performance indicators were not calculated for the standard solutions.