EURL PT 541

EU Official food control laboratories: 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

a) the capabilities of national reference laboratories (NRls) in the determination of the 15+1 EU priority PAHs in olive oil

b) potential trends in performance over time

Only appointed national reference laboratories (NRLs) could participate in the study.

Participation was free of charge.

Test material and analytes

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

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 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 were 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 Horowitz 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 be calculated for the standard solutions.