All calibration data as well as the LOD and LOQ for the cereal
sample spiked with PAs standards are presented in Table 2 and
showed good linearity (R2 > 0.999) for all studied compounds within
the range of 0.5–100 lg/g. The LOD determined in cereal samples
ranged between 0.13 and 0.18 lg/g; the lowest and highest value
being obtained for VA and trans-CA, respectively. Furthermore,
the LOQ values of the studied PAs varied from 0.39 lg/g for VA to
0.55 lg/g for trans-CA. It can be seen that the LOQ for PAs were at
least 2-fold lower than that obtained in preceding studies (Mattila,
Pihlava, & Hellstrom, 2005), implying that the analytical method
developed was sufficiently sensitive. Precision and accuracy of the
method were assessed by performing repeatability and reproducibility
experiments. Spiked cereal samples at three concentration
levels (1, 10 and 25 lg/g) were analysed in order to evaluate repeatability
(within-day precision) and reproducibility (between-day
precision). The results showed satisfactory within- and betweenday
precision of the analytical method with RSD lower than 8.9%
for all compounds tested (Table 3). Accuracy, expressed as recovery,
ranged from 83.9% to 105.6% within-day analysis and from 83.6% to
103.3% between-day analysis. With regard to stability, the results
indicated that up to the 2 weeks storage all analytes were almost
stable, except for SA and PRCA, which were stable up to 1 week,
while VA, SRA and FA were stable up to 4 weeks.