OMA Protocol Review: OMAMAN-56 Sulfites in Shrimp
expected (76% and 78% respectively for boiled and raw head off shrimp), but not so on day 2
(110 % and 106% respectively). This marked difference in the recovery value at this level between
days may be due to the fact that the starting values of the incurred samples are lower than the
validated LOQ (around 3 mg/kg). That is why on day 2, although the values obtained for the
spiked samples at 5 mg/kg are the same as on day 1 (6.79 and 7.02 mg/kg for boiled shrimps and
7.56 and 8.13 mg/kg for raw head off shrimp, for day 1 and day 2, respectively), the experimental
calculated addition is greater due to the lower value of the blank samples (76% vs 110% for boiled
shrimp and 78% vs 106% for raw head off shrimp).
Figure 8 shows the linear regression between the additions of sulfite and the values obtained
by the BIOFIHS HIS 300 for both days for each matrix. In addition to the good correlation obtained
(R 2 ≥0,99) between theoretical and experimental values for each case, it is clear from the figure
that the values obtained for both days are comparable, as the parameters of the linear regression
within a matrix are almost the same.
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