OMA Protocol Review: OMAMAN-56 Sulfites in Shrimp

dissolving 66.1 mg of formaldehyde sodium bisulfite adduct (CAS 870-72-4, MW 134.09 g/mol) in 10 mL

of Extraction Solution. The following working solutions were prepared from this stock solution: 0, 2, 5, 8,

These solutions were prepared fresh at the time of analysis and kept at

10, 12, 15, 30 and 50 mg/L of SO 2.

room temperature during the assay. All solutions were analyzed on the same day by the same technician

with the same BIOFISH 300 device according to the Determination step detailed above.

( b ) Results.-- The linearity and residual plot results are presented in Table 1 and Figure 6. Although the linearity was tested over a larger range than the one claimed, the results show a linear

response from 0 to 50 mg/L, with a correlation coefficient r≥0.999. This means that a loss in activity of the

Biotest will not result in a reduction in the linear range of the method. From 5 to 30 mg/L all the residuals

are less than 10%, demonstrating once again the high lineal tendency of the response.

Table 1. Method developer linearity results of the BIOFISH 300 SUL

Sulfite Standard (mg/L)

BIOFISH 300 SUL (mg/kg)

MEAN (mg/kg)

Residual (%)

S r

RSD r

(%)

0

0.19

0.27

0.17

0.21

0.05

25.20

2

1.73

1.95

1.81

1.83

0.11

6.08

-20.38

5

4.95

4.59

4.79

4.78

0.18

3.78

-7.92

8

7.43

7.31

7.58

7.44

0.14

1.82

-8.35

10

9.74

9.92

9.79

9.82

0.09

0.95

-2.48

12

11.56 11.74 11.91

11.74

0.18

1.49

-2.37

15

14.42 14.66 15.10

14.73

0.34

2.34

-1.53

30

30.36 30.60 30.21

30.39

0.20

0.65

2.53

50

50.58 50.82 50.61

50.67

0.13

0.26

2.94

15