ERP Sulfite Methods-Meeting Materials_4-2020

ERP for Sulfites in Seafood Methods Materials

96

2.3.3.1 Spray shrimp with sulfite solution. 2.3.3.2 Submerge and swirl shrimp in sulfite solution for 15 s, drain in colander in sink. Rinse for 30 s and drain, then toss the shrimp and rinse for 30 s and drain again. 2.3.3.3 Submerge and swirl shrimp in sulfite solution and transfer to colander to drain without rinsing. 2.3.4 Mince each batch of fortified shrimp and one batch of unfortified shrimp. 2.3.5 From each minced batch, weigh out three 50 ‐ g test portions for the OMA method and five 2 ‐ g test portions for the Biofish method. Randomize and blind code the test portions from all batches for each method. 2.3.6 Follow the Biofish method to homogenize, extract, and analyze the 2 ‐ g test portions according to the Turrax method. Analyze the blinded extracts using both measurement ranges. 2.3.7 Follow OMA 990.28 (Appendix 2) to analyze the 50 ‐ g test portions. 2.3.8 Unblind the results and analyze the data for mean concentration and repeatability (RSD r ) by concentration and method. 2.3.9 Compare methods by calculating accuracy of the Biofish method relative to the OMA reference method for each concentration and measurement range where Accuracy (%) = mean Biofish /mean OMA × 100 2.3.10 Calculate bias at each concentration as Bias Biofish = mean Biofish  ‐ mean OMA 2.3.11 Graph replicate candidate method results vs. replicate OMA results and perform regression analysis. 2.3.12 Graph s r vs. mean for the candidate method results. 2.3.13 Calculate the LOD as

  b s m

0 3.3 1 1.65  

X

LOD =

0 X

where

is the mean analytical value of the known negative matrix; is

b s

m

the intercept of the plot; and

is the slope of the plot.

2.3.14 Estimate the LOQ as

LOQ = 3 x LOD

2.0

REPORT

5

04/16/2020