OMA Protocol Review: OMAMAN-56 Sulfites in Shrimp

CONTINUE to begin the sample measurement. 3. Wait until the device records the measurement target and it issues a sound signal. Press CONTINUE and pipette the clear supernatant of the extracted sample (2 mL in case of 30-150 mg/kg Measurement range or 1 mL in case of 50-300 mg/kg Measurement range) into the measuring cuvette.

4. Wait until the process ends and the device shows the result of the analysis. 5. Replace the contents of the cuvette with 10 mL of new Measurement Solution.

Interpretation and Test Result Report

The Biosensor expresses the analysis result in mg of sulfite (measured as SO 2

) per kg of

crustacean, taking into account the dilution involved in the extraction of the sample. 1) To save the result of an analysis, press SAVE. 2) To view the saved results, enter the RECORDS option . Saved results can be downloaded to a computer. 3) To delete the saved results, go to RECORDS and press DELETE ALL.

Validation Study

This validation study was conducted under the AOAC Research Institute Performance Tested Method SM program. The Biofish-300 SULFITE method was validated for raw shrimp head on, raw shrimp head off and boiled shrimp. The method developer studies included linearity, LOD, LOQ, bias, recovery and precision, selectivity, lot–to-lot consistency, stability, and robustness. Anfaco Cecopesca conducted official analysis with OMA method and statistical analysis. The independent laboratory study included bias, accuracy, repeatability precision, LOD and LOQ. Statistical analyses were performed by Microsoft Excel 2010 and SPSS statistics 23 program.

Method Developer Studies

Linearity Study

(a) Methodology.- A calibration line with seven concentrations (including the blank) of sodium sulfite and four replicates per concentration level were analyzed. A Stock Solution of 3000 ppm of sodium sulfite was prepared. Sodium sulfite standard (59 mg) was dissolved in 10 mL of distilled water. Working solutions were prepared from this stock standard solution:

For 30-150 ppm: 0, 10, 30, 50, 100, 150 and 300 ppm. For 50-300 ppm: 0, 30, 50, 100, 150, 300, and 600 ppm.

These solutions were prepared daily and stored at refrigerated temperature (3-8 °C). The standard solutions were measured in the Biofish system according to the Analysis step detailed above.

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