OMA Protocol Review: OMAMAN-56 Sulfites in Shrimp

As a result of the Calibration, the parameters of the linear regression obtained by the interpolation of the two calibration points and the 0.0 point will appear. R values of at least 0.9985 and m values equal to or less than -100,000 are deemed as valid to proceed with the analysis. If the regression is not valid (“calibrate again” appears), change the measurement cuvette, put it on Stand by for 30 seconds and calibrate again. If the regression is valid (“calibration OK” appears), continue to Standard Measurement. 4) Standard measurement.- The calibration status should be tested using the STANDARD option after every 15 measurements or after the device has not been running for 2 hours. 4.1. Press Standard in the analysis option, check that the cuvette is correctly fitted and filled with SUL Measurement Solution and press CONTINUE to begin the Standard measurement. 4.2. Wait until the device records the measurement target and it issues a sound signal. Press CONTINUE and add the Calibration Standard (2 mL of SUL Standard 1 in case of 30-150 mg/kg Measurement range or 1 mL of SUL Standard 2 in case of 50-300 mg/kg Measurement range) into the measuring cuvette. 4.3. Wait until the “Biosensor calibrated” or “Biosensor recalibrate” message appears. 4.4. Replace the contents of the cuvette with 10 mL of new SUL Measurement Solution. If “Biosensor calibrated” message appeared, proceed to Sample Preparation. If “Biosensor recalibrate” message appeared, return to step 3.1.

Sample Preparation

a) Preparation of the sample .-

1) Preparation of crustacean (raw and boiled): 1.1. Clean and dismantle the carapace and cephalothorax and other nonedible parts of the exoskeleton and the visible digestive tract (leave the hepatopancreas in case its measurement is required).

1.2. Homogenize the sample with the aid of a mincer. 1.3. Add 2 g of the homogenized sample to a plastic tube. 1.4. Add 18 mL of SUL extraction solution.

b) Sample extraction .- 1. Homogenize the contents of the plastic tube with the aid of an ultra-turrax (8000-9000 rpm 15-20 seconds). 2. Leave to stand for approximately 15 minutes at room temperature. 3. Proceed to analyze in Turrax mode. Sample extractions without hepatopancreas are stable up to 4 hours at room temperature. On the other hand, sample extractions with hepatopancreas are stable only for 1 hour at room temperature. c) Analysis: 1. Press the option Turrax. 2. Check that the cuvette is correctly fitted and filled with SUL Measurement Solution and press

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