OMA Protocol Review: OMAMAN-56 Sulfites in Shrimp

CALIBRATION: • Calibration is performed by adding the Calibration Standard to the measuring cuvette at two different times. To fit the calibration line, the device will take into account the target, the change in intensity caused by the first addition of the Calibration Standard and the sum of the changes in intensity caused by both additions. 1. Press CALIBRATE , in the Analysis option. 2. Check that the cuvette is correctly fitted and filled with 10 ml of Measurement Solution and press CONTINUE to begin the calibration process. Wait until the device issues a sound signal. Press CONTINUE and pipette the Calibration Standard into the measuring cuvette (ADDITION 1) (See Table 6) in this order, using a micropipette. Wait until the device records the change in intensity and issues another sound signal. Press CONTINUE again and pipette the Calibration Standard into the measuring cuvette again (ADDITION 2) (See Table 6). Wait until the process ends. The parameters of the calibration line will appear o n the screen with the ''Calibration OK'' or ''Calibrate again'' message. 3. 4. 5. 6. Change the contents of the cuvette with 10 ml of new Measurement Solution. It is important to add the Calibration Standard immediately after pressing the CONTINUE button to record the current intensity correctly at the time of adding it. 7.

Table 6. Sulphite Standard and sample volumes.

Range 30-150 mg/kg Standard 1 / Verifying Sol. 2 ml Sample 2 ml

Range 50-300 mg/kg Standard 2 / Verifying Sol 1 ml

Sample 1 ml

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