Yes. The Total and Free Sulfite Assay Kit can be used to measure total sulphite and free sulphite in food samples using the standard sample preparation procedures given below.
Sample preparation for Total Sulphite (TSO2) Homogenise approx. 5 g of sample with 60 mL of distilled water using a mortar and pestle or standard homogeniser for approximately 2 min. Adjust to approximately pH 8.0 using 1 M NaOH or 1 M HCl. Quantitatively transfer the mixture to a 100 mL volumetric flask, fill up to mark with distilled water, mix and filter through Whatman No. 1 filter paper or centrifuge at 13000 x g. If required, dilute the sample using 20 mm sodium phosphate buffer (pH 8.0).
Sample preparation for Free Sulphite (FSO2)
Homogenise approx. 5 g of sample with 60 mL of distilled water using a mortar and pestle or standard homogeniser for approx. 2 min. Adjust to approximately pH 4.0 using 1 M NaOH or 1 M HCl. Quantitatively transfer the mixture to a 100 mL volumetric flask, fill up to mark with distilled water, mix and filter through Whatman No. 1 filter paper or centrifuge at 13000 x g. If required, dilute the sample using 1% (w/v) citric acid.
Notes:
1. It is highly recommended that samples are tested immediately after
sample preparation.
2. The amount of sulphite obtained in the final sample must be within the detectable range of the test. Since the amount of sulphite present will vary between samples the amount of original sample used in the preparation method may have to be experimentally determined.