Cut a 1g piece of a sample fabric (an original fabric or a treated fabric), place the piece in 50cc of distilled water, and boil the distilled water for 30 minutes in a boiling water bath for extraction (while stirring it once in a while). After the extraction, cool it down sufficiently. The resulting extract is used for qualitative analysis as described below. First, prepare two test tubes each containing 10cc of the extract.
i) Add a few drops of an iodine solution into one of the test tubes. Here, the blue coloration indicates the presence of starch. If the blue coloration does not occur, add another few drops of the iodine solution. If the blue coloration still does not occur, starch is not present.
ii) Add 1cc of RACTASE IDN-200 into the other test tube. Place the test tube in a boiling water bath and heat it for 10 to 20 minutes to degrade starch. To check if the starch is fully degraded, place several cc of the RACTOSE-added solution into another text tube, cool it down sufficiently, and add a few drops of the iodine solution. If no blue coloration occurs, starch has been completely degraded. If the blue coloration occurs, add RACTOSE and heat it up again. After confirming the complete degradation of starch, add a few drops of a boric iodine solution into the RACTOSE-added solution (which needs to have been cooled down sufficiently). The blue coloration indicates the presence of PVA. If no blue coloration occurs, PVA is not present. If this judgment is difficult, add another few drops of the boric iodine solution, or add a certain amount of boric acid to check again.
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Size
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Iodine Coloration
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Boric Iodine Coloration
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Starch
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Blue
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Blue
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PVA
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Yellow~Orange
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Blue
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Note: Iodine can be sublimated and so high temperatures should be avoided.
