| 摘要 |
PURPOSE: A kit for verifying the circulation duration according to the change of color is provided, to allow the circulation duration to be verified easily by using the yellowing of lignin due to the oxidation, the sublimation of naphthalene at a room temperature and the change of color of an acid/base indicator in air. CONSTITUTION: The kit comprises a material whose chemical properties change with time; and a substrate whose color is distinguished from that of the material. Preferably the material whose chemical properties change with time is selected from the group consisting of lignin, naphthalene and an indicator whose color changes; and the substrate is made of paper, plastic, metal or glass. Preferably the thickness of naphthalene depends on the circulation duration of a product. Preferably the kit is encapsulated in a gas permeable film, and the gas permeable film is prepared from polyethylene and polypropylene.
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