展示ケース内の有機酸濃度が高い場合，資料への影響が示唆されている。カルボン酸類の酢酸ゃギ酸などが代表的な有機酸物質であり，ごれらのガスは還元性があり，水溶液中で酸性を示し金属素材を腐食させるため清浄化をはからなければならない。東京文化財研究所では，のぞましい空気環境のガイドラインとして，酢酸430μg/m~3以下，ギ酸20μg/m~3以下を推奨している。%In the museum environment, contamination of air in display cases by organic acid gases emitted from interior materials has been a problem because metal objects are deteriorated due to acetic acid and formic acid among organic acids. Therefore, it is necessary to measure acetic acid and formic acid concentration in display cases. An easy method is to use a gas-detecting tube to measure organic acid concentration. However, it is not possible to know the concentration of acetic acid and formic acid separately by this method. So it is important to know the formic acid/acetic acid ratio in organic acid concentration. In the present study, the ratio of formic acid/acetic acid concentration in actual display cases and emission rate from interior materials were analyzed. Then, organic acid concentration measured by gas-detecting tube method was compared with acetic acid concentration measured by ion chromatography method. As a result, it was found that in actual display cases in a museum built after 2003, the ratio of formic acid concentration was estimated to be less than 0.1of acetic acid concentration. Formic acid / acetic acid ratio of the emission rates from the plywood materials on which wallpaper was adhered was smaller than 0.1. There was correlation between organic acid concentration measured by gas-detecting tube method and acetic acid concentration measured by ion chromatography method. From these results it is considered that it is possible to estimate acetic acid and formic acid concentration information using the organic acid concentration obtained by gas-detecting tube method.
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