In order to investigate the stability of the major component of malathion E.C. product, dimethyl S-(1, 2-dicarboxyethoxyethyl) dithiophnsphate, toward the quality of glasswares as container, the amount of extractable inorganic components, change of pH and decomposition of the major component of the product were examined during the storage in brown-colored bottles of 100 ㎖, volume from 3 different companies in comparison with that in a Pyrex flask.
1. Malathion E.C. product was put in three containers A,B and C, and any changes occurring in storage were analyzed at three intervals of 60, 120 and 240 days.
2. It was shown that the amounts of Si, Mg, K, Ca, and via extracted during these periods of storage differed markedly depending on the duality of container. Container A revealed ten times higher extraction of Na and Ca than container B and C in a 8-month period.
3. Three commercial containers revealed the shift of pH from 6.5 to alkaline reaction in the storage whereas the Pyrex flask did not show any detectable change. In particular, the pH in container A changed to 9.2 in 60 days and 9.9 in 240 days.
4. The decomposition of malathion was the greatest in container A which showed the decomposition of 7.37% in 240 days. On the other hand, 0.5% was decomposed in the Pyrex flask.
5. The decomposition of malathion had a high correlation with the change of pH of water in the same container, r² being 0.899.
From the above results, it is concluded that about 10% of malathion E.C. product is decomposed in a year due to the alkaline metallic salts extracted from the container when it is stored in glassware bottles of lower quality.
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