持溫熱重法於農藥原體蒸氣壓測定之應用

Application of Isothermal Thermogravimetry to the Determination of Pesticide Vapor Pressure

林振文(Jen-Wen Lin)

《臺灣農藥科學》 6期 (2019/06) Pp. 37-47

https://doi.org/10.6671/TPS.201906_(6).02

摘要

農藥蒸氣壓應用於環境安全評估，也是化學農藥原體登記所必須要提交審查的重要理化性質之一。傳統上使用飽和蒸氣壓法較耗時間，而利用熱重分析儀（Thermogravimetric Analyzer，TGA）蒸散速率與蒸氣壓間的關聯性，可以在短時間內分析計算蒸氣壓。本研究中採用快速且準確的TGA，以持溫熱重法驗證8種農藥的蒸氣壓，並與農藥性質資料庫（Pesticides Properties DataBase，PPDB）中的蒸氣壓值進行比較，發現8種農藥中只有極低蒸氣壓的益達胺差異較大，其他7種農藥則具一致性，此方法不需化學物質的定量分析，並可推算不同溫度下的蒸氣壓，顯示持溫熱重法優於傳統的氣體飽和法，是一種容易建立的蒸氣壓量測標準方法，並具有快速、省人力、低花費、簡單的優點。

關鍵字

蒸氣壓 ； 熱重分析 ； 揮發速率 ； 熔點 ； 熱安定性

並列摘要

Vapor pressure is one of the physicochemical data requirements that must be submitted for pesticide registration. However, the traditional saturated vapor pressure method is time-consuming. By contrast, the effusion method, which uses a thermo-gravimetric analyzer (TGA), can determine pesticide vapor pressure over a shorter period of time. This study applied a rapid and accurate thermogravimetric method to measure and verify the vapor pressures of eight pesticides. The vapor pressure values of all the tested pesticides except imidacloprid were highly consistent with vapor pressure values listed in the Pesticide Property Database (PPDB). (For imidacloprid, we recorded a vapor pressure of 7.72 ×10^(-13) Pa at 25°C, which is lower than the 4×10^(-10) Pa value recorded for imidacloprid in the PPDB.) Our results reveal that the thermogravimetric method not only preempts the need for tedious quantitative analysis procedures, but can also calculate vapor pressures for other temperatures, which the traditional gas saturation method is unable to do. In conclusion, the isothermal thermogravimetry effusion method has a number of advantages for the determination of vapor pressure, including good speed, reduced labor requirements, lower cost, and easy set up.

並列關鍵字

vapor pressure ； thermogravimetric analysis ； volatilization rate ； melting point ； thermal stability