Background: The vapor pressure of pesticides at room temperature is one of the fundamental properties for predicting their volatilities and the likelihood of their movement into the environment. It is also highly valuable for decision making in agriculture and agro-industries. Direct methods applicable to low-volatile substances include gas saturation and molecular effusion techniques; however, they have several drawbacks. We propose an indirect method based on gas-liquid chromatography using short capillary columns coated with stationary phases with high phase ratio and operated at very high flow rates.

Results: The method was applied to determine the vapor pressure of twenty pesticides, ranging from intermediate to very low volatilities (<0.133 mPa). Chromatographic assumptions were critically and comprehensively discussed, and the precision and accuracy of the method were evaluated using three fatty acid methyl esters (referred as validation solutes) with known and reliable vapor pressures available over a wide range of temperatures. The relative standard deviations of the primary data were below 4 % and increased to 18 % for extrapolated vapor pressures. The measurement conditions allowed for the extension of retention measurements to relatively lower temperatures while ensuring reasonable operational times, thereby, minimizing the extent of temperature extrapolation required. The target pesticides included widely used chemical compounds with multiple functional groups and molecules exhibiting configurational isomerism, whose individual vapor pressure could be distinguished provided that sufficient chromatographic selectivity was achieved.

Significance: This work provides a readily useable technique which employs instruments commonly found in both academic and industrial laboratories. Furthermore, the method is simple, robust, and reliable, allowing to estimate the vapor pressures of low-volatile and semi-volatile pesticides within reasonable analysis time and overcoming the main limitations associated with traditional methods.

Keywords: Gas-liquid chromatography; Low-volatile pesticides; Vapor pressure; Vapor pressure of isomers.

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背景： 农药在室温下的蒸汽压是预测其挥发性和进入环境可能性的基本性质之一。这对于农业和农工业的决策非常有价值。适用于低挥发性物质的直接方法包括气体饱和和分子逸出技术，但这些方法存在一些缺点。我们提出了一种基于使用短毛细管柱并涂有高相比固定相以及在极高流速下运行的气液色谱法的间接方法。

结果： 该方法被用于确定二十种农药（从中等挥发性到非常低挥发性，蒸汽压

意义： 这项工作提供了一种可直接使用的技术，该技术使用在学术和工业实验室中常见的仪器。此外，此方法简单、稳健且可靠，在合理分析时间内可以估计低挥发性和半挥发性农药的蒸汽压，并克服了传统方法的主要局限。

关键词：气液色谱法；低挥发性农药；蒸汽压；异构体蒸汽压。