Detection of trace methanol in high-pressure liquid carbon dioxide

Friends with the surname Tuo are quite rare; you must be from the Sichuan and Hunan areas. There is a significant difference between the boiling point of methanol and that of liquid carbon dioxide; slow vaporization after sampling can lead to serious deviations in the analysis results. This is because these two components undergo fractionation during the vaporization process, a phenomenon known in chromatographic analysis as injection fractionation discrimination. It is recommended to use high-pressure gas cylinders for sampling, and to design a device with heating and vaporization capabilities to be used in conjunction with the chromatography sample injection valve. Manual sampling is not advised; instead, a six-way valve should be used to connect to the quantitation tube. The liquid sample is directly connected to the vaporization device, and the amount of liquid released is controlled so that the vaporization rate is as fast as possible; this allows carbon dioxide and methanol to vaporize together, thereby eliminating the effect of fractionation.

Okay, thank you very much. I come from one of the two lakes in that region.:lol

The content is not low, but methanol has a boiling point of 64.6 degrees; at 15°C it should be in liquid state. The pressure used is a bit high, so it is recommended to use a high-pressure liquid cylinder for sampling. The outlet should be connected to a high-pressure flash sampler customized by the factory, which will ensure that the liquid flows out quickly turns into gas, thereby reducing the pressure. The gas can then be sent to the chromatography valve sampling device. There is no difficulty in using either packed columns or capillary columns for this separation. It mainly involves custom-made high-pressure flash injectors; you can talk to the instrument manufacturers about this.