文档介绍：该【总溶剂生产中乙醇产品气相色谱分析法 】是由【niuww】上传分享，文档一共【3】页，该文档可以免费在线阅读，需要了解更多关于【总溶剂生产中乙醇产品气相色谱分析法 】的内容，可以使用淘豆网的站内搜索功能，选择自己适合的文档，以下文字是截取该文章内的部分文字，如需要获得完整电子版，请下载此文档到您的设备，方便您编辑和打印。总溶剂生产中乙醇产品气相色谱分析法
Abstract
This paper focuses on the gas chromatographic analysis method of ethanol product in the production of total solvents. The properties of ethanol, the basic principle of gas chromatography, the selection of stationary phase and carrier gas in gas chromatography, the sample preparation, the conditions of gas chromatography analysis and the determination of ethanol concentration are introduced in detail. The paper provides a comprehensive understanding of the gas chromatographic analysis method and lays a foundation for the research on the determination of ethanol concentration in the production of total solvents.
Keywords: gas chromatography, ethanol, total solvents, stationary phase, carrier gas, concentration determination
Introduction
Total solvents are a type of mixed solvent consisting of various components such as alcohols, ketones, esters, and hydrocarbons. Among them, ethanol is an important raw material and solvent in the production of total solvents. During the production process, the determination of ethanol concentration is necessary for quality control and process optimization. Gas chromatographic analysis is a commonly used method for determining ethanol concentration in total solvents production due to its high accuracy, repeatability, and sensitivity.
Basic principle of gas chromatography
Gas chromatography is based on the principle that different compounds have different partition coefficients between the stationary phase and the mobile phase. The sample is first vaporized into the gas phase and then introduced into the column packed with stationary phase. The compounds in the sample are separated by the different retention time in the stationary phase and eluted out of the column one by one. The detector at the outlet of the column detects the compound and generates a corresponding signal, which is then recorded and analyzed to obtain the chromatogram.
Selection of stationary phase and carrier gas
The choice of stationary phase and carrier gas is crucial in the gas chromatographic analysis for ethanol determination in total solvents production. The stationary phase can affect the selectivity and capacity of the column, while the carrier gas can affect the efficiency, sensitivity, and performance of the detector. Commonly used stationary phases for ethanol separation include polar phases, nonpolar phases, and mixed phases. Polar phases such as Carbowax are often used for the separation of ethanol from other alcohols and ketones, while nonpolar phases such as SE-30 and OV-101 are used for the separation of ethanol from hydrocarbons. Mixed phases such as OV-225 and OV-275 have both polar and nonpolar properties and can be used for the separation of ethanol from a wide range of compounds. In terms of carrier gas, helium, nitrogen, and hydrogen are commonly used. Helium is inert and has a high elution efficiency, but is expensive. Nitrogen is cheaper but has a lower elution efficiency and may react with some compounds. Hydrogen is also inert and has a high elution efficiency, but requires special precautions due to its flammability.
Sample preparation
The sample preparation is an important step in the gas chromatographic analysis of ethanol in total solvents production. The sample should be representative, homogeneous, and accurately measured. A small amount of sample is usually collected from the production process and diluted with a suitable solvent, such as methanol or acetonitrile, to achieve a desired concentration. The solution is then filtered to remove impurities and injected into the gas chromatograph. The injection method can be split or splitless, depending on the sample size and the sensitivity required. In the split injection, a small portion of the sample is introduced into the column, while the rest is vented out. In the splitless injection, the sample is introduced into the column and held for a certain time before venting.
Conditions of gas chromatography analysis
The conditions of gas chromatography analysis are designed to optimize the separation and detection of ethanol in the sample. The conditions can vary depending on the type and concentration of the sample, the column and detector used, and the analysis objective. Commonly used conditions include the column temperature, the flow rate of carrier gas, the injection volume, the detector temperature, and the type of detection mode.
Determination of ethanol concentration
The determination of ethanol concentration is based on the peak area or height of the ethanol chromatogram. The area or height is proportional to the concentration of the ethanol in the sample. The concentration can be calculated by comparing the area or height of the ethanol peak with that of a standard ethanol solution of known concentration. The calibration curve can be obtained by plotting the peak area or height against the concentration.
Conclusion
Gas chromatographic analysis is a reliable and accurate method for determining ethanol concentration in the production of total solvents. The choice of stationary phase and carrier gas, the sample preparation, the conditions of gas chromatography analysis, and the determination of ethanol concentration are crucial for obtaining valid and reproducible results. The gas chromatographic analysis method provides a powerful tool for quality control and process optimization in the total solvents production.