Gas chromatography has the advantages of good separation ability, high sensitivity, fast analysis speed, and convenient operation. However, due to technical limitations, substances with high boiling points or poor thermal stability are difficult to analyze using gas chromatography. Generally, derivatization or pyrolysis methods can be used for substances that are not easily volatile or easily decomposed under 500 ℃. High performance liquid chromatography only requires the sample to be able to be made into a solution without the need for gasification, so it is not limited by the volatility of the sample. For organic compounds with high boiling points, poor thermal stability, and a relative molecular weight greater than 400 (some substances account for almost 75% to 80% of the total organic matter), high-performance liquid chromatography can be applied for separation and analysis in principle. According to statistics, about 20% of known compounds can be analyzed by gas chromatography, while about 70-80% can be analyzed by liquid chromatography.