What is the principle of HPLC separation?

The separation principle of HPLC is based on the different partition coefficients of sample molecules between the stationary phase and the mobile phase. The stationary phase is usually solid particles packed in the chromatographic column, while the mobile phase is a liquid propelled by high pressure. In the HPLC process, sample molecules exhibit different retention times based on their interactions (such as polarity, hydrophobicity, charge, etc.) with the stationary phase and the mobile phase. As the sample passes through the chromatographic column with the mobile phase, different components are eluted at different speeds, achieving separation. The detector then analyzes the eluted components to generate a chromatogram for qualitative and quantitative analysis.