C18 HPLC Chromatographic Columns Plays an Important Role in HPLC
Important role of C18 column
Liquid chromatography column is an important part of high performance liquid separation system. The industry often compares chromatography column to the heart of liquid chromatography. HPLC columns are divided into normal phase HPLC columns and reverse phase HPLC columns according to their polarity. Normal phase HPLC columns are mostly silica gel HPLC columns, or bonded phase silica gel columns with functional groups such as -CN, -NH3 bonded on the surface of silica gel; reversed-phase HPLC column packing is mainly silica gel as the matrix, and non-polar ten is bonded on the surface. The octaalkyl functional group (ODS) is called a C18 column, and other commonly used reversed-phase HPLC columns include C8, C4, C2, and phenyl HPLC columns.
The reversed-phase HPLC chromatography with carbooctadecane silane chemically bonded to the silica stationary phase (C18 or ODS) excellently completes the liquid chromatography analysis task and compared with other chromatography, C18 reversed-phase HPLC chromatography has obvious advantages, it can be directly injected.
The analysis of water-soluble samples has a wide range of applications and is known as the “standard stationary phase separation mode”. Among the pharmacopeias of various countries involving the use of liquid chromatography for the detection of varieties, C18 HPLC chromatographic columns are widely used as stationary phases.
Hundreds of C18 HPLC chromatographic columns with different separation options have appeared on the market. The selection of C18 mainly considers two issues, that is, the influence of column packing and column specifications on the chromatographic column. The main physical properties of the filler include the following: particle size, pore size, pore volume, bonded phase chemistry, carbon content, and alkylation treatment.
Attention should be paid when choosing the C18 HPLC chromatographic column
1) In the normal range of pH value (2~8), a modern high-purity silica chromatographic column can be selected, which has the characteristics of good peak shape, high reproducibility, and long life. Choosing a shorter column can improve the separation efficiency, and choosing a longer column can increase the retention, the choice of small particle size packing can improve the resolution, and the column with large pore size packing should be used for the components with large molecular weight.
2) Separate the components with high polarity (the mobile phase and the aqueous phase are too large) using a chromatographic column similar to AQ.
3) For the separation of alkaloid compounds, the packing that has been sealed by alkylation treatment can prevent the tailing phenomenon of alkaline compounds.
4) Choose stable bond C18 chromatographic column or wide pH chromatographic column under acidic conditions (pH less than 2).
5) Choose extend-C18 and other chromatographic columns under low-end alkaline conditions (pH greater than 8).
6) Choosing a column with a high carbon content can increase retention.