1. Selection method of liquid chromatographic column
1. Determine the separation purpose. Determine whether your application requires high resolution, short analysis time, high sensitivity, long column life, low operating cost, etc.
2. Evaluate the chemical properties of the analyte. Evaluate the chemical properties of the analyte: such as chemical structure, solubility, stability, etc.
3. Choose the appropriate chromatography column to understand the physical and chemical properties of the chromatography packing.
Second, the method of liquid chromatography column selection | Guoda company liquid chromatography column selection conditions
A filler matrix
1. Silica gel matrix: high purity, low cost, high strength, easy chemical modification, but limited pH range. Most silica-based fillers are stable between pH 2-8, but the specially modified silica-bonded phase can be stabilized at pH 1.5-10.
2. Polymer matrix: wide application pH range, stable temperature (high temperature can reach above 80 degrees), low mechanical strength.
B particle shape
Most modern HPLC packings are spherical particles, but sometimes they are irregular particles. Spherical particles provide lower column pressure, higher efficiency and stability, and longer column life when using a high-viscosity mobile phase; irregular particles have a larger specific surface area and a relatively low price.
C particle size
The smaller the particle size, the higher the column efficiency and the higher the resolution, but at the same time it will result in a higher column pressure drop. Choose 1.5-3μm packing to solve some complex samples. UPLC can use 1.5μm packing; another 10μm or larger packing can be used as semi-preparative or preparative column.
D carbon content
The carbon content refers to the proportion of bonded phase on the surface of silica gel, which is related to the specific surface area and bonding coverage. High carbon content improves column capacity, resolution and analysis time, for complex samples requiring high resolution; low carbon content analysis time is short, exhibits different selectivity, and is used for rapid analysis of simple samples and active phases requiring high water content Conditional samples. Generally, the carbon content of C18 varies from 7-19%.
E pore size and specific surface area
HPLC adsorption media are porous particles, most of the reaction surface is in the pores. Therefore, molecules must enter the pores to be adsorbed and separated.
Pore ​​diameter and specific surface area are two concepts that complement each other. Small pore size and large surface area, and vice versa. Large specific surface area increases the reaction between the sample and the bonded phase, increases storage, sample loading and resolution of complex components; small specific surface area, fast equilibrium time, suitable for gradient analysis.
F pore volume and mechanical strength
Pore ​​volume, also known as "pore volume". Refers to the size of the void volume per particle. It can well reflect the mechanical strength of the filler. A filler with a large pore volume has a slightly weaker mechanical strength than a filler with a smaller pore volume. Packings with a pore volume of 1.5 mL / g or less are mostly used for HPLC separation, while packings with a pore volume greater than 1.5 mL / g are used for size exclusion chromatography and low pressure chromatography.
G-end capping
Capping can reduce the tailing peaks of polar basic compounds due to interaction with bare silanol groups. Uncapped bonded phases will produce different selectivities than blocked capped phases, especially for polar samples.
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