Liquid chromatography maintenance knowledge

1. The column is not used for a long time. When storing, the column should be filled with solvent and sealed at both ends (such as ACN for reversed-phase column and normal phase column for corresponding organic phase)
2. For manual injectors, when using a buffer solution, flush the inlet with water and move the injection valve several times per milliliter.
3. The mobile phase must be filtered before use. Do not use distilled water (easy bacteria) stored for many days.
4, with seal-wash 1100, to prepare 90% water + 10% isopropanol, siphon discharge at a rate of 2-3 drops per minute, the solvent can not dry.
5. For other ideas, see the instruction manual or introduce it by the field engineer. Maintenance knowledge question and answer
1. Why do solvents and samples need to be filtered?
Solvent and sample filtration is very important, it will protect the column and instrument, and eliminate the impact of pollution on the analysis results.
Column: Because the packing particles are very thin, the column lumen is small, and the small particles in the solvent and sample can easily block the column and capillary.
Instrumentation: Solvents and fine particles in the sample increase plugging and wear of the injection valve and also increase wear on the sapphire piston rod and piston in the pump head. Type of sample filter:
30mm inner diameter: suitable for large injection volume filtration, from 0.2μm and 0.45μm, the material is cellulose, acetate, polytetrafluoroethylene. The sample volume was processed to be less than 50 μl.
13mm inner diameter: suitable for a wide range of filtration, from 0.2μm and 0.45μm, the material is cellulose.
3mm inner diameter: suitable for small injection volume filtration, from 0.2μm and 0.45μm. The sample volume was treated at 7 μl.
Filter type:
1. PTFE filter: Suitable for all solvents, acids and salts, without any solubles.
2. Cellulose acetate filter: Not suitable for organic solvents, especially for water-based solutions, recommended for proteins and related samples.
3. Nylon 66 filter: suitable for most organic solvents and aqueous solutions, can be used for strong acid, 70% ethanol, dichloromethane, not suitable for dimethylformamide
4. Regenerated cellulose filter: It has low protein absorption and is also suitable for water-soluble samples and organic solvents.
2. Why do you need to add the online Seal-wash option when using buffer salts for HPLC?
When buffering salt is used in HPLC, the precipitated salt particles are very hard due to the high-pressure salt-dissolving phenomenon in the buffer salt solution in the pump head. It adheres to the sapphire piston rod, and is easily scratched with the reciprocating motion of the sapphire piston rod. And wear the gasket, causing leakage and other faults. The online Seal-wash option effectively removes the crystallization of buffer salts that may be present. The on-line rinse option must be used when the buffer salt concentration is 0.1 mole or greater.

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