Mobile phase composition plays a crucial role in most separations.In most cases, mobile phase is mixed of water and organic solvents.In isocratic operation the composition is pre- decided and remains unchanged during the analytical run. On the other hand in gradient elution the final solvent composition is a lot different from the initial composition and changes are programmed during the course of analysis.
In order to achieve the desired objectives, the flow has the following basic functions：
1.The sample should be completely dissolved in the mobile phase. Any insolubility will result in flow restriction.Before injecting into the system, be sure to check the solubility of the sample in the mobile phase.
2.The mobile phase components should be non-toxic and harmless.
3.The mobile phase is inert to sample components and stationary phase. Any reaction may lead to the formation of insoluble suspensions, which can lead to clogging of the chromatographic column. Once the chromatographic column is blocked, it will cause the peak width to expand and affect the service life of the chromatographic column.
Some chemicals that are invisible to the naked eye may also cause clogging of the chromatographic column. Therefore, a guard column can be added in front of the chromatographic column to retain the chemicals and particulates that cause clogging of the chromatographic column sieve, column head collapse, and reduced column efficiency.
UPLCS (Guard) Column Holder contains a chromatography protection cartridge and packing materials. They can intercept some strong retention, strong acid and strong alkaline substances in the sample to prevent them from contaminating and damaging the packing in the chromatographic column. UPLCS protect HPLC column have advantage of less dead volume. Compared with other protect column, it can greatly reduce the band broadening caused by ectra-column effect while protecting HPLC column.Improve the sensitivity and separetion of chronatographic column analysis. Therefore using the liquid chromatography UPLC column is the useful way to protect HPLC columns.
4.Good compatibility with the detector, the mobile phase should not give its own response when passing through the detector. In other words, The detector signal should only reflect the response of the sample composition. But it is not suitable for bulk property detectors, such as refractive index detectors, that respond to changes in the bulk refractive index of the mobile phase containing the eluted compound.
5.The viscosity should be low. Because the high-viscosity solvent will affect the diffusion and mass transfer of the solute, reduce the column efficiency, but also increase the column pressure drop and prolong the separation time.
HPLC technology has broad application prospects in different fields, and more and more fields are applied to various HPLC technologies. The chromatographic operator should control the operating conditions (including the consistency of the mobile phase) to ensure the reproducibility of the results.
Post time: Apr-14-2021
