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.
Function and Main Strategies
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 extra-column effect while protecting HPLC column. Improve the sensitivity and separation of chronatography 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.
Some Factories You Should Care
Some Factories You Should Care When Choosing The Right Mobile Phase In Chromatography
When choosing the right mobile phase in chromatography, factors are more important than specific factories. However, choosing solvents from reputable manufacturers with high-quality control standards is crucial for successful separations. Here are some key factors to consider:
Solvent purity:
- Ensure the solvents are HPLC or MS grade, ensuring minimal impurities that could interfere with your analysis.
- Purchase solvents from companies known for their stringent quality control measures.
Solvent properties:
- Polarity: Consider the polarity of your analytes and match it to the mobile phase for optimal interaction.
- Solubility: Both your analytes and the stationary phase should be sufficiently soluble in the mobile phase.
- Viscosity: Optimal viscosity ensures proper flow rate and peak shape. Common solvents like acetonitrile have good viscosity for LC.
- Chemical reactivity: Choose solvents that are stable and won’t degrade your analytes or the stationary phase.
- UV transparency: If using UV detection, the solvent shouldn’t absorb UV light at your detection wavelength.
- pH: For methods involving charged analytes like ion exchange chromatography, pH control is crucial. Use buffers to adjust the pH if necessary.
Cost and safety:
- While cost is a factor, prioritize quality over the cheapest option. Contaminated solvents can ruin your analysis and equipment.
- Consider the safety hazards of your chosen solvents and implement proper ventilation and personal protective equipment when handling them.
Here are some reputable manufacturers of high-quality chromatography solvents:
- Sigma-Aldrich
- Fisher Scientific
- EMD Millipore
- J.T. Baker
- Honeywell
Remember, the “best” factory depends on your specific needs and requirements. Research different suppliers, compare their quality control standards and specifications, and choose the one that offers the best combination of quality, price, and availability for your particular application.
Additionally, focusing solely on factors like solvent purity and chemical properties is essential. Choosing a mobile phase based on the manufacturing source shouldn’t be the primary consideration.
I hope this information helps you choose the right mobile phase for your chromatography experiments!
