degassing of mobile phase in hplc degassing of mobile phase can be done by

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degassing of mobile phase in hplc degassing of mobile phase can be done by


degassing of HPC mobile phase plays a very important role in HPLC analysis.

what is degassing?

Degassing is a technique in which removal of dissolved air or air bubbles from the solvent mixture or mobile phase.


why degassing of HPLC mobile phase necessary?

Bubble formation on mixing of solvent that creates problems in HPLC analysis, which can be minimised by degassing of mobile phases.several gases are soluble in organic solvents. When high pressure is pump & the formation of gas bubbles increases,interferes with separation process.when air bubbles passing through detectors lead to spurious peak.air bubbles can contribute to flow transfer or mobile phase through the HPLC column due to creation of dead volumes.


What is the degassing techniques?

Commonly used degassing practice for HPLC mobile phase are three types.

1) helium purging

2) vacuum degassing

3) sonic acid

1)helium purging. This is very effective technique, but most of the left are not generally used in this technique, because helium is most expensive. It is done by passing helium through the solvent. Helium purging removes up to 80 percent of dissolved air. For organic aqueous mobile phase, an equal volume of helium for purging is adequate. The rate of supply of helium can be reduced after sometime as excessive purging can lead to loss of more

volatile mobile phase components.

2) vacuum degassing. It is done by applying a partial vacuum to the solvent container, but it is not always reliable and complete.Vacuum degassing removes up to 60 percent of dissolved air. One option is to apply vacuum during filtration of mobile phase through 0.45 or 0.22 micron porosity membrane filter. Online vacuum degassing is available on most commercial available system. Mobile phase is passed through the porous polymer tubing placed in a vacuum chamber inside the HPLC. The porosity of the tubing allows expulsion of gases through the walls, but the liquid is written in the tubing.

3) sonic acid. It is done by using ultrasonicator which converts ultra high frequency to mechanical vibration. Sonic acid using ultrasonic bath is common in most Laboratories, but as a strain alone technique, it removes only up to 30 percent dissolved air. So

sonic acid in combination with any other technique is recommended.



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