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Process Media - HA FAQ's


The following are Hydroxyapatite Process Media FAQ's. Please click on the corresponding tab below for the questions and answers.

  1. What does HA mean and how does it work?

  2. How do I use HA reproducibly?

  3. Is Ca⁺⁺Pure-HA® pH stable?


1.  What does HA mean and how does it work?

HA is an acronym for hydroxyapatite. HA has become one of the best characterized multimodal chromatography media in existence, with valuable research and industrial applications throughout the field of bioprocessing. Its combination of cation exchange and calcium-affinity mechanisms have given it the ability to achieve separations that no other chromatography media can match, and it continues to provide unique solutions for emerging challenges in the field.



2.  How do I use HA reproducibly?

Performance of Ca⁺⁺Pure-HA® can be improved for non-mAb molecules, such as lysozyme, by conditioning the media prior to use with a phosphate wash. Using 5 mmol/L NaPO4, pH 6.8, for 10 CV delivers reproducibility from run-to-run.



3.  Is Ca⁺⁺Pure-HA® pH stable?

Uncontrolled pH variations that occur in conjunction with changes in conductivity take place with all charged media, such as HA, and are referred to as pH excursions. During elution with a salt in cation exchange chromatography, the positively charged ion of the salt will displace hydronium ions adsorbed to the media. As a result of the ion exchange, the pH of the solution will decrease due to the increase in hydronium ion concentration in the eluate. This transient pH drop, or excursion, during elution can be problematic for competitive hydroxyapatite chromatography media, as the hydroxyapatite is vulnerable to dissolution at low pH. Ca⁺⁺Pure-HA® experiences less pH excursions, which demonstrates the increased durability of this media.