Chromatography Forum

Dear all,

I am developing an eye drops solution that contains Cremophor RH40 and Cremophor EL in percentages form 0.25% - 5%.
When analyzing the product in normal-phase HPLC with silica columns, i have noticed that the life time of columns is decreasing dramatically, thus making it difficult to have trustworthy results.
What i see is that the retention time of the main peak is moving towards smaller retention times and that the baseline becomes smoother.
I wonder and would like to ask the following:
a) Is there a way of protecting the silica column (eg. Use of precolumn or a special cleaning treatment that removes cremophor or something else)?
b) Is there a special treatment for removing cremophor from the final eye drops formulation, before preparing the impurities sample for HPLC analysis?


Thank you in advance!

a) Is there a way of protecting the silica column (eg. Use of precolumn or a special cleaning treatment that removes cremophor or something else)?

If the problem is really accumulation of your surfactant on the stationary phase then yes, a guard cartridge should help. You will have to do a loading study on the cartridge to establish how often it should be replaced.

b) Is there a special treatment for removing cremophor from the final eye drops formulation, before preparing the impurities sample for HPLC analysis?

Solid phase extraction (SPE) is a possibility. My first guess would be to use a reversed-phase cartridge, but there are a wide range of chemistries available and it's easy to try different ones.