Related Compound Method Development for Soft Gelatin Capsule

[VaibhavModi]

Hello,

This is for the first time I am posting on this forum.
I am working on the method development for the impurities analysis. This formulation is soft gelain capsules and mainly contains oil.The amount of active ingredient is on lower side and it dissolved in oil.

The problem is, I am getting so many peaks from the oil which are interfering with peaks of impurities. I tried to modify chromatogrphic parameters like using different buffers, solvents, columns and also tried different gradient. But still those peaks are interfering.

I also tried SPE (Solid phase extraction). With this approach, I am able to separate some of the oil peaks on SPE. Out of 4 impurities, 2 impurities are good but still at the retention time of 2 impurites, oil peaks are eluting.

How to get rid of these oil peaks???
I need some advise on this.
Thank you very much for your help.

[Gerhard Kratz]

You need to find a solvent were the oil can be disolved but not your active compound. Maybe Chloroform will do the job. Or another organic solvent. Did you try pure silica to do the clean up? But first I would try to do an extraction with a Chloroform. Good luck.

[VaibhavModi]

Hey Gerhard,

Thanks for your suggestion..I tried all different organic solvents including chloroform. But my active is soluble in most of the organic solvents where my oil is also miscible with.

Even I tried with 4% SLS in water, where my drug is soluble, but the oil is immiscible. Still I am not getting full extraction.

For sample clean up, I tried Amino cartridge, also C18 and polymeric reversed phase. The best results achieved with polymeric reversed phase.

I will try with silica as per your suggestion.
Once again thanks for your help.

Vaibhav

[SIELC_Tech]

What is nature of your analyte? If it is ionic, you can design a method with guard column and switching valve when you trap components of oil on the guard and analyze your compounds while washing the guard column:
http://www.sielc.com/pdf/SIELC_September_2004.pdf

Contact me if you have questions


Vlad Orlovsky
SIELC Technologies

[HW Mueller]

If these substances are dissolved in oil, because they are highly hydrophobic (lipophilic) this my be a chromatograopher´s nightmare. A multistep chromatography with at least two full sized columns may do the trick, or some chemistry is needed. The lack of info does not allow a more specific suggestion.

[VaibhavModi]

Thanks Vlad..I will contact you shortly.

[VaibhavModi]

Hi Mueller,

Yes you are right. My active is highly hydrophobic. The oil is a mixture of Mono & Di-glycerides. Its a mixture of Capric and Caprylic acid.

What do you mean by multistep chromatography? You want me to do column coupling?? OR

You want me to design a method with guard column and switching valve as suggested by SIELC_Tech. (You can see the post)

What kind of more information you need for specific suggestion?

Thanks
Vaibhav

[HW Mueller]

The mono and diglycerides contain a mixture of capric and caprylic, or your analytes are those two acids? If the latter is correct an extraction with water that has the right acidic pH should be possible. You may have to lower the viscosity with chloroform, or another organic solvent.
To trap the acids via a cation exchanger is another idea. If free acid analytes and those of the glycerides are the same you will have to make sure that acid solutions don´t hydrolyze the glycerides.

[HW Mueller]

Gee whizz, that should read anion exchanger, above.