Chromatography Forum

I am working on developing a method for solubility analysis of a compound in various Oils. Basically I will be adding excess of the compound into a known quantity of the oils and then analyzing to determine how much was dissolved.

Here are some of the basic facts so far:
I have a RP Hplc method for analysis that I would like to continue to use. The major problem with dissolving the oil prior to injection is that the compound is not soluble in the same solvents as the oil.
I've considered extraction, but I worry about incomplete recovery and due to the fact that the solubility in the Oils is unknown I have no way of determining if I get complete recovery.

My questions are:
Has anyone ever done direct oil injection?
Are there any potentially harmful affects to the auto sampler system?
I'm assuming a guard column would be absolutely essential.

Any help would be greatly appreciated

* I am also working on a GC method, however I am trying to keep my LC options open

My questions are:
Has anyone ever done direct oil injection?
Are there any potentially harmful affects to the auto sampler system?
I'm assuming a guard column would be absolutely essential.

yes, but it was a pretty highly diluted compound in sesame oil,
Maybe, but I'd be a lot more concerned about the column,
They (almost) never hurt.

Since you do not know the solubility of your compound(s) in oil, may I suggest the addition of an internal standard? Find a molecule that is readily available in high purity, has a chromophore and is highly soluble in oil. It would also help if it did not coelute with any of the compounds you're testing, and if it were amenable to solid phase or liquid/liquid extraction.

Or, if the compounds of interest do have decent chromophores, you could do a liquid/liquid extraction and inject small quantities from both phases (diluted in your MP) to help define the partition coefficient (or just look up how partition coefficients are usually determined - I doubt an LC is required).

Our German office demonstrated a method for direct injection of melted cocoa butter at 40 °C with a heated autosampler. It is not on our website, but I can send you the poster.