Thanks for the advice.
But I was looking for something that would work at the push of a button.
Any manufactures come to mind?
Sebastian is right ... there is no inexpensive machinery to do this. You can either do the solvent extraction yourself (not recommended unless you are comfortable with bench chemistry and have the equipment already) or send it out to a lab for analysis.
There is at least one machine you can buy to do this. I don't know the price but it uses NMR (Nuclear Magnetic Resonance) techniques so it's not likely to be cost-effective unless you are going to be measuring hundreds of samples. Attached is a PDF brochure.
PS. Search for "cocoa fat content measure" on Google. The first search result is this discussion.
Clay who do you work for? , you have great knowledge on all things chocolate. Regards Mark at Barry Callebaut Canada.
I'm surprised nobody has asked this question: Why do you want to? Can you provide some background to the reason why you would need this information?
Seems like the most cost effective way is to send samples to a lab that already has the expensive equipment, then pay them per sample. Unless you have hundreds of samples, it will be orders of magnitude cheaper than buying analytical gear (sebastian's $30k estimate is for just one machine, but what about everything needed to support that machine (computers, reagents, glassware...?) You might be able to save some money by going to a college chemistry department and asking if any labs have the equipment you need, they might run a sample or two for free for you....