Science Buddies: "Ask an Expert"

Hey all,

I want to do a project to determine if a certain solution is a chelating agent of certain metals. I want to test R-alpha lipoic acid on different metals and see if it can bind to them.

I need an experiment that can help me do this. I found one, but it is too vague. Can someone give me specific steps for it? http://www.usc.edu/CSSF/History/2005/Projects/J0524.pdf

I am fine with doing it at a lab if I have to.

Thanks

Hi,

You have posed some tough questions related to your project to test the chelation capacity of R-alpha lipoic acid [LA]. I read the curcumin project on the link in your message and i see what you mean about the lack of details--concentrations not given, pH of solutions not given, length of time the curcumin was incubated with the metal salts not specified, no description of the method of how the complexes were isolated, etc.

I did some searching on PubMed and found several reviews about using LA and other chelators in treating various diseases, but i doubt if they have the information you need. The main difficulty I see is how to separate the unbound metal ions and LA from the chelated LA complex. Do you have a method for doing that? Once you have the complexes, you can analyze them by mass spec and determine how much metal was bound. I attached one paper that uses liquid chromatography to separate the complexes followed by mass spec. If you can get access to a lab with these instruments and someone to help you use them, then you can do the experiments.

The other details about concentration and time of incubation I think you will just have to work out empirically. If your hypothesis is that LA can be used for therapy in humans, then you need to use concentrations that would be in the physiological range. LA has been used therapeutically, so the doses have been published. As for the concentration of copper, iron or other metal ions for the chelation test, I would think that they should be in the micromolar range in order to be similar to what would be naturally found in the human body.

Sorry i can't be more specific in the details. Maybe someone else has some direct experience with these assays that can help you. Please repost with other questions and we will try to find answers for you.

Best wishes,

Sybee