I am running an experiment that requires the determination of the oxalate concentration in an aqueous solution. The solution also contains a bunch of other stuff including some cells, trace minerals and trace amounts of EDTA. Currently we are using an oxalate assay kit, which appears to work, but it is very expensive (around $500 per box). This means that we are wasting a lot of our money on this kit rather than on other things that could be much more useful.
It is not clear to me what instruments we have access to. I know that we have some voltammetry stuff and a spectrophotometer. I want to try some Raman spectroscopy but I don't know anyone who has that and before I ask anyone else I want to make sure I am not crazy.
What would be the best way to figure out the oxalate concentration in an aqueous solution?