[Gesunderheiter]

I know the usual way to detect glutamate electrochemically is to use enzymes but is it possible to detect glutamate directly with a high enough potential? It's probably not convenient but at what potential glutamate oxidizes? I've been trying to search with Google Scholar but can't seem to find any reference to such a potential.

[Arkcon]

If you want to analyze something that has a red-ox potential, and you don't want to use a reagent, one method you'd like to use is cyclic voltammetry: http://en.wikipedia.org/wiki/Cyclic_voltammetry  Once you have the basics understood, you can investigate specific applications.  A Google search led to a useful PDF: http://www.scielo.oces.mctes.pt/pdf/pea/v25n1/v25n1a15.pdf as well as this more specialized reference: http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F5271854%2F5285368%2F05285556.pdf%3Farnumber%3D5285556&authDecision=-203

[Gesunderheiter]

If you want to analyze something that has a red-ox potential, and you don't want to use a reagent, one method you'd like to use is cyclic voltammetry: http://en.wikipedia.org/wiki/Cyclic_voltammetry  Once you have the basics understood, you can investigate specific applications.  A Google search led to a useful PDF: http://www.scielo.oces.mctes.pt/pdf/pea/v25n1/v25n1a15.pdf as well as this more specialized reference: http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F5271854%2F5285368%2F05285556.pdf%3Farnumber%3D5285556&authDecision=-203

Thanks for the reply!

The method described in the second link utilizes glutamate oxidase which I wanted to avoid but the first link seemed interesting. My area of interest concerning this topic lies with glutamate detecting biosensors, specifically the amperometric ones, and all of them seem to use glutamate oxidase or dehydrogenase in the detection process. Still, the first article suggests that glutamate has a clear cathodic peak (with gold electrodes) at -0,8 V. Why don't the biosensors in use utilize this and instead go for the seemingly more complicated route of using enzymes?

Sorry if these questions are really obvious, this area really isn't my specialty and I'm not even sure what I want to ask

[Arkcon]

I really don't know myself, but cyclic voltammetry is an analytical method that relies on an alternating current, not at specifically 60 or 50 Hz like distributed power, but a variable frequency to determine ... well, this is where I draw a blank.  But you can check oxidizing and reducing species, either inorganic or even enzymes.  You'll want to read more, but a CV analytical rig is usually pretty big.

[Gesunderheiter]

I really don't know myself, but cyclic voltammetry is an analytical method that relies on an alternating current, not at specifically 60 or 50 Hz like distributed power, but a variable frequency to determine ... well, this is where I draw a blank.  But you can check oxidizing and reducing species, either inorganic or even enzymes.  You'll want to read more, but a CV analytical rig is usually pretty big.

I'm no expert in CV either but from what I gather the variable frequency is just used to bring out the different reaction kinetics of different chemical species and use those then to identify them. As I said, I'm more interested in the idea of using an amperometric sensor with a constant potential to detect glutamate. Like these: http://www.sarissa-biomedical.com/products/sarissaprobes/glutamate.aspx but without the enzymes.