Posted 17 March 2009 - 01:47 AM
Accuracy and precision is better with enzymatic methods but you could try 0-toluidine. In hot acetic acid this reacts with glucose to form a green derivative. Set your spectrometer to 630nm. I'm not sure what the limit of detection is with this system but I think it has a similar range to the enzymatic methods.
There is (or was) also a REDOX method. The neocuproine method uses ferricyanide (Fe3+) which is coloured. In the presence of glucose this forms the ferrocyanide (Fe2+) which is clear. Read at 420nm. I don't think this method has a very high specificity. If you are analysing serum, for instance, then high creatinine and urea concentrations will give falsley elevated glucose readings.
Last thought, what about a home glucose monitoring unit. Depending on your sample it may not be validated and it may have huge CVs at the concentration of glucose you want to measure. (These are linear between fairly narow ranges, often between 2mmol/L and 20mmol/L).
Hope that helps.