Q. 1: I have been storing mixed GOPOD reagent at 4oC, how long can this be stored to give acceptable
results?
A: This reagent, after preparation, can be stored for 3 months at 4oC. If you need to store for >3 months,
store at –20oC (in lots of 200 ml in polypropylene bottles).
Q. 2: If the GOPOD reagent has a slight pink colour after storage is it still alright to use for glucose
determination?
A: Yes, it is normal for the GOPOD reagent to change from a pale yellow colour when fresh to pale pink
after storage overnight. The optical density at 510 nm should be approx. 0.05 or less. This does not
affect the performance of the reagent.
Q. 3: Can the absorbance for the GOPOD colour reaction be measured at alternative wavelengths if 510 nm
is not available.
A: If the absorbance readings for 100 micrograms of glucose is between 0.9–1.0, then the results should
be fine. The most important thing is that all solutions must be read at the same wavelength.
Q. 4: What might be the cause of very low absorbance readings for glucose controls and samples?
A: Always ensure that both components of the GOPOD reagent; i.e. Glucose Reagent Buffer and Glucose
Determination Reagent are well mixed, as per the data booklet.
Q. 5: Is the glucose colour reaction affected by any components likely to be present in samples?
A: The colour reaction may be affected by high salt concentrations above 0.2 M and possibly by
ascorbate. To test for possible effects on colour development, run glucose controls in the presence and
absence of the suspected component and determine whether the colour intensity is changed.
Q. 6: What kind of precautions should be taken for handling the GOPOD reagent containing sodium azide?
A: Use disposable gloves when handling the concentrate. After dilution, the concentration of azide is
very low (0.02%) but the buffer should still be handled with care and any spills on the skin should be
well washed with water.
Q. 7: Is it possible to omit sodium azide from the Glucose Buffer when making this up from dry reagents as
outlined in the data booklet?
A: Yes, the sodium azide is used solely as a preservative but without it the buffer will be stable at 2-8oC
for several months and the GOPOD reagent is stable for > 12 months when stored at –20oC