Clinically significant chromatic interference is a serious problem in traditional glucose detection; however, the problem is not widely recognized. The reason for the lack of awareness of chromatic interference in glucose assays is that the problem occurs with only some types of samples:
Diabetics in ketoacidosis tend to have high levels of serum fatty acids and turbid sera. Glucose test results for diabetics with low glucose levels may appear as normal because of chromatic interferences.
Laboratories frequently assess chromatic interference in their glucose method using control sera with glucose levels near the upper limit of normal. The control sera are not turbid and do not contain high levels of free fatty acids. Consequently, the serious problem of ketoacidotic patient samples is underestimated, especially when the patient's glucose level is low.
The Synermed® method uses infrared detection between 650-660 nm which allows accurate detection of glucose in problem samples.
Glucose oxidase catalyzes the conversion of glucose to gluconolactone which then forms gluconic acid and hydrogen peroxide.
H2O + O2 + beta-D-glucose -> gluconolactone -> gluconic acid + H2O2
The hydrogen peroxide reacts with the Synermed chromogen in the presence of peroxidase (POD) to form a blue azo dye which is quantitated at 660 nm.