Question

Glucose in biological material may be determined by reaction with o-toluidine in 6% glacial acetic acid at 100 C, after deproteinization with 3% (w/v) trichloroacetic acid, forming a 1:1 glucose-o-toluidine complex that is blue-green in colour and that absorbs radiation at 630 nm and 635 nm. The reagent is stable for many months at room temperature, and the reaction follows Beer's Law over a very wide range of concentrations. A standard glucose sample containing 100.0 mg/dL was reacted with excess o-toluidine as described above. The coloured product, analysed in a 2.00 cm quartz cell, absorbed 31.2% of the incident radiation at a wavelength of 630 nm using a UV-VIS spectrophotometer. A diluted blood sample (1 part blood to 1 part deionized water) from a patient, analysed in a similar manner to the above, absorbed 75.3% of the incident radiation when a 1.00 cm cell was used. Calculate the following:

i.the molar absorptivity of the glucose-o-toluidine complex, and

ii. thee concentration of the glucose in the patient’s blood sample in mmol/L.

Answer 1