Question

determine the concentration of glucose in the original glucose solution. report a relative standard deviation for the original concentration

Glucose solution / mL: Tube 1: 0 mL Tube 2: 2 mL Tube 3: 4 mL Tube 4: 6 mL Tube 5: 8 mL Tube 6: 9.5 mL

Absorbance at 420 nm for each solution: Tube 1: 0.617 Tube 2: 0.578 Tube 3: 0.736 Tube 4: 0.653 Tube 5: 0.843 Tube 6: 0.895

Answer 1

Glucose cannot be measured directly in a spectrophotometer, but can be measured indirectly by coupling its consumption to the production of NADPH

we know that

Beer's Law --> A = e.c.l

Where;
A = absorption,
e = specific extinction coefficient,
c = concentration,
l = path length --> be consider as 1 cm

the initial tube will have only NADPH and glucose = 0 mL

Extinction coeffecient of NADPH = 6.22

0.617 = 6.22 X c X 1

concentration = 0.099 mM

Now initially tube will have x mL of 0.099 mM of NADPH