Question

The molar extinction coefficient of reduced NADH (nicotinamide adenine dinucleotide phosphophate) at 340nm is 6220 L/mole·cm. 11ml of solution containing 0.8 micromoles of NADH were placed in a cuvette of 1.6cm light path. Calculate the percentage light transmission of this sample at 340nm.

Answer 1

Given:

molar extinction coeffecient, = 6220 L/mol.cm

concentration of solution = c = (0.8 x 10^-6 mol)/(11 x 10^-3 L) = 7.27 x 10^-5 M

path length = b = 1.6 cm

Therefore, Absorbabnce, A = bc = (6220 L/mol.cm)(1.6 cm)(7.27 x 10^-5 M) = 0.724

Transmittance (T) and absorbance (A) are related as follows:

A = ln(1/T)

therefore, 0.724 = ln(1/T)

solving for T, we get:

T = 0.484

% T = 0.484 x 100 = 48.4

Hence, percentage of light transmission of the given sample at 340 nm is 48.4 %