Question

3) You have isolated compound X from panda pancreas. You started with a whole pancreas, and finished up with 5 ml of a pure solution of X. Assume you got 100% recovery of compound X. You take 300 µl of this solution, and add it to 1.7 ml of buffer. The absorbance of this dilute solution at 340nm was 0.557 The molar extinction coefficient at 340nm for compound X is 13,200 l/mol cm. The formula weight of compound X is 14,000 g/mol

How many total mg of X are there in the panda pancreas?

Answer #1

Panda's Pancreas-----------(Processing------------> 5 mL of Solution (X)

Recovery: 100 %

Aliquot taken from 5 mL = 0.3mL

**Spectrophotometric studies:**

A = 0.557

Wavelength : 340 nm

ε = 13200 L/mol cm

l = 1 cm (not given, but assumed)

Buffer added: 1.7 mL

Total soln in cuvette: 1.7 + 0.3 = 2 mL

A = εcl

c = A/εl = 0.557/(13200 L/mol cm) x 1 cm = 4.21 x
10^{-5} mol/L

The formula weight of compound X is 14000 g/mol

Amount of compound X in cuvette: 4.21x10^{-5} mol/L x
14000g/mol = 0.5894 g/L

1L of the sample contains 0.5894 g

0.3mL (aliquot) contains 0.176 mg (0.3x0.5894/1000)

so 5mL in the actual sample contains **0.884mg** of
compound X in the pancreas

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