# Question #9ef4e

##### 1 Answer

#### Answer:

Use the Beer-Lambert Law to establish the unknown protein concentration using the absorbance values and the molar extinction coefficient for both the standard sample and the unknown sample:

#### Explanation:

Where:

The absorbance value for the 0.25ml in 2.25ml 0.9% NaCl sample = 0.42

The absorbance for a 0.5mg/ml sample = 0.25

The length of the cuvette (the tube that the sample is placed in order to find the absorbance via spectrophotometry is usually 1cm) so we will use that for

Therefore we can then find

So we''ll have:

Since

We want to find

Plugging in what we have:

Since this concentration was from a dilution made from 0.25ml serum and 2.25ml of a 0.9% NaCl solution, which formed a total of 2.50ml we must find the *original concentration* using the dilution equation:

Rearranged, this gives: