Question

The Biuret protein assay is performed by mixing 1.5 mL protein sample with 1.5 mL Biuret reagent and incubating the sample 15 min at room temp. Calculate the protein concentration in the assay for a tube using 0.1 mL of the 2.0 mg/mL standard BSA. Your Answer: Answer units

Answer 1

According to the information given for the Biuret protein assay:

1.5mL protein sample → 1.5mL Biuret reagent

For a tube using 0.1 mL of BSA (Protein sample), the volume of the Biuret reagent used is calculated with the following cross multiplication:

1.5mL protein sample → 1.5mL Biuret reagent

0.1mL protein sample . >

Solving for x, we have:

0.1mL protein sample *1.5mL Biuret reagent 1.5mL protein sample

The volume of Biuret reagent used is:

r = 0.1mL Biuret reagent

To calculate the protein concentration in the assay, we need to calculate first the amount of protein in the sample used for the assay. With a standard concentration of 2.0 mg/mL and a volume used of 0.1 mL, the mass of BSA (m_BSA) protein is:

mBSA = 0.1mL * 2.0mq BSA ?7m

0.2mgBSA m BSA

After mixing protein sample and Biuret reagent, the total volume in the tube is then 0.2 mL. The protein concentration is given by the quotient:

BSA Vassay

Where

C_BSA is the protein concentration (BSA)

m_BSA is the mass of BSA

V_assay is the volume of the assay after mixing protein sample and Biuret reagent

Substituting the calculated values, we have a protein concentration of:

0.2mg 2

CBSA = 1.0mg/mL