Albumin Assay, BCG Method

Bromocresol green is a dye that is found to form a blue-green complex

when reacted with albumin.

Procedure:

1. Label 8 clean, dry, large test tubes as indicated in the table below, and place them into

a test tube rack.

2. Fill each of the tubes as indicated in the table. Vortex the tubes to mix their contents.

mL / 0% / 2% / 4% / 6% / 8% / 10% / Unk T1 / Unk T2
BCG / 5 / 5 / 5 / 5 / 5 / 5 / 5 / 5
2% Std / 0.02
4% Std / 0.02
6% Std / 0.02
8% Std / 0.02
10% Std / 0.02
Unk T1 / 0.02
Unk T2 / 0.02
Total / 5.0 / 5.02 / 5.02 / 5.02 / 5.02 / 5.02 / 5.02 / 5.02

3. Iincubate for 10 minutes at room temperature.

4. Set the wavelength of your spectrophotometer to 637nm.

5. Obtain 8 rectangular cuvets/spectronic 20 tubes. Label them appropriately, and

fill them with the appropriate solution from you large test tubes.

7. Read and record the absorbances/%T’s for each tube, using the saline tube as the

blank.

Tube / Abs. / %T
BCG
2%
4%
6%
8%
10%
Unk T1
Unk T2

Results: The following should be contained in your lab report:

Your Unknown Number

A graph of Absorbance vs. Standard Concentration

Record the concentration for each trial of the unknown, then average them.

Calculate the % difference for each unknown sample:

100 x [unk. value - average]/average

Any observations/anomalies encountered during the performance of this experiment.