Coomassie Brilliant Blue R 250 is the most commonly used staining procedure
for the detection of proteins. It is the method of choice if SDS is used in the
electrophoresis of proteins, and is sensitive for a range of 0.5 to 20 micrograms
of protein. Within this range, it also follows the Beer-Lambert law and, thus, can
be quantitative as well as qualitative. The major drawback is the length of time
for the procedure and the requirement for destaining. Overstaining results in a
significant retention of stain within the gel, and thus, a high background stain,
which might obliterate the bands. The length of time for staining must be carefully
monitored, and can range from 20 minutes to several hours. If maximum sensitivity
is desired, one should try 2 hours for a 5% gel and 4 hours for a 10% gel.
Destaining must be monitored visually and adjusted accordingly.