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QC Colloidal Coomassie Stain
161-0803
QC Colloidal Coomassie Stain, 1 L
Gel Size
Fixing Solution*,
QC Colloidal
Water Washes,
Ordering Information
Catalog # Product
Introduction
Bio-Rad’s QC colloidal Coomassie stain is a ready-to-use single-bottle protein stain that does not require the
mixing of any components or addition of any alcohols. It is a special formulation of Coomassie G-250 that
provides maximum sensitivity with low background for a wide variety of acrylamide gel chemistries. The QC
colloidal Coomassie stain can reliably detect BSA in amounts down to 3 ng.
The QC colloidal Coomassie stain does not contain any methanol or acetic acid, which must be disposed of as
hazardous waste.
Kit Contents
Kit contains 1 L of QC colloidal Coomassie stain, which is sufficient to stain 10 Criterion™ gels or 20
Mini-PROTEAN® gels.
Storage Conditions
The QC colloidal Coomassie stain should be stored and used at room temperature. Do not freeze or refrigerate
the stain.
User-Supplied Materials
• Deionized water
• Shallow tray with cover for gel staining and destaining
• Ethanol and acetic acid, if gel fixation is desired
Staining Protocol
This protocol provides the maximal sensitivity while maintaining low background levels and provides the most
consistent and robust results. This protocol allows detection of amounts down to 3 ng of BSA.
ml
Criterion 100 100 100
Mini-PROTEAN 50 50 50
* 40% ethanol, 10% acetic acid
Coomassie Stain, ml
ml
Gel Fixation
Fixation is recommended for maximum sensitivity and staining of low molecular weight proteins <20 kDa.
• Prepare fixing solution (40% ethanol, 10% acetic acid)
• Remove gel from cassette and rinse in a shallow staining tray with deionized water
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• Fix gel for 15 min with gentle agitation
• Discard the fixing solution
o Dispose of fixing solution properly
• Alternatively, the gel can be fixed with 50% methanol and 10% acetic acid with no loss in sensitivity.
Fixing can be replaced with three 5 min water washes or no wash at all, but sensitivity will be reduced.
Gel Staining
• Rinse the gel in a shallow staining tray with deionized water
• Add QC colloidal Coomassie stain to the gel and incubate with gentle agitation at room temperature
for 1–20 hr
o Maximum sensitivity is obtained after staining for 10–20 hr. Staining for 16 hr allows detection
of amounts <10 ng of BSA
o If rapid staining is desired, gels may be stained for only 1 hr with a slight reduction in sensitivity
o Cover the staining container to reduce evaporation of the staining solution
Gel Destaining
• Discard the staining solution
o QC colloidal Coomassie stain is formulated without methanol or acetic acid, which need to be
disposed of as hazardous waste
• Destain the gel in deionized water. Destain for 1–3 hr with gentle agitation. Change the water at least
three times
o Highest signal-to-background levels are obtained with 3 hr of destaining
o If rapid destaining is desired, destain 1 hr with 3 changes of water; signal-to-background
decreases slightly
• Destained gels are now ready for imaging and analysis
o Gels can be stored in water for up to 3 days without a significant decrease in sensitivity
Bio-Rad Laboratories, Inc. 10032602 Rev A
2000 Alfred Nobel Drive, Hercules, CA 94547
510-741-1000
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