Molecular Biology Grade chemicals

What molecular biology grade means

Molecular biology grade describes buffers, salts, detergents, sugars and other biochemicals that are tested for properties critical in nucleic-acid and protein work. Chemical purity alone is not enough: a trace of ribonuclease can destroy an RNA sample, and trace metals or unknown contaminants can inhibit PCR polymerases. The grade therefore combines a conventional purity specification with functional and enzymatic tests.

Typical specifications

Values in the table are typical of the grade. The limits that apply to a given product are those stated on its specification and lot Certificate of Analysis.

Where it is used

• PCR and qPCR buffer preparation, including Tris, EDTA, magnesium chloride and potassium chloride
• DNA and RNA extraction and purification, using guanidine salts, phenol and detergents such as SDS
• Electrophoresis buffers like TAE, TBE and MOPS
• Cloning, sequencing library preparation and protein expression work

How it differs from neighbouring grades

AR grade biochemicals can have excellent chemical purity yet have never been tested for nuclease activity, so they carry a risk for sensitive RNA work. Cell culture grades focus instead on endotoxin, sterility and cytotoxicity, which matter for living cells. Pharmacopoeial grades address regulatory quality for medicines rather than enzymatic contamination. Molecular biology grade does not by itself mean sterile or endotoxin-tested unless the COA states so.

Handling to preserve the grade

Nuclease-free status is easily lost after opening. Use nuclease-free water and consumables, wear gloves, avoid returning unused material to the container, and prepare solutions in dedicated glassware or certified plastics. For RNA work, many laboratories aliquot reagents on receipt.

What we supply

Typical molecular biology grade items include Tris base and Tris hydrochloride, EDTA, HEPES, MOPS, glycine, sodium dodecyl sulfate, guanidine salts, dithiothreitol, sucrose, agarose and nuclease-free water. Each lot COA states which enzymatic activity tests were performed and their results, so you can check suitability before opening a container in a clean workspace.