Guanidine hydrochloride

CAS 50-01-1

CAS: 50-01-1
Grades: AR and BR, inquired separately
Working level: About 6 mol/L is laboratory practice, not a factory specification

The guanidinium cation unfolds proteins. This hydrochloride is the salt for inclusion bodies and protein denaturation. It is not guanidine isothiocyanate, CAS 593-84-0, which is the salt more often used when nucleic acids are released.

What it is

Guanidine hydrochloride is a chaotropic salt. The guanidinium cation disrupts hydrogen bonding and hydrophobic interactions in proteins, and at about 6 M most proteins are fully unfolded. Denaturation is generally reversible, which is the basis of refolding by dilution or dialysis.

Where it is used

Solubilizing inclusion bodies, typically 6 M with a reductant such as DTT, followed by refolding.
Denaturing Ni-NTA purification of His-tagged proteins in 6 M buffer.
Unfolding and stability studies, using titrations up to about 6 M.
Binding buffers for silica-based DNA clean-up, and some IVD sample-treatment formulas.

Handling tips

Dissolving is endothermic, so the solution cools; warm gently and adjust the final volume afterwards. 6 M is close to the practical solubility limit.
Guanidinium precipitates with SDS. Remove it by dialysis or precipitation before SDS-PAGE.
The solid is hygroscopic and an irritant; keep it sealed and wear gloves and eye protection.

What to specify when ordering

AR or BR grade.
Solid or ready 6 M / 8 M solution.
Pack size. The comparison with the thiocyanate salt is in guanidine HCl or isothiocyanate.

Properties and storage

Formula: CH6ClN3
Molecular weight: 95.53
Appearance: White crystalline powder, hygroscopic
Solubility: Very soluble in water (6–8 M in common use)
Storage: Room temperature, dry, sealed
Typical packs: 100 g, 500 g, 1 kg, 25 kg

Typical literature values. The batch COA / SDS governs.

Before you inquire

Can this replace GITC in an RNA prep?

No. The hydrochloride is a weaker chaotrope and does not inactivate RNases as reliably. Use guanidine isothiocyanate, CAS 593-84-0.

Guanidine HCl or urea?

Guanidine HCl is the stronger denaturant and does not form cyanate. Urea is uncharged, so it suits ion-exchange steps and IEF. Choose based on the next step.

What is the molecular weight?

About 95.53 g/mol. A 6 M solution needs roughly 57.3 g per 100 mL final volume.

Pack sizes and catalogue numbers