Acetonitrile and methanol are two major organic solvents in the mobile phase of high performance liquid chromatography (HPLC). Their polarity difference directly affects the separation performance, peak shape, and elution sequence.
Why is acetonitrile more polar than methanol?
The key factor is molecular dipole moment. Acetonitrile contains a cyano group (-C≡N), a highly electronegative triple-bonded functional group. This structure creates extreme electron separation and a strong permanent dipole across the molecule.
Methanol only carries a hydroxyl group (-OH). While the hydroxyl group is polar and enables hydrogen bonding, its overall charge separation is weaker. Acetonitrile's strong dipole moment gives it a higher fundamental polarity value.
Acetonitrile vs Methanol Polarity Comparison
| Item | Acetonitrile | Methanol |
|---|---|---|
| Solvent type | Polar aprotic | Polar protic |
| Dipole moment | Higher (3.92 D) | Lower (1.70 D) |
| Key polar group | Cyano group (–C≡N) | Hydroxyl group (–OH) |
| Hydrogen bonding | No | Strong |
| Overall polarity | More polar | Less polar |
| Main intermolecular force | Dipole-dipole | Hydrogen bond |
Acetonitrile Organic Solvent CAS 75-05-8
Why are ACN and methanol used in HPLC?
Acetonitrile (ACN): Low viscosity, low UV absorption, high elution strength, good for fast separation and low baseline noise.
Methanol: Stronger polar selectivity, lower cost, suitable for separating polar compounds and adjusting retention.Both are miscible with water, high purity, and ideal as reversed-phase HPLC mobile phase solvents.
about us
As a leading manufacturer and exporter of chemical solvent, TIANJIN GNEE BIOTECH CO., LTD. provides high-quality industrial chemicals. We supply to customers across the chemical, pharmaceutical, and materials industries, ensuring consistent quality, reliable logistics, and professional technical support.
Our chemical products hold international certifications (REACH, ISO, FMQS, HALAL) for global quality recognitio. We have warehouses in coreports such as Qingdao, Tianiin, and Shanghai, with a 15-day express delivery service.
Other Hot-Selling Products
| Dimethyl Sulfoxide (DMSO) | CAS 67-68-5 |
| Dichloromethane / Methylene Chloride | CAS 75-09-2 |
| Glacial Acetic Acid / Ethanoic Acid | CAS 64-19-7 |
| Ethyl Acetate / Ethyl Ethanoate | CAS 141-78-6 |
| Ethylene Glycol / Monoethylene Glycol (MEG) | CAS 107-21-1 |
| Trichloroethylene | CAS 79-01-6 |
| Cyclohexanone | CAS 108-94-1 |
Gneebio Product Packaging
| Packaging Type | Net Weight |
|---|---|
| Steel Drum | 250 kg |
| IBC Tank | 1250 kg |
| ISO Tank | Bulk shipment |
Customer Visit
