Why is Acetonitrile Used in HPLC?

Acetonitrile: solvents for HPLC and UHPLC

Acetonitrile together with Methanol are the most commonly used solvents for HPLC and UHPLC Chromatography processes because most substances are easily soluble in both solvents, but not saturated hydrocarbons.  Acetonitrile has a low wavelength which means that the solvent will elute first from the column, therefore pressure is reduced on the column.  Lower pressure in the column will have the long term effect of prolonging the life of the column, pressure within the column varies depending on the solvent used and the mixture ratio between the solvent and the sample.  An Acetonitrile based solution generally has a higher elution strength against the same strength solution using Methanol. Some scientists report that the same retention times can be achieved using acetonitrile with less than half the ratio of methanol.  Operator errors can have a significant impact of reproduceable results.  

Acetonitrile produces less pressure than Methanol, however the choice between using Acetonitrile against Methanol should not be made on price, (Acetonitrile is generally more expensive than Methanol), choice should be made on performance for your particular instrument and the effect of the chromatography process on the durability of the column.  High grade Acetonitrile has a lower absorbance in routine HPLC and UHPLC procedures and causes less interference than other solvents that can be used.

Biosolve solvents, including Acetonitrile, supplied by Greyhound Chromatography, are filtered at 0.1µm and are packed under inert nitrogen gas for longer shelf life, with very low amounts of inorganic metallic contaminants.  Acetonitrile is bottled in pure glass containers to minimise leaching and degradation of the solvent.  Acetonitrile is a clear colourless liquid with an acidity as low as 0-0.001% depending on the grade.  The presence of acid in the solvent improves the chromatographic peak shape.  Full certificates of analysis are available to view before selecting the right grade of solvent for your application.   Acetonitrile Surpa-gradient grade, available from Biosolve, is the highest-grade Acetonitrile solvent available for HPLC and UHPLC in today's worldwide market.

Notes of acetonitrile

Acetonitrile is shipped under Dangerous Goods regulations as it is a highly flammable liquid and vapour.  Safety procedures should be closely followed for the safe handling of Acetonitrile, including keeping away from sparks and open flames, hot surfaces and heated storage rooms.  When handling take reasonable precautions to ensure that it does not go on skin or near eyes.  If Acetonitrile does come into contact with clothes, remove the clothing and rinse thoroughly in water.  If it comes into contact with the skin, wash cautiously with water.  If acetonitrile comes into contact with the eyes, remove contact lenses if they are present, rinse with water for several minutes and seek medical advice.