HPLC goes green

As an analytical technique, HPLC provides fast separation and quantification of compounds in complex matrices with high efficiency, resolution and sensitivity; but the use of acetonitrile and methanol as solvents give it a number of drawbacks, environmentally. A water-enriched mobile phase has been proposed, which could provide a new environmentally friendly methodology.

Acetonitrile and methanol are common in mobile phases, but their toxicity means the mixtures have to be treated as chemical waste. Cyclodextrins are semi-natural compounds produced from starch; they are non-toxic, can be chemically modified to suit a number of techniques, and can allow the reduction of the solvent/water ratio. A study published in Green Chemistry¹ has investigated their use as a mobile phase additive for greener HPLC separations.

According to the study, the use of cyclodextrins as mobile phase additives allowed the researchers to increase the proportion of water in the mobile phases without a loss in resolution or efficiency, reducing the proportion of organic solvent content in the mobile phase from 70% to 50%, and allowing the more toxic acetonitrile to be replaced with methanol and ethanol as the organic component.

The study concluded that the presence of cyclodextrins in the mobile phases offers the potential for traditional HPLC to become “an attractive eco-separation technique using conventional and inexpensive columns and stationary phases, under simple and user-friendly experimental conditions."

1. V. González-Ruiz et al., Green Chem., 13, 115–126 (2011).