Automating Liquid-Liquid Extractions using a Bench-top Workstation

Abstract

Liquid-liquid extractions have long been performed manually and are used to extract and concentrate analytes from aqueous matrices. Inclusion of liquid-liquid extraction in many official methods attests to the wide acceptance of the technique. Following solvent extraction it is also common to include an evaporation and reconstitution step to improve detection limits or exchange solvents for compatibility with subsequent chromatographic separations. Modern analytical labs are looking to automation to help reduce solvent usage and increase sample throughput while increasing data accuracy and precision.

An X-Y-Z coordinate autosampler, the GERSTEL MultiPurpose Sampler (MPS), commonly used for sample introduction in GC or HPLC can be used to perform a wide variety of sample preparation techniques using a single instrument and controlling software. The sampler can be configured as part of a GC or LC system or can be configured as a bench-top workstation and can also include a six position evaporation station.

In this report, the automation of liquid-liquid extractions using the MPS autosampler is discussed. Examination of a new, automated vortexing option that allows samples to be rapidly and effectively mixed using speeds of up to 3000 rpm is described. Automated liquid-liquid extractions methods for a variety of analytes from different matrices are examined and resulting precision and accuracy data are provided.