AppNote 222: Automated Liquid-Liquid Extraction of Vitamins in Infant Formula using a Bench-top Workstation.
Liquid-liquid extractions are used to extract and concentrate analytes from aqueous matrices. This extraction technique is widely accepted as shown by its inclusion within many official methods. Analytical laboratories are looking to automation to help reduce solvent usage and increase sample throughput while ensuring the high quality of the resulting data.
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.
In this study, the automation of the liquid-liquid extraction of vitamins in infant formula using the MPS is discussed. Two key GERSTEL options make the automated extraction possible: (1) The quickMIX option that allows samples to be rapidly and effectively mixed using agitation speeds of up to 3000 rpm, (2) The CF200 Centrifuge option that enables the centrifugation of extracts. Automation of the extraction of infant formula samples and subsequent HPLC determination of the vitamins listed in the official AOAC® 2012.09  and 2015.09 Official MethodsSM  are examined and resulting precision and accuracy data are provided.