Fully Automated Vortex-Assisted Liquid-Liquid Microextraction Coupled to Gas Chromatography-Mass Spectrometry for the Determination of Trace Levels of Phthalate Esters in Liquor Samples

A fully automated vortex-assisted liquid-liquid microextraction (VALLME) system coupled to gas chromatography-mass spectrometry (GC/MS) was developed for the determination of phthalate esters (PAEs) in liquor samples. The whole analytical procedure, including spiking, extraction, phase separation, extractant collection, and GC/MS quantification, were automatically carried out. The use of a commercially available sample vial and a multipurpose sampler equipped with a highly efficient orbital vortex shaker facilitated the accessibility and automation of the method. Key factors, such as type and volume of the extractant, time and speed for VALLME, agitation speed and time required for phase separation, sample pH, salt effects, and matrix effects, were thoroughly investigated. Under the optimum conditions, linearity was in the range 0.05 to 120 mu g L-1. Limits of detection ranged from 0.003 to 0.006 mu g L-1. Enrichment factors were in the range 211 to 304. Reproducibility and recoveries were assessed by testing a series of liquor samples spiked with different concentrations of phthalate esters. This work provided an innovative way to automate the VALLME method and couple it on-line with GC/MS.