A novel method of ultrasound-assisted dispersive liquid–liquid microextraction coupled to liquid chromatography–mass spectrometry for the determination of trace organoarsenic compounds in edible oil

A novel approach, ultrasound-assisted dispersive liquid–liquid microextraction combined with liquid chromatography–mass spectrometry (UA-DLLME with LC–MS) is demonstrated to be quite useful for the determination of trace amounts of organoarsenic compounds in edible oil. The organoarsenic compounds studied include dimethylarsinic acid (DMA), monomethylarsonic acid (MMA) and 3-nitro-4-hydroxyphenyl arsenic acid (Roxarsone). Orthogonal array experimental design (OAD) was utilized to investigate the parameter space of conditions for UA-DLLME. The optimum conditions were found to be 4 min of ultrasonic extraction using 1.25 mL of mixed solvent with 50 μL of buffer solution. Under these optimal conditions, the linear range was from 10 ng g−1 to 500 ng g−1 for DMA and Roxarsone, from 25 ng g−1 to 500 ng g−1 for MMA. Limits of detection of DMA, MMA and Roxarsone were 1.0 ng g−1, 3.0 ng g−1 and 5.8 ng g−1, respectively. The precisions and recoveries also were investigated by spiking 3-level concentrations in edible oil. The recoveries obtained were over 89.9% with relative standard deviation (RSD) of 9.6%. The new approach was utilized to successfully detect trace amounts of organoarsenic compounds in various edible oil samples.