A highly efficient three-phase single drop microextraction technique for sample preconcentration.

A highly efficient three-phase single drop microextraction (SDME) method is presented by using an organic-aqueous compound droplet. A coupling microdevice is designed to produce compound droplets in different sizes conveniently. In this way, the volume ratio of organic phase to aqueous phase in a compound droplet can be significantly reduced. Good operability and droplet stability were observed during extraction under vigorous stirring conditions. Five statins were used as model compounds and spiked in river water and human serum samples to evaluate the analytical performance of the proposed method. By using a 1.2 μL toluene-aqueous compound droplet (volume ratio 0.2 : 1), a 350 to 1712 fold enrichment of statins was obtained within 4 minutes. The results indicate that the proposed method is a very rapid and efficient sample pretreatment method, and is promising for automated and high-throughput applications.