Advancing liquid/liquid extraction through a novel microfluidic device: theory, instrumentation and applications in gas chromatography.

A new chip-based liquid-liquid extraction technique for sample preparation of aqueous samples for GC was developed. Extraction is performed in a segmented flow system with additional mixing provided by an etched channel structure. The dimensions of the device are optimized to allow benefiting of the advantages of chip technology without suffering from the limitations of over-miniaturization. Phase separation is performed with a novel phase separator developed in house. The instrumental set-up is simple. The results obtained for selected test analytes show that the extraction is quantitative (recoveries = 92-110%, RSD < 6%) for a wide range of hydrophobicities (LogK(o/w) = 0.86-4.79). The performance at different flow rates (0.5-6.0 mL/min) and flow ratios (β = 1-10) was evaluated, confirming the flexibility and the possibility to perform enrichment. The results obtained for a few selected applications demonstrate the suitability of the method to perform quick, simple and reliable sample preparation for analytes of interest in real samples.