In-line cold column trapping of organic phase in dispersive liquid-liquid microextraction: enrichment and determination of curcumin in human serum.

A new temperature controlled cold column trapping (CCT) system was developed for in-line sequestration of organic phase in dispersive liquid-liquid microextraction (DLLME) method. In the developed CCT-DLLME method, the dispersed organic extraction phase is solidified and trapped in the CCT, packed with glass particles. Subsequently, the sequestered phase is washed out in an elevated temperature by using an appropriate solvent. The column temperature is controlled by a pair of thermal electric cooler (TEC) plates. The new device is simple and portable and can eliminate the need for centrifugation in the DLLME method for solvents with an appropriate melting point. Some important parameters such as types of extraction and disperser solvents and their volumes, minimum and maximum column temperatures and extraction time were optimized for the extraction of curcumin, as a model compound. Using 1-dodecanol as the organic solvent and acetone as the disperser, recoveries exceeding 90% and a relative standard deviation of 2.87% were obtained for 5 replicated analyses of curcumin by an HPLC method. The detection limit of curcumin (3σ) extracted by the CCT-DLLME system was 28 μg L⁻¹. The method was successfully applied to the determination of curcumin in some human serum samples.