Dispersive liquid–liquid microextraction followed by high-performance liquid chromatography–ultraviolet detection to determination of opium alkaloids in human plasma

Abstract A novel, simple, rapid and sensitive dispersive liquid–liquid microextraction method based on the solidification of floating organic drop (DLLME-SFO) combined with high-performance liquid chromatography–ultraviolet detection (HPLC–UV) was used to determine opium alkaloids in human plasma. During the extraction procedure, plasma protein was precipitated by using a mixture of zinc sulfate solution and acetonitrile. Some effective parameters on extraction were studied and optimized. Under the optimum conditions (extraction solvent: 30.0 μl 1-undecanol; disperser solvent: 470 μl acetone; pH: 9; salt addition: 1%(w/v) NaCl and extraction time: 0.5 min), calibration curves are linear in the range of 1.5–1000 μg l −1 and limit of detections (LODs) are in the range of 0.5–5 μg l −1 . The relative standard deviations (RSDs) for 100 μg l −1 of morphine and codeine, 10.0 μg l −1 of papaverine and 20.0 μg l −1 of noscapine in diluted human plasma are in the range of 4.3–7.4% ( n  = 5). Finally, the method was successfully applied in the determination of opium alkaloids in the actual human plasma samples. The relative recoveries of plasma samples spiked with alkaloids are 88–110.5%. The obtained results show that DLLME-SFO combined with HPLC–UV is a fast and simple method for the determination of opium alkaloids in human plasma.