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

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 mu l 1-undecanol; disperser solvent: 470 mu l 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 mu g l(-1) and limit of detections (LODs) are in the range of 0.5-5 mu g l(-1). The relative standard deviations (RSDs) for 100 mu g l(-1) of morphine and codeine, 10.0 mu g l(-1) of papaverine and 20.0 mu g 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. (C) 2013 Elsevier B.V. All rights reserved.