Development of Novel Dynamic Drop-to-Drop Microextraction Coupled with GC-MS for the Trace Level Screening of Phenothiazine Drug in Human Biological Samples

  A novel analytical technique of dynamic drop-to-drop solvent microextraction (DDSME) is developed to determine phenothiazine drug promethazine commonly used in cough syrups and in aesthetic drinks, purple drank most common among youths. Here we apply coupling of highly sensitive technique of GC-MS with dynamic DDSME for the subnanomolar detection of promethazine drug from human biological samples (blood and urine). The method is a virtually solvent free and miniaturized version of traditional Liquidliquid microextraction (LLME), where the solvent to aqueous ratio is greatly reduced. The best optimum parameters for the dynamic DDSME technique were: extraction time of 10 m, using 1-Octanol as the extraction organic solvent, volume of extraction solvent 3 µl, volume of donar aqueous phase 20 µl and with no salt addition, the calibration range for dynamic DDSME is from 0.0 to 5.0 µg ml-1 with correlation coefficient (R2) of >0.984. LOD for the drug was found to be 0.007 µg/ ml.