Development of a dispersive liquid–liquid microextraction technique for the extraction and spectrofluorimetric determination of fluoxetine in pharmaceutical formulations and human urine

摘要

Purpose:Fluoxetineis the most prescribed antidepressant drug worldwide.In this work, anew dispersive liquid¨Cliquid microextraction (DLLME) method combined with spectrofluorimetry has been developed for the extraction and determination of FLXin pharmaceutical formulations and human urine.Methods:For FLX determination, the pH of a 10 mL of sample solution containing FLX, was adjusted to 11.0. Then, 800 |ìL of ethanol containing 100 |ìL of chloroform was injected rapidly into the sample solution. A cloudy solution was formed and FLX extracted into the fine droplets of chloroform. After centrifugation, the extraction solvent was sedimented and supernatant aqueous phase was readily decanted. The remained organic phase was diluted with ethanol and its fluorescence was measured at 292?à3 nm after excitation at 234?à3 nm. Results: Some important parameters influencing microextraction efficiencywere investigated. Under the optimum extraction conditions, a linear calibration curve in the range of 10 to 800 ng/mL with a correlation coefficient of r2=0.9993 was obtained. Limit of detection (LOD) and limit of quantification (LOQ) were found to be 2.78 and 9.28 ng/mL, respectively. The relative standard deviations (RSDs) were less than 4%. Average recoveries for spiked samples were 93¨C104%.Conclusion:The proposed method gives a very rapid, simple, sensitive, wide dynamic range and low¨Ccost procedure for the determination ofFLX. var currentpos,timer; function initialize() { timer=setInterval("scrollwindow()",10);} function sc(){clearInterval(timer); }function scrollwindow() { currentpos=document.body.scrollTop; window.scroll(0,++currentpos); if (currentpos != document.body.scrollTop) sc();} document.onmousedown=scdocument.ondblclick=initialize158 |Bavili Tabriz and RezazadehAdvanced Pharmaceutical Bulletin,2012, 2(2), 157-164Copyright . 2012by Tabriz University of Medical Sciencesconsuming.5-7Other methods were time consuming, tedious and/or dedicated to sophisticated and expensive analytical instruments.5,9On the other hand, several methods have been described for the determination of FLX in biological fluids. The most widely used methods involve HPLC with ultraviolet,3,4,12,17fluorescence,18-20mass spectrometry (MS)20,21or diode array detection.22,23FLX levels can also be measured in biological samples using GC,24GC¨C MS25and CE.2Liquid¨C liquid extraction (LLE),3,4,18,20,21,25solid phase extraction (SPE),2,22,25and solid phase microextraction (SPME)23are the most common sample preparation techniques to analyze FLX and NFLX in biological fluids. LLE is considered a tedious, time¨C consuming procedure, which can produce emulsions and requires large amounts of high purity organic solvents for analyte extraction. SPE techniques often introduce artifacts into the sample extracts and can require lengthy processing (i.e., washing, conditioning, eluting and drying).19Thus, there is a need for developing new and efficient methods to overcome these drawbacks. Recently miniaturized techniques, such as DLLME has been developed for sample preparation.26It is based on a ternary component solvent system like homogeneous LLE and cloud point extraction (CPE). In this method, the appropriate mixture of extraction and disperser solvent is injected into aqueous sample rapidly by syringe, and a cloudy solution is formed. The analyte in the sample is extracted into the fine droplets of extraction solvent. After extraction, phase separation is performed by centrifugation and the enriched analyte in the sedimented phase is determined by proper instrumental method. The ease of the operation, speed, lower sample volume, low cost, high recovery and high enhancement factor are some advantages of DLLME.27With the development of DLLME, the principles and the applications of this new technique have been reviewed recently28,29and its application extended to separation, preconcentration and determination of organic26,30-33and inorganic27,34-37compounds in different samples. However, to the best of our knowledge, this is the first report concerning FLX extraction using the DLLME method and second one concerning liquid¨Cphase microextraction techniques. In this study, DLLME followed by spectrofluorimetry has been investigated and optimized for the extraction and determination of FLX in pharmaceutical formulations and human urine. The effects of various experimental parameters, such as the kind and volume of extraction and dispersive solvent, extraction time, sample solution pH, salt effect, sample volume, centrifugation time and speed were studied and optimized systematically. Using the developed method FLX can be analyzed in pharmaceutical formulations and human urine in a simpler, cheaper and more rapid manner. Materials and Methods Apparatus All fluorescence measurements were made using a Shimadzu RF¨C5301 PC spectrofluorophotometer equipped with a 150 W Xenon lamp and quartz micro¨Ccell with a path length of 10 mm and a volume of 700 |ìL. Instru