Somayeh Ghodoosi and Farideh Mofazzeli* Pages 626 - 633 ( 8 )
Background: Tricyclic Antidepressants (TCAs) can be used for the treatment of depression, psychiatric disorders and insomnia. They are used extensively in all the countries especially in the developed countries and therefore, can enter the aquatic environment mainly through the human excretion. These drugs cannot be completely removed or degraded during the sewage treatment process and their concentrations in the aquatic environment are relatively low; therefore, the development of sensitive analytical methods for determination of their concentrations is very important. In biofluids, the measurements of TCAs are very important to ensure the quality of the preparation and to obtain the optimal therapeutic concentrations, while minimizing the risk of inappropriate dose or overdose. So, the methods for determining these drugs concentrations in human samples for forensic purposes are required.
Methods: The aqueous sample solution was transferred into a glass centrifuge tube with flat bottom and 1-octanol as extraction solvent was withdrawn into an HPLC microsyringe and then, rapidly injected into the tube via syringe needle in order to form a mixture of the aqueous sample solution and the organic solvent. Then, this mixture was repeatedly aspirated from the tube and infused into it several times. This caused the solution to become turbid. This operation resulted in the extraction of the target analyte from the sample solution into the fine droplets of 1-octanol. After then, the mixture was centrifuged to gather the drops of low density extractant above the sample solution as a thin film. For sampling, by inserting a PTFE coated stirring bar at the flat bottom of the tube and turning on the stirrer, the thin film of the organic extraction solvent was converted into a conical vortex with enough volume for easy collection by the needle syringe.
Results: Several important factors affecting the microextraction efficiency, such as the type and volume of the extraction solvent (180 µL of 1-octanol), the volume of the aqueous sample solution (7 mL), the number of air injected (7 times), pH of the sample solution (pH 10) and the ionic strength (no salt addition) were investigated. Under the optimal extraction conditions, the method exhibited low limit of detection (0.52 ng mL-1) and good linearity (2-1000 ng mL-1) with coefficient of determination (R2) of 0.9979. The relative standard deviation was 4.5 % and the enrichment factor was 32. Finally, the applicability of the proposed method was evaluated by extraction of amitriptyline in the biological and environmental water samples and the calculated relative recoveries were more than 85%.
Conclusion: In this research work, a novel microextraction method based on DLLME has been presented for the extraction, preconcentration and determination of amitriptyline in various real samples without using disperser solvents. Also, the developed method was appropriate for the use of low density extraction solvents without any special device and complicated operation which permitted the use of a wider range of the organic extraction solvents. On the other hand, by using an innovative simple method, the internal volume of the quartz UV-Vis microcell decreased and consequently, the volume of the organic extraction solvent reduced as much as possible which led to the proximity to the aspects of green chemistry. In addition, under the optimal extraction condition, the method offers good LOD, as well as good linearity range and repeatability along with acceptable relative recoveries.
Air-agitated dispersive liquid–liquid microextraction (AADLLME), low density organic solvents, Amitriptyline, UV-Vis spectrophotometry, urine, water analysis.
Department of Chemistry, Quchan Branch, Islamic Azad University, Quchan, Department of Chemistry, Quchan Branch, Islamic Azad University, Quchan