تشخیص و پیش‌تغلیظ مولیبدن به روش میکرو استخراج مایع– مایع پراکنده شده بر پایه انجماد قطره آلی شناور همراه با طیف‌سنج فرابنفش- مرئی

نوع مقاله : مقاله پژوهشی (کاربردی)

نویسنده

استادیار، گروه شیمی، دانشگاه فنی و حرفه‌ای، تهران، ایران.

چکیده

مولیبدن، عنصری دارای اهمیت بیولوژیکی و زیست‌محیطی، در مقادیر کم می‌باشد. یک روش جدید براساس میکرواستخراج مایع- مایع پراکنده‌شده بر پایه انجماد قطره آلی شناور[1] پیش از اندازه‌گیری با طیف‌سنج فرابنفش- مرئی[2] برای پیش‌تغلیظ و تشخیص مولیبدن در مقادیر کم ایجاد شده است. این روش براساس واکنش مولیبدن با یون تیوسیانات به‌منزله معرف کمپلکس‌دهنده برای تشکیل Mo(SCN)5 در محیط اسیدی می‌باشد. یک مقدار دقیق از مخلوط استون و 1 –آندکانول به‌سرعت به داخل محلول نمونه تزریق می‌شود سپس کمپلکس قرمزرنگ مولیبدن به داخل حلال 1 –آندکانول استخراج می‌گردد. پس از سانتریفیوژ، لوله نمونه در داخل حمام آب و یخ به مدت 5 دقیقه سرد می‌شود و حلال 1 –آندکانول[3] به‌صورت جامد روی محلول تشکیل‌شده به داخل سل میکرو انتقال می‌یابد تا مولیبدن با طیف‌سنج فرابنفش- مرئی تشخیص داده شود. جذب[4] کمپلکس در طول موج 470 نانومتر اندازه‌گیری می‌شود. چندین پارامتر مهم مرتبط مانند حجم 1 –آندکانول و استون، غلظت هیدروکلریک اسید و زمان استخراج بررسی می‌شود. در شرایط بهینه عملکرد، منحنی کالیبراسیون در ناحیه خطی با غلظت 12 تا 100 نانوگرم در میلی‌لیتر از مولیبدن رسم می‌شود. حد تشخیص روش 3.8 نانوگرم در میلی‌لیتر براساس 3Sb/m به‌دست آمد. انحراف استاندارد نسبی روش برابر با  3.3  درصد برای پنج اندازه گیری تکرارپذیر می‌باشد. روش پیشنهادی با موفقیت برای تعیین مولیبدن در نمونه‌های حقیقی آب لوله‌کشی و چاه با بازیابی در محدوده 103 -95 درصد استفاده می‌شود. این روش مزایایی از جمله: سریع، حساس، ارزان، استفاده از حجم بسیارکم حلال‌های آلی دارد و حلال دوستدار محیط زیست است.
 
[1] Dispersive liquid-liquid microextraction technique based on solidification of a floating organic drop (DLLME-SFOD)
[2] UV-Visible spectrophotometric
[3] 1-Undecanol
[4] Absorbance

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Dispersive Liquid-Liquid Microextraction Technique Based on Solidification of Floating Organic Drop for Preconcentration and Determination of Molybdenum Prior to UV-Visible Spectrophotometry

نویسنده [English]

  • َAbolfazl Darroudi
Assistant Professor, Department of Chemistry, Technical and Vocational University (TUV), Tehran, Iran.
چکیده [English]

Molybdenum (Mo) is a trace element of biological and environmental relevance. A novel method according to dispersive liquid-liquid microextraction technique based on solidification of a floating organic drop prior to UV-Vis spectrophotometry for determination of Mo at trace amounts in environmental samples was established. This method was based on the reaction of Mo with thiocyanate (SCN-) as a chelating agent for formation of Mo (SCN)5 in acidic medium. An appropriate mixture of acetone and 1-undecanol was rapidly injected into an aqueous sample and the red Mo complex was then extracted into 1-undecanol. After centrifugation, the sample tube was cooled for 5 min and the solidified formed 1-undecanol drop on the top of the solution was transferred into a micro-cuvette for determination of Mo by UV-Vis spectrophotometry. Absorbance of the complex was measured at 470 nm. Several important relevant parameters such as the amount of 1-undecanol and acetone, concentration of hydrochloric acid and extraction time were investigated. Under optimum operating conditions, the calibration curve in the linear region and concentration range of 12 to 100 ng mL-1 of Mo were plotted. The limit of detection (LOD) of the method obtained was 3.8 ng mL-1 based on 3Sb/m. The relative standard deviation (RSD %) of the method was found to be 3.3% for five replicate measurements. The proposed method was successfully applied for the determination of the Mo in tap and well water real samples with recoveries in the range of 95-103%. The proposed method was fast, sensitive, cheap, and used very small volumes of organic and environmentally friendly solvents.

کلیدواژه‌ها [English]

  • Microextraction Dispersive liquid
  • liquid microextraction technique based on solidification of a floating organic drop UV
  • Vis spectrophotometer Determination of Molybdenum ions
[1] Machado, I., & Tissot, F. (2020). Dispersive liquid-liquid microextraction as a preconcentration alternative to increase ETAAS sensitivity in the analysis of molybdenum in bovine meat and pasture samples. Talanta, 212, 120783. https://doi.org/10.1016/j.talanta.2020.120783
[2] Barros, J. A. V. A., Aguirre, M. Á., Kovachev, N., Canals, A., & Nóbrega, J. A. (2016). Vortex-assisted dispersive liquid–liquid microextraction for the determination of molybdenum in plants by inductively coupled plasma optical emission spectrometry. Analytical Methods, 8(4), 810-815. https://doi.org/10.1039/C5AY02561C
[3] Gharehbaghi, M., & Shemirani, F. (2011). Ionic liquid-based dispersive liquid–liquid microextraction and enhanced spectrophotometric determination of molybdenum (VI) in water and plant leaves samples by FO-LADS. Food and Chemical Toxicology, 49(2), 423-428. https://doi.org/10.1016/j.fct.2010.11.017
[4] Tuzen, M., Altunay, N., Hazer, B., & Afshar Mogaddam, M. R. (2022). Synthesis of polystyrene-polyricinoleic acid copolymer containing silver nano particles for dispersive solid phase microextraction of molybdenum in water and food samples. Food Chemistry, 369(1-3), 130973. https://doi.org/10.1016/j.foodchem.2021.130973
[5] Ghiasvand, A. R., Shadabi, S., Mohagheghzadeh, E., & Hashemi, P. (2005). Homogeneous liquid–liquid extraction method for the selective separation and preconcentration of ultra trace molybdenum. Talanta, 66(4), 912-916. https://doi.org/10.1016/j.talanta.2004.12.04 1
[6] Dos Santos, H. C., Korn, M. G. A., & Ferreira, S. L. C. (2001). Enrichment and determination of molybdenum in geological samples and seawater by ICP-AES using calmagite and activated carbon. Analytica Chimica Acta, 426(1), 79-84. https://doi.org/10.1016/S0003-2670(00)01192-2
[7] Gürkan, R., Korkmaz, S., & Altunay, N. (2016). Preconcentration and determination of vanadium and molybdenum in milk, vegetables and foodstuffs by ultrasonic-thermostatic-assisted cloud point extraction coupled to flame atomic absorption spectrometry. Talanta, 155, 38-46. https://doi.org/10.1016/j.talanta.2016.04.012
[8] Tuzen, M., Shemsi, A. M., & Bukhari, A. A. (2017). Vortex-Assisted Solidified Floating Organic Drop Microextraction of Molybdenum in Beverages and Food Samples Coupled with Graphite Furnace Atomic Absorption Spectrometry. Food Analytical Methods, 10(1), 219-226. https://doi.org/10.1007/s12161-016-0571-x
[9] Mansour, F. R., & Danielson, N. D. (2017). Solidification of floating organic droplet in dispersive liquid-liquid microextraction as a green analytical tool. Talanta, 170, 22-35. https://doi.org/10.1016/j.talanta.2017.03.084
[10] Darroudi, A., & Enferadi, S. (2021). Measurement of Sulfide in Real Samples by Vortex-Assisted Liquid-Liquid Microextraction Method with Detection of UV-Vis Spectrophotometry. Karafan Quarterly Scientific Journal, 18(1), 217-229. https://doi.org/10.48301/kssa.2021 .130974
[11] Klochkova, A., Barbalat, D., Chebotarev, A., & Snigur, D. (2021). Dispersive liquid–liquid semi-microextraction of molybdenum(VI) with 6,7-dihydroxy-2,4-diphenylbenzopyrylium chloride for its spectrophotometric determination. Journal of the Iranian Chemical Society, 18(1), 109-115. https://doi.org/10.1007/s13738-020-02008-8
[12] Madrakian, T., & Ghazizadeh, F. (2008). Cloud-point preconcentration and spectrophotometric determination of trace amounts of molybdenum(VI) in steels and water samples. Journal of Hazardous Materials, 153(1-2), 695-700. https://doi.org/10.1016/j.jhazmat.2007.09.013
[13] Snigur, D., Chebotarev, A., Dubovyiy, V., Barbalat, D., & Bevziuk, K. (2018). Salicylic acid assisted cloud point extraction at room temperature: Application for preconcentration and spectrophotometric determination of molybdenum(VI). Microchemical Journal, 142, 273-278. https://doi.org/10.1016/j.microc.2018.07.010
[14] Oviedo, J. A., Fialho, L. L., & Nóbrega, J. A. (2013). Determination of molybdenum in plants by vortex-assisted emulsification solidified floating organic drop microextraction and flame atomic absorption spectrometry. Spectrochimica Acta Part B: Atomic Spectroscopy, 86, 142-145. https://doi.org/10.1016/j.sab.2013.02.005