*Corresponding Author: Tel.: +98 (919) 4726342 E-mail: ha_kazemi@sut.ac.ir 137 Int. J. New. Chem., 2020, Vol. 7, Issue 1, pp. 137-149. International Journal of New Chemistry Published online April 2020 in http://www.ijnc.ir/. Open Access Print ISSN: 2645-7236 Online ISSN: 2383-188x Original Research Article Spectrophotometric Study of Complex Formations between Alprazolam and Some Transition Metal Ions in Non Aqueous Solution Mohammad Ashrafi 1 , Behzad Gholamveisi 2 , Behzad Kazemi Haki 3 , Hamid Kazemi Hakki *4 1 Chemical Engineering Faculty, Ahar Branch, Islamic Azad University, PB BOX 5451116714, Ahar, Iran 2 Department of Operating Room, Faculty of Nursing and Midwifery, Kurdistan University of Medical Science, PB BOX 6616797161, Sanandaj, Iran 3 Department of Anesthesiology, Urmia Imam Khomeini Hospital, Urmia University of Medical Sciences, PB BOX 5714783734, Urmia, Iran 4 Chemical Engineering Faculty, Sahand University of Technology, PB BOX 513351996, Tabriz-Sahand New Town, Iran Received: 2019-08-08 Accepted: 2020-02-10 Published: 2020--01-04 ABSTRACT In this study, the complexation reaction between Alprazolam (ALP) and metal ions (Zn 2+ , Ni 2+ , Cu 2+ and Co 2+ ) was investigated by using spectrophotometry in ethanol solvent. The stoichiometry of M + /ALP complexes was calculated by applying the Job, molar ratio and Continuous Changes methods and the relevant diagrams were plotted for each metal ions in each method. The results show that the obtained complexes are 1:3. In the Continuous Changes method a defeat was observed at molar fraction of 0.66 for all complexes, which confirms complexes with 1:3 mole ratio. The formation constants of complexes were determined by using nonlinear least square method (KINFIT software) and it was concluded that the stability of complexes is varied in the order Cu 2+ > Co 2+ > Ni 2+ > Zn 2+ . Therefore, Cu is the strongest and Zn formed with Alprazolam ligand is the weakest complex. Keywords: Spectrophotometric, Alprazolam, Metal ions, Stability, Complexation Reaction.