INTRODUCTION Benzodiazepines, called “benzos”, are considered to be medicines that treat insomnia, anxiety, and psychological efects and reduce depression. One of the most important species is chloroziban. Clonazepam (CZP) its Known; 5-(o-chlorophenyl)-1,3-dihydro-7-nitro-2H-1,4-benzo- diazepin 2-one) is a benzodiazepine. It is used to treat muscle spasms tooth extraction operations, and treat muscle imbalance, and it is also used to treat cases of insomnia, anxiety and epilepsy. 1-4 Diferent ways have been reported in the literature to determination of CZP drug in pharmaceutical forms or fuids biological, having electrical ways spectrophotometry, 5-8 liquid and gas chromatography voltammetry (LC-MS/ MS), high performance liquid chromatography (HPLC), flow injection, 9 Ag nanoparticles/MWCNT modified electrode, capillary electrophoresis, chemiluminescence and electro-chemiluminescence, paleography. 10,11 The literature reported several way for estimated of benzodiazepines in biological samples and pharmaceutical formulations, counting spectrophotometry, polarography, capillary electrophoresis, fluorimeter, GC-MS, HPLC, electro-chemiluminescence, dispersive nanomaterial ultrasound assisted microextraction, chemiluminescence, fow injection, and electrical methods. Despite the sensitive visible spectrophotometric ways being so little, the literature contained easy colorimetric ways for the estimation of benzo- diazepine drugs. 12-15 In this study, the colorimetric method for spectrophotometric determination was used to identify chloroziban drug, based on a reaction known as oxidative coupling reaction, The method was sensitive, simple, fast and inexpensive based on the oxidative coupling reaction of chloroziban and phenylephrine hydrochloride conjugation reagent in the presence of sodium periodide oxidizing agent. ABSTRACT A simple, fast, sensitive and selective spectrophotometric method has been developed based on the oxidative coupling reaction process, which depends on the determination of clonazepam (CZP) drug using an oxidizing agent sodium periodate (NaIO 4 ) in the presence of a reagent, phenylephrine hydrochloride (PH-HCL), that uses the pink color of CZP at a wavelength of 495 nm. Where several factors afecting the color intensity and absorbance were studied, including the efect of color stability time, efect of the volume of the reagent, the efect of the volume of the oxidizing agent, order of addition and temperature. The calibration curve found to obey Lambert beer at range concentration (2–20 mg/L), while the limit of detection (LoD) (8. 9*10 -2 ), limit of quantitation (LoQ) (2.6*10 -2 ) and molar absorbance is 1.4 × 10 2 liters mol -1 cm -1 . The method was applied to pharmaceutical preparations (Tablet) and was found to characterize the best precision and accuracy. The standard methods not need any control of temperature and also not afected by interferences and henceforth successfully utilized to determine CZP in pharmaceutical preparations. Keywords: Benzodiazepine, Clonazepam, Oxidative coupling, Phenylephrine hydrochloride, Spectrophotometric method. International Journal of Drug Delivery Technology (2023); DOI: 10.25258/ijddt.13.1.51 How to cite this article: Aljeboree AM, Essa SM, Dawood FA, Ali MS, Alkaim AF. Eco-friendly Analytical Method for Estimation for Benzodiazepine Drug in Pure and Pharmaceuticals Formulations by Oxidative Coupling Reaction with Phenylephrine Hydrochloride. International Journal of Drug Delivery Technology. 2023;13(1):313-316. Source of support: Nil. Confict of interest: None Eco-friendly Analytical Method for Estimation for Benzodiazepine Drug in Pure and Pharmaceuticals Formulations by Oxidative Coupling Reaction with Phenylephrine Hydrochloride Aseel M. Aljeboree *1 , Shaimaa M. Essa 2 , Farah A. Dawood 3 , Mohammed S. Ali 4 , Ayad F. Alkaim 1 1 Department of Chemistry, College of Sciences for Girls, University of Babylon, Hilla, Iraq 2 Department of Chemistry, College of Education, University of Al-Qadisiyah, Al-Qadisiyah, Iraq 3 Department of Pharmacy, AL-Nisour University College of Baghdad, Baghdad, Iraq 4 Department of Dentistry, Al-Zahrawi University College, Karbala, Iraq Received: 27 th December, 2022; Revised: 10 th January, 2023; Accepted: 25 th February, 2023; Available Online: 25 th March, 2023 RESEARCH ARTICLE *Author for Correspondence: annenayad@gmail.com