Vol.:(0123456789) 1 3 Journal of the Iranian Chemical Society https://doi.org/10.1007/s13738-020-02030-w ORIGINAL PAPER A validated RP‑HPLC method for determination of nitroxinil and investigation of its intrinsic stability Marwa Soliman 1  · Ahmed Sayed Saad 2  · Nahla Sayed Ismail 1  · Hala El‑sayed Zaazaa 2 Received: 16 June 2019 / Accepted: 3 August 2020 © Iranian Chemical Society 2020 Abstract A fast, sensitive and selective RP-HPLC method was developed for extensive investigation of nitroxinil’s stability. The sta- bility of the studied drug was tested under diferent stress conditions, namely hydrolytic, oxidative, photolytic and thermal. Separation of nitroxinil and its degradation products was achieved in less than 5 min using Venusil XBP C18 (150 × 2.1 mm id, 5 um particle size) column and isocratic mobile phase composed of 0.1% triethylamine pH 2.5 (adjusted with phosphoric acid) and acetonitrile mixture in a ratio of (70:30; v/v). UV detection at 270 nm was employed for monitoring nitroxinil degradation behavior over a linearity range of 1–75 µg/mL. Plackett–Burman experimental design was adopted for robustness testing of the developed chromatographic method. LC-mass identifcation of nitroxinil’s hydrolytic and oxidative degradations was attempted, and the suggested mechanism was deduced. The proposed method was successfully applied in determination of the drug in raw material and pharmaceutical dosage form. Keywords Nitroxinil · Stability · HPLC · Experimental design Introduction Nitroxinil (NIT) (4-hydroxy-3-iodo-5-nitrobenzonitrile) is an anthelmintic veterinary drug [1] (Fig. 1). The drug is of- cially available in the British Pharmacopeia, where its raw material and its formulated preparation momographs adopt non-selective assay methods, i.e., iodometric titration and direct UV spectrophotometric methods [2]. The literature review revealed the presence of many reported analytical methods for determination of NIT in pharmaceutical prod- ucts and biological matrices. They are mainly chromato- graphic methods coupled with UV, electrochemical, and MS detection [3–11], voltammetric and immunoassay methods [12, 13]; none of these methods studied the chemical stabil- ity of NIT. The availability of a stability indicating method for quantitative monitoring of drug substances as a raw material or as a fnished product has become an essential aspect of the pharmaceutical drug industry; therefore, the current work aims to develop a simple and time-saving sta- bility indicating HPLC method for the comprehensive study of NIT’s chemical stability and to serve as a high selec- tive alternative to non-selective ofcial assay methods [2]. Additionally, the identifcation of its degradation products is attempted. Method and materials Standard and pharmaceutical preparation NIT (99.02%) was supplied by Arab CO. for gelatin and pharmaceutical product (Alexandria, Egypt). Its purity was assessed by the ofcial method [2]. Dovenix injection batch number DC J125BA was pur- chased from local markets, manufactured by Miral, France, labeled to contain 250 mg/mL. Reagents The following reagents were obtained: analytical reagent- grade sodium hydroxide, sodium acetate trihydrate, sodium dihydrogen phosphate, glacial acetic acid, boric acid and * Marwa Soliman marwasoliman@live.com; marwasoliman_80@yahoo.com 1 National Organization of Drug Control and Research (NODCAR), 51 Wezzart Elzeraa Street, Elagouza Giza12618, Egypt 2 Analytical Chemistry Department, Faculty of Pharmacy, Cairo University, Kasr ElـAini Street, Cairo 11562, Egypt