Development and Validation of a New Analytical Method for Estimation of Narasin Using Refractive Index Detector and Its Greenness Evaluation

Narasin (NAR) is a commonly used ionophoric antibiotic used in the poultry industry, cattle and pig production both for treating coccidiosis and increasing feed conversion efficiency. To ensure safe administration of NAR into the feed is important to avoid toxicity to farm animals caused by incorporation of large doses or non-homogenous mixing, which requires a simple and sensitive chromatographic method to quantify NAR. However, NAR detection by HPLC is challenging as it lacks a chromophore making it less susceptible to UV and fluorescence detection, and the published analytical methods suffer from disadvantages such as the need for complex derivatization or the use of high volumes of hazardous organic solvents. Herein, a novel, simple, rapid, and costeffective HPLC method is reported to quantify NAR and a study of forced degradation under acidic, basic, temperature, and oxidative conditions are proposed. The separation was performed using a Phenomenex C18 analytical column (4.6 x 150 mm, 5 mu m) and the mobile phase composed of 920 mL methanol, 80 mL water and 10 mL glacial acetic acid. A flow rate of 1 mL/min, and sample injection volume of 50 mu L was used to detect NAR using the refractive index detector. The HPLC method was validated according to FDA guidelines and was found to be accurate, precise, sensitive and robust. It was shown to be linear at ranges of 200 to 900 mu g/mL with a limit of detection (LOD) and limit of quantitation (LOQ) of 7.1 mu g/mL and 21.5 mu g/mL respectively. The method was successfully used to quantify the drug in its commercial formulation and a forced degradation study was performed under acidic, basic, temperature, and oxidative conditions. The greenness profile of the method was also investigated and compared to reported methods using the green analytical procedure Index (GAPI), and Analytical GREEnness Metric Approach and Software (AGREE) tools. The results indicated the greenness of the developed method.