A Novel Derivatization-Free Approach for Analysis of (+)2-Aminobutanol and Ethambutol Hydrochloride in Tablets Preparation Using RP-HPLC-NQAD

A novel and rapid RP-HPLC coupled with nano quantity analyte detector (NQAD) method was developed for determination of ethambutol hydrochloride and (+)2-aminobutanol in drug products. NQAD is an aerosol-based detector that can be used for the direct detection of the substance lacking ultraviolet chromophores. The two highly polar analytes were separated on a C₁₈ column with mobile phase consists of trifluoroacetic acid solution and methanol and detected with NQAD. A thorough investigation was conducted into the experimental and instrumental parameters, including the composition and ratio of mobile phase, the flow-rate of mobile phase, and nebulizer and evaporator temperature, to achieve the highest sensitivity of analytes. The method was validated as per ICH guidelines and proved to be specific, accurate, precise, linear, sensitive, and robust. The method showed adequate performance, with excellent sensitivity for limits of detection (LODs) of 5.6 and 9.8 ng for ethambutol and (+)2-aminobutanol (Impurity I), respectively. Good linearity was obtained for ethambutol and Impurity I in their concentration range both with an R² value of 0.999. Overall, the method established in this study, utilizing a new detection technique, proved to be accurate and rapid and is applicable for directly detecting Impurity I and ethambutol in quality control.