Employing Diaryl Pyrrolone Fluorescence With Ninhydrin and Phenylacetaldehyde for Sensitive Determination of Alendronate Sodium in Bulk and Pharmaceutical Tablets: Evaluation of Method Greenness

Abstract

Alendronate sodium (ALN) is used to treat osteoporosis in men and women who experienced menopause. A new, sensitive, environmentally friendly, selective, and reasonably priced spectrofluorimetric technique was devised for ALN determination utilizing the reaction of the drug with ninhydrin and phenylacetaldehyde in the presence of Teorell–Stenhagen buffer (pH 7). The interaction yielded a highly luminescent diaryl pyrrolone product with strong emission at 464 nm following excitation at 390 nm. Optimization of various method parameters was performed, and a calibration curve was constructed. Linear regression statistical analysis shows a highly strong correlation (r = 0.9995). The method could determine ALN in the linear concentration range of 0.5–4.0 μg mL⁻¹. Adopting ICH guidelines criteria, method validation was done, and the results confirmed the acceptable accuracy and precision. The LOD and LOQ values were computed as 0.13 and 0.41 μg mL⁻¹, respectively. Application of the method for the analysis of oral tablets containing ALN alone or combined with vitamin D3 was successfully performed with no interferences from vitamin D3 or other coformulated excipients, proving excellent selectivity. Moreover, the method was evaluated for environmental greenness via three different tools confirming its acceptable greenness. Hence, the method can be successfully utilized in quality control laboratories.