Content determination of ampicillin by Ni(ii)-mediated UV-Vis spectrophotometry

Ampicillin could be degraded under alkaline conditions, of which the degradation products formed a complex with Ni²⁺ in a ratio of 2 : 1 in ammonium hydroxide. According to the study, it was found that there was a characteristic absorption peak at the wavelength of 269 nm, and the molar absorption coefficient and the stability constant of the complex was 4.28 × 10³ L mol^-1 cm^-1 and 5.95 × 10⁹, respectively. The linear relationship between the concentration and absorbance was favorable at the range of 17.47-69.88 μg mL^-1. The regression equation was calculated as A = 0.0124C + 0.0053. The R ² was 0.9990 and the detection limit was 0.52 μg mL^-1. Thus, the Ni²⁺ complex-based ultraviolet spectrophotometry has been created as a new method for indirect determination of ampicillin, with recovery rates from 98.68 to 102.7%, and the relative standard deviation (RSD) is from 0.7% to 1.7%, when applied for determining the content of practical samples.