Determination of Tylosin Tartrate by Resonance Light Scattering Spectrometry and Visible Spectrophotometry

The sample of tylosin tartrate injection was diluted a certain degree, and then an aliquot (1.20 mL) of sample diluent was taken and mixed with 1.25 mL of pH 3.0 Clark-Lubs buffer solution and 1.25 mL 1×10^-4 mol·L^-1 tiger red solution. After reacting at room temperature for 20 min, the solution was diluted to 10 mL by water. The resonance light scattering intensities of the blank solution (I₀) and the determination solution (I) were measured at 315 nm, respectively. The difference (ΔI) in resonance light scattering intensities was calculated by I-I₀. An aliquot (1.00 mL) of sample diluent was taken, and mixed with 0.75 mL of pH 3.4 Clark-Lubs buffer solution and 2.50 mL of 5×10^-4 mol·L^-1 tiger red solution. After reacting at room temperature for 30 min, the solution was diluted to 10 mL by water. The absorbance of the blank solution (A₀) and the sample solution (A) was measured at 564 nm using water as a reference, and the absorbance difference (ΔA) was calculated by A-A₀. It was shown that the mass concentration of tylosin tartrate showed a linear relationship with ΔI in the range of 0.3-1.2 mg·L^-1, and a linear relationship with ΔA in the range of 4.0-48.0 mg·L^-1. For the 2 methods, detection limits were 0.022 mg·L^-1 and 0.107 mg·L^-1, recoveries were 99.0%-101% and 98.2%-101%, and RSDs of the determined values were less than 1.0%. The reaction mechanisms of the 2 methods were inferred, and phenomenon about ΔI and ΔA increasing with the increase of the mass concentration of tylosin tartrate was related to the formation of ion associated supramolecular aggregates. The molar ratios of tylosin tartrate to tiger red in the ion associated supramolecular aggregates were 1∶6 and 1∶24, respectively.