在pH 5的Tris-盐酸缓冲介质中,溴甲酚绿与大观霉素反应生成具有正、负吸收峰的离子缔合物,最大正吸收波长位于580 nm处,最大负吸收波长位于449 nm处,表观摩尔吸光率(ε)分别为3.41×104,2.86×104L·mol-1·cm-1,大观霉素在0.6~9.2 mg·L-1(正吸收)和0.6~11.1 mg·L-1(负吸收)范围内遵从比尔定律。当改用双波长法并用双吸收峰法检测时,灵敏度可提高到6.26×104L·mol-1·cm-1。方法用于市售大观霉素药物中大观霉素含量的测定,测定值与标示量相符。

In a Tris-HCl buffer medium of pH 5, an ion-association complex was formed by the reaction of bromocresol green and spectinomycin (SPM), having its positive and negative absorption maxima at the wavelengths of 580 nm and 449 nm respectively, with apparent molar absorptivities of (ε580) 3.41×104L·mol-1·cm-1 and (ε449) 2.86×104L·mol-1·cm-1. Beer′s law was obeyed in the ranges of 0.6-9.2 mg·L-1 (measured at 580 nm) and 0.6-11.1 mg·L-1 (measured at 449 nm). When dual wavelengths spectrophotometry was applied and absorbance was measured by the double absorption peak method, value of apparent molar absorptivity was increased to 6.26×104L·mol-1·cm-1. The proposed method was applied to the analysis of a sample of injection of SPM, giving values of SPM content in consistency with the labelled value.