氯化血红素比色法检测乳制品中土霉素

建立了一种新的土霉素（OTC）的比色检测方法。 以具有辣根过氧化物酶活性的氯化血红素（hemin）溶液作为催化剂，以 3,3',5,5'-四甲基联苯胺（TMB）和双氧水（H2O2）为底物，检测其产物在波长450 nm处的吸光度值，通过吸光度变化值ΔA450 nm与土霉素 含量回归方程计算样品中土霉素含量，并对实验的各个相关因素进行了优化。 结果表明，最优实验条件下，在浓度0～30 nmol/L的范 围内，ΔA450 nm与OTC浓度呈良好的线性关系，最低检测限度为21.89 nmol/L，通过牛奶样品的加标回收实验得知，加标回收率范围为 90%～108%，相对标准偏差（RSD）为1.39%～4.02%。 本方法对其他抗生素的抗干扰能力较强，具有较好的准确性和重复性。

Determination of oxytetracycline in dairy products by hemin colorimetry

A new colorimetric assay for oxytetracycline (OTC) determination was established. Using hemin with horseradish peroxidase activity as cat- alyst, 3,3',5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2) as catalytic substrates, the absorbance value of its product at 450 nm was detected, and the content of oxytetracycline in the sample was calculated by the value change of A450 nm and regression equation of oxytetracycline content. The relative factors of the experiments were optimized, results showed that under the optimal experimental conditions, in the range of 0-30 nmol/L, there was a good linear relationship between ΔA450 nm and OTC concentration, the minimum detection limit was 21.89 nmol/L. Through the standard recovery experiment for milk sample, the recovery range was 90%-108%, and the relative standard deviation (RSD) was 1.39%-4.02%. The method had strong anti-interference ability for other antibiotics, and had good accuracy and repeatability.