An enzymatic method for cost-effective and reliable spectrophotometry was described based on the catalytic reaction of peroxidase enzyme to detect and determine tetracycline. Daikon (Raphanus sativus L.), a local vegetable, was exploited as a source of peroxidase enzyme, extracted by a simple method and utilized for tetracycline detection without any purification steps. A blue color product which absorbed maximal wavelength at 600 nm was observed when mixing tetracycline, 4-aminoantipyrine and hydrogen peroxide in the presence of daikon peroxidase under pH 7.5. Parameters influencing the proposed method as pH, concentration of hydrogen peroxide, concentration of 4-aminoantipyrine, volume of crude enzyme extract, incubation temperature and incubation time were investigated and optimized. Cloud-point extraction using Triton X-114 as surfactant was employed for preconcentration of the blue color product prior to spectrophotometric analysis. The calibration curve of standard tetracycline showed good linearity in the range 0.05–10 mg L⁻¹ with linear regression of r² = 0.9982. Limit of detection and limit of quantification for tetracycline by this analytical method were 0.02 and 0.10 mg L⁻¹, respectively. Relative standard deviation was lower than 5%. Recovery was determined between 81.1–112.8 and 97.2–114.8% for pharmaceutical formulations and water samples, respectively. Results indicated that the developed method provided many advantages including a cost-effective, suitable and reliable procedure to detect tetracycline in pharmaceutical formulations and water samples. Results obtained were not significantly different from those achieved by HPLC–UV.

中文翻译：

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基于过氧化物酶促反应的分光光度法测定药品和水样中的四环素

基于过氧化物酶的催化反应，以检测和测定四环素为基础，描述了一种酶促方法，具有成本效益和可靠的分光光度法。萝卜（Raphanus sativusL.）是一种本地蔬菜，被用作过氧化物酶的来源，通过一种简单的方法提取，无需任何纯化步骤即可用于四环素检测。当在pH 7.5的daikon过氧化物酶存在下将四环素，4-氨基安替比林和过氧化氢混合时，观察到蓝色产物在600 nm处吸收最大波长。研究和优化了影响该方法的参数，包括pH，过氧化氢浓度，4-氨基安替比林浓度，粗酶提取物的体积，孵育温度和孵育时间。在分光光度分析之前，使用Triton X-114作为表面活性剂的浊点萃取法对蓝色产物进行预浓缩。标准四环素的校准曲线在0.05–10 mg L范围内表现出良好的线性^-1，线性回归为r ²  = 0.9982。该分析方法的四环素检出限和定量限分别为0.02和0.10 mg L ^-1。相对标准偏差低于5％。药物制剂和水样的回收率分别确定在81.1–112.8和97.2–114.8％之间。结果表明，所开发的方法具有许多优势，包括经济高效，合适且可靠的检测药物制剂和水样中四环素的方法。所得结果与HPLC-UV所得结果无显着差异。