A colorimetric assay for the determination and quantification of ascorbic acid (AA) is presented using silver nanoparticle (AgNP) single‐walled carbon nanotube (AgNP/SWCNT) nanocomposites prepared using a microwave‐assisted method. The AgNP/SWCNT nanocomposites possessed oxidase‐like properties toward 3,3′,5,5′‐tetramethylbenzidine (TMB) and could catalyze the oxidation of TMB to form a blue oxidation product (λ_max = 652 nm) in the absence of H₂O₂. AA can specifically inhibit the oxidation of TMB, resulting in a decline of the absorbance value and blue colour fading. As such, amounts of AA can be assessed easily by the unaided eye and quantitatively using an ultraviolet–visible light spectrophotometer. Under the optimal reaction conditions, this strategy showed a good linearity ranging from 0.4 μM to 5.0 μM for AA detection, and the limit of detection was 130 nM. This assay was also applied for AA measurement in vitamin C tablets and juice samples that yielded satisfactory results.

中文翻译：

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基于银纳米粒子单壁碳纳米管复合材料氧化酶样活性的抗坏血酸检测比色策略。

使用通过微波辅助方法制备的银纳米颗粒（AgNP）单壁碳纳米管（AgNP / SWCNT）纳米复合材料，进行了比色测定法测定和定量抗坏血酸（AA）。AgNP / SWCNT纳米复合材料对3,3'，5,5'-四甲基联苯胺（TMB）具有类似氧化酶的性质，并且可以在不存在H的情况下催化TMB氧化形成蓝色氧化产物（_λmax = 652 nm）。₂ O ₂。AA可以特异性抑制TMB的氧化，导致吸光度值下降和蓝色褪色。这样，可以用肉眼很容易地评估AA的量，并使用紫外可见分光光度计进行定量。在最佳反应条件下，该策略对AA的检测显示出良好的线性范围，从0.4μM到5.0μM，检测限为130 nM。该测定法还用于维生素C片剂和果汁样品中的AA测定，结果令人满意。