Abstract In this paper, a simple voltammetric method has been reported for the thymol determination using MnY nanozeolite modified carbon paste electrode (MnY/CPE). X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and N2 adsorption-desorption isotherm were used to characterize the structure of synthesized NaY and MnY nanozeolites. Also, cyclic voltammetry (CV), chronoamperometry, amperometry and differential pulse voltammetry (DPV) were used to investigate the performance of the modified electrode. The oxidation peak current of thymol was increased dramatically at the MnY/CPE surface against bare CPE and their overpotentials decreased. The effects of pH, modifier amount (MnY%), scan rate and step potential were investigated on the electrochemical response of thymol electro-oxidation based on response surface methodology. Results from this method indicated that pH of 7.0, 20% of MnY nanozeolite in the modified CPE, scan rate (0.06 V s−1) and step potential (7 mV) results in the maximum current density. Under the optimized conditions, linear response was obtained over the range of 0.5–28 μM and also, detection limits was found to be 0.243 μM by DPV method in the MnY/CPE surface. The diffusion coefficient and catalytic rate constant for the electrooxidation of thymol were calculated to be 1.5 × 10−6 cm2 s−1 and 2.6 × 105 cm3 mol−1 s−1, respectively. The fabricated electrode (MnY/CPE) showed good stability, reproducibility and repeatability as well as high recovery. The practical application of the MnY/CPE was demonstrated by measuring the concentration of thymol in thymex syrup as real samples. The proposed method is simple, rapid and inexpensive and can be utilized as a valuable analytical tool in quality control of the pharmaceutical industry.

中文翻译：

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基于MnY纳米沸石改性碳糊电极的响应面法灵敏伏安测定百里酚

摘要 本文报道了一种使用MnY 纳米沸石改性碳糊电极(MnY/CPE) 测定百里酚的简单伏安法。X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、场发射扫描电子显微镜（FESEM）和N2吸附-解吸等温线被用来表征合成的NaY和MnY纳米沸石的结构。此外，循环伏安法 (CV)、计时电流法、电流法和差分脉冲伏安法 (DPV) 用于研究修饰电极的性能。与裸CPE相比，MnY/CPE表面百里酚的氧化峰电流显着增加，过电位降低。pH、改性剂用量（MnY%）的影响，基于响应面法研究了百里酚电氧化电化学响应的扫描速率和步进电位。该方法的结果表明，pH 为 7.0、改性 CPE 中 20% 的 MnY 纳米沸石、扫描速率 (0.06 V s-1) 和步进电位 (7 mV) 导致最大电流密度。在优化条件下，在 0.5-28 μM 范围内获得线性响应，并且通过 DPV 方法在 MnY/CPE 表面发现检测限为 0.243 μM。计算百里酚电氧化的扩散系数和催化速率常数分别为 1.5 × 10−6 cm2 s−1 和 2.6 × 105 cm3 mol−1 s−1。制备的电极（MnY/CPE）显示出良好的稳定性、重现性和重复性以及高回收率。MnY/CPE 的实际应用是通过测量百里香酚糖浆中百里酚的浓度作为真实样品来证明的。所提出的方法简单、快速且价格低廉，可用作制药行业质量控制的宝贵分析工具。