Wardak Cecylia, Morawska Klaudia, Paczosa-Bator Beata, Grabarczyk Malgorzata
Department of Analytical Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska Sq. 3, 20-031 Lublin, Poland.
Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow, Poland.
Materials (Basel). 2023 Jan 21;16(3):1003. doi: 10.3390/ma16031003.
A new solid-contact ion-selective electrode (ISE) sensitive to lead (II) ions, obtained by modifying a polymer membrane with a nanocomposite of carbon nanofibers and an ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate, is presented. Electrodes with a different amount of nanocomposite in the membrane (0-9% ), in which a platinum wire or a glassy carbon electrode was used as an internal electrode, were tested. Potentiometric and electrochemical impedance spectroscopy measurements were carried out to determine the effect of the ion-sensitive membrane modification on the analytical and electrical parameters of the ion-selective electrode. It was found that the addition of the nanocomposite causes beneficial changes in the properties of the membrane, i.e., a decrease in resistance and an increase in capacitance and hydrophobicity. As a result, the electrodes with the modified membrane were characterized by a lower limit of detection, a wider measuring range and better selectivity compared to the unmodified electrode. Moreover, a significant improvement in the stability and reversibility of the electrode potential was observed, and additionally, they were resistant to changes in the redox potential of the sample. The best parameters were shown by the electrode obtained with the use of a platinum wire as the inner electrode with a membrane containing 6% of the nanocomposite. The electrode exhibited a Nernstian response to lead ions over a wide concentration range, 1.0 × 10-1.0 × 10 mol L, with a slope of 31.5 mV/decade and detection limit of 6.0 × 10 mol L. In addition, the proposed sensor showed very good long term stability and worked properly 4 months after its preparation without essential changes in the E or slope values. It was used to analyze a real sample and correct results of lead content determination were obtained.
本文介绍了一种新型的对铅（II）离子敏感的固体接触离子选择性电极（ISE），它是通过用碳纳米纤维与离子液体1-己基-3-甲基咪唑六氟磷酸盐的纳米复合材料修饰聚合物膜而制得的。测试了膜中含有不同量纳米复合材料（0-9%）的电极，其中使用铂丝或玻碳电极作为内电极。进行了电位和电化学阻抗谱测量，以确定离子敏感膜修饰对离子选择性电极分析和电学参数的影响。结果发现，添加纳米复合材料会使膜的性能发生有益变化，即电阻降低、电容和疏水性增加。因此，与未修饰的电极相比，修饰膜电极具有更低的检测限、更宽的测量范围和更好的选择性。此外，还观察到电极电位的稳定性和可逆性有显著改善，而且它们对样品氧化还原电位的变化具有抗性。使用铂丝作为内电极且膜中含有6%纳米复合材料的电极表现出最佳参数。该电极在1.0×10⁻¹.0×10⁻⁶mol/L的宽浓度范围内对铅离子呈现能斯特响应，斜率为31.5 mV/十倍浓度，检测限为6.0×10⁻⁷mol/L。此外，所提出的传感器显示出非常好的长期稳定性，在制备后4个月仍能正常工作，其电位（E）或斜率值没有实质性变化。它被用于分析实际样品，并获得了铅含量测定的正确结果。
