Electrochemical Sensor for Ascorbic Acid, Acetaminophen and Nitrite Based on Organoclay/Zr-MOF Film Modified Glassy Carbon Electrode

A composite (Sa-HTDMA/UiO-66) consisting of organoclay (Sa-HTDMA) and a metal-organic framework (UiO-66) was prepared using organically modified natural Cameroonian clay and Zr-MOF. The organoclay was obtained by intercalating in its interlayer hexadecyltrimethyl ammonium cation (HTDMA). The composite was then used to form a film onto a glassy carbon electrode (GCE) by drop coating (Sa-HTDMA/UiO-66/GCE). Electrochemical responses recorded at the as-prepared modified electrodes for ascorbic acid (AA), acetaminophen (AC) and nitrite (NO₂⁻) were investigated using cyclic and linear sweep voltammetry. The results revealed that Sa-HTDMA/UiO-66/GCE exhibited a favorable behavior for individual and simultaneous sensing of AA, AC and NO₂⁻. Additionally, compared with UiO-66 modified GCE, the composite enabled good performance of the electrode. Under the optimum conditions, the linear calibration curves were attained in the following ranges: 1–650 μM for AA, 1–700 μM for AC and 1–600 μM for NO₂⁻ with the respective detection limits of 0.01, 0.19 and 0.33 μM. Application of the sensors to determine AA and AC in pharmaceutical preparations, and NO₂⁻ in tap water, was successful.