Calcium-Doped Lanthanum Cobaltite-based Electrochemical Sensor for Sensitive Detection of Salicylic Acid in Real Samples: Pond Water and Acne Gels

Salicylic acid (SA) is a kind of Contaminants of Emerging Concern (CECs) belonging to the category of pharmaceutical products. It is commonly used as drug in treatment of various skin diseases and as an over-the-counter (OTC) drug used in an undisciplined manner across the world. It is also used as a supplement for yield improvement in plants. Exposure to high doses of SA can lead to a toxic condition as known as Salicylism. To better monitor the levels of SA, Ca doped LaCoO 3 (LCCO)/GCE is fabricated in this study. CLCO is synthesized by solvothermal method and characterised by SEM, FE-TEM, XRD, EDX, and XPS techniques.Substitution of Ca 2+ with La 3+ results in formation of oxygen vacancies due to variation in oxidation states of Co. The similar ionic radius of La 3+ and Ca 2+ deliver better structural stability as well as better catalytic activity for the perovskite. LCCO/GCE with its excellent catalytic activity could detect SA with the limit of detection (LOD) of 30 nM and a linear range of 0.05-800 µM. The fabricated sensor is also reproducible with relative standard deviation (RSD) less than 1% and stable up to 30 days with less than 5% variation from the initial current value. The sensor is also selective for sensing SA even in presence of hundred-fold concentrations of other interferents. In addition, the real-world applicability of the sensor is investigated in pond water and acne gel which both give excellent recovery percentages.