Evolving Analytical Techniques for the Determination of Benzocaine and Its Metabolites: A Critical Review

Benzocaine (BC) (ethyl 4-aminobenzoate) is an ester-type local anesthetic extensively used in topical, oral, and dermatological formulations for rapid, localized pain relief. Despite its widespread application, accurate quantification remains challenging due to poor aqueous solubility, susceptibility to hydrolysis into para-aminobenzoic acid (PABA), and the risk of methemoglobinemia associated with improper exposure. This review presents a critical and comparative evaluation of chromatographic, electrochemical, and spectroscopic methods for determining BC and its metabolites, integrating analytical performance, matrix applicability, and methodological evolution within a unified framework. Evidence was synthesized from major scientific databases, including Scopus, Web of Science, ScienceDirect, PubMed, and Google Scholar. High-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC) remain gold-standard techniques, offering high selectivity, precision, and stability-indicating capability for trace-level analysis. Electrochemical and voltammetric approaches using advanced electrodes, such as boron-doped diamond and carbon nanocomposites, provide excellent sensitivity with low detection limits and improved environmental sustainability. UV-Vis and fluorescence spectrophotometry continue to support routine quality control, particularly when combined with chemometric tools. Ongoing challenges include analyte instability and complex matrices. Future perspectives highlight nanomaterial-based sensors, hybrid analytical platforms, and artificial intelligence integration for sensitive, automated BC monitoring.