Experimentally Designed Sensor for Direct Determination of the Environmentally Hazardous Compound and Occupational Exposure Biomarker (p-aminophenol) in Different Sampling Matrices

p -Aminophenol (PAP) is a potentially toxic and mutagenic compound used and/or emitted in industrial, pharmaceutical and agriculture fields. Ion-selective electrode potentiometry (ISE) introduces an effective tool for real-time, portable and direct analysis to overcome lengthy sample preparation, treatment and derivatization steps. The current work aims to develop a portable ISE-potentiometric sensor for direct assay of PAP in industrial, environmental and biological matrices. Sensor assembly included a glassy carbon electrode upon which membrane cocktails were drop-casted. Optimization was carried out using a custom experimental design for the comprehensive evaluation of the main effects of the critical quantitative (percentage of ion-exchanger, PVC to plasticizer ratio and membrane thickness) and qualitative (ionophore type) factors on the sensor performance (Nernstian slope, LOD, LOQ, correlation coefficient). The optimized sensor included 1.20% ion exchanger, PVC: plasticizer ratio 1:4 and calix-[8]-arene as ionophore in 0.07 mm thick PVC membrane. The sensor proved a near-Nernstian slope of 61.9 mV decade −1 within a linear range of 2.99 × 10 −5 −1 × 10 −2 M, a LOD of 2.86 × 10 −5 M and rapid response time (1–5 s). The developed method was validated for PAP assay in urine, plasma, water, soil, hair dyes and in paracetamol marketed formulations. Eventually, the developed sensor can have multifarious applications in environmental, clinical and industrial fields.