Extraction and determination of malathion pesticide using a molecularly imprinted polymer via microextraction by packed sorbent and colorimetric detection

In this study, a novel analytical method was developed for the selective extraction and subsequent colorimetric determination of malathion, a representative organophosphorus pesticide, in environmental samples. Molecularly imprinted polymers (MIPs) were synthesized on glass powder via a sol-gel process using 3-aminopropyltriethoxysilane and tetraethyl orthosilicate. The combination of MIPs with microextraction in packed syringe (MEPS) performed all selective extraction, enrichment and matrix cleanup, leading to improved analytical efficiency. Malathion was then detected by a silver nanoparticle-based colorimetric assay, where AgNPs acted only as a post-extraction detection reagent via nanoparticle aggregation. The binding selectivity of the MIP was confirmed by calculating the imprinting factor (IF = 4.0) and cross-reactivity factors (CRFs = 0.03–0.04), highlighting the high specificity of the method. Under optimum conditions, the absorbance ratio (A 555 /A 400 ) exhibited linearity in the concentration range of 0.01–5 mg/L, with a detection limit of 0.004 mg/L. The proposed method was successfully applied to real samples such as apple, tomato, and tap water, demonstrating its reliability, sensitivity and suitability for routine monitoring of pesticide residues in complex matrices. • Novel Hybrid Method for Sensitive Detection: This study develops a novel, highly sensitive, and selective method by combining Molecularly Imprinted Polymer (MIP)-based microextraction (MEPS) with a simple colorimetric silver nanoparticle sensor for the detection of malathion. • Excellent Analytical Performance: The proposed sensor demonstrates a wide linear range (0.01–5 mg/L) and a very low detection limit (0.004 mg/L) for malathion, with high accuracy (recoveries of 96–102%) and precision in real sample analysis. • High Selectivity via Molecular Imprinting: The use of a synthesized MIP as the adsorbent provides exceptional selectivity for malathion over other pesticides, significantly enhancing the method's reliability for analyzing complex real-world samples like fruits and water. • Cost-Effective and Practical Platform: The sensor utilizes a low-cost glass powder substrate and a straightforward colorimetric readout (visible by the naked eye), offering a simple, affordable, and environmentally friendly alternative to methods requiring sophisticated instrumentation.