In-syringe dispersive solid-phase microextraction of oxalate using starch/dextrin- calcium/Silver nanoparticles...

The in-syringe dispersive solid-phase microextraction (IS-DSPME) technique was employed for the extraction of oxalate (OXA) utilizing starch/dextrin-calcium/silver nanoparticles (STR/DEX-Ca/Ag NPs) as a sorbent, followed by analysis through UV-visible spectrophotometry. The nanoparticles were analyzed using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX), and Brunauer-Emmett-Teller (BET) surface area analysis. The engineered material exhibited excellent dispersibility, high surface activity, and strong affinity toward oxalate, attributed to synergistic Ca²⁺-oxalate chelation and interactions with silver nanoparticle surfaces. Under optimized extraction conditions, the sorbent achieved outstanding recovery values ranging from 98.9% to 99.6%. The analytical method demonstrated strong linearity over 0.5-100 µg/mL (R² = 0.99), with low detection and quantification limits of 0.6382 and 2.1277 µg/mL, respectively. Selectivity studies confirmed minimal interference from common ions, and the method was successfully applied to real water samples, demonstrating high precision and reliability. This work represents the first application of STR/DEX Ca/Ag NPs in IS-DSPME and highlights their potential as an eco-friendly, cost effective, and high-performance sorbent for oxalate determination. The proposed methodology offers a practical, sensitive, and scalable platform suitable for routine environmental and food quality monitoring.