Response surface methodology-optimized mildly carboxylated cellulose for dispersive solid-phase extraction and trace determination of heavy metals in commercial beverages.

Abstract

While certain transition metals are biologically essential at ultra-trace concentrations, the persistent presence of non-essential heavy metals poses severe risks to human health due to their toxicity and bioaccumulation potential. Accurate monitoring in commercial beverages is mandatory to ensure compliance with international safety standards but is frequently hampered by complex matrices containing high levels of organic acids and sugars. This study presents a comprehensive framework, ranging from the multi-objective optimization of carboxylated cellulose synthesis to its application in dispersive solid-phase extraction (d-SPE) for the trace determination of Cu²⁺, Co²⁺, Cd²⁺, Ni²⁺, and Pb²⁺ in commercial beverages. Using Response Surface Methodology (RSM), a multi-target optimization scheme established the precise equilibrium between functionalization efficiency and structural preservation. For the d-SPE process, systematic evaluation determined that a pH of 8.0, 50.0 mg of adsorbent, and 30 seconds of ultrasonic dispersion provided the ideal conditions for simultaneous metal recovery. The method utilized a preconcentration step to bridge the sensitivity gap for inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis via rapid desorption with 0.2 M HNO₃. Validation conducted according to AOAC and ICH guidelines demonstrated excellent performance in both bottled mineral water and canned fruit juice matrices. Across spiking levels of 30.0 and 60.0 µg L^-1, average recoveries consistently fell within the 80-110% range. Notably, the method remained robust in fruit juice samples despite high organic content, maintaining stable recoveries for all target analytes and effectively mitigating matrix-induced interferences. These results underscore the stability of optimized functionalized cellulose as an eco-friendly and efficient d-SPE sorbent for routine trace metal monitoring in commercial food products.