Sulfonated nanocellulose for the efficient dispersive micro solid-phase extraction and determination of silver nanoparticles in food products

• Excellent absorption of AgNPs onto sulfonated nanocellulose (s-NC).
• Dispersive solid phase microextraction method based on s-NC as sorbent material.
• Thioctic acid, a strong silver ligand, proved usefulness to elute AgNPs from s-NC.
• Method validated by the good recoveries in enriched orange juices and mussels.
• Both the analytical tool (s-NC) and the target analyte (AgNP) belong to the nanoscale.

This paper reports a simple approach to Analytical Nanoscience and Nanotechnology (AN&N) that integrates the nanotool, sulfonated nanocellulose (s-NC), and nanoanalyte, silver nanoparticles (AgNPs), in the same analytical process by using an efficient, environmentally friendly dispersive micro solid-phase extraction (D-μSPE) capillary electrophoresis (CE) method with s-NC as sorbent material. Introducing negatively charged sulfate groups onto the surface of cellulose enhances its surface chemistry and enables the extraction and preconcentration of AgNPs of variable diameter (10, 20 and 60 nm) and shell composition (citrate and polyvinylpyrrolidone coatings) from complex matrices into a cationic surfactant. In this way, AgNPs of diverse nature were successfully extracted onto the s-NC sorbent and then desorbed into an aqueous solution containing thiotic acid (TA) prior to CE without the need for any labor-intensive cleanup. The ensuing eco-friendly D-μSPE method exhibited a linear response to AgNPs with a limit of detection (LOD) of 20 μg/L. Its ability to specifically recognize AgNPs of different sizes was checked in orange juice and mussels, which afforded recoveries of 70.9–108.4%. The repeatability of the method at the limit of quantitation (LOQ) level was 5.6%. Based on the results, sulfonated nanocellulose provides an efficient, cost-effective analytical nanotool for the extraction of AgNPs from food products.