Determination and characterization of silver nanoparticles in bivalve molluscs by ultrasound assisted enzymatic hydrolysis and sp-ICP-MS

Abstract

A method based on single-particle inductively coupled plasma mass spectrometry (sp-ICPMS) using a dwell time 50 μs for acquisition has been developed for silver nanoparticles (Ag NPs) determination and characterization in bivalve molluscs. Ultrasound assisted enzymatic hydrolysis has been proposed for a fast isolation of Ag NPs from seafood using pancreatin and lipase as extracting enzymes. Optimum extraction conditions imply ultrasonication at 80% amplitude for 10 min, using 10 mL of enzymatic solution (2 g L−1/2 g L−1 pancreatin:lipase, pH 7.4). Repeatability of the over-all procedure was 8%, and the limit of detection (LOD) in Ag NPs concentration was 0.417 × 107 NPs g−1 (the LOD in size was 13.6–16.2 nm). The analytical recovery was 92 and 103% when using Ag NPs standards of 40 and 60 nm, respectively. Several bivalve molluscs (clams, cockles, mussels, razor clams, oysters and variegated scallops) were analysed for total silver content (ICP-MS after microwave assisted acid digestion), and for Ag NPs by the proposed method. Ag NPs concentrations were from 1.56 × 107 to 59.2 × 107 NPs g−1. Mean sizes were within the 26–35 nm range.