Automated optosensor for the determination of carbaryl residues in vegetable edible oils and table olive extracts

Carbaryl, which belongs to the carbamate family, is a broad-spectrum insecticide used to control over 100 species of insects. In this paper, we propose a flow-through optosensor for the determination of this compound in edible vegetable oils (olive, sunflower and corn oils) and table olives. Two automated flow methodologies have been compared in order to develop the proposed system, Sequential Injection Analysis and Multicommutated Flow Injection Analysis, using C18 silica gel as solid support placed in the flow-cell. After proper extraction with a QuEChERS method, the proposed system presents a detection limit of 1 mg kg−1, which is suitable taking into account the maximum residue limits (MRLs) established by Codex Alimentarius in olive oil (25 mg kg−1) and table olives (30 mg kg−1), obtaining relative standard deviations lower than 4% in all cases. Recovery experiments have been carried out in several samples of oils and table olives, at levels equal to and below those established by legislation, ranging between 85 and 115%, therefore demonstrating that the proposed analytical method fulfills the requirements for its applications in quality control analyses.