Ionic imprinted polymer - Vortex-assisted dispersive micro-solid phase extraction for inorganic arsenic speciation in rice by HPLC-ICP-MS.

This study combines ultrasound-assisted extraction and vortex-assisted dispersive micro-solid phase extraction using an ionic imprinted polymer as a selective sorbent for rapid isolation and pre-concentration of inorganic arsenic species (As(III) and As(V)) in extracts from rice samples prior to their determination by high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry. All factors affecting the ultrasound assisted extraction of the species from rice (ultrasound amplitude, sonication time and sonication mode) and their selective pre-concentration by ionic imprinted polymer-based vortex-assisted dispersive micro-solid phase extraction (sorbent amount, extract pH, vortex extraction time and speed, eluting solution and vortex elution time and speed) were optimized. The analytical performance of the procedure was studied at optimum conditions: ultrasound continuous sonication at 40% amplitude for 2.0 min using 1:1 methanol/ultrapure as an extractant, 50 mg of sorbent, extract pH at 8.0, vortex loading at 1000 rpm for 1.0 min, and elution with ultrapure water by vortexing at 1000 rpm for 1.0 min, pre-concentration procedure which leads to a pre-concentration factor of 10. The limits of detection obtained for As (III) and As (V) were 0.20 and 0.41 μg kg, respectively, and were well below the maximum levels established by the European Union in rice and rice containing products. The method was found to be precise (intraday and interday relative standard deviations ≤ 11%) and selective. The accuracy was confirmed by analysing the ERM-BC211 (rice, As species) certified reference material, and the method was successfully applied to commercial rice samples.