A bimodal electrochemiluminescence method based on dual-enhancement Ru(bpy)32+/CQDs/AA system combined with magnetic field enhanced solid-phase microextraction for the direct determination of ascorbic acid

Herein, the paper developed a bimodal electrochemiluminescence (ECL) method based on dual-enhancement Ru(bpy) 3 2+ /CQDs/AA system combined with magnetic field enhanced solid-phase microextraction (MFE-SPME) for the direct determination of ascorbic acid (AA). The nanocomposite of Fe 3 O 4 @CS@GO, as a magnetic adsorbent, could efficiently extract AA under the external magnetic field provided by the magnetic glassy carbon electrode (MGCE) with the extraction efficiency up to 89.2%. Based on carbon quantum dots (CQDs) as the co-reactant for Ru(bpy) 3 2+ , when the potential was swept cyclically between −3.5 and 2.0 V, the bimodal ECL emissions were obtained in the Ru(bpy) 3 2+ /CQDs/AA system and were enhanced as AA concentration increased. The method could quantitatively detect AA, because the ln(ECL-1/ECL-2) of bimodal ECL system was in a good linear relationship with the negative logarithm of the AA concentration in the range of 10 −5 –10 −9  M with the limit of detection (LOD, S/N = 3) of 330 pM. After a series of evaluations, the method exhibited good sensitivity, satisfactory repeatability and excellent anti-interference, demonstrating that the developed method had great application potential in analysis fields.