DEVELOPING A FOLIC ACID SENSOR BASED ON BEESWAX SCREEN-PRINTED ELECTRODE MODIFIED WITH PRINTEX L6@CHITOSAN/Au

The present work reports the development of a highly sensitive electrochemical device, produced using screen printed electrode based on Apis mellifera beeswax (SPWE) – employed as substrate – modified with Printex L6 Carbon (PL6C) at Chitosan (Chi) and electrodeposited Au. The sensor was applied for folic acid (FA) since it is a crucial vitamin for regular physiological functions, as well as is essential for DNA and RNA formation [1]. The electrode was designated as SPWE/PL6C@Chi/Au. For the electrodes production, the beeswax was melted on Petri plates with thickness of 0.1 cm, and the graphite ink was applied on its surface. Different graphite ink proportions of graphite powder (G)/varnish glass (VG) (w%/w%) were studied along with a study varying the number of graphite ink layers (2 to 4) by cyclic voltammetry (CV).  Wax reutilization was evaluated by CV which demonstrated stability, with a decay of 6.2% in current only. The electrochemical characterization was performed also by CV with 1.0 mmol L-1 (KCl 0.1 mol L-1) Fe(CN)3-/4 as supporting electrolyte for the reversibility parameters. The electrode with 3 ink layers and 70% G:30% VG proportion, presented better reversibility parameters. The kinetic study was made in the potential range of 5 to 100 mV s-1, obtaining R2 values of 0.99271 and 0.98993 for the anodic and cathodic linearity, respectively. An analytical curve was realized in the linear range of 0.025 – 0.75 µmol L-1 of FA (BR buffer pH 7.0) and LOD= 0.00945 µmol L-1 was obtained, with mean recovery rates of FA in female urine of 101.7%, making SPWE/PL6C@Chi/Au a viable alternative for FA detection in real samples.