A Novel Electrochemical Biosensor Based on Hematite (α-Fe2O3) Flowerlike Nanostructures for Sensitive Determination of Formaldehyde Adulteration in Fruit Juices

High-performance electrochemical enzymatic biosensor based on flowerlike alpha-Fe2O3 nanostructures was successfully developed for the detection of potential food adulterant, formaldehyde (formalin). The biosensor was found to be highly sensitive (744.15 mu A mg(-1) Lcm(-2)) with linear range of detection (0.01-0.3 mg/L) and showed high shelf-life (9 weeks) and precision (0.73% RSD) with reasonably good reproducibility. The biosensor application in real sample analysis was successfully accomplished using cyclic voltammetry (CV) technique. The developed biosensor exhibited detection limits of 0.02 mg/L and 0.04 mg/L in extracted and commercial orange juice samples, respectively, while 0.03 mg/L in extracted mango juice and 0.05 mg/L in commercial mango juice were obtained. The obtained detection limits are well below the maximum daily dose reference set by Environmental Protection Agency (EPA), USA, for formaldehyde. Biosensor results were found in good agreement with those obtained with HPLC (p < 0.05) and highlight market acceptability with usefulness and effectiveness of the proposed method for food quality and safety evaluation.