A novel and sensitive electrochemical method was proposed for the determination of Sunset yellow (SY) using an expanded graphite paste electrode (EGPE). The EGPE was prepared by mixing expanded graphite (EG) with solid paraffin. EG was characterized with scanning electron microscopy. Compared with flake graphite paste and carbon paste electrode, the EGPE showed a higher electrocatalytic activity toward the oxidation of SY. The EGPE exhibited wide linear response of 5.0 × 10⁻⁸−2.0 × 10⁻⁶ mol/L with a detection limit down to 5.0 nmol/L (S/N = 3) and good accuracy, precision, reproducibility. The proposed method was successfully applied in the determination of SY in jelly and fruit juice.

Sustained silver (Ag) electroless deposition onto copper (Cu) surface was achieved from a simple and stable solution, which only containing silver salt, choline chloride (ChCl) and H₂O, without using of catalyst and reductant. The mechanism of Ag deposition in ChCl-H₂O solution was proven by ultra violet spectroscopy and cyclic voltammetry techniques. Through a study of the Ag coatings using atomic absorption spectroscopy, X-ray diffractometer and scanning electron microscope, we demonstrate that sustained deposition of Ag was achieved in ChCl-H₂O solution with mole ratio higher than 1 ChCl : 5 H₂O and the calculated activation energy of Ag deposition was 13.0 kJ·mol⁻¹.