Ultrasensitive determination of melamine in milk products and biological fluids by luminol-hydrogen peroxide chemiluminescence

An ultrasensitive chemiluminescence (CL) method for determination of melamine at picogram level was reported in a flow system. It was found that melamine can accelerate the electrons transferring rate of excited 3-aminophthalate with notable enhanced CL intensity of luminol-hydrogen peroxide reaction. The increased CL intensity was proportional to the concentration of melamine in the range from 2.5 to 250 pg mL⁻¹ (R² = 0.9953), with a detection limit of 0.9 pg mL⁻¹ (3σ) and the relative standard deviations lower than 5.0%. The proposed method was successfully applied to determine the melamine in liquid milk, yogurt, human urine and serum samples with the recovery of 98–105%, 93–105%, 98–105%, 97–109%, respectively.