Abstract: The sodium copper chlorophyllin in toothpaste was adsorbed by polyamide under acidic conditions,eluted by desorption,separated by YMC Carotenoid C₃₀ chromatographic column (4.6 mm×250 mm,3 μm),and detected by photodiode array detector (PDA).A method for the determination of sodium copper chlorophyllin in toothpaste by high performance liquid chromatography (HPLC) was established.The sample was subjected to gradient elution with methanol-tert-butyl methyl ether-0.5% acetic acid mixed solution as a mobile phase at a flow rate of 1.0 mL/min,a column temperature of 30 °C,and a detection wavelength of 405 nm.The results show that sodium copper chlorophyllin a and sodium copper chlorophyllin b have a good linear relationship in the range of 5.0-100.0 mg/L,and the correlation coefficients are 0.999 8 and 0.999 7 respectively.The detection limits are 1.5 μg/kg;the limits of quantitation are 5.0 μg/kg;the recovery rate is 87.2%-97.8% and the relative standard deviation is 1.7%-2.9%.

Key words: toothpaste, sodium copper chlorophyllin, polyamide, high performance liquid chromatography