Determination of Amaranth and Brilliant Blue in Drink by Fluorescent Spectrometry

Fluorescent spectrometry was applied to the determination of amaranth and brilliant blue in drink. The acidity of the sample solution was adjusted to pH 6.0 with critic acid solution and the analytes in the solution were adsorbed by polyamide powders. After desorption, amaranth and brilliant blue were determine at the excitation wavelengths of 320 nm , 382 nm and the emission wavelengths of 425 nm, 445 nm, respectively. Linear relationships was found between the fluorescence intensity and the concentrations of amaranth and brilliant blue in the ranges of 2.5×10-6-2.50×10-5mol·L-1 and 5.0×10-6-5.00×10-5mol·L-1, respectively, with detection limits (3s) of 2.0×10-7mol·L-1 and 1.0×10-6mol·L-1, respectively. The proposed method was used to determine amaranth and brilliant blue in the commercially avaliable drink, giving recovery rates obtained by standard addition method in the range of 102%-104% and RSDs less than 5%.