The simultaneous detection of food dyes from different samples in a 96-well plate by spectrophotometry

A screening method for the simultaneous detection of the synthetic food dyes tartrazine (TA), Sunset Yellow (SY), Allura Red (AR), Ponceau 4R (PO), Amaranth (AM), and Bright Blue (BB) in different samples was developed. The measurements were performed on a spectrophotometry microplate reader and the concentrations of the dyes in samples were calculated using a multi-primary linear equation group. Standard solutions containing dye concentration ranges from 4–35 μg mL−1 and carbonated beverages from supermarkets were used to evaluate the precision and accuracy of the method. Six-equation groups and three-equation groups were used to predict the dye concentrations in the mixtures or in the drinks. The results indicated that the three-equation groups gave better predictions for dyes, both in the standard mixture solutions and in the carbonated beverages. The recoveries of the dyes from the drink samples were 70–108% when the spiked concentrations were 5 μg mL−1 and 10 μg mL−1, with a RSD range of 0.01–0.33%. In comparison with high performance liquid chromatography (HPLC), the method could find most of the additive dyes in the drinks with a low detection limit of around 2 μg mL−1. The standard deviations of six repeat measurements from one plate and three repeat measurements among three different plates were both within ±0.5 μg mL−1. We also tried to identify three red dyes with highly overlapping spectra: AR, PO, and AM; the results indicated that the method could also identify the three red dyes in mixed solutions.