Structural Determination of Subsidiary Colors in Food Red No. 104 and Their Contents in Commercial Products

Subsidiary colors (P1 and P2) in commercial food red No. 104 (R104) were isolated as acidic forms by preparative high performance liquid chromatography (HPLC). Their structures were characterized on the basis of physicochemical evidence. The structures of P1 and P2 are 4′, 5′-dibromo-4, 5, 6, 7-tetrachloro-3′, 6′-dioxidospiro[isobenzofuran-1(3H), 9′-[9H]xanthen]-3-one and 2′, 4′, 5′-tribromo-4, 5, 6, 7-tetrachloro-3′, 6′-dioxidospiro[isobenzofuran-1(3H), 9′-[9H]xanthen]-3-one, respectively. Quantitative HPLC analyses of P1 and P2 were performed on commercial R 104 (9 samples from 4 makers). P2 was contained in all the samples in the range from 0.08% to 5.21%, while P1 was not detected in 5 samples and the highest content was 0.06%.