Author(s)

Yusai Ito, Kyoko Ishizuki, Wakana Sekiguchi, Atsuko Tada, Takumi Akiyama, Kyoko Sato, Takeshi Yamazaki, Hiroshi Akiyama

Division of Food Additives, National Institute of Health Sciences: Kamiyoga, Setagaya-ku, Tokyo, Japan.

An analytical method for the quantification of residual solvents in annatto extracts, natural food colorants, was established using a static headspace gas chromatography (HSGC) coupled with a flame ionization detector (FID). As a sample diluent in a headspace sampling, dimethylformamide (DMF) was selected owing to its high capacity for dissolving both bixin-based and norbixin-based annatto extracts. The quantification of residual solvents was performed using the external standard method. The linearity of the calibration curves was assured with relative coefficients (R²) that were greater than 0.999. The recoveries of all standard solvents spiked in the annatto extracts were in the range from 95.1% to 107.1% to verify the accuracy and the relative standard deviation (RSD%) values (n = 3) were in the range from 0.57% to 3.31%. The quantification limits (QL) were sufficiently lower than the limits specified by Joint FAO/WHO Expert Committee on Food Additives (JECFA). With the established HSGC method, six residual solvents (methanol, ethanol, 2-propanol, acetone, ethyl acetate, and hexane) in 23 commercial annatto-extract products that consist of seven bixin-based and 16 norbixin-based products were quantified. The levels of residual ethyl acetate and hexane in all products were lower than the specified limits of JECFA. However, three samples of bixin-based products showed higher levels of residual 2-propanol (approximately 313.9 - 427.7 ppm) than the specified limit. Other bixin products also showed higher concentrations of residual methanol (approximately 166.6 - 394.7 ppm) and residual acetone (approximately 75.2 - 179.8 ppm) than the limits of JECFA. In the case of norbixin-based products, nine samples showed higher levels of residual acetone (approximately 42.6 - 139.5 ppm) than the limits of JECFA. This is the first survey of residual solvents in annatto extracts using the validated HSGC method.

Annatto Extracts; Bixin; Norbixin; Headspace Gas Chromatography; Residual Solvents

Y. Ito, K. Ishizuki, W. Sekiguchi, A. Tada, T. Akiyama, K. Sato, T. Yamazaki and H. Akiyama, "Analysis of Residual Solvents in Annatto Extracts Using a Static Headspace Gas Chromatography Method," American Journal of Analytical Chemistry, Vol. 3 No. 9, 2012, pp. 638-645. doi: 10.4236/ajac.2012.39083.