Analysis of Residual Solvents in Annatto Extracts Using a Static Headspace Gas Chromatography Method

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.

DOI: 10.4236/ajac.2012.39083                

Abstract

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.

Keywords

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

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	M. Scotter, “The Chemistry and Analysis of Annatto Food Colouring: A Review,” Food Additives and Contaminants, Vol. 26, No. 8, 2009, pp. 1123-1145. doi:10.1080/02652030902942873
[2]	M. J. Scotter, S. A. Thorpe, S. L. Reynolds, L. A. Wilson and P. R. Strutt, “Characterization of the Principal Colouring Components of Annatto Using High Performance Liquid Chromatography with Photo-diode-Array Detection,” Food Additives and Contaminants, Vol. 119, No. 3, 1994, pp. 301-315. doi:10.1080/02652039409374229
[3]	Codex Alimentarius Commission, “Report of the 39th Session of the Codex Committee on Food Additives,” Beijing, 24-28 April 2007.
[4]	Joint FAO/WHO Expert Committee of Food Additives; FAO JECFA Monographs 3 Combined Compendium of Food Additive Specification, Vol. 3, Food and Agriculture Organization of the United Nations, Rome, 2006, pp. 3-7.
[5]	“Commission Directive 2008/128/EC of December 22, 2008 Laying down Specific Purity Criteria Concerning Colours for Use in Foodstuffs,” Official Journal of the European Union, Vol. 6, 2009, pp. 20-63.
[6]	“Code of Federal Regulations, Title 21, Part 73 Listing of Color Additives Exempt from Certification, Subpart A Foods, Sec. §73.30 Annatto Extract,” 2011.
[7]	Joint FAO/WHO Expert Committee of Food Additives; FAO JECFA Monographs 1, Combined Compendium of Food Additive Specification, Vol. 4, Food and Agriculture Organization of the United Nations, Rome, 2006, pp. 87-89.
[8]	C. Cheng, S. Liu, B. J. Mueller and Z. Yan, “A Generic Static Headspace Gas Chromatography Method for Determination of Residual Solvents in Drug Substance,” Journal of Chromatography A, Vol. 1217, No. 41, 2010, pp. 6413-6421. doi:10.1016/j.chroma.2010.08.016
[9]	R. Otero, G. Carrera, J. F. Dulsat, J. L. Fabregas and J. Claramunt, “Static Headspace Gas Chromatographic Method for Quantitative Determination of Residual Solvents in Pharmaceutical Drug Substances According to European Pharmacopoeia Requirements,” Journal of Chromatography A, Vol. 1057, No. 1-2, 2004, pp. 193- 201. doi:10.1016/j.chroma.2004.09.023
[10]	“US Pharmacopeia 32-National Formulary 27, Residual Solvents <467>,” Suppl. 1, Rockville, MD: USP, 2009, 3948.
[11]	J. L. Belsky, A. J. Ashley, P. A. Bhatt, K. V. Gilbert, H. R. Joyce, C. Pan, H. Pappa and S. Z. Wahab, “Optimization of the Water-Insoluble Procedures for USP General Chapter Residual Solvents<467>,” AAPS PharmSciTech, Vol. 2, No. 2, 2010, pp. 994-1004. doi:10.1208/s12249-010-9460-6
[12]	S. Klick and A. Sk?ld, “Validation of a Generic Analytical Procedure for Determination for Residual Solvents in Drug Substances,” Journal of Pharmaceutical and Biomedical Analysis, Vol. 36, No. 2, 2004, pp. 401-409. doi:10.1016/j.jpba.2004.06.014
[13]	Y. Uematsu, M. Hirokado, K. Hirata, K. Nakajima and M. Karamu, “Determination of Residual Organic Solvent in Natural Color Preparations by Standard Addition Head-Space Gas Chromatography,” Journal of the Food Hygienic Society of Japan, Vol. 34. No. 3, 1993, pp. 232-238. doi:10.3358/shokueishi.34.232
[14]	Y. Uematsu, M. Ogimoto, K. Suzuki, J. Kabashima, K. Ito and M. Nakazato, “Survey of Residue Levels of Organic Solvents in ‘Existing Food Additives’ and Health Food Materials by Head-Space GC,” Journal of the Food Hygienic Society of Japan, Vol. 49, No. 5, 2008, pp. 366-375. doi:10.3358/shokueishi.49.366
[15]	Y. Uematsu, K. Hirata, K. Suzuki, K. Iida and K. Kamata, “Survey of Residual Solvents in Natural Food Additives by Standard Addition Head-Space GC,” Food Additives and Contaminants, Vol. 19, No. 4, 2002, pp. 335-342. doi:10.1080/02652030110088301
[16]	M. J. Scotter, L. A. Wilson, G. P. Appleton and L. Castle, “Analysis of Annatto (Bixa orellana) Food Coloring Formulations. 1. Determination of Coloring Components and Colored Thermal Degradation Products by High-Performance Liquid Chromatography with Photodiode Array Detection,” Journal of Agricultural and Food Chemistry, Vol. 46, No. 3, 1998, pp. 1031-1038. doi:10.1021/jf970063+
[17]	K. Sato and T. Maitani, “Determination of Methanol in Gardenia Blue and Gardenia Red,” ShokuhinEiseigakuZasshi, Vol. 44, No. 1, 2003, pp. 73-76. doi:10.3358/shokueishi.44.73