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

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 (R 2 ) 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.

An analysis method for determining residual hexane in health functional food products using static headspace gas chromatography

“…Oh et al (3) reported that the analyses of the residual hexane in 87 commercial vegetable oils using HS-GC/FID showed values of the order of trace-2.8 mg/kg. Ito et al (5) reported that the residual hexane in six commercial bixin products using HS-GC/FID was of the order of ND-0.7 ppm. In this study, hexane was measured at less than 5 mg/kg, which complies with the maximum residue limits regulated by the Food Additives Code (1).…”

“…A number of studies have been performed previously on the analysis of hexane in food products. A method to analyze the residual hexane in vegetable oil (3), beeswax (4), annatto extracts (5), and drug substance (6) was developed using headspace gas chromatography (GC). A method to analyze the residual hexane in olive oil (7) was developed using headspace-solid phase microextraction (SPME).…”

Evaluation of Hexane Content in Edible Vegetable Oils Consumed in Iran

“…Oh et al (2005) found that hexane residue varied from trace amounts to 2.8 mg/kg in 87 commercial vegetable oils (9). Additionally, Ito et al (2012) evaluated 23 annatto extract products for hexane residue by applying HS-GC/FID, and nearly 91% of the samples were free of hexane and only two samples containing hexane in the value of 0.6 and 0.7 mg/kg (11). Ligor and Buszewski (2008) investigated the presence of some solvents including acetone, n-hexane, benzene, and toluene in various edible oils using SPME-GC-FID and SHS-GC-FID methods.…”

Regulation of Food Additives in Japan

“…The NIHS has researched and developed the analytical methodology in terms of specifications and standards for designated food additives (7)(8)(9)(10)(11)(12)(13)(14). …”