Synthetic colorants sample preparation

The purpose of this section is to provide a review of HPLC methods available for the determination of synthetic colors in foods, including sample preparation, separation techniques, and detection systems. 

P Ashkenazi, C Yarnitzky, M Cais. Determination of synthetic food colors by means of a novel sample preparation system. Anal Chim Acta 248 289-299, 1991. 

Polyamide powder has been proposed in batch experiments for the extraction and HPLC-DAD determination of Sunset Yellow and 13 other synthetic food colorants in fish roe and caviar [23]. This extraction method obtained better recovery rates than other solid materials (AI2O3, XAD-2, anion exchangers) also tested in this work. The sample preparation proposed by Kirschbaum consisted of the extraction of colorants from roe with 1 M aqueous ammonia, defatting with n-hexane, adjustment of the extract to pH 2, adsorption of colorants on polyamide, and desorption with a mixture of aqueous ammonia (25% v/v) and methanol (10 90% v/v) [23]. 

Sweet potato toxins, 1042 Synthetic dyes, 1001-0132 chromatography of dyes, 1002-1003 classification, application, and colors, 1001-1002 HPTLCofdyes, 1024-1026 identification, analysis, and evaluation, 1002 OPLCofdyes, 1023-0124 preparation of samples and thin layers, 1003-1006... 

To avoid quantification errors caused by the multiple manipulations of the sample during the various steps of extraction and preparation, the use of an internal standard (IS) in combination with the external calibration is advisable. The IS must be chosen carefully, as it has to meet a series of minimum requirements. It must be a carotenoid pigment not present in the sample to be analyzed, it must be chromato-graphically separable from the others under the analytical conditions used, it must have a A ax absorption as close as possible to the A of detection employed, and it must be as stable as possible. Various ISs have been proposed (3-apo-8 -carotenal and canthaxanthin are commonly used in the analysis of vegetable foods.The use of artificial colorants, such as Congo red and Sudan 1, and of synthetic carotenoids not present in natural samples, such as C45-(3-carotene, has also been proposed. ... 

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