Liquid Chromatographic Determination of Natural and Synthetic Colorants in Lyophilized Foods Using an Automatic Solid-Phase Extraction System

Abstract

Five synthetic and five natural colorants were determined in lyophilized dairy products and fatty foods using an automatic method based on lixiviation and a solid-phase extraction process that includes cotton and RP-C(18) columns for the sequential retention of synthetic colorants and natural colorants, respectively. The lyophilization of the sample coupled with the separation procedure provides clean extracts despite the complexity of the matrices studied. In addition, the lyophilization process preserves the sample for at least 2 months without changes in the concentrations of the colorants. Identification and determination of synthetic and natural colorants were carried out using a liquid chromatograph equipped with a diode array detector. The detection limits achieved for all of the colorants (0.03-75 microg/g of lyophilized sample) allowed their determination within the limits established by the European Union, with good precision (approximately 4.5%). In addition, colorants spiked to different foods provided average recoveries (spiked at three concentration levels in four types of dairy samples and in three types of fatty foods) near 94 +/- 4%.

Determination of 8 Synthetic Food Dyes by Solid Phase Extraction and Reversed-Phase High Performance Liquid Chromatography

“…The recoveries were slightly better than those reported in literature [17][18][19]. The method was also validated using a CRM sample.…”

“…High-performance ion chromatography [11], reversed-phase liquid chromatography [12][13][14] and ion-pair liquid chromatography [15][16][17][18][19][20] are the most preferred methods, as they provide high resolution, sensitivity, and selectivity. Solid phase extraction is selected reduce the effect of matrix interference and enrich analyte.…”

Highly sensitive and accurate screening of 40 dyes in soft drinks by liquid chromatography–electrospray tandem mass spectrometry

“…Comparing with the detection limits reported in literatures [5,7,22,[25][26][27][28], the detection sensitivity was improved more than 10 times (see Table S1, Supporting information).…”

“…Various methods for the determination of dyes in foods have been reported, including capillary electrophoresis [6][7][8][9][10], thinlayer chromatography [11], ion-pair chromatography [12,13], high performance liquid chromatography (HPLC) with ultraviolet/visible (UV/Vis) or diode-array detector (DAD) detection [14][15][16][17][18][19][20][21][22][23][24][25] and liquid chromatography-mass spectrometry (LC-MS) [26][27][28][29][30][31][32]. HPLC coupled with UV/Vis or DAD detection is the most commonly used technique because dyes absorb strongly at the ultraviolet and/or visible wavelength.…”

Methods for the analysis of azo dyes employed in food industry – A review

“…González, Gallego, and Valcárcel (2003) have determined natural and synthetic colorants in lyophilized foods using an automatic solid-phase extraction system using ammonia, methanol mixture as eluents and RP-C 18 cotton as stationary phase. Harp, Miranda-Bermudez, Baron, and Richard (2012) have performed the extraction of seventeen food colorants in forty-seven food products employing a simple SPE process.…”