High-throughput Screening And Fast Analytical Technology Of Synthetic Colors In Foods And Environment Water

Color is a very important property for foods, which plays a key role in affecting thedetermination for the purchase of food. With the development of food industry and the abundantvariety of food, more and more synthetic dyes are used to improve the color of food, makeproducts more attractive and appetizing. For protecting the public health, many countries havetheir own regulations about the varieties of food dyes and their maximum levels permitted.However, on the one hand, it was found that synthetic dyes was illegal used in food fields orthe permitted colorants were abused; on the other hand, many food products contains lowconcentration of synthetic colors because they was contaminated by the environmental industrywater during the planting and manufacture of foodstuffs. So the people were the medium highsynthetic colors exposure levels that suffered the health risk. For food safety, the managementand surveillance of synthetic colors is the important and critical fields.To date, although several national standard analytical method had been published, most ofthem are suitable for the determination of several synthetic colors, focus on the simple foodmatrix, and are time-consuming. Thus it is very necessary to develop a high-throughout, fastand sensitive and interference-free method for the screening and determination of syntheticcolors in foods. In our paper, we studied the synthetic colors of food in details, including sixparts as follows:(1) The common illegal dyes and abused colorants, about49colors, were summarized.They were classified as two groups. The first group included19acid (negative) colors. Thesecond group included30basic and neutral (positive) colors. Based on the HPLC-MS/MS, thescreening method for the simultaneous determination of acid, basic and neutral synthetic colorsin foods via negative/positive switching mode during one time running was developed.(2) A simple, rapid, inexpensive and robust solid phase extraction (SPE) cleanup methodcoupled with high performance liquid chromatography (HPLC-DAD) for the determination oftrace four Sudan dyes in chilli products was developed. The interference substances wereremoved completely by normal SPE-Alumina N resulting in a clean and interference-freebaseline. Without the expensive LCMS\MS instrument the low levels of Sudan dyes wereidentified and quantified in chilli foods with the good precision and recovery. This method issuitable for the routine analysis of Sudan dyes for the common factory laboratory due to itssensitivity, simplicity, and low-cost. (3) A simple, rapid and sensitive analytical method for the determination of rhodamine Bin chili-containing foodstuffs is described. The dye is extracted from samples with methanoland analyzed without further cleanup procedure by high-performance liquid chromatography(HPLC) coupled to fluorescence detection (FLD). The influence of matrix fluorescentcompounds (Capsaicin and Dihydrocapsaicin) on the analysis was overcome by theoptimization of mobile-phase composition on the basis of the best compromise amongefficiency, resolution, and analysis time. Finally, the chromatographic separation was achievedon a reverse phase C18column with isocratic elution, using a mobile phase of methanol/water(65:35, v/v). Compared with the national standard analytical method, this method is moreenvironmental friendly and less impurity interference.(4) An efficient, fast and sensitive method for the simultaneous determination of elevenabused synthetic colors (Allura red, Amaranth, Azo rubin, Brilliant blue, Erythrosine,Indigotine, Ponceau4R, New red, Sunset yellow, Quinoline yellow and Tartrazine) in flour andmeat foodstuffs is developed and validated using HPLC coupled with DAD and MS/MS. Thecolor additives were extracted with ammonia-methanol (80:2:18, v/v/v) solution from samples.The extract was further purified with SPE procedure using Strata-AW column in order toreducing matrix interference. This HPLC-DAD method is intended for a comprehensive surveyof color additives in foods. HPLC-MS/MS method was used as the further confirmation andidentification purpose. Because the two charged ions [M-3Na+H]2-or [M-2Na]2-was selectedas the precursor ions, the sensitivity of HPLC-MS/MS was improved. Validation data showedthe good recoveries in the range of75.2-113.8%, with relative standard deviations less than15%. These methods are suitable for the routine monitoring analysis of eleven synthetic coloradditives due to its sensitivity, reasonable time and cost.(5) On the negative ESI tandem MS mode, the mechanism of azo-β-naphthol acid dyefragmentation was investigated and discussed. We found that it was popular for the loss of Na+and the adduct of H+in the these molecular of dyes, resulting in the form of a series of [M-xNa+yH](y-x)molecular ions. But the abundant molecular ions are the two charged ions [M-3Na+H]2-or [M-2Na]2-. We speculated that the azo-β-naphthol acid dyes transformed intohydrazone acid dyes during the MS fragmentation. Because of tautomeric equilibrium, thehydrogen migration happened from the β-naphthol (OH) to the nitrogen of azo double bond,which formed the hydrazone (R1-NH-N=R2). And then the breakage of NH-N bond ofhydrazone lead to the other fragment ions. This mechanism can well explain the fragmentationpath of these dyes, and corrected the previous wrong option that speculated the leakage of C-Nand form the major fragment ions. (6) Current research has demonstrated the presence of sub parts per billion levels of Sudandye in chili products, since these foods were contaminated by the industry waste water duringthe growth of plant and manufacture process of food. Magnetic nanoparticles have attractedmuch attention in sample preparation because of their excellent performance compared withtraditional sample-preparation sorbents. In this paper, we studied the absorption andpurification ability of magnetic nanoparticle Fe3O4and Fe3O4@SiO2modified by SDS andCTAB respectively for the synthetic dyes in the environmental waste water. Meanwhile, themechanisms of absorption on different type of synthetic dyes were discussed by means of theinvestigation of kinetic, isotherm, effects of PH, Zeta potential, SDS/CTAB dosage onmagnetic nanoparticle absorption ability. In addition, based on magnetic mixed hemimicellessolid phase extraction, the HPLC methods for the determination of multiple synthetic dyes inenvironment water was proposed and developed.