Fluorescence Study Carmine, Tartrazine And Sunset Yellow And BSA Interaction Mechanism

Synthetic food pigments can be converted into cancinogenic substance causingvarying degrees of damage to humans, after they are substantially absorbed by ourbodies. In recent years, the events of edible synthetic pigments emerge frequently, suchas the Sudan events, the Red Eggs events, the Dyed Bread events. Although regulationshave been made on the species and amount of synthetic food pigments allowed in ourcountry, most of the regulations were obtained according to the foreign standards, whichmay be caused by the tedious work for pigment detection. To this end, the purpose ofthis paper was to study the interactions between bovine serum albumin (BSA) andlemon yellow, sunset yellow, or carmine in order to establish a method for pigmentdetection and provide a new way for food safety-related segments.Interactions between bovine serum albumin (BSA) and lemon yellow, sunsetyellow or carmine were studied by UV-Vis absorption spectra and fluorescenceemission spectrum, respectively in this paper. The effects of buffer solution kinds, pH,temperature, and reaction time on the results were studied. The optimal reactiveconditions were determined by mono-factor test as follows: using Tris-HCl buffer atpH7.4under room temperature for15min. The maximal ultraviolet-visible absorptionwavelengths of BSA, lemon yellow, sunset yellow, and carmine were283nm,480nm,425nm and507nm. The best fluorescence emission wavelength of BSA was340nmwith both the exciting light slit and the emission light slit were5nm. The dynamicquenching constants at298K were calculated according to Stern-Volmer equation andthe values were3.8×106L·mol-1,7.1×106L·mol-1and4.7×105L·mol-1for lemonyellow, sunset yellow and carmine, respectively; The static quenching constants at298Kwere calculated according to Lineweaver-Burk double-reciprocal equation and the valuewere6.6×105L·mol-1，4.9×105L·mol-1, and1.9×105L·mol-1, respectively; The number of binding sites at298K was calculated according to lg[(F0-F)/F]=lgK0+nlgCQand the value were0.7605,0.6117, and0.4716, respectively. By using the principle ofthe F ster radiation energy transfer, the distance between lemon yellow, Sunset yellow,carmine and bovine serum albumin was5.36nm,6.32nm and3.12nm, respectively;the radiation energy transfer efficiency was78%,62%, and41%, respectively. Based onthe above research results, a new method of detecting the three kinds of edible syntheticpigment was established---fluorescence quenching method. The method is of highsensitivity (detection limit mu0.02μg/mL), wide linear range (0.1-8.0μg/mL), goodprecision (RSD <8.6%), high recovery rate (94%~108%).