Physical–chemical characterization of titanium dioxide layers sensitized with the natural dyes carmine and morin

The titanium dioxide (TiO₂)-based layers sensitized with carmine and morin dyes were prepared using commercial P25 TiO₂ powder as starting material. The influence of natural colorants as natural photosensitizers on TiO₂ photoactivity was discussed from the point of view of UV–VIS and Fourier transform infra-red (FTIR) spectroscopy, fluorescence analysis, microscopy, X-ray diffraction and nitrogen adsorption-desorption isotherms determination. A shift to visible region of the sensitized TiO₂ layers is observed. The decrease of sensitized TiO₂ band gap improves its photoactivity in the visible domain. The fluorescence quenching of TiO₂ sensitized with carmine is correlated with better adsorption of the dye molecules to the TiO₂ surface and with electron injection process, also. The FTIR absorption spectra of samples proved the presence of dye molecules on TiO₂ nanoparticles surface. Thus, the investigated sensitized TiO₂-based layers could have potential in photoelectrochemical applications.     

Determination of optimum operating conditions of carmine decoloration by UV/H2O2 using response surface methodology

In this study, the photolytic decoloration of carmine (C.I. Natural Red 4) via UV radiation in the presence of H2O2 was optimized using response surface methodology (RSM). According to analysis of variance (ANOVA) results, the proposed model can be used to navigate the design space. It was found that the response of carmine degradation is very sensitive to the independent factors of carmine concentration, H2O2 concentration, pH and reaction time. The proposed model for D-optimal design fitted very well with the experimental data with R2 and R(adj)2 correlation coefficients of 0.998 and 0.997, respectively.     

Research Note Interferences due to Ozone-Scavenging Reagents in the GC-ECD Determination of Aldehydes and Ketones as the (2, 3, 4, 5, 6, -Pentafluorobenzyl) oximes

In order to study ozonation byproduct (OBP) formation as a function of time, it is necessary to quench ozone and thereby fix the concentrations of the byproducts. Reagents chosen for this purpose must not react with the OBPs or otherwise adversely impact the analysis. Six potential ozone-scavenging reagents were tested for possible interference in the GC-ECD determination of aldehydes and ketones after derivatization with O-(2,3,4,5,6-pentafluorobenzyl)oxylamine (PFBOA). All six—sodium nitrite, sodium cyanide, sodium methanoate (formate), indigo-5,5′-disulfonate disodium (Indigo Carmine), indigo-5,5′,7-trisulfonate tripotassium, and tin(II) chloride—were found to interfere in the analysis.     

Estimated daily intake and safety of FD&C food-colour additives in the US population

ABSTRACT

A refined exposure assessment was undertaken to calculate the estimated daily intake (EDI) of the seven FD&C straight-colour additives and five FD&C colour lakes (‘synthetic’ food colours) approved in the United States. The EDIs were calculated for the US population as a whole and specific age groups, including children aged 2–5 and 6–12 years, adolescents aged 13–18 years, and adults aged 19 or more y. Actual use data were collected from an industry survey of companies that are users of these colour additives in a variety of products, with additional input from food colour manufacturers. Food-consumption data were obtained from the National Health and Nutrition Examination Survey (NHANES). The assessment was further refined by adjusting the intake to more realistic scenarios based on the fraction of products containing colour within specific food categories using data provided by the Mintel International Group Ltd. The results of the analysis indicate that (1) the use levels reported by the industry are consistent with the concentrations measured analytically by the US Food and Drug Administration; and (2) exposure to food-colour additives in the United States by average and high-intake consumers is well below the acceptable daily intake (ADI) of each colour additive as published by the Joint WHO/FAO Committee on Food Additives (JECFA) and allows wide margins of safety. It is concluded that food colour use as currently practised in the United States is safe and does not result in excessive exposure to the population, even at conservative ranges of food consumption and levels of use.     

Dye use in fresh meat preparations and meat products: a survey by a validated method based on HPLC-UV-diode array detection as a contribution to risk assessment

The use of dyes in meats has to be monitored, due to food safety concerns. The presence of twelve dyes (Amaranth, Ponceau 4R, Carmine, Ponceau SX, Ponceau 3R, Allura Red AC, Carmoisine, Erythrosine, Sudan I, Sudan II, Sudan III and Sudan IV) in meat was investigated in 130 meat product and fresh meat preparation samples, and the dietary exposure was estimated. Carmine and Ponceau 4R were the identified dyes. Except for one sample of salami, they were regularly indicated on the label, and their concentrations were in the range 1.3–8.1 and 6.2–86.4 mg kg⁻¹ for Ponceau 4R and Carmine, respectively. Concerning fresh meat preparations, Carmine was detected in three samples, confirming that this dye is still used, although it is no longer authorised in these products. Regarding dietary exposure estimate, the daily intake from meat product consumption resulted lower than 1% of the ADI, both for Carmine and Ponceau 4R.     

饮料中胭脂红的荧光测定方法研究

建立了荧光分光光度法检测定饮料中的合成色素胭脂红的新方法。以320.0 nm为激发波长时,胭脂红有一灵敏的荧光发射现象,最大发射波长为432.0 nm。在2.00×10-7～2.20×10-5mol/L浓度范围内,胭脂红的荧光强度与浓度呈良好的线性关系,线性回归方程为F(%)=2.93×106c(mol/L)+12.9(相关系数r=0.994),检出限为1.00×10-7mol/L。将该方法应用于两种市售饮料中胭脂红的测定,加标回收率在94.4%～109.2%之间。     

食品添加剂胭脂虫红的定性和定量分析

采用分光光度法对标题化合物进行了定性和定量分析,并对其理化指标和有毒有害成分进行了讨论.     

胭脂红的伏安行为研究及其应用

采用循环伏安法和方波伏安法研究了胭脂红在碳糊电极上的伏安行为和反应机理。在pH3．2．9的B．R．缓冲溶液中,胭脂红有一对准可逆氧化峰和还原峰,峰电位分别是＋0.67V和＋0.65V（均VS．饱和甘汞电极）,显示扩散控制的2电子单质子氧化还原过程。胭脂红方波还原峰电流与其浓度在4．0×1O^-6mol／L～8．0×1O^-6mol／L的范围内,呈良好线性关系,检出限为2．05×1O^-6mol／L,由此建立测定胭脂红的方波伏安法。该方法可用于测定实验室染色废水水样中胭脂红的含量,平均回收率在94-103％。     

Determination of contact parameters of Au/Carmine/n-Si Schottky device

An Au/Carmine/n-Si Schottky device was fabricated and the current-voltage (I-V) and the capacitance-voltage/frequency characteristics of the structure have been measured at room temperature. A good rectifying behavior was seen from the I-V characteristics. The characteristic parameters of the structure such as barrier height, ideality factor, interface states density and series resistance were determined from the electrical measurements. Also, Cheung functions and Norde method were used to evaluate the I-V characteristics and to obtain the characteristic parameters of the Schottky contact. It was seen from the capacitance measurements that the values of capacitance were almost independent of frequency up to a certain value of frequency whereas at high frequencies the capacitance decreased quickly. The higher values of capacitance at low frequencies were attributed to interface states and the excess capacitance resulting from the interface states in equilibrium with the Si that can follow the alternating current signal.     

Laccase Catalyzed Indigo Carmine Transformation

SUMMARY

A novel application of laccase for Indigo Carmine transformation with possible applications in enzymatic re-coloration of denim fabric is described. Indigo is used for dyeing denim fabric (“blue jeans”). For a fashionable “stone-washed” look, dyestuff is partially removed from dyed fabric mechanically with plim stones or enzymatically using cellulase-laccase cocktails. Laccases degrade indigo to isatin and anthranilic acid. However, upon systematic variation of pH, dye concentration, and enzyme activity we found that under appropriate reaction conditions a different reaction pathway leads to an intensively red coloured, stable reaction product of higher molecular weight. This reaction could be used to generate a wide variety of different new colour hues directly on the fabric.