In this study, four extraction technologies for the extraction of anthocyanins (Acyns) from red rose petals (RRPs) were investigated and compared, including ultrasound-assisted extraction (UAE), reflux extraction, Soxhlet extraction, and marinated extraction. UAE was the most suitable for the extraction of Acyns from RRPs because of its high extraction efficiency and short extraction time. The results showed that the best conditions for UAE are an extraction solution of ethanol-0.1 N HCl (80 + 20, v/v), a solid-to-liquid ratio of 1:40 g/mL, a temperature of 30°C, and an extraction time of 15 min performed three times. Using such conditions, 320.4 mg Acyns/100 g RRPs was extracted. UAE was followed by two new difference spectrophotometric (DS) methods, which were developed for the fast and simple determination of Acyns in RRPs. Under the optimum experimental conditions, a linear response was observed for Acyns in the range of 12.5-62.5 μg/mL for the two proposed methods, with correlation coefficients (r) ranging from 0.9988 to 0.9995. The mean recovery values of Acyns for the DS methods were in the range of 99.8-101.5%, and the RSD was 0.5%. The respective LOD and the LOQ values were 1.4 and 4.8 for DS1 and 1.1 and 3.6 μg/mL for DS2. The stability of Acyns was also studied.

Four simple, rapid, and accurate spectrophotometric methods were developed for the simultaneous determination of two food colorants, Carmoisine (E122) and Ponceau 4R (E124), in their binary mixtures and soft drinks. The first method is based on recording the first derivative curves and determining each component using the zero-crossing technique. The second method uses the first derivative of ratio spectra. The ratio spectra are obtained by dividing the absorption spectra of the binary mixture by that of one of the components. The third method, derivative differential procedure, is based on the measurement of difference absorptivities derivatized in first order of solution of drink samples in 0,1 N NaOH relative to that of an equimolar solution in 0,1 N HCl at wavelengths of 366 and 451 nm for Carmoisine and Ponceau 4R, respectively. The last method, based on the compensation method is presented for derivative spectrophotometric determination of E122 and E124 mixtures with overlapping spectra. By using ratios of the derivative maxima, the exact compensation of either component in the mixture can be achieved, followed by its determination. These proposed methods have been successfully applied to the binary mixtures and soft drinks and the results were statistically compared with the reference HPLC method (NMKL 130).

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Two simple spectrophotometric methods have been proposed for simultaneous determination of two colorants (Indigotin and Brilliant Blue) and two sweeteners (Acesulfame-K and Aspartame) in synthetic mixtures and chewing gums without any prior separation or purification. The first method, derivative spectrophotometry (ZCDS), is based on recording the first derivative curves (for Indigotin, Brillant Blue, and Acesulfame-K) and third-derivative curve (for Aspartame) and determining each component using the zero-crossing technique. The other method, ratio derivative spectrophotometry (RDS), depends on application ratio spectra of first-and third-derivative spectrophotometry to resolve the interference due to spectral overlapping. Both colorants and sweeteners showed good linearity, with regression coefficients of 0.9992-0.9999. The LOD and LOQ values ranged from 0.05 to 0.33 gmL −1 and from 0.06 to 0.47 gmL −1 , respectively. The intraday and interday precision tests produced good RSD% values (<0.81%); recoveries ranged from 99.78% to 100.67% for all two methods. The accuracy and precision of the methods have been determined, and the methods have been validated by analyzing synthetic mixtures containing colorants and sweeteners. Two methods were applied for the above combination, and satisfactory results were obtained. The results obtained by applying the ZCDS method were statistically compared with those obtained by the RDS method.

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Sumac Leaves (SL) (Rhus Coriaria L. ) were investigated as an inexpensive and effective adsorbent for the adsorption of methylene blue (MB) from aqueous solution. The effects of initial dye concentration, initial solution pH, phases contact time, and adsorbent dose on the adsorption of MB on SL were investigated. The amount of dye adsorbed was found to vary with initial solution pH, Sumac Leaves dose, MB concentration, and phases contact time. The Langmuir and Freundlich adsorption models were evaluated using the experimental data and the experimental results showed that the Langmuir model fits better than the Freundlich model. The maximum adsorption capacity was found to be 151.69 mg/g from the Langmuir isotherm model at 25°C. The value of the monolayer saturation capacity of SL was comparable to the adsorption capacities of some other adsorbent materials for MB. The adsorption rate data were analyzed according to the pseudo-first order kinetic and pseudo-second order kinetic models and intraparticle diffusion model. It was found that kinetic followed a pseudo-second order model.