Validated Spectrophotometric Methods for Simultaneous Determination of Food Colorants and Sweeteners

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 μgmL−1 and from 0.06 to 0.47 μgmL−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

Simultaneous determination of ascorbic acid and caffeine in commercial soft drinks using reversed-phase ultraperformance liquid chromatography

AbstractA new reversed-phase ultraperformance liquid chromatography method with a photodiode array detector was developed for the quantification of ascorbic acid (AA) and caffeine (CAF) in 11 different commercial drinks consisting of one energy drink and 10 ice tea drinks. Separation of the analyzed AA and CAF with an internal standard, caffeic acid, was performed on a Waters BEH C18 column (100 mm × 2.1 mm, 1.7 μm i.d.), using a mobile phase consisting of acetonitrile and 0.2M H3PO4 (11:89, v/v) with a flow rate of 0.25 mL/min and an injection volume of 1.0 μL. Calibration graphs for AA and CAF were computed from the peak area ratio of AA/internal standard and CAF/internal standard detected at 244.0 nm and 273.6 nm, respectively. The developed reversed-phase ultraperformance liquid chromatography method was validated by analyzing standard addition samples. The proposed reversed-phase ultraperformance liquid chromatography method gave us successful results for the quantitative analysis of commercial drinks containing AA and CAF substances

Simultaneous determination of dazomet and propanil by partial least squares (PLS-2) and zero-crossing derivative spectrophotometry methods

Multicomponent analysis has become one of the most appealing topics for analytical chemists in the last few years. In recent years Partial Least Squares multivariate spectrophotometric calibration (PLS-2) and derivative spectrophotometry have been widely used for the resolution of binary and ternary mixtures and satisfactory results were reported. A simple and fast spectrophotometric method is proposed for the simultaneous determination of Propanil (P), and Dazomet (D) by means the partial least square treatment of the spectrophotometric absorbance data between 200 nm and 320 nm, taken at 5 nm intervals. The method involves the use of 9 standard mixtures of two compounds assayed, considered at three concentration levels and the measurement of the absorbance of samples in 75% ethanol in water solution. A computer program for PLS-2 was written according to the algorithm given by Marten and Naes. For the comparison of the results derivative spectrophotometric procedure (Zero-crossing technique) was used. In this method the D content was determined from the second derivative spectrum by measuring the signal at 284 nm (D-2(284)) (Zero-crossing point for P) and by using appropriate calibration graph. The P content was determined in the same way by measuring the signal at D-2(256.1) (Zero-crossing point for D). Calibration graphs were obtained between 2.0-6.0 mu g.ml(-1) for P and between 3.0-9.0 mu g.ml(-1) for D. When we used first derivative spectrum by measuring the signal at 262.5 nm and 286.9 nm for P and D respectively, we could measure 0.2-1.0 mu g.ml(-1) and 0.5-2.5 mu g.ml(-1) concentration level of D and P. The methods were checked by applying them to the analysis of laboratory prepared mixtures over the concentration ranges 2.0-6.0 for P, and 3.0-9.0 mu g.ml for D

Nickel(II) and copper(II) complexes of Schiff base derived from isatin with 4-ethylaniline

Ni(II) and Cu(II) complexes of Schiff base ligand derived from 4-ethylaniline with isatin (1H-indole-2,3-dione) were prepared. The chemical structures were confirmed by means of analytical and spectroscopic (IR, UV-Vis, FAAS, Mass) techniques as well as magnetic and thermal measurements. The complexes have 1 : 2 metal : ligand ratios and are paramagnetic. The IR spectra indicate that the ligand coordinates as bidentate through metal(II) ions via the carbonyl oxygen and the azomethine nitrogen. The complexes with the molecular formula [Cu(HL)(2)Cl(2)]. [Ni(HL)(2)]Cl(2) are nonelectrolyte and I : 2 electrolyte, respectively. Solid state conductivities of synthesized compounds were measured using four-probe technique on a compressed pellet at room temperature. The ligand and Ni(II), Cu(II) complexes were studied potentiometrically in different aqua-organic solvent mixtures and temperatures. Protonation constants of the ligand and overall formation constants of the complexes were calculated from potentiometric data using the program TITFIT

Simultaneous determination of dazomet and propanil by partial least squares (PLS-2) and zero-crossing derivative spectrophotometry methods

Multicomponent analysis has become one of the most appealing topics for analytical chemists in the last few years. In recent years Partial Least Squares multivariate spectrophotometric calibration (PLS-2) and derivative spectrophotometry have been widely used for the resolution of binary and ternary mixtures and satisfactory results were reported. A simple and fast spectrophotometric method is proposed for the simultaneous determination of Propanil (P), and Dazomet (D) by means the partial least square treatment of the spectrophotometric absorbance data between 200 nm and 320 nm, taken at 5 nm intervals. The method involves the use of 9 standard mixtures of two compounds assayed, considered at three concentration levels and the measurement of the absorbance of samples in 75% ethanol in water solution. A computer program for PLS-2 was written according to the algorithm given by Marten and Naes. For the comparison of the results derivative spectrophotometric procedure (Zero-crossing technique) was used. In this method the D content was determined from the second derivative spectrum by measuring the signal at 284 nm (D-2(284)) (Zero-crossing point for P) and by using appropriate calibration graph. The P content was determined in the same way by measuring the signal at D-2(256.1) (Zero-crossing point for D). Calibration graphs were obtained between 2.0-6.0 mu g.ml(-1) for P and between 3.0-9.0 mu g.ml(-1) for D. When we used first derivative spectrum by measuring the signal at 262.5 nm and 286.9 nm for P and D respectively, we could measure 0.2-1.0 mu g.ml(-1) and 0.5-2.5 mu g.ml(-1) concentration level of D and P. The methods were checked by applying them to the analysis of laboratory prepared mixtures over the concentration ranges 2.0-6.0 for P, and 3.0-9.0 mu g.ml for D

Four Derivative Spectrophotometric Methods for the Simultaneous Determination of Carmoisine and Ponceau 4R in Drinks and Comparison with High Performance Liquid Chromatography

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)