Determination of ascorbic acid in vegetables by derivative spectrophotometry

Determination of ascorbic acid (AA) in garlic, green pepper and chestnut was performed by derivative spectrophotometry without using any pre-separation or background correction techniques. The method is based on the measurement of the distances between two extremum values (peak-to-peak amplitudes) in second and third order derivative spectra of the extracts. Ten percent trichloroacetic acid was found to be the most suitable extraction solution. In the second order derivative spectrum the extrema of 253.2 and 259 nm for garlic, and in the third order derivative spectrum, the extrama of 256.4 and 261.6 nm for green pepper and chestrut samples were used for the determination of AA

Simultaneous determination of anthocyanin and ponceau 4R in drink powders by derivative spectrophotometry and partial least-squares multivariate spectrophotometric calibration

Two methods for the simultaneous determination of anthocyanin and ponceau 4R in drink powders by second derivative spectrophotometry and by partial least-squares multivariate spectrophotometric calibration are described. The procedures do not require any separation step. The methods were applied to determine both colorants in commercial gelatin powders; the results obtained are compared

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

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

(3E)-3-[(4-butylphenyl)imino]-1,3-dihydro-2H-indol-2-one

The title compound, C18H18N2O, has a non-planar conformation. The indol and butylphenyl groups are connected by a C-N bond [1.433 (3) Angstrom]. The crystal structure is stabilized by intermolecular N-H...N and C-H...O interactions

Novel isatin-Schiff base Cu(II) and Ni(II) complexes. X-ray crystal structure of bis[3-(4-hexylphenylimino)-1H-indol-2(3H)-one]-dichlorocopper(II) complex

Schiff base ligand (HL) derived from 4-hexylaniline with isatin (1H-indole-2,3-dione) and its complexes with Cu(II), Ni(II) were prepared and characterized by analytical, spectroscopic (IR, UV-Vis, Mass) techniques, electrical conductivity, magnetic and thermal measurements. The crystal and molecular structure of [Cu(HL)(2)Cl-2] was determined by a single-crystal X-ray diffraction study. The molecular structure of the title compound has an inversion center on the Cu atom