Complementary Tristimulus Research Articles

Screened indicators in anhydrous acetic acid medium: Chromatic evaluation of their transitions

Three efficient indicators consisting of Malachite Green and a screening dye for use in anhydrous acetic acid media have been designed by use of complementary tristimulus data. The transition quality can be evaluated by plotting the relative greyness of the indicator against free perchloric acid concentration. Several bases have been successfully determined titrimetrically with use of these indicators.

Some studies on the determination of indicator transition and its use in the titration of weak basic samples

In the titration of a weak basic sample, especially in the dilute solution, the transition color of the indicator is not sharp at the equivalence point. In order to avoid the indicator error, the color transition near the equivalence point must be known accurately. The color transition of an acid-base indicator can be calculated from complementary tristimulus data. To ensure accuracy, however, the chemical stoichiometric relationships about the acid-base equilibria are considered. A general expression for determination of the equivalence point is presented and factors influencing the titration are discussed.

コンプリメンタリートリスティミュラス法を利用した混合注射液中の亜硫酸水素ナトリウムの定量

Spectrophotometric determination of sodium bisulfite in parenteral admixture was attempted by use of spectral changes due to complexation with pyridoxal phosphate. By applying complementary tristimulus method with consideration of the stability constant, the exact concentration of each chemical species in the solution could be estimated accurately. When this method was applied to Primperan ® injection, the sodium bisulfite content could be determined rapidly. The coefficient of variation (n=3) in this determination was 1.92%.

指示薬の変色率をパラメータとするアミノピリンの滴定法

Concentration of compound AB can be determined by acid base titration from Eq. 1. CAB=[CH-{(KaIND·((1-φ))/φ)+CIND·(1-φ)}]·(1+KaAB/KaIND·φ/((1-φ))) (1) CAB : molar concentration of AB, CIND : molar concentration of indicator, CH : hydrogen concentration of the solution, KaAB : acid dissociation constant of AB, KaIND : acid dissociation constant of indicator, φ : color transition ratio of indicator. In Eq. 1 value of φ can be measured by complementary tristimulus colorimetry (CTS method). Values of CH, CIND, KaAB and KaIND are determined by using an appropriate kind of method before the titration. AB can be determined by setting the values of parameter to the Eq. 1. By this principle aminopyrine (2.2-2.85g) could be determined by adding a prescribed amount of 0.5 N HCl standard solution in ±2% and by using bromphenol blue as a indicator.

The use of xanthine oxidase for a specific and sensitive fluorimetric determination of 6-mercaptopurine in serum

A specific and highly sensitive fluorimetric method was developed for the determination of 6-mercaptopurine (6MP) in serum. The method is based on the enzymatic oxidation of 6MP with xanthine oxidase to the oxypurine, followed by oxidation with acidic chromate to the corresponding 6-sulfonate. The fluorescent product has excitation and emission maxima at 330 and 400 nm, respectively. The limit of sensitivity was approximately 22 pg/ml for 6MP in water. The sensitivity limit for 6MP in serum containing azathioprine was approximately 2.2 ng/ml. The rate constants for conversion of 6MP into the final product (6-thiouric acid) and the apparent Michaelis constant were also determined by a nonlinear regression analysis based on the integrated Michaelis-Menten equation using the ultraviolet absorbance data and the simplified complementary tristimulus colorimetry.

Determination of some basic samples in anhydrous acetic acid by complementary tristimulus colorimetry.

In non-aqueous titration, the color shade at the equivalence point was decided graphically by utilizing complementary tristimulus colorimetry. It was also shown that the color shade at the equivalence point could be decided from the pKa value in aqueous solution of a weakly basic sample. Visual detection of the end-point in anhydrious acetic acid was possible when the sample concentration was higher than 10-2 M. A general expression for determination of the equivalence point is presented, and factors influencing the titration are discussed.

α-ナフトールベンゼインを指示薬とした非水滴定への簡易化コンプリメンタリー トリスティミュラス法の応用

α-ナフトールベンゼインを指示薬とした非水滴定への簡易化コンプリメンタリー トリスティミュラス法の応用

Analysis of binary mixtures of tertiary amines by measurement of the decomposition rates of .PI.-complexes with tetracyanoethylene.

A method has been developed for the determination of the fraction of a single species in a binary mixture of tertiary amines, by measurement of the pseudo first-order reaction rates for decomposition of the π-complexes with tetracyanoethylene. The initial absorbances at three wavelengths (u, v and w) and their sum in a simplified complementary tristimulus colorimetry were calculated by a numerical method. The color points of the reaction solution at the initial time were calculated, so that the fraction of as single species in a mixture of tertiary amines could be evaluated.

Relationship between the color transition and the equivalence point of methylrosaniline chloride in non-aqueous titration.

The determination of some weak bases at low concentrations was investigated photometrically in non-aqueous solvents. To ensure accuracy, the chemical stoichiometric relationship between color transition of the indicator and the equivalence point was considered. The color transition of the indicator was calculated by complementary tristimulus colorimetry, which is preferable to ordinary colorimetry when dealing with several species in solution. Theoretical titration curves of titration ratio versus color transition were drawn and compared with the experimental data. It was found that 10-2 M-10-4 M sample solution could be determined in non-aqueous solvents.

Application of simplified complementary tristimulus colorimetry to chemical kinetics in solution—II Determination of rate constants of consecutive irreversible first-order reactions

A simple but highly reproducible method based on simplified complementary tristimulus colorimetry is proposed for determination of the rate constants of two consecutive irreversible first-order reactions. For the binary system the complementary colour points can be calculated in the same manner as in conventional tristimulus colorimetry. Hence the mole fractions of the three reacting species can be calculated as a function of time. Application of the method is illustrated by the assay of xanthine oxidase with hypoxanthine.

Microionization constants of sulphonamides

The macroionization constants and thermodynamic parameters of twelve commercial sulphonamides were determined by potentiometric titration at 15°, 25° and 35° and by spectrophotometry at 25°, in aqueous solution of ionic strength 0.1 (NaClO 4). The microionization constants and the tautomeric constants (concentration ratios of zwitterion to uncharged or neutral species) were obtained according to the Edsall method combined with complementary tristimulus colorimetry. By utilizing the microionization constants, the species distribution as a function of pH were calculated for the three kinds of sulphonamides.

Differential kinetic determination of mixtures of aniline and its derivatives using N,N-dimethyl-p-phenylenediamine.

The oxidative coupling reaction between the quinonediimine (QDI) of N, N-dimethyl-p-phenylenediamine (DMPD) and aromatic amines was utilized for the simultaneous determination of binary mixtures of aniline and its derivatives by the differential reaction rate method. A mixture of oxidant and DMPD was used instead of QDI because QDI was unstable. The effects of pH and the oxidant (K3Fe (CN)6, K2Cr2O7 and their mixture) on the stability of the first oxidation product of DMPD, semiquinone (SQ), and on the equilibrium among DMPD, SQ and QDI, were investigated. The second-order rate constants of two amines reacting with QDI and the overall pseudo first-order rate constant of a mixture were determined from the slope of the straight line (the concentration of SQ vs. time) and by simplified complementary tristimulus colorimetry. Mixtures of amines down to 1.0×10-4M were determined. Most relative errors were in the range of 0 to 14%. Among the compounds examined for interference, phenols and carbonyl compounds showed serious effects.

A statistical method for the determination of serum uric acid.

A sensitive and accurate UV-assay procedure based on multiple linear regression analysis (MLR method) was developed for the measurement of uric acid with uricase. The absorbance at 290 nm of uric acid as a function of time was calculated from the color points of a mixture of uric acid, an intermediate (1-carboxy-2, 4, 6, 8-tetraazabicyclo [3.3.0] octa-4-ene-3, 7-dione) and the final product (allantoin) by the simplified complementary tristimulus colorimetry (SCTS method). The MLR method allowed the evaluation of both initial and final absorbances at the same wavelength with high accuracy. The average recovery of uric acid added to an aqueous solution was 99.9±0.02%, and the coefficient of variation was less than 3% (n=4) even at low concentration. The assay could also be performed directly on serum samples without deproteinization. An average recovery of 103.1±0.7% was obtained for 0.17-1.33 mg/dl of uric acid in serum solutions, and the coefficients of variation of 0.32 mg/dl and 0.41 mg/dl were 1.6% (n=4) and 2.4% (n=4), respectively.

Studies on an application of the complementary tristimulus colorimetry using the internal standard to the dissolution test of tablet (author's transl)

Complementary Tristimulus Colorimetry (CTS) was applied in dissolution tests of multi-ingredient tablets. In the test, internal standards were used for improved accuracy. Two kinds of internal standard situations were studied, in one, the absorption spectra of tablet components and the internal standard overlapped, and in the other, they did not. In the latter situation, carbazochrome sodium sulfonate, and in the former, chloperastine hydrochloride was used as the internal standard for the dissolution test of EA tablets which contained aspirin and ascorbic acid. Our results indicate that the internal standard method is useful in the dissolution test.

Application of simplified complementary tristimulus colorimetry to chemical kinetics in solution—I Analysis of reaction mixtures and determination of first- or pseudo first-order rate constants

A graphical method is described which allows estimation of the number of reacting light-absorbing species from the plots of complementary colour points which are obtained with the use of simplified complementary tristimulus colorimetry (SCTS method) from absorption spectra of a series of kinetics solutions. It is shown that the mole function of the reactant or the product at any time can be calculated from the complementary colour points, so that the rate constant can also be determined. The present method has some advantages over the common approach to the determination or reaction rates in presence of a colour impurity.

Indirect Micro-determination of Primary and Secondary Amines by Copper (II)-catalyzed Oxidation of Pyrocatechol Violet

An indirect method is described for the micro-determination of primary and secondary amines in the presence of tertiary amine by means of a catalytic indicator reaction. The copper bis (dithiocarbamate) complex formed from primary or secondary amine and carbon disulfide in the presence of copper was removed by extraction into chloroform. The remaining copper in aqueous solution was determined by measuring the rate of oxidation of pyrocatechol violet by hydrogen peroxide. A simplified complementary tristimulus colorimetry (SCTS method) was used for determination of the reaction rates, since it has the advantage of permitting accurate determination of the rate constants in the presence of color impurities. Quantitative recoveries were obtained of microamounts of primary and secondary amines with good accuracy (from -2.9% to +2.9% error). The method presented is sensitive and does not require a separate calibration curve for each primary and secondary amine.

Microscopic acid dissociation constants of 3,4-dihydroxyphenylbutyric acid and 3,4-dihydroxybenzoic acid.

The two phenol ionizations of 3, 4-dihydroxyphenylbutyric acid and 3, 4-dihydroxybenzoic acid were studied by detailed potentiometric titration and complementary tristimulus colorimetric method (CTS method). The thermodynamic parameters were calculated from the dissociation constants. From a comparison of the related compounds of 3, 4-dihydroxyphenylbutyric acid, it was indicated that the effect of carboxylate group on the dissociations of two phenol groups was not present when more than two methylene groups were introduced between benzene ring and carboxylate group. The microscopic acid dissociation constants of 3, 4-dihydroxyphenylbutyric acid and 3, 4-dihydroxybenzoic acid were calculated by two different methods. In Method A, the dissociation constants of 3-methoxy-4-hydroxyphenyl derivatives were used as substituted values. Method B is a modification of Edsall method. There were no effect of carboxylate group on the tautomeric constants when more than one methylene group are introduced between benzene ring and carboxylate group.

Studies on an application of the complementary tristimulus colorimetry to the dissolution test of multi-ingredient tablet (author's transl)

Complementary Tristimulus Colorimetry (CTS method) which has the advantage of simultaneous determination of several components, was applied to the dissolution test of tablets. The test (National Formulary Method) was performed on EA tablets which contain two and Tridocelan tablets which contain three components. Our data indicated that the CTS method is useful in dissolution tests for each tablet component.

Coloration and photolytic degradation of some sulfonamide tablets under exaggerated and ordinary ultraviolet irradiation.

Five sulfonamide tablets, those of sulfaphenazole, sulfadimethoxine, sulfisomidine, sulfisoxazole, and sulfamethizole, were exposed to exaggerated and ordinary ultraviolet (UV) rays for stability studies in the solid state, and the relationship between coloration stability and chemical degradation was investigated. The color change of tablet surface was measured by colorimetric method. Sulfisoxazole and sulfamethizole were photostable in coloration, and sulfadimethoxine was eventually not colored contrary to what was stated in the Pharmacopeia of Japan. Photosensitive similarity between exaggerated and ordinary exposure was not established in coloration. Photolytic degradation was examined spectrophotometrically and crystallographically. Interesting absorption changes were observed in UV spectra, whereas no apparent changes in either infrared spectra or X-ray diffraction patterns. These evidences were discussed in relation to the results obtained by the complementary tristimulus colorimetry using the UV absorption data. For all the sulfonamides, evident correlation did not exist between coloration and photolytic degradation.

Microscopic acid dissociation constants of 3,4-dihydroxyphenethylamine (dopamine).

The acid dissociation equilibria in aqueous solution of dopamine were determined by potentiometry and complementary tristimulus colorimetry (CTS method), at 25°and μ=0.1 (NaClO4). From these data, microscopic equilibrium constants were calculated by the use of the substitution method. At physiological pH region (pH 7.2-7.4), dopamine is present as an ammonium species (I), and at pH 9.75 as zwitter-ionic species, (III) and (IV) in about 30% and 20%, respectively. The concentration of mono-phenolate anionic forms, (V) and (VI), are about 40% and 30%, respectively, at pH 11.0.