Absorbance Of Iodine Research Articles

Determination and Degradation of Potassium Bromate Content in Dough and Bread Samples Due to the Presence of Metals

Potassium bromate (PB) is used in bread making as an agent of maturation; however, it is classified as a potential carcinogen. In the present study, a rapid, simple, precise and accurate testing method has been developed to determine the level of bromate ions in bread, which is based on a reaction of bromate ions with iodide ions in acidic medium to produce iodine (I2). The absorbance of iodine (I2) was measured at 352 nm, and bromate ions reacted with iodide during the first 3 minutes after initiation of the reaction. The proposed method has been successfully applied to the determination of bromate ions in commercial bread. In this work, we found that bromate ions alone degraded at about 400°C, however, during bread making they degraded at 150°C - 200°C, this mightbe due to the presence of metals [Fe, Mg, Zn, Mn, Cu and Al] in flour which served as catalysts. In this study we found that the use of two grams (2 g) of PB per bag flour (60 kg) was safe.

Teaching the Rovibronic Spectroscopy of Molecular Iodine

Molecular iodine absorbance and fluorescence spectroscopy has a long history in the undergraduate physical chemistry laboratory curriculum. A review of articles from the pedagogical literature reveals surprising variability in reported X-state and B-state potential parameters derived from such well-studied spectra. The variation is a result of errors in spectral interpretation and analysis, and this article clarifies the correct methods for treating the data. Parameters obtained from student data are compared with accepted values from the primary literature, and expectations for accuracy and precision are established. This article also points out that the internuclear separation of X-state I2 can be calculated from the spacing of an easily resolved rotational doublet in the argon ion laser-induced fluorescence spectrum. This doublet has not been identified before in pedagogical articles.

Relationship between Chain-length Distributions of Waxy Rice Amylopectins and Physical Properties of Rice Grains

Chain-length distributions of amylopectins by HPAEC-PAD from japonica and indica waxy-rice samples were characterized, and the relationship between the chain-length distributions and pasting properties of rice flour by RVA and the physical properties of cooked rice grains by Tensipresser were studied. In comparison with jaonica and indica types, the pattern of chain-length distribution of indica amylopectin typically differed, and the ratio of degree of polymerization (DP) 6-12, fa short chains of indica type was clearly lower, while the ratio of DP>13, fb1+2+3 long chains was clearly higher. The physical properties of cooked rice grains and powder pasting of the indica type showed clearly as hard type starch. There were differences in the chain-length distribution among japonica waxy-rice starches. The ratios of fb3, DP>37 for japonica waxy amylopectins were positively correlated with RVA paste viscosity parameters, such as minimum viscosity, final viscosity, pasting temperature and setback, and iodine absorbance. Iodine absorbance was negatively correlated with properties of cooked rice grains, such as overall adhered mass, L6. The results showed the possibility that the long chain portion of the amylopectin structure is a factor in regulating its starch physical properties.

Combined treatment of glatiramer acetate and low doses of immunosuppressive drugs is effective in the prevention of graft rejection

The immunomodulator glatiramer acetate (GA, copolymer 1, Copaxone, GLAT), currently used for the treatment of multiple sclerosis, is a well-tolerated drug with a high safety profile. We have previously demonstrated that GA suppresses the immune rejection manifested in graft versus host disease, as well as in graft rejection. In an attempt to reduce the dosage and toxicity of the current immunosuppressive regimens, we have now tested the ability of GA, combined with low doses of cyclosporin (CyA) or tacrolimus (FK506), to suppress the rejection of mismatched allografts across major histocompatibility barriers. We report herewith that such combination therapy was effective in several animal models: (1) it led to a significant delay of the vigorous process of skin rejection in mice, manifested by evidential prolongation in skin graft survival (higher than that obtained with at least double dose of the immunosuppressive drug alone). (2) The combined treatment led to efficient inhibition of the functional deterioration of thyroid grafts in mice, manifested by 2.2- to 20.1-fold increase in iodine absorbance of the transplanted thyroids, as compared to each drug alone. (3) Combination therapy inhibited significantly the rejection of vascularized heart transplants in rats. Thus, cardiac allograft survival following the combined treatment with GA and low dose of CyA was longer than the survival obtained by fourfold higher dose of CyA alone. In all transplantation systems, combination therapy of GA with either CyA or FK506 significantly suppressed graft rejection and was more effective than treatment with either GA or the immunosuppressive drug alone, suggesting that such treatment may be beneficial for human transplantation.

Sensitive kinetic spectrophotometric determination of captopril and ethamsylate in pharmaceutical preparations and biological fluids

A highly sensitive kinetic spectrophotometric method was developed for the determination of captopril (CPL) and ethamsylate (ESL) in pharmaceutical preparations and biological fluids. The method is based on a catalytic acceleration of the reaction between sodium azide and iodine in an aqueous solution. Concentration range of 0.1–1.5 μgml –1 for CPL and 0.3–3 μgml –1 for ESL was determined by measuring the decrease in the absorbance of iodine at 348 nm by a fixed time method. The decrease in absorbance after 5 min was markedly correlated to the concentration. The relative standard deviations obtained were 1.30 and 1.87 for CPL and ESL, respectively, in pure forms. Correlation coefficients were 0.9997 and 0.9999 for CPL and ESL, respectively. The detection limits were determined as ( S/N = 3) were 20 ngml –1 for CPL and 50 ngml –1 for ESL. The proposed procedure was successively applied for the determination of both drugs in pharmaceutical preparations and in biological fluids.

Kinetic Spectrophotometric Determination of Ranitidine

AbstractTwo spectrophotometric methods were developed for the determination of ranitidine. The first method was a kinetic spectrophotometric method based on the catalytic effect of ranitidine on the reaction between sodium azide and iodine in an aqueous solution. The calibration graph was linear from 4–24 μg/mL. The drug was determined by measuring the decrease in the absorbance of iodine at 348 nm using a fixed time method. The decrease in the absorbance after 1 minute from the initiation of the reaction was related to the concentration of drug. The detection limit of the procedure was 0.76 μg/mL. The proposed procedure was successfully utilized in the determination of the drug in pharmaceutical preparations with mean recovery in the range of 99.83 ‒ 101.16%.The second method is a colorimetric method, which depends on the measurement of absorbances of tris (o‐phenanthroline) iron(II) [method 2A] and tris (bipyridyl) iron(II) [method 2B] complexes at 512 nm. The complexes obeyed Beer's law over the concentration range of 2–16 μg/mL and 4–40 μg/mL for methods 2A and 2B, respectively. The developed method has been successfully applied for the determination of ranitidine in bulk drugs and pharmaceutical formulations. The common excipients and additives did not interfere in its determination.

Kinetic spectrophotometric determination of some sulfur containing compounds in pharmaceutical preparations and human serum

A kinetic spectrophotometric method was developed for the determination of carbocisteine, ethionamide, thioctic acid and penicillamine based on the catalytic effect on the reaction between sodium azide and iodine in aqueous solution. Ten to 100 μg ml −1 of carbocisteine and ethionamide, 0.1–1 μg ml −1 of thioctic acid and 0.01–0.1 μg ml −1 of penicillamine could be determined, respectively, by measuring the decrease in the absorbance of iodine at 348 nm by a fixed time method. The decrease in the absorbance in the first 5 min from the initiation of the reaction is related to the concentration of the drugs. The detection limits were 0.47, 0.71, 0.018 and 9.38×10 −4 μg ml −1 for the four drugs, respectively. The proposed procedure was successfully applied in the determination of these drugs in pharmaceutical preparations and human serum.

Kinetic Spectrophotometric Determination of Sulbutiamine in Pharmaceutical Preparations and in Human Serum

A kinetic spectrophotometric method was developed for the determination of sulbutiamine based on the catalytic effect on the reaction between sodium azide and iodine in an aqueous solution. Sulbutiamine at concentrations of 0.5 to 20 ¼g/ml was determined by measuring the decrease in the absorbance of iodine at 348 nm by a fixed-time method. The decrease in the absorbance in the first 5 min from the initiation of the reaction is related to the concentration of the drug. The detection limit of the procedure was 0.2 ¼g/ml. The relative standard deviation for the replicate determination (n = 10) of 4 ¼g/ml was 1.05%. The proposed procedure was successfully utilized in the determination of the drug in pharmaceutical preparations and human serum.

Evaluation of variations in amylose–iodine absorbance spectra

Evaluation of the variations in spectra of the amylose–iodine complex of starches and amyloses from various botanical sources provide a useful aid for identification and characterization of these substances. Variations in absorptivity, wavelengths of maximum absorbance, and the slopes of the absorbance peaks provide characteristic data for starches as a result of variations in amylose molecular weight. This data can be used to provide a convenient and relatively rapid means for detecting major differences, as between starches from normal and high amylose maizes, or between raw and modified starches and to evaluate effect of processing conditions.

Spectrophotometric Reaction-Rate Method for The Determination of Sulfide by Catalytic Action on the Oxidation of Sodium Azide by Iodine

Abstract A catalytic kinetic method has been used for the determination of ultra trace amounts of total dissolved sulfide based on its catalytic effect on the reaction between sodium azide and iodine in aqueous solution. Sulfide over the range of 0.020-0.500 μg.ml−1 was determined spectrophotometrically by measuring the decrease in absorbance of iodine at 348 nm by the fixed-time method. The decrease in absorbance during the first 0.5-3.0 min from initiation of the reaction is related to the concentration of sulfide. The detection limit is 0.010 μg.ml−1. The relative standard deviation for the determination of 0.050 μg.ml−1 of sulfide was 2.2%. The proposed method was successfully applied for the determination of sulfide in synthetic samples, spring water and of sulfur in steel.

Enzymatic Modification of Low Conversion Starch Products

AbstractRecently produced low conversion starch products (maltodextrins) contain relatively low level of mono‐ and disaccharides such as glucose and maltose. A study on obtaining starch hydrolyzates containing significant amounts of glucose and maltose without fundamental change of their dextrose equivalent was conducted. The influence of glucogenic and maltogenic amylases (NOVO) on low conversion starch products was investigated by measurement of their sugar composition, viscosity, filterability, iodine absorbance value and turbidity. The results show different properties of novel starch hydrolyzates depending on the enzymes used.

Kinetic spectrophotometric determination of thiobenzamides and their partition coefficients in water/1-octanol by using an iodine/azide indicator reaction

The kinetic method is based on catalysis, by thiobenzamide and/or its derivatives, of the oxidation of azide by iodine at 25°C in 0.1 M acetate buffer (pH 4.7) containing iodate, iodide and azide. Thiobenzamide and its 4-methoxy-, 4-methyl-, 4-chloro- and 4-nitro derivatives (0.5–3 μM) are determined by measuring the decrease in the absorbance of iodine at 350 nm at a fixed time (2 min). The detection limits are 0.05–0.1 μM and the relative standard deviations are <2%. The proposed method is used to determine the partition coefficients of thiobenzamide and its derivatives in water/1-octanol; the equilibrated aqueous phase was analysed.