Iodate Method Research Articles

Studying the Quality of Micromixing in a Single-Stage Microreactor with Intensively Swirled Flows

The work considers the results of experimental and numerical study on the hydrodynamic characteristics of a jet vortex reactor mikro-VSA-1, for which one of the application fields is the synthesis of oxide materials (e.g., perovskite-like material for solar panels). The energy-dissipation rate and micromixing quality are studied (by the iodide–iodate method) for various methods of supplying micro-VSA-1 and T-shaped millireactors with solutions. Numerical modeling reveals the volumes with the highest energy-dissipation rate. The quality of micromixing in the micro-VSA-1 is shown to be much higher than in the T-shaped millireactor, due to, among other things, the fact that the zone with the highest energy-dissipation rate is localized near the neck of the micro-VSA-1.

Wijs, Potassium Iodate, and AOCS Official Method to Determine the Iodine Value (IV) of Fat and Oil

Fatty acid, present in edible oil, is a key constituent in our diet. The iodine number is a measure of the amount of unsaturated fatty acid in fat and oil. Iodine is a trace element that is required by humans for normal biological function. The iodine value (IV) of four edible oils was determined in this study: castor oil, peppermint oil, almond oil, and coconut oil. Iodine is a wonderful reagent for converting the unsaturation into the saturation of fat and oil. The purported technique offered a reliable and rapid determination of IV. The Wijs, or iodine monochloride, potassium iodate, and American Oil Chemists' Society's (AOCS) Fourier transform infrared spectroscopy (FT-IR) are all used to determine IV. Both Wijs and potassium iodate are iodometry-based titrations, whereas the AOCS method is applied through FT-IR. C=C stretching in the range of 1635.48cm-1-1652.77 cm-1, C=O band in the range of 1744.23 cm-1- 1747.49 cm-1, C-H stretching in the range of 2923.9 cm-1- 2925.85 cm-1, O-H stretching in the range of 3448 cm-1- 3472 cm-1 were observed in different dilution for identification of unsaturated fatty acid in numerous oils through FT-IR. All methods are satisfactory; meanwhile, the potassium iodate method is safer than the Wijs method experimentally and more economical than the AOCS method. IV for castor oil, peppermint oil, almond oil, and coconut oil were computed at 84.67 I2/100g,5.56 I2/100gm,99.09 I2/100gm,8.21 I2/100gm along with the deviation by three methods.

An improved model for interpretation of micromixing experiment with iodide–iodate method and sulphuric acid

The Villermaux–Dushman test reaction for micromixing characterization has been used by many researchers to investigate homogeneous mixing systems. Due to the complexity of the iodine-forming reaction, the strong effect of ionic strength of reaction medium on its reaction rate constant, as well as the dependence of the sulfuric acid dissociation on its concentration, the kinetic model of the iodide/iodate test reaction with sulfuric acid is complicated. Therefore, a quantitative evaluation of such a test reaction is challenging and remains an open problem. In this paper, the pH of the sulfuric acid solutions with different values of ionic strength is investigated using the model of Pitzer. The numerical results of the simulation are compared with the experimental data and good agreement is obtained. It is also shown that simple equilibrium calculations for sulfuric acid do not give correct pH results when the ionic strength of its solution is increased by the addition of sulfate salts. However, such an assumption yields satisfactory results for the cases without additional salt and with an acid concentration lower than 0.2 M. Finally, the engulfment model of micromixing using activities to calculate proton concentrations is applied to analyze the experimental results from previous papers employing the iodide/iodate method.

Analytical monitoring of sodium borohydride

Sodium borohydride (NaBH4) determination, both qualitative and quantitative, is of great significance in a plethora of areas. These include NaBH4 for energy systems such as direct borohydride fuel cells and in hydrogen production and storage, as well as use as a reducing agent in organic and inorganic synthesis reactions or in electrodeposition processes. Herein the main methods for NaBH4 monitoring have been summarised and described, including hydrogen evolution, hydride hydrolysis and iodate methods, and different electrochemical and spectroscopic techniques overviewed.

A specific method of assay of strong solutions of benzalkonium chloride and other quaternary ammonium germicides.

Abstract A method of assay of quaternary ammonium germicides in strong solutions or concentrated solid form is described. It can be used for solutions down to about 1 per cent in content. A known excess of iodide is added to the sample solution and the quaternary ammonium iodide is removed by shaking with chloroform. The excess iodide is titrated by an iodate method. When the chloroform extraction is made from a slightly alkaline solution only quaternary ammonium compounds are measured; if it is made from a slightly acid solution, non-quaternary cationic amine impurities are also included. The difference between assay results obtained from acid and alkaline extractions represents the non-quaternary amine content.

Characterization of mixing in a hollow fiber membrane contactor by the iodide–iodate method: Numerical simulations and experiments

Abstract This paper presents numerical simulations and experimental data on the iodide–iodate reaction in a hollow fiber membrane device. The principle of reactive mixing in a membrane device is the following. Component A flows through the inlet of the lumen side and component B comes from the membrane pores (shell side). Components A and B then mix and react inside the lumen side. Experimental measurements of the segregation index were carried out under various experimental conditions and for two different hollow fiber devices. The numerical and experimental segregation indexes, X S , were found in the range 10 −2 –10 −3 , indicating effective mixing. The numerical simulations showed that I 3 − ions were produced mainly in the first part of the lumen side of the hollow fiber. This confirmed our previous results on precipitation which showed that high supersaturation data and experimental fouling were obtained in this part of the hollow fibers.

The iodide iodate method to characterize microstructured mixing devices

AbstractThe iodide iodate method (also known as Villermaux method) was used to characterize multilamination‐type mixers, manufactured at the Institute for Micro Process Engineering of the Forschungszentrum Karlsruhe. Mixing sensitive results were obtained using different reactant concentrations. It is shown that the experimentally obtained data cannot be treated as quantitative data in sense of a “mixing quality.” © 2008 American Institute of Chemical Engineers AIChE J, 2008

Spectrophotometric study of the reaction mechanism between DDQ as π-acceptor and potassium iodate and flucloxacillin and dicloxacillin drugs and their determination in pure and in dosage forms

Two simple and accurate spectrophotometric methods are presented for the determination of β-lactam drugs, flucloxacillin (Fluclox) and dicloxacillin (Diclox), in pure and in different pharmaceutical preparations. The charge transfer (CT) reactions between Fluclox and Diclox as electron donors and 2,3-dichloro-5,6-dicyano- p-benzoquinone (DDQ) π-acceptor and potassium iodate via oxidation reduction reaction where the highly coloured complex species or the liberated iodine have been spectrophotometrically studied. The optimum experimental conditions have been studied carefully. Beer's law is obeyed over the concentration range of 2–450 μg ml −1 for Fluclox and 10–450 μg ml −1 for Diclox using DDQ reagent and at 50–550 μg ml −1 for Fluclox and 50–560 μg ml −1 for Diclox using iodate method, respectively. For more accurate results, Ringbom optimum concentration range is calculated and found to be 6–450 and 15–450 μg ml −1 for Fluclox and Diclox using DDQ, respectively, and 65–550 and 63–560 μg ml −1 for Fluclox and Diclox using iodine, respectively. The Sandell sensitivity is found to be 0.018 and 0.011 μg cm −2 for DDQ method and 0.013 and 0.011 μg cm −2 for iodate method for Fluclox and Diclox, respectively, which indicates the high sensitivity of both methods. Standard deviation (S.D. = 0.01–0.80 and 0.07–0.98) and relative standard deviation (R.S.D. = 0.13–0.44 and 0.11–0.82%) ( n = 5) for DDQ and iodate methods, respectively, refer to the high accuracy and precision of the proposed methods. These results are also confirmed by between-day precision of percent recovery of 99.87–100.2 and 99.90–100% for Fluclox and Diclox by DDQ method and 99.88–100.1 and 99.30–100.2% for Fluclox and Diclox by iodate method, respectively. These data are comparable to those obtained by British and American pharmacopoeias assay for the determination of Fluclox and Diclox in raw materials and in pharmaceutical preparations.

A modified method for determining protein binding capacity of plant polyphenolics using radiolabelled protein.

A modified radiochemical protein binding method for determining the protein binding capacity of plant polyphenolics (tannins) is described. Purified tannin or unfractionated plant extracts were immobilised on filter paper discs and incubated with the 125I-labelled bovine serum albumin. Protein bound to the disc was proportional to the amount of tannin applied to the disc, although at high concentrations of polyphenolics the discs became saturated and the relationship was no longer applicable. The method was validated using purified procyanidin from Sorghum grain and has been applied to crude polyphenolic extracts from maple, white oak, black oak, walnut and tulip poplar leaves. Specific chemical assays for the determination of proanthocyanidins (acid butanol method) and hydrolysable tannins (modified potassium iodate method) were employed to validate the new protein binding method with the complex plant extracts.

The loading capacity of selected cation exchange resins and activated carbons for gold-thiourea complex

The loading capacities of several types of cation exchange resin and activated carbon for gold-thiourea complex has been evaluated. The maximum loading capacity after 96 hours at ambient temperature (22°C) ranged from 189 to 243 kg Au/t for the cation exchange resins and 159 to 208 kg Au/t for the activated carbons. These values are higher than the capacity values reported by previous investigators. The capacity data were used to generate equilibrium loading isotherms based on the Langmuir and Freundlich models to determine the isotherm equilibrium constants. Some major problems associated with the thiourea system for gold recovery are discussed. They include (i) analytical procedure for the determination of thiourea in solution, (ii) autodecomposition of thiourea, (iii) stabilization of thiourea and (iv) flame AAS for determination of gold in thiourea solutions. The potassium iodate method was found to be better suited than the mercuric nitrate method for the determination of thiourea in solution. Autodecomposition of thiourea was slowed down considerably by the addition of reducing agents such as cysteine. An effective procedure for the use of flame AAS to determine gold in thiourea solutions is recommended.

A rapid air titration method for determining SO2 concentration in inhalation chambers.

A rapid air titration method for determining SO2 concentration in inhalation chambers has been validated using the pararosaniline-formaldehyde (PRA) method of West and Gaeke. This air-titration (iodate) method is an adaptation of iodometric methods using a starch indicator. Potassium iodate and an excess of potassium iodide are used in the reaction. Sampling is completed in ten minutes or less and concentration is calculated by use of a simple formula. Linear equations were derived over the range of concentrations from 0.5 to 100 ppm SO2 for uncorrected iodate bubbler results, data corrected for tandem bubbler concentrations and data corrected for mean iodate bubbler efficiency. Linear correlation with the PRA method over this range was 0.999 for all three sets of data.

125I]Diiodoinsulins: Binding Affinities, Biologic Potencies, and Properties of their Decay Products

Insulin was iodinated with 0.3-0.4 mol 125I/mol insulin using the lactoperoxidase method. About one-third of the radioactivity incorporated into insulin was in diiodoinsulins and about 40% of these molecules contained diiodotyrosine in residue 14 of the A chain. Most of the remaining molecules contained one A14-monoiodotyrosine and one monoiodotyrosine in either position A19, B16, or B26. The binding affinity and biologic potency of this heterogeneous diiodoinsulin preparation was not significantly different from that of A14-[125I]monoiodoinsulin in rat adipocytes, whereas it was slightly reduced in hepatocytes and IM-9 lymphocytes. From the iodine distribution and previous data on the binding affinity of each of the four monoiodoinsulin isomers it was calculated that A14-diiodotyrosine-insulin possesses full binding affinity and biologic potency in adipocytes. Diiodoinsulins isolated from another iodoinsulin preparation (iodate method) contained 58% A19-diiodotyrosine-insulin, and most remaining molecules contained one A19-monoiodotyrosine. The binding affinity of this mixed diiodoinsulin preparation was approximately one-fourth of that of A14-monoiodoinsulin in adipocytes, IM-9 lymphocytes, and hepatocytes. It was calculated that A19-diiodotyrosine-insulin is nearly devoid of binding affinity. The diiodoinsulins (lactoperoxidase method) decayed to iodide (probably from diiodotyrosine-insulin) or to polymers with little specific but a markedly increased nonspecific binding. In addition, the polymers had a marked tendency to adsorb to cellulose acetate filters. 1. The binding affinities of diiodoinsulins range from very low values to values at least as high as that of insulin depending on the positions of the iodine moieties. 2. The relative binding affinities vary among tissues. 3. Polymeric decay products give high nonspecific binding.

Adrenal homologue inScardinius erythrophthalmus(Teleostei, Cyprinidae): light and electron microscopic observations

Abstract The adrenal homologue of Scardinius erythrophthalmus, a freshwater cyprinid, is located in the head kidney and is composed of interrenal and chromaffin cells. Both types of cells are near the renal blood-vessels and in the lymphoid tissue. Employing the dichromate and iodate method, or glutaraldehyde + dichromate and glutaralde-hyde followed by dichromate, adrenaline and noradrenaline cells can be differentiated. The percentage of adrenaline cells is higher. Furthermore, the chromaffin cells are more numerous in the right kidney. The ultrastructure of chromaffin cells confirms the presence of two main types: noradrenaline and adrenaline cells. Noradrenaline cells are characterized by highly electron dense granules (average diameter 200 nm). In the adrenaline cells are granules of low electron density (average diameter 130 nm) and also clear vesicles, in diameter 50–70 nm, isolated or in groups. The chromaffin cells are richly innervated and the nerve endings are cholinergic. The interrenal cells are positive to Sudan Black B. At E.M. level these cells display mitochondria with tubulovesicular cristae, a network of smooth endoplasmic reticulum, a few cisternae of rough endoplasmic reticulum, some free ribosomes and polysomes, and a scarcity of liposomes. These histochemical and morphological data are discussed.

The Iodometric Determination of P(III) in Flame Retardants for Cotton

Three iodometric methods have been investigated for the determination of P(III) in cotton fabrics finished with THPOH/ammonia resins. The iodine method developed previously for Thpc/amide resins gives P(III) values that are much too high. The iodate method gives P(III) values that are too low or too high, depending on whether the cotton substrate is present or absent during the titration of the excess iodate. The preferred method is the peroxide method, which gives P(III) values that do not, within the limits of experimental error, vary with time or disposition of the cotton substrate. When applied to Thpc/amide resins, the peroxide method shows good agreement with the iodine method. The behavior of key resin precursors toward these oxidants has also been investigated.

Polarographic microdetermination of sulphur in organic compounds after oxygen flask combustion

Three polarographic micro-methods are described for the determination of sulphur in organic compounds after oxygen-flask combustion. The products are converted into sulphuric acid by oxidation with hydrogen peroxide, the excess of which is expelled through boiling. The methods are based upon allowing the sulphuric acid to react with an excess of barium iodate or bromate, then recording polarographically the cathodic reduction wave of the iodate or bromate ion. The bromate methods are superior to the iodate method being simpler and more rapid, and the results are correct to within ca. ±0.5%.

The microdetermination of soluble iodides in biological fluids

A modified titrimetric method for the microdetermination of soluble iodides, e.g., potassium iodide or sodium iodide is described. The mechanism of the reaction between N-bromosuccinimide and potassium iodide in aqueous solution is discussed. The determination is done within the range from 10 mg to 50 μg for soluble iodides. The experimental error does not exceed ±2%. Comparative analysis of potassium iodide by the proposed method and the official potassium iodate method is reported. The method has been applied to determine potassium iodide in biological fluids within the limits of 10 to 1 mg giving satisfactory results.

The microdetermination of soluble iodides with N-bromosuccinimide

Abstract A new titrimetric method for the microdetermination of soluble iodides e.g., potassium iodide or cadmium iodide is described. The mechanism of the reaction in the presence of dilute hydrochloric acid is discussed. The determination is done within the limits of 20 mg to 50 μg for potassium iodide and from 15 to 1 mg with cadmium iodide. The experimental error does not exceed ±2%. Comparative analysis of potassium iodide by the proposed method and the official potassium iodate method is reported. The method has been applied successfully to determine potassium or sodium iodide in certain pharmaceutical preparations.

Oxidimetric determination of sulphides

Hypoiodite oxidises sulphides much more rapidly than does iodate under comparable experimental conditions. A procedure is reported for the determination of soluble and insoluble sulphides by oxidation to sulphate with hypoiodite. This is an improvement over Bethge's iodate method.

Microdetermination of Chloride in Blood Plasma and Cells, by Spectrophotometric Analysis Using Solid Silver Iodate

Abstract As an extension of the silver iodate method of Sendroy, a convenient, reproducible, and sensitive method for analysis of chloride in 0.02-ml. samples of serum, whole blood, or red cells is described. The procedure involves (1) preparation of a protein-free filtrate of the sample, (2) Agl03 reaction with the filtrate, and (3) spectrophotometric analysis of iodine as the quantitative measure of the amount of iodate exchanged for chloride. Conditions important for each of these steps have been investigated. A precision of ± 0.85 (S.D.) mM CI per liter has been found for this method, the results of which are within 1% of those obtained by the macro nitric acid digestion method of Van Slyke.

Volumetric iodate method for the determination of thiocyanate

Direct titration of thiocyanate with standard potassium iodate solution is found to yield accurate results in a final hydrochloric acid concentration regulated between 1.5 and 3 N. The end-point is determined either potentiometrically or with carbon tetrachloride indicator.