Kinetic determination of traces of iodide by its catalytic effect on oxidation of sodium pyrogallol-5-sulfonate by hydrogen peroxide.

The kinetic method is based on a catalytic effect on the oxidation of sodium pyrogallol-5-sulfonate by hydrogenperoxide. The reaction is followed spectrophotometrically at 436.8 nm. The kinetic parameters of the reaction are reported and a rate equation is suggested. The calibration graph is linear in the range 10-200 ng cm(-3). The effects of certain foreign ions upon the reaction rate were determined for the assessment of the selectivity of the method. This method has high sensitivity and good selectivity when anions are concerned as well. That is why it can be successfully applied to determination of iodide in real samples (mineral water and soil) directly after the elimination of cations, which interfere. The method was applied to determine iodide in natural waters and soil.     

石墨炉原子吸收光谱法测定碘化铯晶体中铊

采用平台石墨炉原子吸收光谱法测定了碘化铯晶体中铊。研究了碘化铯对钯－硝酸镁基本改进剂中铊吸光度影响,用预混合钯－硝酸镁和样品溶液,由于在碘化物溶液中易析出金属钯而使测定结果降低。用样品溶液和基体改进剂分别加入到石墨炉中的标准加入法可得到满意的结果。     

Determination of iodate and sulphate in iodized common salt by ion chromatography with conductivity detection

A simple, rapid and accurate method for the determination of iodate in iodized common salts has been developed. The quantitative determination of iodate was accomplished by anion exchange chromatography with conductimetric detection. The method requires a sample pretreatment for the removal of large excess of chloride from the sample matrix. Onguard silver cartridges were found most suitable for this purpose. The sulphate content in the salt was simultaneously determined. The lower limits for the determination of iodate and sulphate in solution are 0.5 and 0.05 mug ml(-1), respectively. Quantitative recovery of the anions in synthetic samples has been obtained and the interferences from different cations and anions have been studied. The method has been successfully applied to the determination of iodate and sulphate in the commercially available salts. The concentrations of iodate measured by this method are in good agreement with those claimed by the manufacturer.     

Elimination of the interferences of anions in the kinetic spectrophotometric determination of vanadium (V) solution

Accurate determination of vanadium (V) in industrial waste water is of great importance in environmental, biological and toxicological studies. Most of kinetic spectrophotometric methods based on the catalytic effect of vanadium (V), when applied to real samples for determination of trace levels of vanadium (V) lack the satisfactory sensitivity and selectivity. This may be attributed to the serious interferences of various anions which are common pollutants in industrial waste water. The oxidation of gallic acid by ammonium persulphate, catalysed by vanadium (V) was chosen for our study. The effect of the serious interferences of various anions such as chloride, bromate, bromide, chromate, iodide, iodate, molybdate, carbonate and sulphate on the net absorbance given by 4 microg l(-1) of vanadium (V) solution were studied. The minimum concentrations of citric acid, EDTA, ascorbic acid and oxalic acid as leveling off agents required to level off interfering effects due to the aforementioned anions in the kinetic determination of vanadium (V) were 50, 70, 80 and 120 microg ml(-1), respectively. In the presence of optimum concentrations of effective leveling off agents, the dynamic range can be extended and sensitivity increased as compared with the proposed method without levelling off agents. The proposed method is a rapid, sensitive and selective method for the determination of ultra trace amounts of vanadium (V) in real samples with satisfactory results.     

Investigation of A New Catalytic Reaction of Complex Formation of Cobalt (III) With Nitroso-R-Salt for the Determination of Microquantities of Phosphate-Ions

ABSTRACT

The catalytic action of phosphate-ions on the reaction of complex formation of cobalt (III) with nitroso-R-salt in a weakly acid medium has been found. The dependence of the rate of the catalytic reaction on temperature, concentrations of reagents and catalyst, pH of the medium, as well as on the presence of some anion and non-ion surface-active substances and accompanying inorganic minerals was studied. The optimum conditions for the determination of 0.1 μg/ml PO^3- ₄ in water were determined. A technique for the determination of phosphate-ion impurity up to 9×10^-5% in the high-purity sodium iodide and 2×10^-4% cesium iodide used for the single crystals growth is suggested.     

Capillary electrophoresis determinations of trace concentrations of inorganic ions in large excess of chloride: soft modelling using artificial neural networks for optimisation of electrolyte composition

In this work, using a combination of experimental design (ED) and artificial neural networks (ANN), the composition of a triethanolamine-buffered chromate electrolyte was optimised for determination of sulphate anions in the presence of high chloride excess. The optimal electrolyte, allowing a baseline-resolved separation of sulphate from chloride present in a 1500 multiple excess in less than 170 s, consists of 10 mmol/L CrO(3), 2 mmol/L hexamethonium hydroxide, 10% methanol, and triethanolamine added to adjust the pH to 8.0. The method is suitable to a wide concentration range of chloride (4-1757 mg/L) and sulphate (4-590 mg/L) with linear calibration plots (R(2) = 0.9937-0.9999). Relative standard deviations are less than 2.0% for both anions for migration times and peak areas. The detection limits (hydrodynamic injection of 1 s) were 0.6 mg/L for sulphate and 0.5 mg/L for chloride. The method was successfully applied to determination of sulphate in mineral waters containing a high chloride concentration and to determination of sulphate traces in an anticancer drug injection preparation containing a physiological level of chloride. It was shown that alpha-cyclodextrin as an electrolyte additive has a significant potential for further increasing the separation selectivity for inorganic anions.     

Determination of UV-absorbing anions in environmental samples by microcolumn high-performance liquid chromatography

The Chromatographic retention and separation of NO ₂ ^- , Br^-, NO ₃ ^- , and I^- anions on a column packed with Nucleosil 100-5 C18 dynamically modified with trimethyloctadecylammonium bromide (TMODAB) was studied using direct UV detection. A procedure was developed for the determination of the above anions in the concentration range 0.06-2500 Μg/L without preconcentration. Sample preparation involved only the elimination of organic impurities (if present) from the test sample. The procedure was used for the determination of NO ₂ ^- and NO ₃ ^- anions in Baikal Lake water and in an aerosol extract.     

Ion-chromatographic determination of iodide in sea water with UV detection

A highly sensitive and selective ion-chromatographic procedure with UV detection at 227 nm was developed for the determination of trace amounts of iodide. The procedure utilizes 0.1M NaOH as eluent, which enables the determination of 1–100 g I^–1 I^– with a precision of ca. 6%. 1000-fold amounts of other anions such as fluoride, chloride, phosphate, sulphate, bromide, nitrite and nitrate do not interfere. The method has been applied to determine iodide in sea water samples from the Indian coast.     

Direct and rapid determination of sulphate in environmental samples with diffuse reflectance Fourier transform infrared spectroscopy using KBr substrate

The feasibility of employing diffuse reflectance Fourier transform infrared spectroscopy (DRS-FTIR) as a sensitive tool in the submicrogram level determination of sulphate (SO₄²⁻) was checked in this work. This paper presents the development of a new, rapid and precise analytical method for ppb levels of sulphate (SO₄²⁻) in environmental samples like coarse and fine aerosol particles, dry deposits and soil. The determination of submicrogram levels of sulphate is based on the selection of a quantitative analytical peak at 617 cm⁻¹ among the three observed vibrational peaks and preparing calibration curve using different known concentrations of sulphate by diffuse reflectance-Fourier transform infra red spectrometric (DRS-FTIR) technique. Pre-weighed and ground IR grade KBr was used as substrate over which remarkably wide range of known concentration of sulphate was sprayed and dried. The dried sample was analysed by DRS-FTIR. Three calibration curves for three different concentration ranges of sulphate were prepared for samples containing low and relatively higher sulphate contents. The relative standard deviation (n = 8) for the sulphate concentration ranges, 2.5-35.5, 25.5-165, 55-1000 μg/0.5 g KBr, as used to prepare calibration curves, were 2.4%, 2.1% and 1.5%, respectively. The relative standard deviation for the sulphate concentration in real samples were found to be in the range, 3.11-5.76% (n = 16), 4.05-7.75% (n = 16) and 1.48-3.52% (n = 10) for aerosol, dry deposits and soil, respectively. The LOD of the method is 0.20 μg/g SO₄²⁻. The F- and t-tests were performed to check the analytical quality assurance test. The noteworthy feature of the reported method is the non-interference of any of the associated anions and cations. The results were compared with that of ion-chromatographic method with high degree of acceptability. The method can be applied in wide concentration ranges. A method for sulphate determination was introduced that did not require pretreatment of samples. This method employed the direct determination of the sulphate. The method is reagent less, nondestructive, very fast, repeatable, and accurate and has high sample throughput value.     

Determination of iodide in seawater samples by ion chromatography with chemically-bonded poly(ethylene glycol) stationary phase

An ion chromatographic method for the rapid and direct determination of iodide in seawater is reported. Poly(ethylene glycol) (PEG) groups were chemically bonded onto silica gel or C30-bonded silica gel via diol groups. PEG-bonded C30 binary phases allowed determination of iodide in seawater samples without any interference. Effects of eluent composition on retention behavior of inorganic anions have been investigated. Both cation and anion of the eluent affected the retention of analyte anions. The retention time of anions increased with increasing eluent concentration. The detection limit for iodide obtained by injecting 0.2 microl of sample was 13 microg l(-1) (S/N=3) while the limit of quantitation was 43 microg l(-1) (S/N=10). The present method was successfully applied to the rapid and direct determination of iodide in seawater with long-term durability.     

Using ratiometric indicator-displacement assays in semi-quantitative colorimetric determination of chloride, bromide, and iodide anions

A ratiometric indicator-displacement assay (RIDA) array has been developed for the semi-quantitative colorimetric determination of chloride, bromide, and iodide anions. Determinations of these halide anions follow the displacement reaction using the chelate compound of (2-(3,5-dibromo-2-pyridylazo)-5-(diethylamino)phenol) (3,5-Br2-PADAP) and heavy metal salts as colorimetric reagent. Different from regular silver nitrate titrations, the chloride, bromide, and iodide anions compete with the 3,5-Br2-PADAP ligand and change the colour of the 3,5-Br2-PADAP-metal chelate compound dramatically. These clearer colour changes make the semi-quantitative colorimetric determination of chloride, bromide, and iodide anions possible. The colour changes are imaged using a conventional flatbed scanner, and digitized. After statistical analysis, these colour changes in the RIDA array provide facile identification of chloride, bromide, and iodide anions at a wide concentration range (10 μM to 10 mM) without any misclassification. The RIDA array is able to discriminate without misclassifications among seven concentrations of chloride, bromide, and iodide anions. No shelf life issue exists because the chelating compounds react with halide anions directly without any pre-immobilizations.     

Flame AAS determination of dopants and trace metal impurities in single crystals of potassium titanylphosphate

A flame AAS method is used for the determination of dopants and impurities in potassium titanylphosphate (KTP) single crystals. Sample digestion using sulphuric acid and hydrofluoric acid is proposed as being the most appropriate procedure. The effect of major and minor components in the sample solution on the analytical signal is studied. The content of the dopants Cr, Mn and Ni (at a level of about 1 mg g(-1)) as well as the content of the impurities Fe, Na, Mg, W and Al (from 4 mug g(-1), depending on the trace metal) in the KTP single crystals is determined. The precision of the method is characterized by a relative standard deviation of 3-10%. The accuracy is checked by comparison with ICP-AES data for the trace element content in the KTP single crystals.     

Some ion-exchange resins for anion-chromatography

The quaternary ammonium salts, n-butyltrimethylammonium iodide, 1,1,3,3-tetramethylbutyltrimethylammonium iodide, n-octadecyltrimethylammonium iodide and tri-n-dodecylmethylammonium iodide were synthesized from commercially available amines and together with n-hexadecyltrimethylammonium bromide tested for retention by a series of macroreticular resins (XAD-2, XAD-4, XAD-7, XAD-8 and XAD-11) for use as "surface" ion-exchangers in the chromatography of anions. Exchange-capacity studies of the coated resins showed that the non-polar XAD-2 and XAD-4 resins had retention characteristics superior to those of the polar resins and that pore size in the resin was more important than surface area per unit weight of resin. Tri-n-dodecylmethylammonium salts in XAD-2 gave the highest exchange capacity, with best retention under elution conditions. Columns prepared from this anion-exchanger were used to separate and analyse simple mixtures of anions (chloride, nitrate and sulphate) each within the 1-30 ppm range, by single-column operation with indirect photometric detection and also by conductivity detection with background-ion suppression. Though of use for the determination of anions in simple mixtures, the resolution and performance were generally poorer than those displayed by a commercial (Dionex) column. This is at least partly attributable to the inferior column-packing properties of the granular XAD-resin.     

Determination of nitrite, sulphate, bromide and nitrate in human serum by ion chromatography

An ion chromatographic method has been developed for the determination of trace amounts of nitrite, sulphate, bromide and nitrate in human serum, using an ODS column dynamically coated with cetylpyridinium chloride. The anions studied were eluted with 1 mM citrate - 2.5% methanol (pH 6.5) as the mobile phase and detected by an ultraviolet detector. The interfering proteins in human serum were removed by an initial filtration through an ultrafilter-paper. The many inorganic and organic anions commonly found in serum had little effect on the determination of the four anions. Recoveries of nitrite, sulphate, bromide and nitrate in serum were 107-110, 94-106, 106-110 and 92-100%, respectively. The proposed method was also applied to human saliva and urine.     

Microcolumn ion chromatography of inorganic anions using bovine serum albumin stationary phase with indirect photometric detection

Summary Microcolumn ion chromatography of inorganic anions has been studied using bovine serum albumin immobilized on silica gel as a stationary phase. Several mobile phase solutions were examined, involving sodium iodide, potassium hydrogen phthalate, 2,6-anthraquinone disulfonate (2,6-AQDS) and sodium salicylate. 2,6-AQDS achieved better separation of the analytes tested. Chloride, nitrate, iodide, thiocyanate and sulphate could be separated within 8 min. Detection limits were in the range of 0.9–2.9 M, corresponding to mass detection limits of 0.18–0.59 pmol. The system was applied to the determination of inorganic anions in environmental water and biological samples.     

靛蓝胭脂红-溴酸钾体系催化光度法测定微量碘

研究了在室温及0．4mol/L H2SO4介质中碘离子对KBrO3氧化靛蓝胭脂红褪色反应的催化作用,建立了一种测定微量碘的新方法。碘离子浓度在0．20－2．0μg/mL范围内与△A呈线性关系,检测限为0．14μg/mL。多数常见离子无干扰。可用于海带中微量碘的测定。     

Analysis of chloride, bromide and iodide using miniaturised isotachophoresis on a planar polymer chip

A new method has been developed to allow the determination of the halide anions chloride, bromide and iodide using isotachophoresis. This method employs a new electrolyte system which incorporates the novel application of indium(III) as a complexing agent. This electrolyte system was devised based on the findings of an investigation into the potential for using indium(III) as a complexing counter ion to selectively manipulate the effective mobilities of halide ions. A leading electrolyte incorporating 3.5 mmol dm(-3) of indium(III) allowed the simultaneous determination of chloride, bromide and iodide to be successfully achieved. The new procedure allows such separations to be made without interference from common inorganic anions such as sulfate and nitrate. Separations were performed using a miniaturised planar poly(methyl methacrylate) chip with integrated platinum wire conductivity detection electrodes. Using this instrumentation the limits of detection were calculated to be 0.7 mg dm(-3), 1.7 mg dm(-3) and 2.2 mg dm(-3) for chloride, bromide and iodide respectively.     

Sur la thermogravimétrie des précipités analytiques : Dosage du césium

A new method of gravimetric determination. of cesium is described, based on weighing the residue [CoO + 3NO₃Cs] from the destruction, between 219o and 194o, of the hexanitritocobaltate. Study has also been made of the pyrolysis of the chloride, perchlorate, sulphate, hexachlorostannate and hexachloroplatinate. In each case there is specified the temperature range in which the salts should be heated in order that they may be determined correctly by weighing.     

Catalytic titration of iodide, bromide and thiocyanate by use of the silver catalysed phloxin-persulphate reaction

A method for the catalytic titrimetric determination of iodide, bromide and thiocyanate is described, based on the inhibitory effect of these anions on the silver-catalysed oxidation of phloxin by persulphate in the presence of 2,2'-bipyridyl. The end-point is determined photometrically by measuring the absorbance at 537 nm. Amounts of iodide, bromide and thiocyanate in the 0.01-7.94, 0.11-4.73 and 0.12-3.59mg ranges, respectively, are titrated with a relative error of about 1%.     

增效试剂在动力学分析法中的应用研究Ⅱ: 锰(Ⅱ)-氨三乙酸-十二烷基硫酸钠-高碘酸钾-罗丹明B催化体系

基于存在活化剂氨三乙酸和增敏剂十二烷基硫酸钠, 锰(Ⅱ)催化高碘酸钾氧化罗丹明B的反应, 拟定了测定痕量锰的新催化光度法。讨论了有关的反应机理。本法由于添加了表面活性剂, 灵敏度提高3.4倍。测定锰含量线性范围为10-120ng·25mL^-^1, 相对标准偏差为2.6%(n=9), 检出限为8.0×10^-^1^1g·mL^-^1。用于测定水样和酒样中锰。