Indirect spectrophotometric determination of micro-amounts of Tin(II) in the presence of Tin(IV) and in dental gels.

A method for determining microgram amounts of tin(II) in synthetic samples containing tin(IV) and in dental gels has been developed. The procedure involves the oxidation of tin(II) with iron(III) in hydrochloric acid and spectrophotometric determination of the resulting iron(II) as a FerroZine complex.     

十二烷基硫酸钠—水杨基荧光酮痕量锡的光度测定

提出一种高选择性、高灵敏度吸光光度测定痕量锡的方法。试验表明阴离子表面活性剂十二烷基硫酸钠具有特殊的选择性,在十二烷基硫酸钠的存在下,锡与水杨基荧光酮在强酸性介质中形成高灵敏度的三元配合物,常见干扰离子均不发生类似的显色反应,具有很高的选择性,不需分离可直接测定钢铁样品中的痕量锡。     

Preconcentration and selective determination of traces of tin in natural waters

A combined preconcentration-photometric determination technique has been worked out for trace concentration of tin in fresh and sea waters. After refluxing the sample acidified to 1M HCl for 2 h, tin is preconcentrated by anion-exchange in the presence of thiocyanate and recovered by elution with dilute HNO₃. Tin is then generated as stannane, caught in permanganate solution, and determined spectrpphotometrically with phenylfluorone. The results are quoted on the determination of tin in several fresh and sea waters in the order of submicrogram of tin per litre. The results for tin are in good agreement with those obtained for these samples by manganese dioxide coprecipitation-hydride generation-phenylfluorone spectrophotometric method that is also newly developed.     

A rapid extractive spectrophotometric method for the determination of tin in canned foods with 5,7-dichloro-8-quinolinol

A rapid method for the spectrophotometric determination of tin in canned foods, based on formation of the binary Sn(IV)-5,7-dichloro-8-quinolinol complex and extraction into chloroform has been developed. The absorption maximum at 390nm ( = 1.26 x 10(4) l.mole(-1).cm(-1)) is used for the determination. Beer's law is obeyed up to 6mug of tin per ml. Organic matter is destroyed by digestion with acid. Potential interferences have been studied. The detection limit for tin is 2.5mg kg .     

A spectrophotometric study of the reaction of tin with bromopyrogallol red in the presence of cetylpyridinium bromide

A sensitive spectrophotometric method for determining tin in the range 0.04–0.8 μg ml^-1 has been developed on the basis of a detailed study of the colour reaction of tin with bromopyrogallol red in the presence of cetylpyridinium bromide. The method proved satisfactory for various industrial and natural samples. The kinetics of the reaction and the mechanism of the influence of cetylpyridinium bromide are discussed.     

Determination of platinum and iridium in reforming catalysts by second derivative and absorptiometric spectrophotometry

Summary Investigations on the spectrophotometric determination of platinum as a complex formed by tin(II)chloride in hydrochloric acid are reported. The determination of platinum was found to be interfered with by iridium, because it also forms a complex with tin(II) chloride. The features of the derivative absorption spectrophotometry for the quantitative determination of platinum and iridium was also studied. The analytical application of the method for the determination of platinum and iridium in catalysts was investigated.     

Determination of total tin in geological materials by electrothermal atomic-absorption spectrophotometry using a tungsten-impregnated graphite furnace

An electrothermal atomic-absorption spectrophotometric method is described for the determination of total tin in geological materials, with use of a tungsten-impregnated graphite furnace. The sample is decomposed by fusion with lithium metaborate and the melt is dissolved in 10% hydrochloric acid. Tin is then extracted into trioctylphosphine oxide-methyl isobutyl ketone prior to atomization. Impregnation of the furnace with a sodium tungstate solution increases the sensitivity of the determination and improves the precision of the results. The limits of determination are 0.5-20 ppm of tin in the sample. Higher tin values can be determined by dilution of the extract. Replicate analyses of eighteen geological reference samples with diverse matrices gave relative standard deviations ranging from 2.0 to 10.8% with an average of 4.6%. Average tin values for reference samples were in general agreement with, but more precise than, those reported by others. Apparent recoveries of tin added to various samples ranged from 95 to 111% with an average of 102%.     

Spectrophotometric determination of tin(IV) by extraction of the ternary tin/iodide/5,7-dichloro-8-quinolinol complex

The characteristics of the ternary complexes formed by fluoride, bromide, iodide and thiocyanate with tin(IV) and 5,7-dichloro-8-quinolinol (HCQ) have been studied. A spectrophotometric method is proposed for the determination of tin(IV) (1–20 μg ml^?1), based on the extraction into chloroform of the tin/iodide/HCQ complex. Aluminium, bismuth and lead do not interfere, but antimony, copper, iron(III) and fluoride do. Copper and iron can be eliminated by preliminary extraction in the absence of iodide.     

A rapid hydride-evolution electrothermal atomic-absorption method for the determination of tin in geological materials

A rapid, semi-automated electrothermal atomic-absorption spectrophotometric method involving lithium metaborate fusion and hydride evolution has been developed for the determination of tin in geological materials. The sample is fused with lithium metaborate and brought into solution with hydrochloric acid: the tin in the solution is then converted into its hydride with sodium borohydride in an autosampler. The hydride is decomposed and atomized in an electrically heated quartz furnace, and the atomic absorption of tin at 286.3 nm is measured. The detection limit and the linear working range for tin are 1 ng/ml and 0-140 ng/ml respectively. The method has wide tolerance for variation in reagent concentrations and possible interferences, and when tested on some certified rocks and soils having a wide range of tin values, was found to be satisfactorily accurate and precise. The procedure is now used routinely in our laboratories. At least 10-12 samples can be analysed per hour.     

Determination of tin in lead/tin solder leachates from copper piping by graphite platform furnace atomic-absorption spectrometry

A stabilized-temperature platform furnace/atomic-absorption spectrophotometric(STPF-AAS) method has been developed for the determination of tin leached from lead/tin-soldered copper pipes. The method involves the use of a modifier composed of diammonium hydrogen phosphate, magnesium nitrate and nitric acid. Aqueous tin standards in the composite matrix modifier are used for calibration. The characteristic mass and detection limit (three standard deviations of the blank) for peak-height measurement of tin are 5 pg and 1.7 microgl., respectively. The corresponding peak-area values are 26.8 pg and 12.8 microgl., respectively. The accuracy, precision, and interferences (especially of sulphate) have been assessed.     

Microanalytical determination of tin in organotin compounds

Existing procedures for the determination of tin in organotin compounds are reviewed, and a new procedure is described which can be used for the rapid microanalysis of most organotin compounds. Wet oxidation with sulphuric acid and 30% hydrogen peroxide is followed by spectrophotometric determination of the extracted ternary tin(IV)-chloride-oxine complex in chloroform. Time for a single determination is 20 min, and the relative standard deviation is 0.7% for 1-5 mg of tin. On account of their volatility, methyltin compounds must be subjected to a sealed-tube wet oxidation in sulphuric-nitric acid mixture. Addition of sulphamic acid after boiling to remove most of the nitric acid makes this compatible with the solvent extraction step. Tin present as organotin stabilizer in PVC samples can also be determined by this method, after destruction of the organic matter with sulphuric acid and 50% hydrogen peroxide.     

Spectrophotometric and gravimetric determination of sulfur in sebacate-base lubricants

Sulfur is determined in sebacate-base lubricants spectrophotometrically and gravimetrically. In the spectrophotometric method, a 0.2–0.3-g sample is treated with mixed acids, magnesium chloride is added, and the solution is evaporated to dryness. The sulfate is reduced to hydrogen sulfide by treatment with a mixture of hydriodic. hypophosphorous, and hydrochloric acids, and the hydrogen sulfide is distilled into ammonia solution. Lead citrate reagent is added and the brownish yellow color of lead sulfide sol is measured. An improved technique and apparatus for the distillation is described. In the gravimetric method, a 5-g sample is treated with mixed acids, antimony and tin are volatilized by treatment with hydrobromic acid, and sulfur is precipitated as barium sulfate. The recommended range of the spectrophotometric method is 0.005–0.15%,and that of the gravimetric method is 0.01–1% sulfur.     

Analysis of vanadium-titanium ores and alloys

A new spectrophotometric method for determining titanium in vanadium-titanium ore with 2,2'-biquinoxalyl was developed. The analytical procedure to dissolve samples and separate titanium from vanadium and tin was elaborated as well. Furthermore, vanadium and iron were determined in the ore investigated.     

Analyse des alliages légersá base d'aluminium par les méthodes spectrophotométriques II

Colorimetric methods of analysis of light alloys of aluminium have been examined by the spectrophotometric method.In particular, four methods of determination of iron have been studied. The method which makes use of sulphophenyl pyrazolone carboxylic acid is recommended; the accuracy is of the same order as that of the phenanthroline method; the reagent is a much used product and is less expensive than phenanthroline.Simple and rapid methods are proposed for the determination of chromium, cobalt and titanium, and studies have been made leading to relatively new and original techniques for bismuth, tin and zirconium.     

Extraction and spectrophotometric determination of trace amounts of tin(II) with diphenylglyoxal bis(2-hydroxybenzoylhydrazone)

Diphenylglyoxal bis(2-hydroxybenzoylhydrazone) has been used as a sensitive reagent for the spectrophotometric determination of tin. This reagent forms an orange-yellow complex with stannous ion at pH 3.5–7.0 (λ_max = 455 nm, ? = 2.25 × 10⁴ liter mol^?1/cm^?1 while no reaction is observed with quadrivalent tin. The colored complex extracted into isobutyl methyl ketone has been used for the spectrophotometric determination of trace amounts of tin(II). The molar absorption in the organic solvent is 3.54 × 10⁴ liter mol^?1 cm^?1 and the compound shows its maximum absorbance at 455 nm. The interferences of foreign ions have been determined.     

Determination of rhenium in the URe2 binary compound by differential spectrophotometry

A differential spectrophotometric determination of rhenium in its binary compound with uranium is described; the method is based on the action of tin(II) chloride on perrhenate in the presence of dimethylglyoxime with measurement at 445 nm. Uranium does not interfere. For solutions containing about 1 mg of rhenium, the coefficient of variation was 0.08%.     

Effects of γ-radiation on spectrophotometric determination of uranium as thiocyanate

The effects of γ-radiation on the spectrophotometric determination of uranium as the thiocyanate complex in water and acetone-water solutions have been studied. When tin(II) chloride is present, the absorbance of uranium thiocyanate in aqueous solution decreases with increasing radiation dose until the appcarance of radiolytic elemental sulfur causes an apparent increase. In the absence of tin(II) chloride, the turbidity caused by radiolytic sulfur causes an increase in absorbance over the whole dose range studied. In acetone-water solution, similar but much more severe effects occur. Observations of radiation effects of some of the individual reagents used in the spectrophotometric determinations are included, as well as indications of the errors caused by specific radiation doses.     

Spectrophotometric determination of molybdenum in steel,tantalum, niobium or tungsten

A rapid, accurate spectrophotometric method for the determination of 0.001–0.1% of molybdenum in steel, tantalum, niobium or tungsten is presented. The molybdenum is isolated, when required, by solvent extraction with α-benzoinoxime-chloroform solution or cupferron- chloroform solution and then determined by the thiocyanate method. Conditions for obtaining high sensitivity by quantitative reduction of molybdenum (VI) to molybdenum (V) with tin(II) chloride have been established. It has been shown that fading of the molybdenum(V)-thiocyanate color can be minimized by adding hydroquinone to prevent air oxidation of molybdenum (V).     

Flow-Injection Study and Analytical Applications of the Reactions of Palladium(II) and Platinum(IV) with Tin(II) Chloride in Hydrochloric Acid Solutions

The interaction of palladium(II) and platinum(II) with tin(II) chloride in hydrochloric acid solutions was studied by flow-injection (FI) spectrophotometry. It was found using kinetic measurements in the stopped flow mode that the composition of detected products and the rate of their formation depend on the concentrations of tin(II) and chloride ions in the reaction zone and on the acidity of the solution. Optimal FI conditions were found, and the selectivity of interaction of palladium(II) with tin(II) chloride was estimated for the detection of the signal at 407 nm (yellow form) and 646 nm (green form). It was demonstrated that the reaction of the formation of yellow platinum(IV) complexes is slower than that for palladium(II), especially at rather low concentrations of hydrochloric acid in the reaction flow. Based on the detection of green complexes of palladium(II) with tin(II) chloride, a flow injection method was proposed for the selective spectrophotometric determination of palladium(II) in the presence of other platinum-group metals. The height of the recorded peak is directly proportional to the concentration of palladium(II) in the injected solution in the range of 0.028–0.300 mM. The method was used for the analysis of pharmaceuticals and industrial catalysts.     

Oxidaiton of tin/II/ in air-kept hydrochloric acid solutions

An air-storage stability of tin/II/ chloride solution was studied by voltammetric and spectrophotometric methods. The chosen concentration range was due to the problems of the kits preparation for a^99mTc generator. The rate of oxidation of tin/II/ in the range of 0.04–12.5 mg.ml^–1 was shown to decrease with an increase in tin concentration. According to the obtained results one can determine maximal storage time for the correct practical use.