Traces Of Tin Research Articles

Aluminio pulvimetalúrgico: desarrollo y mejora de sus aleaciones y materiales compuestos

Powder metallurgy components demand is increasing in the last few years mainly due to the necessity of products assigned to automotive and aerospace industries, which has allow an important development of aluminium alloys and composites (AMCs). Consolidation of aluminium alloys by sintering present a main problem: the oxide layer that cover aluminium particles. Several alternatives are studied in this work as solution to the oxide layer problem during the sintering of series 2xxx aluminium alloys. One of these solutions is related to the addition of tin traces, and the other is the addition of a second alloy. Moreover, aluminium metal matrix composites are characterized by excellent properties as combination of properties which comes from the matrix and from the reinforcement. The last part of this study is focused to the analysis of one aluminium matrix composite as the influence of several quantities of reinforcement.

Development of Aluminium Alloys and Metal Matrix Composites by Powder Metallurgy

Consolidation of aluminium alloys by sintering present a main problem: the oxide layer that cover aluminium particles. Some alternatives are studied in this work as solution to the oxide layer problem during the sintering of series 2xxx aluminium alloys. One of these solutions is related to the addition of tin traces, and the other is the addition of a second alloy. Moreover, aluminium metal matrix composites are characterized by excellent properties as combination of properties which comes from the matrix and from the reinforcement. In the first part of this work is analyzed the influence of trace additions, and the last part of this study is focused to the analysis of one aluminium matrix composite as the influence of several quantities of reinforcement.

Determination of Trace Tin by Anodic Stripping Voltammetry at a Carbon Paste Electrode

AbstractA sensitive and selective procedure for the determination of trace tin at a carbon paste electrode was described. Each measurement cycle consisted of three steps: accumulation, reduction and stripping. The tin complex with bromopyrogallol red (BPR) was accumulated on the electrode surface in 0.10 mol/L acetate buffer (pH 4.5). After electrochemical reduction of Sn(II) had been carried out, the reoxidation wave of Sn(0) appeared at −0.69 V (vs. SCE) on scanning the potential in the positive direction in 4.0 mol/L HCl. For a preconcentration time of 2 min, the detection limit was 0.06 μg/L (5×10−10 mol/L ) and the linear range was from 0.1 to 50 μg/L. The proposed method was applied to the determination of tin in canned food and waste water samples with satisfactory results.

Determination of trace tin by stripping potentiostatic coulometry

On the basis of voltammetric and coulometric studies of the behavior of tin(II) in a 2 M HCl solution at a carbon-graphite bulky electrode made of fibrous porous felt (FPF), we have found the optimum conditions for the stripping potentiostatic coulometric determination of 10–1000 μg tin(II) by the reaction Sn(0)-ē ⇌ Sn(I) after preconcentrating Sn(0) at the electrode surface. The relative standard deviation varied from 0.5 to 4%. The results of the coulometric determination of the number of electrons involved in the oxidation of Sn(0) suggest that the stripping Sn(0) from the surface of the FPF electrode proceeds in two stages. The first stage Sn(0) → Sn(I) was electrochemical, and the second stage Sn(I) → Sn(II) was chemical. The procedure was applied to the determination of ∼1% tin in a jewelry alloy based on gold, silver, platinum, and copper.

Determination of trace tin by catalytic adsorptive cathodic stripping voltammetry

A highly sensitive and selective catalytic adsorptive cathodic striping procedure for the determination of trace tin is presented. The method is based on adsorptive accumulation of the Sn(IV)–3,4-dihydroxybenzoic acid (DHBA) complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species. The reduction current is enhanced catalytically by vanadium(IV). The optimal experimental conditions include the use of 0.10 M formate buffer (pH 3.1), 8.0 × 10 −5 M DHBA, 3.0 × 10 −3 M V(IV), an accumulation potential of −0.30 V (versus SCE), an accumulation time of 60 s, a scan rate of 200 mV/s and a second-order derivative linear scan mode. The peak current is proportional to the concentration of tin over the range of 0.01–40 μg/L, and the detection limit is 0.005 μg/L for a 60 s adsorption time. The proposed method was applied to the determination of tin in canned food, human hair and waste water samples with satisfactory results.

Preconcentration and Determination of Tin in Water Samples by Using Cloud Point Extraction and Graphite Furnace Atomic Absorption Spectrometry

A method based on cloud point extraction and graphite furnace atomic absorption spectrometry (GFAAS) was developed for the analysis of trace tin in water samples. After cloud point extraction, the tin in the water samples was preconcentrated and successfully separated from most interferents. During the procedure, 8-hydroxyquinoline (8-HQ) was used as chelating reagent, and Triton X-114 was added as surfactant. The parameters affecting the sensitivity and the extraction efficiency, such as solution pH, concentration of 8-HQ and Triton X-114, equilibration temperature and centrifuge time, were evaluated and optimized. Under the optimum conditions, a preconcentration factor of 96.2 was obtained for a 20 mL water sample. The detection limit (LOD) was as low as 0.012 ng mL−1, and the analytical curve was linear in the range of 0.05–2.0 ng mL−1 with satisfactory precision (RSD <4.1%). The proposed method was successfully applied to the determination of trace tin in water samples with recoveries in the range of 85.0–112.0%.

Determination of trace tin by solid substrate-room temperature phosphorimetry using sodium dodecyl sulfate as sensitizer

The effects of different surfactants on solid substrate-room temperature phosphorescence (SS-RTP) properties of Sn4+–morin systems were investigated. It was found that the SS-RTP intensity of luminescence system was increased greatly in presence of sodium dodecyl sulfate (SDS). A new highly sensitive method for the determination of trace tin has been proposed based on sensitization of SDS on SS-RTP intensity of morin–tin system on the filter paper substrate. The linear dynamic range of this method is 8.0–112 ag per spot (with the volume of 0.4 μl per spot) with a detection limit of 4.0 ag per spot, and the regression equation is ΔIp=199.7+3.456mSn(IV) (ag per spot), with the correlation coefficient r=0.9998 (n=7). This simple, rapid and reproducible method has been applied to determine the amount of tin in real samples with satisfactory results.

Radiochemical neutron activation analysis of total trace tin and determination of its differentiated compounds in aquatic biota

Summary The optimization of extraction and determination of trace tin using radiochemical neutron activation analysis (RNAA) in selected aquatic specimen (algae, fish, mussels) is described. Neutron activation analysis (NAA) using the induced 117mSn (13.6 days) or 113Sn (115 day) nuclides is in principle a sensitive method for determination of total trace tin. However, due to the high contents of arsenic (As) in most marine matrices, neutron irradiation induces high levels of 76As (26.3 h) in comparison to weak 117mSn activities. Selective removal of As by absorption on Acidic Aluminum Oxide (AAO) would be advantageous and reduce the activities required to be handled during tin purification. It was found that perchloric acid medium is the best eluent for separating Sn from As, whereas sulfuric acid and a mixture of the two were not as effective. The standard radiochemical separation procedure based on solvent extraction and purification of tin iodide in toluene from sulfuric acid-potassium iodide (KI) medium with recoveries ranging between 90%–95% is applied. Interferences from the 47Ca/47Sc decay and 199Au with similar gamma energies were effectively removed by the liquid/liquid separation. Comparing the total tin content in freeze-dried samples with the total organotin content in fresh samples shows that the drying process has changed the tin species pattern of the material. The total butyltin content represents 60% and 90% of the total tin content in eel-pout and bream muscles, while it represents about 76%–83% and 58%–88% in mussels and algae, respectively.

Determination of trace tin in flow systems at an epoxy–carbon powder–8-hydroxyquinoline composite electrode

An epoxy–carbon powder composite electrode bulk modified with 8-hydroxyquinoline was fabricated for the continuous flow and flow injection anodic differential pulse voltammetric determinations of Sn(II) after open circuit preconcentration. Factors affecting Sn(II) determination were systematically investigated and an optimized procedure was developed. Under the optimized conditions for the continuous flow system with 10 min accumulation, the calibration plot was linear from 5.00 × 10−9 to 1.00 × 10−6 M and a detection limit of 4.6 × 10−10 M (0.055 ppb, S/N = 3) was found. For six consecutive differential pulse stripping experiments each of Sn(II) concentrations of 5.00 × 10−9, 5.00 × 10−8 and 5.00 × 10−7 M (10 min accumulations), relative standard deviations of 9.68, 7.45 and 3.38%, respectively, were obtained. For the flow injection mode, a detection limit of 5.4 ng (500 μl injection of 0.91 × 10−8 M, S/N = 3) was achieved. Selected metal ions and other substances were investigated for interferences. The developed method was tested with a spiked United States Environmental Protection Agency water quality control sample (USEPA WP 386) and then applied to the determinations of tin in human hair, canned fruit juice and spiked sea-water samples.

Determination of trace tin in foods by single-sweep polarography

A new method for the determination of trace tin in a solution of oxalic acid–methylene blue by single-sweep polarography is developed. The mechanism for the polarographic waves and the conditions for determining tin are discussed in this report. The peak height is directly proportional to the concentration of tin (IV) over the range 2.0×10 −8–1.0×10 −6 g ml −1. The detection limit and the recovery of the method are 1.0×10 −8 g ml −1 and 93–98%, respectively. The method was successfully employed for the determination of tin in juices of canned fruits.

Determination of tin in marine materials by using hydride generation–high resolution inductively coulped plasma mass spectrometry

A hydride generation system combined with high-resolution inductively coulped plasma mass spectrometry was used to determine tin in marine materials. The optimization conditions for determination of tin in this system are 0.015 M of sulfuric acid solution as medium, 0.2% (w/v) of sodium tetrahydroborate(III) in 0.015 M of sodium hydroxide solution as a reductant and argon as the carrier gas at a flow rate of 1.1 l min −1. In order to remove the interferences from transition element ions, a strongly basic anion exchanger was used in this method. Tin was converted to its chlorostannate with 2 M hydrochloric acid followed by passing to an anion exchanger. The tin absorbed on the column was then eluted with 1 M nitric acid. Under the optimized conditions, the detection limit of the method was 12 ng l −1 without using the anion column as preconcentration method. The results obtained using this method were in good agreement with the certified values of marine standard reference materials. The recoveries for the method when applied to determine trace tin in river water were 95–115%.

Determination of tin traces in water samples by adsorptive stripping voltammetry

A sensitive and selective adsorptive stripping voltammetric method was employed to determine traces of tin in water samples. The spontaneously formed tin complex with 2,5-dichloro-1,4-dihydroxy-3,6-benzoquinone (chloranilic acid) is adsorbed at the surface of a mercury drop electrode. The analyte can be preconcentrated in this way applying a potential between +100 and −200 mV to the working electrode. The adsorption behaviour is investigated by means of alternating current voltammetry. Tin traces were determined after UV-digestion in drainage water samples.

Studies on Some Nitramine based Low Vulnerability Ammunition Propellants with Cellulose Acetate as a Binder

Several formulations of propellants based on RDX as an energetic solid ingredients and cellulose acetate (CA) as a binder were processed using either dioctyl pthalate(DOP) or tracetin(TA) as plastisizer and a small amount of nitrocellulose(NC). The Performance of these propellants was evaluated on the basis of closed vessel firing data. The vulnerability aspects of these formulations were compared with those of conventional picrite propellant, NQ on the basis of their ignition temperatures and sensitivity to friction and impact. Triacetin was found to be better plasticizer than DOP for CA binder. Some RDX/CA/TA/NC/-based propellants were found to have energy levels comparable with NQ propellant and had less sensitivity to heat, impact and friction, and therefore have the potential for being used as low-vulnerability ammunition propellants for gun applications.

Adsorptive Complex Wave of Tin(IV) with Some Thiazine Dyes.

Tin(IV) in a medium of sulfuric acid-oxalic acid with some thiazine dyes, e.g. new Methylene Blue (NMB) or Toluidine Blue (TB), at -0.60 V (vs. SCE) produced a highly sensitive adsorptive complex wave. The sensitivity was increased to about 16-times higher than that without those dyes in the above-mentioned medium. The detection limit was 0.8 ng/ml (6.7×10-9 mol/1) Sn(IV). The existing form and the apparent stability constant (k) of these complexes, the reversibility of the electrode process, the character of adsorption and the mechanism of the electrode reaction were investigated, and a series of constants and parameters were calculated. The proposed method was applied to determine trace tin in drinking-water samples and reagents with satisfactory results.

ChemInform Abstract: The Determination of Trace Tin by Cathodic Stripping Voltammetry with a Nafion‐Modified Electrode.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Electrochemistry and analytical application of the tin(IV) complex ofN-benzoyl-N-phenylhydroxamic acid in 2-propanol solution

The tin(IV) complex of N-benzoyl-N-phenyl-hydroxamic acid (HX) and chloride ions [SnIVX2Cl2]0 is reduced in 2-propanol solution via two different pathways depending on the scan rate. At scan rates higher than 20 mV/s, the reduction proceeds via [SnIIX2Cl2]2− and [Sn0X(H2O)2]−, and at slower scan rates the reduction proceeds via [SnIIXCl3]2− and [Sn0Cl(H2O)2]−. This is the first time that experiments have indicated the existence of tin0 complexes. The studied tinIV complex can be used for the determination of tin traces in aqueous solutions. Therefore the tinIV complex is preliminarily extracted from aqueous solution and the differential pulse anodic stripping voltammograms are recorded in the organic solution after addition of 2-propanol. The 3σ limit of detection is 4 × 10−8 mol/L.

The determination of trace tin by cathodic stripping voltammetry with a Nafion®-modified electrode

The cathodic stripping voltammetry of tin (IV) in a solution of 0.01 mol l− 1NaCl (pH 1.9) by a Nafion®-modified glassy carbon electrode is described. Tin(IV) can be determined down to a level of 0.1 ng ml− 1. The method has been used to determine a trace amount of tin in hair with satisfactory results.

Determination of tin in copper by radiochemical proton activation analysis

A new method for the determination of traces of tin in copper by radiochemical proton activation analysis was developed. The possibilites of (p,n) induces reactions leading to antimony-120m, -122, abd -124 have been investigated. Special attention was paid to the proper choice of the proton energy with respect to the detection limit and the nuclear interferences. A quantitative and selective separation of antimony, based on cation exchange and precipitation, was developed. The method has successfully proved its capabilities in the BCR (Community Bureau of Reference) certification campaign and has significantly contributed to the certification of the tin content at the submicrogram per gram concentration level.

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.

Pre-concentration of traces of tin by coprecipitation with yttrium hydroxide for electrothermal atomisation atomic absorption spectrometry

Trace amounts of tin were concentrated by coprecipitation and determined by electrothermal atomisation atomic absorption spectrometry. Yttrium hydroxide coprecipitated quantitatively 0.1–3 μg of tin from 50–500 ml of sample solution at pH 9.5–11.2. The atomic absorbance of tin increased about twice by using an impregnated graphite tube with yttrium. The impregnated graphite tube, furthermore, improved the reproducibility of the measurement of tin. A linear calibration graph was obtained in the range of 0.004–0.12 μg/ml of tin. Twenty-three foreign ions did not interfere seriously. The method was applicable to the determination of tin in zinc metal.