Determination of total tin in silicate rocks by graphite furnace atomic absorption spectrometry

A method is described for the determination of total tin in silicate rocks utilizing a graphite furnace atomic absorption spectrometer with a stabilized-temperature platform furnace and Zeeman-effect background correction. The sample is decomposed by lithium metaborate fusion (3 + 1) in graphite crucibles with the melt being dissolved in 7.5% hydrochloric acid. Tin extractions (4 + 1 or 8 + 1) are executed on portions of the acid solutions using a 4% solution of trioctylphosphine oxide in methyl isobutyl ketone (MIBK). Ascorbic acid is added as a reducing agent prior to extraction. A solution of diammonium hydrogenphosphate and magnesium nitrate is used as a matrix modifier in the graphite furnace determination. The limit of detection is > 10 pg, equivalent to > 1 μg l^?1 of tin in the MIBK solution or 0.2–0.3 μg g^?1 in the rock. The concentration range is linear between 2.5 and 500 μg l^?1 tin in solution. The precision, measured as relative standard deviation, is < 20% at the 2.5 μg l^?1 level and < 7% at the 10–30 μg l^?1 level of tin. Excellent agreement with recommended literature values was found when the method was applied to the international silicate rock standards BCR-1, PCC-1, GSP-1, AGV-1, STM-1, JGb-1 and Mica-Fe. Application was made to the determination of tin in geological core samples with total tin concentrations of the order of 1 μg g^?1 or less.     

Determination of tin and methyltin species by hydride generation and detection with graphite-furnace atomic absorption or flame emission spectrometry

A method for the determination of tin and organotin species by hydride generation is described. Tin hydrides are detected by graphite-furnace atomic absorption, quartz-cuvette atomic absorption, or flame emission spectrometry with detection limits of 50, 50, and 20 pg as tin, respectively. Germanium interferences are eliminated with a dual-detector flame photometer with an electronic cancellation circuit.     

The influence of the sample introduction system on signals of different tin compounds in inductively coupled plasma-based techniques

The influence of the sample introduction system on the signals obtained with different tin compounds in inductively coupled plasma (ICP) based techniques, i.e., ICP atomic emission spectrometry (ICP–AES) and ICP mass spectrometry (ICP–MS) has been studied. Signals for test solutions prepared from four different tin compounds (i.e., tin tetrachloride, monobutyltin, dibutyltin and di-tert-butyltin) in different solvents (methanol 0.8% (w/w), i-propanol 0.8% (w/w) and various acid matrices) have been measured by ICP–AES and ICP–MS. The results demonstrate a noticeable influence of the volatility of the tin compounds on their signals measured with both techniques. Thus, in agreement with the compound volatility, the highest signals are obtained for tin tetrachloride followed by di-tert-butyltin/monobutyltin and dibutyltin.The sample introduction system exerts an important effect on the amount of solution loading the plasma and, hence, on the relative signals afforded by the tin compounds in ICP–based techniques. Thus, when working with a pneumatic concentric nebulizer, the use of spray chambers affording high solvent transport efficiency to the plasma (such as cyclonic and single pass) or high spray chamber temperatures is recommended to minimize the influence of the tin chemical compound. Nevertheless, even when using the conventional pneumatic nebulizer coupled to the best spray chamber design (i.e., a single pass spray chamber), signals obtained for di-tert-butyltin/monobutyltin and dibutyltin are still around 10% and 30% lower than the corresponding signal for tin tetrachloride, respectively. When operating with a pneumatic microconcentric nebulizer coupled to a 50 °C-thermostated cinnabar spray chamber, all studied organotin compounds provided similar emission signals although about 60% lower than those obtained for tin tetrachloride. The use of an ultrasonic nebulizer coupled to a desolvation device provides the largest differences in the emission signals, among all tested systems.     

The microdetermination of stannous tin with N-bromosuccinimide

A new titrimetric method for the microdetermination of stannous tin, e.g., stannous chloride is proposed. The mechanism of the reaction in the presence of dilute hydrochloric acid is discussed. The determination of stannous tin is done on concentrations ranging from 10 mg to 100 μg. The experimental error does not exceed ±2%. Comparative analysis of tin sheets, rods, and foils by the proposed method and the iodine method is reported. The method has been shown to be suitable for the determination of tin in canned foods.     

Direct determination of tin in tap waters by electrothermal atomization atomic absorption spectroscopy

Summary A method is described for the direct determination of tin in tap waters by electrothermal atomization atomic absorption spectroscopy (ETA-AAS), using magnesium-nitric acid and palladium-magnesium as chemical modifiers. The charring and atomization temperatures and times, and the amount of modifier were optimized. The calibration and addition graphs, detection limit, quantitation limit, precision, accuracy, interferences and characteristic mass were also investigated. The method was applied to the determination of tin in tap water samples.     

Determination of total tin in geological materials by electrothermal atomic absorption spectrometry

A graphite-furnace atomic-absorption spectrometric method is described for the determination of total tin in geological materials. Samples are decomposed by fusion with lithium metaborate and the melt is dissolved in diluted (1 + 9) nitric acid. Spectral and non-spectral interferences are minimized by a combination of platform volatilization, “normal” heating rate, addition of ammonia as chemical modifier, use of integrated absorbance values and Zeeman background correction. Results are reported for six reference materials showing good accuracy and a precision of 12% at the 3 μg g^?1 level. The detection limit for tin in the original materials in 0.7 μg g^?1.     

Application of experimental design in a method for screening sediments for global determination of organic tin by electrothermal atomic absorption spectrometry (ETAAS)

An experimental design was developed to obtain a simple procedure for global determination of organic tin compounds in sediment. Sediment was extracted by a two-phase method and tin was determined in the organic extract by electrothermal atomic absorption spectrometry (ETAAS), with palladium as chemical modifier. A Plackett-Burman design for screening and a fractional central composite design (CCD) for optimizing were used for evaluation of the effects of several variables. The results showed that sediment mass, volume and concentration of extracting acid, pyrolysis and atomization temperatures, and modifier concentration affect the determination. Reference material PACS-2 was analyzed to evaluate the procedure. It was possible to extract 82% of the organotin content certified in the reference sediment. The limit of detection (LOD) was 0.08 microg g(-1) and the relative standard deviation was 4%. The method was applied to the analysis of estuarine superficial sediments from Gipuzkoa (Spain). The organotin content of these samples ranged from 0.7 to 7.7 microg g(-1), as tin, on a dry-weight basis.     

Determination of tin in marine sediment slurries by electrothermal atomic absorption spectrometry using palladium-magnesium nitrate as chemical modifier

 A method was optimized for the determination of tin in slurries of marine sediment samples using palladium-magnesium nitrate as chemical modifier and Triton X-100 (0.1%) surfactant as stabilizer. To obtain a complete pyrolysis of the slurry sample, two charring steps were used, the first at 480 °C and the second at 1300 °C. The precision and accuracy of the method were studied using the Reference Material PACS-1 (marine sediment) from National Research Council Canada. The detection limit (LOD) was 57.6 μg kg^-1. The method was applied to the determination of tin in marine sediment samples from the Galicia coast. Received: 16 February 1996/Revised: 26 March 1996/Accepted: 12 April 1996     

Determination of fluoride and tin in fluoride-doped tin oxide films on glass

Time-consuming fusion and pyrohydrolysis methods for quantifying fluoride and tin in fluoride-doped tin oxide films on glass are replaced by a simple electrolytic reduction for sample preparation. The unusual conductivity of these films enables solutions to be produced in which fluoride can be quantified by ion chromatography. Tin is quantified in the original sample by x-ray fluorescence spectrometry. Electrolytic reduction and the fusion/pyrohydrolysis methods are compared for films with Sn/F ratios of 10–40 (71–183 μg cm^?2 tin and 0.54–2.8 μ cm^?2 fluoride). The Sn/F ratios and precision are similar for the two methods. The older method only yields the tin/fluoride ratio; the electrolytic method gives results as mass per unit area and requires much less time per sample.     

Determination of total tin and tributyltin in marine biological materials by electrothermal atomic absorption spectrometry

Total tin and tributyltin in marine biological tissue are determined at the sub-μg g^?1 level by graphite-furnace atomic absorption spectrometry. Total tin is extracted by digestion with nitric acid, and tributyltin is extracted by n-hexane after treatment with hydrochloric acid. A matrix modifier (ammonium dihydrogenphosphate), and a stabilized-temperature platform furnace are used to overcome matrix effects. Zeeman background correction is used. Results of analyses of oyster (Crassostrea gigas), salmon (Salmo salar) and a reference material (Bowen's kale) are presented. The detection limit for both methods is ca. 30 ng of tin with a relative standard deviation (n = 6) of 7.8% for a sample containing 200 ng of tin.     

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.     

Ascorbic acid as a matrix modifier for determination of tin in concentrated boric acid solutions by electrothermal atomic-absorption spectrometry

It has been found that the atomic-absorption signal for tin is reduced in the presence of 5 micro1 of 0.05-0.30M boric acid at STPF-conditions. It has been proposed that the reason for the boron interferences is the formation of SnB(g) at the atomization stage. In the presence of palladium chloride the interferences from 0.2M boric acid are reduced by a factor of 1.3. The interferences are reduced most effectively when the sample is atomized from a polycrystalline graphite platform or in the presence of ascorbic acid. The interference of up to 0.2M boric acid can be suppressed and the area of the tin signal doubled. It is proposed that the observed phenomenon is connected with the bonding of boron as non-volatile B(4)C. Ascorbic acid is the most effective matrix modifier for the determination of different trace elements in boron compounds.     

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.     

Chelatometric titration of tin in non-ferrous alloys with hedta

A new titrimetric method for determination of tin (4%) in aluminium alloys, tin- and lead-base alloys, solders, white bearing alloys, special bronzes and silver brazing alloys is proposed. HEDTA, Semi-Xylenol Orange and bismuth perchlorate are used as titrant, indicator and back-titrant respectively. Measures are taken to overcome the hydrolysis of Sn(IV). Monochloroacetic acid and ethylene glycol are added as auxiliary agents. The standard deviation of this method was found to be 0.2 mg and its coefficient of variation to vary from 0.25 to 2%, according to amount of tin. A novel method of sample decomposition and a modified method for separating Sn(IV) are also suggested.     

Development of a new method for direct determination of selenium associated with atmospheric particulate matter using chemical modifiers and graphite probe furnace atomic absorption spectrometry

Direct determination of selenium on or in atmospheric particulate matter (APM) has been achieved using an integrated filtration and analysis system developed in our laboratories. The filtration (sampling) and analysis system consists of a porous electrographite plate which is used initially for the purpose of collecting APM and subsequently as a probe in graphite probe furnace atomic absorption spectrometry. Selenium produced a double peak when it was atomized from such an electrographite probe. Palladium nitrate+magnesium nitrate, as a mixed chemical modifier or ascorbic acid as a chemical modifier, eliminated the double peak. The addition of the chemical modifier(s) also removed the unpredictable changes in the peak-height and the peak-area absorbance which occurred from one atomization cycle to the next if the chemical modifier was not used. Precision of 5% RSD (peak-area absorbance) was obtained for an aqueous solution of selenium standard containing 1.25 ng of selenium with palladium nitrate+magnesium nitrate mixed chemical modifier, or ascorbic acid chemical modifer. The characteristic masses and the limits of detection for the aqueous solution of selenium standard with palladium nitrate+magnesium nitrate mixed chemical modifier are 27 and 41 pg (peak-area absorbance), respectively, and with ascorbic acid chemial modifier are 29 and 36 pg, respectively (peak-area absorbance). The results of analysis of the NIST (formerly National Bureau of Standards) Standard Reference Material No. 1648, Urban Particulate Matter, for selenium with palladium nitrate+magnesium nitrate mixed chemical modifier gave a recovery of 92%, and a precision of 10% RSD, and characteristic mass and the limit of detection of 20 and 37 pg, respectively.     

Determination of tin and triorganotin compounds in sea-water by graphite-furnace atomic-absorption spectrophotometry

An analytical method based on graphite-furnace atomic-absorption spectrophotometry employing a suitable signal-enhancing medium for determination of inorganic tin and two of its trisubstituted organic derivatives in sea-water has been established. This method allows determination of triphenyltin and tributyltin compounds down to 2 x 10(-12) and 2.8 x 10(-12)M respectively by means of enrichment by collection on graphitized carbon black (enrichment factor up to 8 x 10(4)) and a separation on a small silica-gel column. Inorganic tin, which is not adsorbed on the graphitized carbon black, is isolated from the matrix by liquid-liquid extraction of its pyrrolidinedithiocarbamate complex into dichloromethane. The method gives good recovery (95%) and precision ( less, similar5%) at the ng/l. level.     

石墨炉原子吸收光谱法测定锡和锗时基体改进剂硝酸钙的作用

石墨炉原子吸收光谱法测定低温易挥发元素锡和锗时灵敏度较低。本文以硝酸钙为基体改进剂,使锡和锗的灵敏度分别比不加基体改进剂时提高9倍和50倍,同时也显著提高灰化温度,并降低原子化温度。本文也探讨了基体改进剂硝酸钙对锡和锗的增感机理。锡的增感是由于固相和气相中钙的作用,而锗的增感仅是气相钙的作用。     

X射线荧光光谱法测定锡矿石中锡

本文采用向样品中加入硼酸来降低基体效应,加入氧化镧来稳定样品总质量吸收系数,建立固体粉末压片制样-X射线荧光光谱法测定锡矿石中锡含量的方法。通过将标准物质按一定比例混合配制和选取部分自制标样来补充标准物质样品,以解决锡矿石标准物质样品缺乏的问题。实验优化了稀释比,确定了以最佳稀释比为m（矿物质样品）:m（硼酸）：m（氧化镧）=1.0:2.0:0.5。在最优的实验条件下,Sn的荧光强度（kcps）与Sn浓度CSn呈良好的线性关系,R2=0.9989。方法中锡元素的最低检出限为0.005 %,测定范围在0.015 %-4.47 %之间。样品的混合均匀性实验表明各元素测定结果的相对标准偏差（RSD,n=6）在1.0 %-2.64 %之间。对3个不同含量段的物质进行测定来验证方法的准确度和精密度,准确度分别为0.0082-0.0367,均小于0.04,精密度分别为0.39 %-1.18 %,均小于8.0 %,准确度和精密度均符合地质样品分析规范要求。测定值均在误差范围内,各组分测定结果的相对标准偏差（RSD,n=11）在1.20 %以下。粉末压片-X射线荧光光谱法测定锡矿石中锡含量具有分析范围广、分析时间短、重现性好、精度高且操作简单等特点。能应用于地质、环境、材料等领域。     

The complexometry of tin(IV)

Tin(IV) very readily hydrolyses in solution, and forms hydrous tin oxide SnO(2)2.nH(2)O even in rather strongly acidic solution. In spite of a lack of reliable data on the hydrolysis of tin(IV) a consistent picture of the behaviour of tin(IV) in solution has been constructed. Some values for the formation of hydroxide and chloride complexes were deduced from electrochemical data. In agreement with more or less qualitative remarks by other investigators a value of log k(so) = -3 has been found for the solubility constant. For the stability constant of tin(IV)-EDTA, log K(SnY) = 34.5 was found experimentally. A survey is given of the pitfalls which exist in handling tin solutions. A back-titration procedure is presented that provides for the complexometric determination of tin(IV) at concentrations down to 3 ppm, with an error of 1% or better. Thorium is used as back-titrant with Semi-Xylenol Orange as indicator. The method has successfully been applied to the analysis of organotin compounds.     

Layered microporous tin(IV) bisphosphonates

This article reports the hydrothermal synthesis and characterization of two new series of porous tin(IV) phosphonophenoxyphenylphosphonates with controlled pore size distributions, using as precursor the 4-(4'-phosphonophenoxy)phenyl phosphonic acid, [H2O3P-C6H4]2-O. Supermicroporous solids (S(BET), 300-400 m2 g(-1)) were obtained employing n-alcohol (C1-C6)-water mixtures (solvents ratio 1 : 1), in the presence of hydrofluoric acid. X-Ray powder diffraction shows that these compounds are semi-crystalline and the local environments around the phosphorus and tin elements have been studied by 31P and 119Sn MAS-NMR spectroscopy, respectively. The microstructure (particle sizes and shapes) of these phosphonates has been analyzed by scanning and transmission electron microscopy. This study shows that the microstructures of single-ligand (for instance tin(IV) phenylphosphonate) and cross-linked tin(IV) bisphosphonates are different. Tin(IV) phenylphosphonate crystallizes as micron-sized spheres, theta approximately 1-2 microm, formed by the aggregation of nanospheres, whereas tin(IV) bisphosphonates crystallize as microparticles larger than 20 microm. The textural properties of these porous solids were characterized by N2 and CO2 sorption isotherms. The key result of this work is that maxima of pore size distributions smoothly shift from 12 to 16 angstroms upon increasing the chain length of the alcohol. The microporosity of tin(IV) bisphosphonates is compatible with a double role played by the phosphonate groups acting as a pillar between adjacent layers and as a component of the hybrid organic-inorganic layers.