Determination of metallic iron, iron(II) oxide, and iron(III) oxide in a mixture

A procedure is described for the estimation of metallic iron, ferrous oxide, and ferric oxide when present together. The sample is treated with bromine dissolved in ethanol, and filtered. Iron in the filtrate is titrated iodometrically, and corresponds to the metallic iron present in the mixture. The oxide residue is dissolved in hydrochloric acid under a carbon dioxide atmosphere. The iron(II) formed, equivalent to FeO present, is titrated with a standard vanadate solution, and the total iron(III) (FeO + Fe₂O₃) in the titrated solution is then estimated iodometrically.     

Determination of hydrogen sulphide and sulphur dioxide in a mixture

A method has been proposed for the determination of hydrogen sulphide and sulphur dioxide in a mixture. The method is based upon the quantitative oxidation of sulphide and sulphite with an excess of radiochloramine-T in alkaline medium /0.1N NaOH/. The released chloride activity is proportional to the total amount of sulphide and sulphite present. Addition of 1% CdSO₄ solution to the mixture of sulphide and sulphite precipitates sulphide, and sulphite in the filtrate determined by the reagent. From the difference in activities, the amount of sulphide can be calculated. This method can be employed for the determination of hydrogen sulphide and sulphur dioxide in air samples.     

Oxidation of sulphide minerals--I: determination of ferrous and ferric iron in samples of pyrrhotite, pyrite and chalcopyrite

A method has been developed for determining small amounts of both ferrous and ferric iron in oxidized samples of pyrrhotite, pyrite and chalcopyrite. The oxidized iron is selectively dissolved in 10M phosphoric acid under reflux and can be determined with the accuracy generally accepted in chemical phase analysis.     

Oxidation of sulphide minerals-VI Ferrous and ferric iron in the water-soluble oxidation products of iron sulphide minerals

A pseudo-kinetic method has been developed for determining the ferrous and ferric iron in the water-soluble oxidation products of pyrrhotite, pyrite and chalcopyrite, and ores and concentrates containing them. Two determinations are required for each material. In one, the total iron is determined with 1,10-phenanthroline after reduction to Fe(II). In the other, the reduction of Fe(III) is retarded by complexation with fluoride. The difference in the amount of ferrous phenanthranoline complex produced in these two determinations is a function of the original FE(III) concentration and of time.     

Microdetermination of calcium and magnesium in a mixture

Summary A procedure is presented for the chemical separation and determination of mg quantities of calcium and magnesium, which is based on the selective carrying of calcium by ignited strontium sulphate leaving magnesium in the solution phase; the carried calcium is recovered by leaching with alcoholic sulphuric acid solution. Calcium and magnesium in the separated fractions are determined complexometrically using Eriochrome Black T as the indicator.

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Zusammenfassung Ein Verfahren zur chemischen Trennung und Bestimmung von mg-Mengen Calcium und Magnesium wird vorgeschlagen, wobei Ca selektiv mit geglühtem Strontiumsulfat abgetrennt wird, während Mg in Lösung bleibt. Ca wird mit alkoholischer Schwefelsäure eluiert. Beide Metalle werden getrennt gegen Eriochromschwarz T komplexometrisch titriert.

     

Determination of calcium,magnesium, and phosphate in the presence of iron and each other

Excess EDTA and MgSO₄ solution is added to a mildly acidic solution of the sample containing calcium, magnesium, iron, and phosphate ions. Addition of NH₄OH to this solution results in the precipitation of MgNH₄PO₄·6H₂O and various iron compounds. Calcium ions and a portion of the magnesium ions stay in the solution as the respective EDTA chelates. The mixture is adjusted to a known volume and filtered. The EDTA content of the filtrate with the exception of the EDTA tied up as calcium-EDTA chelate, is titrated with standard CaCl₂ solution at pH 12.5–13.0 in the presence of hydroxy naphthol blue indicator. The calcium content of the sample can be calculated from the result of this titration.     

1,10-二氮杂菲分光光度法测定金属硅中铁

研究了1,10-二氮杂菲分光光度法测定铁的酸度条件以及共存离子的影响,建立了1,10-二氮杂菲分光光度法测定金属硅中铁含量的方法。实验表明,在pH4~6的HAC-NaAC缓冲溶液中,铁质量浓度在0.50～5.0 μg/ml范围内吸光度线性良好,线性回归方程为y=0.00140x(μg/100mL)+0.0003,R2=0.9999。试液中其他共存离子不干扰测定。按照实验方法测定2个金属硅样品中铁的结果与电感耦合等离子体原子发射光谱法和X射线荧光光谱法的测定值均基本一致,于6个不同实验室应用实验方法测定样品和标准样品中铁的结果均与标准值吻合;方法用于实际样品中0.053%～0.77%铁的测定,相对标准偏差(RSD,n=22)为1.27%～2.45%。     

MPT-AES测定奶粉中的Ca和Fe

用微波等离子体(MPT)为激发光源,氩气为等离子体工作气体,用气动雾化进样,采用标准曲线法研究了微波等离子体炬原子发射光谱法(MPT-AES)测定奶粉中Ca、Fe的方法。详细考察了溶液中HCl浓度、HNO3浓度、微波前向功率、载气流量、工作气流量等实验参数对测定的影响,同时考察了共存元素钠、镁、锌对钙和铁发射强度的影响。     

Determination of iron and calcium impurities in magnesium oxide by atomic absorption

Summary An atomic absorption method has been developed for the determination of iron and calcium impurities in magnesium oxide. The effect of the magnesium matrix has been eliminated by the addition of hydroiodic acid and hydrogen peroxide to generate iodinein situ. The relative standard deviations were 0.5% for iron and between 0.5 and 1.5% for calcium.

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Die Bestimmung von Eisen- und Calcium-Verunreinigungen in Magnesiumoxid mit Hilfe der Atomabsorption

Zusammenfassung Zur Bestimmung der Eisen- und Calcium-Verunreinigungen in Magnesiumoxid wurde die Atomabsorptionsspektroskopie herangezogen. Der Einfluß der Magnesiummatrix wurde durch Zugabe von Jodwasserstoffsäure und Wasserstoffperoxid, d. h. durch Freisetzung von Jod in situ beseitigt. Die rel. Standardabweichung für Eisen betrug 0,5%, für Calcium 0,5–1,5%.

     

Determination of calcium and iron in silicon and uranium silicide using ion chromatography

Two separate ion chromatography methods were developed for the determination of calcium and iron in silicon and uranium silicide. A cation exchange separation with conductivity detection was developed for Ca. A reversed phase column modified with 50 mM camphor-10-sulphonic acid was used for separating Fe. Iron was detected photometrically. Linear calibrations for Ca (0.1–10 ppm) and Fe (0.5–25 ppm) were performed. Limits of detections for Ca and Fe are 0.03 and 0.2 ppm, respectively. The precision of the methods are better than 2 % for Ca at 0.2 ppm and Fe at 2 ppm.     

Mineral-carbon sorbents based on post-decarbonization lime and mixture of hydrocarbons

Summary An attempt was made to obtain mineral-carbon sorbents from waste products of petrochemical industry: lime from the decarbonization of river water to be used in technology and hydrocarbon wastes obtained in the treatment of industrial waste waters. The sorbents were prepared by thermal decomposition of mixtures of the mineral and carbon components. In order to optimize the preparation conditions, physicochemical studies were performed of both the mineral matrix and the mineral-carbon sorbents. Adsorption measurements involving nitrogen, water, and benzene as adsorbates were used for determining the parameters of porous structure of the obtained materials and their hydrophilic-hydrophobic properties. The properties influencing the sorptive properties of the organic compounds present in the petrochemical wastes were pointed out.     

Determination of calcium, iron and magnesium in rabbit arteries by inductively coupled plasma atomic emission spectrometry

Regional variations in arterial concentrations of Ca, Mg and Fe may influence susceptibility to atherosclerosis. However, investigation of such hypotheses requires the availability of a sensitive, reliable method for the determination of elements in small arterial samples. These biologically important elements are determined in rabbit arteries by inductively coupled plasma atomic emission spectrometry (ICP-AES). Arterial samples (aorta and iliac arteries) are collected from 4- and 6- to 7-month-old rabbits fed rabbit chow. Closed-vessel microwave acid digestion is used to prepare the samples. The accuracy of the method is tested with a NIST bovine liver (1577b) standard reference material, and the amount of each metal found is within the reported uncertainty in the certified concentration. Also, the recovery from artery samples spiked with 0.5 μg of each metal is nearly 100% (96-105% Ca, 93-105% Fe, and 92-104% Mg). The simultaneous multielement detection of Ca, Fe and Mg at levels more than 1000-fold higher than the detection limit, in arterial samples weighing as little as 5 mg, suggests that this method may be applicable to very small clinical samples or arterial samples from very small animals.     

Determination of traces of calcium, magnesium, iron and nickel in aluminium salts by atomic-absorption spectrophotometry with a microwave-excited source and hollow-cathode lamps

The determination of trace amounts of calcium and magnesium in solutions containing large concentrations of aluminium salts may be accomplished by co-precipitating their hydroxides on iron(III) hydroxide, dissolving the precipitate, and extracting the 8-hydroxyquinolates of calcium and magnesium into methyl isobutyl ketone at about pH 11. The extract may be sprayed into the airpropane flame of a simple unmodulated spectrophotometer and atomic-absorption measurements for calcium and magnesium made at 4227 and 2852 A respectively. The limits of determination correspond to 10 and 1 ppm of calcium and magnesium in solid alumina. Iron and nickel may be co-precipitated on hydrated manganese(IV) oxide and their 8-hydroxyquinolates extracted at pH 4.5. Measurements of atomic absorption for these elements at 2483 and 2320 A respectively yield limits of determination corresponding to 10 ppm in alumina. Hollow-cathode lamps may be used for calcium, magnesium and nickel, but a simple microwave-excited discharge tube gives much better sensitivity than a hollow-cathode lamp for iron.     

The oxidation of iron (II) sulphide

Journal of Thermal Analysis and Calorimetry - The oxidation in air and oxygen of iron (II) sulphide Fe1?x S was studied using TG, DTA, X-Ray powder photography and chemical analysis. A...     

Determination of calcium, iron and zinc in milk powder by reaction cell inductively coupled plasma mass spectrometry

An inductively coupled plasma mass spectrometer (ICP-MS) equipped with a dynamic reaction cell™ (DRC) was used for the determination of Ca, Fe and Zn in milk powder samples. The effect of the operating conditions of the DRC system was studied to get the best signal-to-noise (S/N) ratio. The potentially interfering ⁴⁰Ar⁺, ⁴⁰Ar¹⁶O⁺, ⁴⁰Ca¹⁶O⁺, ⁴⁸Ca¹⁶O⁺ and ³²S¹⁶O¹⁶O⁺ at the masses m/z 40, 56 and 64 were reduced in intensity significantly by using CH₄ as the reaction cell gas in the DRC while a q-value of 0.7 was used. The limits of detection for ⁴⁰Ca, ⁵⁶Fe and ⁶⁴Zn estimated from the external calibration graphs were 1, 0.01 and 0.001 ng ml⁻¹, respectively, which correspond to 1000, 10 and 1 ng g⁻¹ in the original powder sample. This method was applied to the determination of Ca, Fe and Zn in NIST SRM 1549 non-fat milk powder and two milk powder samples purchased locally. The results for the reference sample agreed satisfactorily with the reference values; the accuracy of the determination was better than 3.8, 18 and 2.2% for Ca, Fe and Zn, respectively. The results for which no reference value was available were also found to be in good agreement between different isotopes. Precision (R.S.D.) between sample replicates was better than 10% for all the determinations.     

X射线荧光光谱(XRF)法测定绿泥石中镁、铝、硅、磷、钾、钙、钛、铁元素含量

建立了X射线荧光光谱法测定绿泥石中镁、铝、硅、磷、钾、钙、钛、铁元素含量的快速分析方法。以标准物质及标准物质与基准试剂氧化镁、氧化钙人工混合配制标样的方法建立标准工作曲线,重点讨论了熔剂和脱模剂的选取。最佳熔样条件：采用8.0g四硼酸锂和偏硼酸锂混合熔剂(质量比67: 33)+0.8g样品并添加溴化锂作为脱模剂,熔样温度1100℃,熔样时间10min。该方法相对标准偏差(n=12)均小于5.57%,绿泥石样品测定结果与化学法一致,硅酸盐标准物质测定结果均满足不确定度要求。     

Determination of sodium, potassium, calcium, magnesium, zinc, and iron in emulsified egg samples by flame atomic absorption spectrometry

In this study, oil-in-water formulations were optimized to determine sodium, potassium, calcium, magnesium, zinc, and iron in emulsified egg samples by flame atomic absorption spectrometry (FAAS). This method is simpler and requires fewer reagents when compared with other sample pre-treatment procedures and allows the calibration to be carried out using aqueous standards. Different oily phases such as corn oil, decyl oleate and octyl stearate were tested, as well as Tween 80, Triton X-100 and Triton 114 were analyzed as surfactants. The optimum type and proportion of formulations were determined and their use depended on the element studied. The emulsion preparation was performed by a conventional method that involves mixing both phases at 60 °C by magnetic stirring and phase inversion to change the water-to-oil ratio by increasing the volume of the surfactant-water external phase and correspondingly decreasing the volume of internal phase. The accuracy of the method was further confirmed by determining the metals in a whole egg powder CRM and recoveries ranged from 97.5% for Mg to 102.2% for Na, with relative standard deviations lower than 2.3%. The precision of the procedures was determined through repeatability (intra-day precision) and intermediate precision (inter-day). The repeatability presented RSD values lower than 4.2%. The intermediate precision was evaluated using the RSD and F-test. The RSD values to intermediate precision was lower than 5.3% and the computed F-values were lower than tabulated F-values, indicating no significant difference between the results obtained on different days. The proposed method including, sample emulsification for subsequent metal determination for FAAS, has proved to be sensitive, reproducible, simple and economical.     

Some reactions occurring in lime refractories containing calcium chloride

Refractory products made from CaOCaCl₂ mixtures precalcined at low temperatures have shown a specific volume stability on further firing to 1500°C and higher, in contrast to their equivalents of pure CaO, MgO, or MgOCaCl₂. This phenomenon was studied using simplified systems, including some additives specially chosen; an explanation is offered based on shrinkage data and the observed development of a unique microstructure, resulting from an early formation of a reactive liquid as well as gas evolution effects. The non-shrinking behaviour of the so-called calcite brick (made from ground limestone masses containing CaCl₂) is also dealt with.     

Determination of sulphide, sulphite and thiosulphate with thallic perchlorate or sulphate

Sulphide, sulphite and thiosulphate can be determined separately or in admixture, with thallic perchlorate or sulphate in acid medium. A sample solution is rendered approximately 0.5 M in acid, 5 ml of 0.05 M KI are added and the solution is titrated to a starch end-point with thallium(III) solution. In another method an acid sample solution is titrated with thallium(III) or iodine solution in the presence of indigo carmine indicator. The end-point is improved in the presence of Co(II).