Direct spectrographic determination of impurities in uranium tetrafluoride

A direct spectrographic method for tlic determination of some impurities in UF₄ is described. The sample in the graphite electrode was covered with a layer of alumina before the arc was struck; alumina prevents the volatilization of UF₄ and thus avoids high spectral and background interferences. To stabilize the discharge, a controlled atmosphere of argon and oxygen was used. The impurity elements were divided into 3 categories according to their volatility: high (B, Si), medium (Co, Mn, V, Mo, Ti, etc.), and low (Ni, Pb, alkaline earths, etc.). Impurities of high and medium volatility could be determined with germanium or aluminum as internal standard. The sensitivities found for this method generally agreed with those of the carrier distillation method. The coefficients of variation varied from 8 to 25% at the 25 p.p.m. level.     

The spectrographic determination of impurities in small amounts of radioactive graphite by the cathode layer technique

A modification of the cathode layer technique is suitable for the analysis of radioactive graphite using copper and cobalt as internal standards. The sample is ground with the internal standard mixture and introduced into a specially designed electrode which is burned in a d.c. arc. The cathode layer portion of the arc plasma is examined using a medium quartz spectrograph with photographic recording. The spectra are evaluated visually, by comparison with standard spectra, or by non-recording microphotometry using the “blackening separation” method. Using a 5-mg sample of graphite, the effective concentration range for Al, B, Ba, Be, Bi, Ca, Cr, Fe, Mg, Mn, Mo, Ni, Pb, Si, Sn, Ti and V is from 10 to 500 p.p.m. and the coefficient of variation for single exposures at the 100-p.p.m. level varies from 2 to 6% according to the element determined.     

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%.

     

Spectrographic determination of impurities in ultrapure tungsten and tungsten oxide

The effects of an external magnetic field and of the diameter of the anode on the spectroscopic line intensity of the impurity elements in ultrapure tungsten and tungsten oxide have been studied. The results obtained are used for the development of a more sensitive method for the determination of these impurities (Mn, Pb, Fe, Ni, Al, Mo, V, Cu, Cr).     

Masking of manganese in relation to stepwise complexometric determination of calcium, magnesium and manganese

A critical study has been made of the masking of manganese with potassium cyanide in alkaline medium for complexometric titration of calcium and magnesium. It has been found that there is incomplete oxidation to manganese(III) unless the solution is aged for a sufficient period or air is bubbled through the solution at 35 ± 5° for 10 min. The manganese(III) complex can be reduced with ascorbic acid for titration with EDTA. Procedures are given for stepwise titration of magnesium, manganese and calcium in silicate materials. Mixed indicators are used, to improve the end-points.     

Determination of impurities in single crystals of magnesium oxide by neutron activation analysis

The determination of some trace impurities in single-crystal magnesium oxide is described. Radiochemical separations of iron, cobalt, scandium, manganese and chromium by ion exchange and solvent extraction are applied in conjunction with γ-spectrometry. The impurities that give rise to long-lived γ-emitting isotopes are considered.     

Complexometric determination of magnesium oxide in flyash blended cement

A complexometric titration method is proposed to determine magnesium oxide in flyash blended cement. A 0.50 g of sample was heated with hydrochloric acid for 10 min. The solution was diluted to 500 ml, and 50 ml was pipetted and heated to boiling with 2.5 ml of 5% ammonium oxalate solution. The solution was then made alkaline by ammonium hydroxide. The suspension was cooled and filtered. The filtrate was titrated by standard 0.002M EDTA solution. The concentration of MgO in sample was calculated. The flyash content of the sample was determined by British Standard method and the recovery factor (f) was calculated by the equation of f = 100/(99 - 0.315 x %FA). Concentration of MgO in sample was corrected by multiplying the recovery factor with concentration initially found by EDTA titration. The precision of the method is better with more time saving than the official methods.     

Metal oxide semiconductor sensors for determination of reactive gas impurities in air

Characteristics of metal oxide semiconductor sensors intended for measuring O₃, NO _x , Cl₂, C1O₂, and HCl microconcentrations were discussed. Specific features of detection of these microimpurities with semiconductor sensors were determined. The size of signal generated by sensors with WO₃-, ZnO-, and In₂O₃-based sensing layers was examined in relation to the O₃, NO _x , Cl₂, C1O₂, and HCl concentration. The sensitivities exhibited by the semiconductor sensors with respect to target impurities make them suitable for measuring their maximum permissible concentrations in sanitary zones and for monitoring background ozone level in atmosphere. Examples of application of gas analyzers based on semiconductor sensors in determination of gas impurities in the open atmosphere were given.     

直读光谱法测量镁合金中锰含量的测量不确定度评定

根据GB/T13748.21-2009镁及镁合金化学分析方法(光电直读发射光谱分析方法测定元素含量)对镁合金中锰元素含量进行了分析,对锰含量测量的不确定度来源进行了分析,并对测量过程中产生的不确定度进行了评定.此外,指出了该方法影响锰元素测量不确定度的主要原因,以期为镁合金中锰元素含量的光谱分析提供参考.     

Selective spectrographic determination of trace elements in pure copper

Summary For the determination of various trace elements with the globule-arc technique a method is used where individual shutters are employed in front of the film plane of the spectrograph. The shutters are automatically operated by a conventional tape reader. It permits to optimate the sensitivity in tracing various elements as the analytical lines are registered only at maximum vaporization and excitation. Further it is possible to eliminate coincidence of some lines by using one shutter for each element to be determined. In the analysis a 2m ARL grating spectrograph with photographic registration is used. A sample of 1 g is placed on a carrier electrode of copper. Graphite is used as counter electrode. The sample is melted in a 9 A continuous direct current arc. The total time of exposure is 240 s.

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Selektive spektrographische Bestimmung von Elementspuren in reinem Kupfer

Zusammenfassung Zur Bestimmung von Elementspuren in Kupfer mit der Kugelbogenmethode werden individuelle Blenden vor der Filmebene des Spektrographen verwendet, die automatisch durch ein konventionelles Lochstreifengerät gesteuert werden. Dadurch wird eine optimale Empfindlichkeit für jedes Element erzielt, da die Analysenlinien nur bei maximaler Verdampfung und Anregung aufgenommen werden. Außerdem werden Koinzidenzen vermieden, da für jedes Element eine Blende verwendet wird. Zur Anwendung kommt ein 2m ARL Gitterspektrograph mit photographischer Registrierung. Eine 1 g-Probe wird auf eine Trägerelektrode aus Kupfer gegeben, wobei Graphit als Gegenelektrode dient. Die Probe wird in einem kontinuierlichen Gleichstrombogen von 9 A geschmolzen. Die Gesamtbelichtungszeit beträgt 240 s.

     

Physicochemical modeling of the behavior of impurities in bismuth oxide in the chemical distillation of the sample matrix

The physicochemical modeling of the behavior of impurities in the course of their preconcentration by the chemical distillation of the sample matrix consisting of granules of a solid solution of impurities in bismuth oxide was carried out. It was supposed that the distillation process is conducted in a kinetic mode. The results of calculations by the model are compared with the earlier results of modeling of the behavior of impurities in distilling a heterophase sample consisting of matrix (bismuth oxide) granules and granules of impurity oxides. The experimental data and results of calculations by the model agree well.     

The spectrographic determination of total barium in bone ash

Samples of bone ash are mixed with graphite and anhydrous copper sulphate as spectrographic buffer and lanthanum oxide as internal standard. The mixture is pressed into 30-mg pellets and burnt in a d.c. arc surrounded by a mantle of oxygen and argon. The spectra are evaluated by non-recording microphotometry. The effective concentration range is 2–25 p.p.m. of barium in the ash, and the coefficient of variation is 8% for single exposures at the 8-p.p.m. level     

Separation of lithium and magnesium isotopes by hydrous manganese(IV) oxide

Lithium and magnesium isotopes were separated by chemical ion exchange using hydrous manganese(IV) oxide and elution chromatography. The capacity of manganese(IV) oxide was 0.5 meq/g. The glass ion exchange column used was 35 cm long with an inner diameter of 0.2 cm, and 2.0M CH₃COONH₄ solution served as eluent. The single stage separation factor was determined from the elution curves and isotopic assays according to the method of Glueckauf. The separation factor of ⁶Li⁺-⁷Li⁺ was 1.022±0.002, those of ²⁴Mg²⁺-²⁵Mg²⁺, ²⁴Mg²⁺-²⁶Mg²⁺, and ²⁵Mg²⁺-²⁶Mg²⁺ were 1.012±0.001, 1.021±0.002, and 1.011±0.001, respectively.     

An automatic spectrographic method for the determination of oxygen in steel

A device for the determination of oxygen in steel (20–200 mg samples) is described. A high temperature hollow-cathode discharge is used to melt the sample and excite the atomic spectrum of oxygen. A compact grating monochromator fitted with two red-sensitive photomultipliers is used to record the difference in integrated intensity between the oxygen multiplet at $\text{7772}\text{5}$ A and the adjacent background during a fixed integration period, the corresponding voltage difference being presented on a digital voltmeter linked to an automatic print-out. The automatic cycle of operations takes 2.5 min per sample. The sensitivity of the technique is 1 μg 0. The coefficient of variation per determination varies from 6 to 15% depending upon the homogeneity of the sample.