An improved electrode holder for spectrographic analysis

Scribner, Bourdon F.; Corliss, Charles

doi:10.6028/jres.030.003

Cited by 9 publications

(5 citation statements)

References 3 publications

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“…are difficult to maintain. The electrodes can be watercooled (Sawyer & Vincent, 1940;Scribner & Corliss, 1943), but it has generally been found more convenient to use an interrupted arc. The earliest form was entirely mechanical (Gerlach & Ruthardt, 1932), but moving parts on the arc stand are avoided by the use of a superimposed high-frequency discharge to ignite the current, as described by Pfeilsticher (1937).…”

Section: ( 5 ) the Interrupted Arcmentioning

confidence: 99%

Spectrographic Analysis of Plants and Soils

Mitchell

1947

Biological Reviews

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Summary Spectrographic methods which are applicable to the analysis of plants and soils include those employing flame, arc and spark excitation. Some seventy elements can be determined spectrographically, the most important exceptions being gaseous and non‐metallic elements. The most widely used flame emission method is that devised by Lundegårdh, in which the solution under examination is sprayed into an air‐acetylene flame. This method is particularly suited to the determination of the alkali and alkaline earth metals in soil and plant extracts. The Ramage method, in which the material is introduced on a paper spill, has also been used to some extent. Arc methods are widely employed for the determination of both trace and major constituents, generally with solid material in carbon or graphite electrodes of a shape chosen to suit the object of the investigation. The most sensitive source for most elements is probably the cathode‐layer arc, although the high‐voltage a.c. arc is useful for certain elements in solution. Interrupted arc and spark sources have been less widely used but have advantages for certain purposes, such as the determination of boron. Some direct photometric methods, omitting the use of a photographic plate, are described. Spectrographic methods are applicable to qualitative, semi‐quantitative or quantitative determinations. Semi‐quantitative methods generally employ a visual or subjective assessment of the content of an element, and are useful in giving a general indication of the levels of most of the trace constituents present in any sample, with an accuracy of some 30%. When objective photometric measurements are used, figures reproducible to ± 3–10% may be expected, depending on the method employed and the element being determined. Applications of spectrographic methods to analyses of soils and plants have been along both lines, either the semi‐quantitative survey of as many elements as possible, or the quantitative determination of specific elements. Attention is drawn to the relationship of the soil content to the geological origin of its parent material and to soil effects which may influence plant uptake.

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Section: ( 5 ) the Interrupted Arcmentioning

confidence: 99%

Spectrographic Analysis of Plants and Soils

Mitchell

1947

Biological Reviews

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“…The electrode combination employed, figure 2, is similar to that described by Scribner and Oorliss [10], but it provides a deep cup in the anode in which the sample charge is heated. A further modification is the tapered fit between the cap and pedestal, providing accurate alinement of the electrode.…”

Section: Arc Excitationmentioning

confidence: 99%

Carrier-distillation method for spectrographic analysis and its application to the analysis of uranium-base materials

Bf¹,

Hr²

1946

J. RES. NATL. BUR. STAN.

Self Cite

153

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A method of fractional distillation in the direct-current arc was developed for the spectrographic determination of 33 volatile impurity elements at concentrations as low as a fraction of a part per million in uranium-base materials. The method involves (1) the conversion of the sample matrix to a form having low volatility, (2) the addition of a small amount of a selected volatile "carrier" material, and (3) partial distillation of the mixture in a direct-current arc with an electrode assembly of improved design. In the analysis of uranium-base materials, the sample was converted to the oxide U30S and gallium oxide was added as a carrier (2 parts Ga203, 98 parts UaOs). The procedure was applied to the determination of Ag, AI, As, Au, B, Ba, Be, Bi, Cd, Co, Cr, Cs, Cu, Fe, Ge, H g, In, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sb, Si, Sn, TI, V, and Zn. Repeated results for B, Cd, Si, Fe, Mg, and Mn, determined photometrically, agreed within ± 10 percent. The high sensitivity and general applicability of the method are results of the characteristic that the refractory sample matrix is not volatilized appreciably, during the period that the minute quantities of impurity vapors are swept into the arc by the carrier.

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“…The upper electrode consists of a I-inch length of ~-inch-diameter stock with a tapered "pencil" point. The lower electrode similar to the design of Scribner and Corliss [25] consists of two parts, (1) a base and pedestal cut from X-or ~-inch-di ameter stock, which is clamped to the arc stand and acts as a support for (2) the cap which carries the sample. With this design the samplebearing area of the electrode obtains a more uniform and higher temperature than with the usual one-piece design.…”

Section: Sample Preparation and Electrodesmentioning

confidence: 99%

“…The electrode holder, or arc stand [20,25], should be designed to provide rapid vertical adjustment of both electrodes, adjustment of the upper electrode during the exposure to keep the gap constant, and controlled ventilation.…”

Section: Making the Spectrogrammentioning

confidence: 99%

Spectrographic determination of sodium, potassium, and lithium in portland cement with the direct-current carbon arc

Helz¹

1945

J. RES. NATL. BUR. STAN.

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Spectrographic methods, which are much less time-consuming than the usual chemical m ethods, are described for the determination of sodium, potassium, and lithium in portland cement. For the determination of sodium and potassium the sample is mixed with a mineral base containing silver for the internal standard. For lithium a standard mixture of graphite and strontium carbonate is added to the cement sample. In either case a fixed amount of the resultant mixture is placed in the crater of a graphi te electrode, which is made the lower positive element of a direct-current arc. The Na 8194.81 A, K 7698.98 A, and Li 3232.61 A lines are used for the quantitative calculations. A discussion of the development. of the method is given, followed by details of the adopted analytical procedure. The spectrographic analyses of 41 cements for sodium and potassium are given for comparison with the chemical values. CONTENTS Page

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An improved electrode holder for spectrographic analysis

Cited by 9 publications

References 3 publications

Spectrographic Analysis of Plants and Soils

Spectrographic Analysis of Plants and Soils

Carrier-distillation method for spectrographic analysis and its application to the analysis of uranium-base materials

Spectrographic determination of sodium, potassium, and lithium in portland cement with the direct-current carbon arc

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