Colorimetric Determination of Molybdenum

Hurd, Loren C.; Allen, HArry O.

doi:10.1021/ac50098a013

Cited by 28 publications

(8 citation statements)

References 3 publications

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“…Ethyl ether is not an ideal solvent for the extraction and for making up tbe standard molybdenum solution, because of its volatility. However, there are certain objections to the use of other solvents, such as butyl acetate and cyclohexanol as shown by Hurd and Allen (7), and therefore ethyl ether was employed in the present work; it is satisfactory if reasonable care is taken in its use.…”

Section: Discussion Of the Methodsmentioning

confidence: 90%

Determination of Chromium, Vandium, and Molybdenum in Silicate Rocks

Sandell¹

1936

Ind. Eng. Chem. Anal. Ed.

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Section: Discussion Of the Methodsmentioning

confidence: 90%

Determination of Chromium, Vandium, and Molybdenum in Silicate Rocks

Sandell¹

1936

Ind. Eng. Chem. Anal. Ed.

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“…We found iu priictiee also, that (liflicnlties were enoountt'red in obtaining a elcau separation of the ether and water phases in the presence of stannic chloride. Hurd and Reynolds (1934), who suggested the use of cyclohcxanol, found that the colour was unstable in butyl acetate, the solvent which had been used by James (1932) in place of ether. We have found, liowover, that none of tliesc solvents ia ideal for the extraction of the thiocyanate complex.…”

Section: Choice Of Solvent For Ex1r(teiion Of the Coloured Coviplexmentioning

confidence: 99%

The Determination of Molybdenum in Plant and in Animal Tissue

Dick

Bingley

1947

Aust J Exp Biol Med

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Colorimetric methods of analysis are particularly suited to the inveRtig:ation of biological piublems, where it is often more important to make determinations on a lav^e number of samples tliau to aim ut a very high order of accuracy for each determiiiation. Although, with some eolorimetric methods it is possible to introduce refinements whieh will reduce the experimental error to very low limits, it is often permissible to simplify tbe procedure to achieve the object of rapidity of determination.However, tbe limits of error within which one must work are dictated by the problem itself, aud wben soletitinp: Ihc most suitable analytical procedure these limits must he taken into consideration.The molybdenum content of plant and animal tissues is normally only a few parts per million of the dry matter aud in determining the molybdenum it is necessary to select a method witb a hijih sensitivity, and the procedure must be as simple as pos.sible to enable a larjre number of samples to be handled in a reasonably short time. If one is concerned with the detection of deficient uptake of molybdenum, the low "normal" content of tbe material necessitates tbe use of a method which has tbe further qualification of beins: capable of yielding results of a fairly higb order of accuracy.... Altbougb spectrograpbie methods may possess the necessary sensitivity and be capable of the necessary ac^niracy (Stuart et al., 1946), the refined equipme.nt and bio-hly trained personnel are not always available. We have, therefore, investifraFed' the colorimetric methods for the determination of small amounts of molybdenum.Of the colorimetric methods in the literature, that described by Malo^wan (1919) is based on the formation of a, red-coloured complex of molybdenum with potassium othyl xnnthate; Montipnie (1930) uaed the rod-coloured complex with phenyl hydrazine and Fnlciola (1£I27) developed a method using the reaction of molybdenum in acid solution with eodmm tlnoBulphate eivine a lilac-coloured complex. , , ., However the methods whieh have been employed most extensively are baaed on the reaction, orieinally observed in 1863 by Braun, between molybdenum and an alkali thiocyanate in the Tire^nce'of a reducingr agent." Braun recorded that "a distinct rose-red colour" waa produced when potassium thiocyanate, zine and hydrochloric, acid, were added to fi ml. of a solution containing as little as 10 micrograma of molybdenum. This coloured complex was extrnctnble in King (1923) applied thia reaction in developing a colorimetric, method for the estimation of small amounts of molybdenum in steels. He concentrated the thiocyanate complex by several successive extractions "with ethyl ether and compared the density of the colour with that of a standard of known molybdenum content in a specially designed colorimeter, Maag and McColhim (1925) introduced minor modificationa of the method and James (1932) found that if Ituty! licctatf iveii-RnlifitU.\itt'(l for elher, one pxtrnctiim wys suflioii'nt. Hiird ;IIH1 Rryu'i'-ilfs (1934) found the co...

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“…Estimation. Because the previous investigations on the effect of sulfuric and hydrochloric acids upon the development of the rhenium (6) and molybdenum (5) colors were not extended into the high concentration ranges encountered in distillates of the Geilmann-Weibke type, it was necessary to determine the effect of these variables before attempting to evaluate the efficiencies of various modifications of the conventional distillation.…”

Section: Distillationmentioning

confidence: 99%