A colorimetric method for the quantitative determination of small amounts of silver by use of p-dimethylaminobenzalrhodanine

Schoonover, I.C.

doi:10.6028/jres.015.024

Cited by 28 publications

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“…Many of the problems and anomalies in the Evans Blue literature (1, 2, 7-10, 18) may be the direct result of a failure to appreciate the analytical significance of these adsorption effects. This may not be surprising, for in most other cases in analytical chemistry (4,(12)(13)(14)17) adsorption errors have proved to be negligibly small.…”

Section: Discussionmentioning

confidence: 99%

Analytical Problems in Determination of Evans Blue

Caster¹,

Simon²,

Armstrong³

1954

Anal. Chem.

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Section: Discussionmentioning

confidence: 99%

Analytical Problems in Determination of Evans Blue

Caster¹,

Simon²,

Armstrong³

1954

Anal. Chem.

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“…They are well known with silver and mercury (Freundlich 6L-Sdlner, 1928;Stock & Seuenschwander-Lemmer, 1938;Sandell, 1959). The losses, or rates of loss, increase with temperature (Kolthoff, 1921 ;Schoonover, 1935;Hensley et al 1949;Hensley, 1951); the percentage loss increases with the degree of dilution (Stock & Xeuenschwander-Lemmer, 1938;Hensley, Long & Willard, 1949;Schonfeld & Broda, 1951); and, at least with salts of silver and mercury, is less on Pyrex than on soda glass (Schoonover, 193 j ;Sandell, 1959). The rates of release of some sorbed ions into distilled water increase with temperature (Dwyer, 1938;Hensley et al 1948).…”

Section: I S C U S S I O Smentioning

confidence: 99%

Some variants and possible errors in the test‐tube dilution and slide‐germination methods for laboratory testing of fungicides

McIntosh

1961

Annals of Applied Biology

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Receked 1 3 yarzunrj* 1 9 6 1 ) S U M M A R Y. I method is given for moulding uniform Perspex (polymethyl methacrylate) cavity slides, which are quickly made, almost unbreakable and without joints; they can withstand strong alkalis, but not strong acids or solvents, and are useful for spore germination tests of water-soluble fungicides. When the drops of spore suspension-fungicide mixture in the cavities of these slides or of Bottcher's glass cavity slides are enclosed by cover-slips, there is no meniscus effect, and in tests of long duration the same spores can be counted repeatedly.In such tests, errors may arise from sorption of the fungicide on the surfaces of pipettes and tubes (dilution stage) and on slides and cover-slips (incubation stage); and from changes in the volume of the drops (incubation stage).Ions of many metals may be lost by sorption, and the losses are often greater on soft than Pyrex glass. Hg was lost rapidly. In a three-stage serial dilution of HgCI, solution in soft glassware from 60 to 1.0 p.p.m. of Hg, the loss in strength was 27 06.More Hg was lost from HgC1, than from phenyl mercuric acetate solutions. The losses on glass or Perspex slides with cover-slips from solutions containing 1.0 p.p.m.of Hg (but no spores in suspension) were 30-35 O;, in 15 min. and 61-740., in 24 hr. with HgCl,, but only 5-10",, on glass and 35-3700 on Perspes slides in 24 hr. with phenyl mercuric acetate. Increase in temperature (10--25' C.) slightly increased the loss from HgC1, but not from phenyl mercuric acetate solutions. Perspex slides, which were used repeatedly for tests of water-soluble mercury compounds and washed in distilled water after each test, eventually became toxic to conidia of Rotrytis fahue Sardiiia.When the slides, with drops, are placed in moist chambers for incubation, some evaporation is unavoidable because the air close to them is not initially saturated with water vapour. When the chambers were pre-cooled or pre-warmed, so that the temperature of the air in them was uniform, the loss from 0.30 ml. drops in cavity slides was not serious (about 8 o c l , with or without cover-slips, in 48 hr. at 10 or 25' C,).But when the temperature was not uniform, the possibilities of change in drop volume were much greater: in 48 hr., the volume of open drops could decrease by evaporation (++?,, loss at 10" C.) or even increase slightly by condensation (3 0 , ; gain at 25' C.). \iThen spores have to be counted on several occasions, the evaporation losses may be more serious.

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“…°Results by two analysts. Presence of silver (>0.1%) was suspected, b 0.03% Sn present 6. Bureau of Standards sample 52a, 0.012% Pb.…”

mentioning

confidence: 98%

“…The presence of silver in refined copper metal may be detected by direct spot test on the metal, using p-dimethylaminobenzalrhodanine (6). Tin, if present, is oxidized to the insoluble tin dioxide, and may be removed by filtration.…”

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confidence: 99%

Precision Determination of Lead in High Grade Copper

Silverman¹

1948

Anal. Chem.

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The technique of the determination of lead in copper by the dithizone and electrodeposition methods is discussed in detail. WHEN electrolytic copper is produced by the air oxidation of molten copper, it is important to determine its lead content (0 to 0.03%) because of the undesirable hardness attributed to the presence of small amounts of lead in highly refined copper metal. The most applicable chemical procedures are the lead dithizone photometric and lead dioxide electrodeposition methods. The techniques of these two methods are discussed in detail in this paper. ELECTRODEPOSITION METHODAcidity. When lead dioxide is to be deposited from a copper nitrate solution of 200-ml. volume, the nitric acid content should be (roughly) proportional to the amount of lead present: 0.15 gram of lead, 15% of nitric acid (by volume) 0.05 gram of lead, 5 to 7% of nitric acid 0.002 gram of lead, 1 to 2% of nitric acid plus ammonium ion These figures indicate the desired range of acidity, which must be kept in mind when preparing the electrolyte.Ammonium and Nitrate Ions. Ammonium nitrate is an essential reagent in the electrodeposition of small amounts of lead dioxide. The electrolyte should contain a minimum of 5 grams of ammonium ion per 100 ml.; electrolytes containing less than this amount give poorer plates than those of higher ammonium contents. Ammonium nitrate increases the conductivity of the electrolyte (decreases the resistance), which

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A colorimetric method for the quantitative determination of small amounts of silver by use of p-dimethylaminobenzalrhodanine

Cited by 28 publications

References 0 publications

Analytical Problems in Determination of Evans Blue

Analytical Problems in Determination of Evans Blue

Some variants and possible errors in the test‐tube dilution and slide‐germination methods for laboratory testing of fungicides

Precision Determination of Lead in High Grade Copper

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