Ervin Jungreis

The heterometric micro-analysis of cobalt with α-nitroso - β-naphthol. a general study.

Abstract 1. The reaction between cobaltous or cobaltic and α-nitroso-β-naphthol was extensively studied heterometrically both in water and in alcoholic solutions. The influence of complexing agents and of the acidity on the precipitation of cobalt-α-nitroso-β-naphthol was investigated. In all cases the molar ratios : [Co] [αβ] at the end of the precipitation were established and the possible compounds which were obtained were discussed. 2. Micro-analytical heterometric methods are given for the determination of cobalt or α-nitroso-β-naphthol. The determination can be carried out with precision even in concentrations as low as 0.0001 M Co. Conversely, very dilute alcoholic solutions of α-nitroso-β-naphthol may be titrated with precision with a dilute solution of cobalt nitrate. 0.2–0.5 mg cobalt in 20 ml solution are required for the analysis. The error lies between zero and 3%.

Heterometric micro-determination of cobalt with α-nitroso-β-naphthol in the presence of foreign metal

Abstract A heterometric method is presented for the determination of cobalt in solutions or other metals. The cobalt comprises 0.1–3% of the total metal content. The amount of cobalt determined is 0.2–0.5 mg in 20 ml of solution. The titration generally takes 10–20 minutes at room temperature, and the error is 0–3%.

A micro-heterometric determination of traces of iron (III) in alloys and salts with α-nitroso β-naphthol

Abstract Ferric iron constituting approximately 0.01% — 0.1% may be determined by a heterometric titration with α-nitroso-β-naphthol. The solution may contain 99.9% or more of calcium, barium, magnesium, aluminium, chromium, manganese, nickel, cadmium or lead salts. No previous separation is necessary. The α-nitroso-β-naphthol is dissolved in alcohol. The analysed solution must be acidified. No complexing agents are necessary. Citrate or tartrate must be absent. The maximum optical density values which are obtained at the end of the titration are proportional to the amount of iron which is analysed. These maximum values are entirely unaffected by the concentrated salt solutions. The heterometric sensitivity of the reaction between iron and α-nitroso-β-naphthol is three times higher in 50% alcoholic solution than in water. The titration takes about one hour. The error is 0.0—4%.

The heterometric microdetermination of mercury with mercaptobenzthiazole in the presence of an excess of foreign metals

Abstract 1. A general method is presented for the determination of 1–2 mg mercuric mercury, in the absence of complexing agents, in 20 ml solution, with an error of 0–3 %. The solution may contain: Ca, Ba, Mg, Zn, Mn, Ni, Co or Cd as nitrate of sulphate in a concentration of 0.2 M . The concentration of Pb should be M and that of Al, Cr or Fe ⩽0.05M. 2. A special method is presented for the determination of mercury (1–2 mg Hg in 20 ml) in the presence of large excesses of bismuth (≷98%) by using ethylendiammetetraacetate. Error 0–3 %. 3. A method is presented for the determination of mercury in excesses of copper in an acetic acid solution which contains ethylendiaminetetraacetate. 4. A special method is presented which permits the determination of 1–2 mg mercury in 30 ml solution which contains large excesses of copper (up to 98% or more). The titration is carried out in an alkaline solution of trisodiumcitrate. The titration proceeds rapidly. Error 0–2%.

Copper salicylaldoxime and its use in the heterometric microdeterminatton of copper in the presence of foreign metals

Abstract 1. The initial precipitation of copper-salicylaldoxime occurs at pH~1.5.Between pH 1.5 and 3.0, the precipitation is incomplete. A complete precipitation occurs in the pH-region of 3–10. Between pH 10.1 and 10.7 the precipitate redissolves At higher pHs a clear solution is obtained. 2. The solubility of copper salicylaldoximate is about ten times greater in 0.01M sulfuric acid (~0.5·10 -4 mol) than in 0.1 M acetic acid. 3. In 10 ml of 0.1 M acetic acid solution in the presence of ~99% foreign bivalent metals, one mg copper could be determined heterometrically with an error of 1–2%. 4. In the presence of ~95% alumin um or chromium, either citrate or tartrate (0.2 M ) were used as masking agents. In the presence of iron (~ 95%), clear end-points were obtained only with citrate. One mg of copper could be determined with an error of 0–3%. 5. Whichever pH is used, copper is not precipitated in the presence of ethylenediaminetetraacetate.

A Simple Microdetermination Of Polymer Flocculants (Polyacrylamides And Guar) In Mine Water

Abstract An extremely simple, sensitive and selective microdetermination of polymer flocculants in mine water is feasible by measuring the laminar flow rate through membrane filter under vacuum.

A simple direct estimation of ultramicroquantities of lead in drinking water using sodium rhodizonate

Abstract A simple and sensitive test is suggested for the screening of drinking water for traces of lead. The test is based on the modification of the sodium rhodizonate reaction. Fifty parts per billion of lead can be detected by this technique.

Spot tests for chlorate, bromate and iodate in admixture

Abstract Detection by selective spot tests for each of the halates, chlorate, bromate and iodate, is detailed.

Indirect microdetermination of cyanide by atomic absorption spectroscopy

SummaryAn indirect AAS determination is proposed for cyanide. The method is based on the cuprous cyanide complex formation.ZusammenfassungEine indirekte Atomabsorptionsmethode für die Bestimmung von Cyanid beruht auf der Kupfer(1)cyanid-Komplexbildung.

Approximate Quantitation of Ascorbic Acid in Citrus and Tomato Juices with “Sandwich”-Indicator Sticks

Abstract A rapid field-test of ascorbic acid content in fruit juices is feasible by the application of indicator papers capable for approximate quantitation.