Aplicações

O zinco, como aquele que ocorre como constituinte de ligas leves, pode ser determinado por titulação de precipitação com indicação de ponto final potenciométrico. A determinação de zinco na presença de cádmio também é possível. 2K4[Fe(CN)6] + 3 ZnCl2 → K2Zn3[Fe(CN)6]2 + 6KCl

Este Boletim descreve a determinação simultânea de ouro e cobre por titulação potenciométrica utilizando uma solução de Fe(II) como titulante. O Fe(II) reduz o Au(III) diretamente ao metal livre, enquanto o Cu(II) não reage. Pela adição de íons fluoreto, o Fe(III) é complexado e uma mudança no potencial redox é efetuada. Em seguida, adiciona-se iodeto de potássio, reduzindo assim o Cu(II) a Cu(I), e o iodo livre é novamente titulado com a solução de Fe(II) utilizando um Pt Titrode. Reações químicas: Au(III) + 3Fe(II) → Au + 3Fe(III) 2 Cu(II) + 2 I- → 2 Cu(I) + I2 EU2 + 2Fe(II) → 2 eu- + 2Fe(III)

Dois métodos são descritos para a determinação de cromo: uma titulação biamperométrica e uma análise polarográfica.

Silver is an important metal not only in jewelry and silverware but also in electrical conductors and contacts. The knowledge of the exact silver content in fine silver and silver alloys ensures that quality standards for jewelry and silverware are met. As for the plating industry, the knowledge of the amount of silver in silver plating baths helps to run the bath efficiently. While X-ray fluorescence (XRF) is a fast alternative to determine the silver content in fine silver and silver alloys, it can only determine the silver content of the outermost sections of the metal. In contrast, titration offers a more comprehensive solution considering the whole sample, thus preventing fraud by thick plating. This application bulletin describes the potentiometric determination of silver in fine silver and silver alloys according to EN ISO 11427, ISO 13756, GB/T 17823, and GB/T 18996 as well as in silver plating baths by a titration with potassium bromide or potassium chloride, respectively

This Bulletin describes the complexometric potentiometric titration of metal ions. An ion-selective copper electrode is used to indicate the endpoint of the titration. Since this electrode does not respond directly to complexing agents, the corresponding Cu complex is added to the solution. With the described electrode, it is possible to determine water hardness and to analyze metal concentrations in electroplating baths, metal salts, minerals, and ores. The following metal ions have been determined: Al3+, Ba2+, Bi3+, Ca2+, Co2+, Fe3+, Mg2+, Ni2+, Pb2+, Sr2+, and Zn2+.

A method is described in this Bulletin that allows molybdenum to be determined in steel and other materials containing a high iron concentration. Mo(VI) is determined at the dropping mercury electrode by catalytic polarography. The determination limit is approx. 10 μg/L Mo(VI).

A corrosion inhibitor is a substance that reduces the corrosion rate of a metal. A corrosion inhibitor is usually added in a small concentration to the corrosive environment. This application note shows how Metrohm Autolab instruments can be used to check the quality of inhibitors.

Corrosion of metals is a problem seriously affecting not only many industrial sectors, but also private life, resulting in enormous costs. In this application note, the results gained during electrochemical corrosion studies on different metals are compared to literature data.

The ASTM standard G100 is an electrochemical method to test localized corrosion of aluminum 3003-H14 and other alloys. A cyclic galvanostatic staircase polarization (galvanostaircase) is composed of an upward and a downward scan. The potential values at the end of each step are collected and linearly fitted, and the potential values at zero current are found.

The rotating cylinder electrode (RCE) is a technique used in corrosion research to simulate in a laboratory environment the turbulent flow which usually occurs when liquids are transported through pipelines. The RCE is used to generate a turbulent flow at the surface of a sample, simulating the pipe flow conditions. Experiments that involve an RCE are regulated by the ASTM G185 standard. In this application note, The RCE with a 1018 carbon steel cylinder sample was used with the linear polarization (LP) measurement technique.