Postcolumn Reaction Detection of Cations

While alkali metal and alkaline earth cations are detected routinely using conductivity detection, transition metals and lanthanoids are most commonly detected using a post-column reaction (PCR). In most cases, this involves a post-column addition of a colour-forming ligand, generally a metallochromic

Figure 11 Detection of anions using indirect spectrophotometry. A Vydac 302 4.6 IC surface-functionalized silica anion exchange column was used with 5 mmol L_1 potassium hydrogen phthalate at pH 4.0 as eluent. Detection was at 285 nm. (Reprinted with permission from Heckenberg and Haddad, 1984.)

dye. Typical examples of such dyes are 4-(2-pyridylazo)resorcinol (PAR), which is used for the detection of transition metals, and 2,7-bis(2-arsonophenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid (Arsenazo III), which is used for the detection of lanthanoids. Both dyes react rapidly with a wide range of metal ions to form strongly absorbing complexes that facilitate sensitive detection without the need for complicated reactors or mixing devices. Figure 12 shows a typical chromatogram obtained using Arsenazo I as the PCR reagent.

Figure 12 Use of post-column reaction for the detection of lanthanoids. Separation was achieved on a Nucleosil 10SA silica-based cation exchange column using 2-methyIIactic acid as eluent, with post-column reaction detection with Arsenazo I. (Reprinted with permission from Wang etal., 1984.)
Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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