Chemical preparation techniques dissolving order

Many methods used for qualitative analysis are destmctive, that is, the sample is consumed during the analysis or must be chemically altered in order to be analyzed. The most sensitive and comprehensive elemental analysis methods for inorganic analysis are inductively coupled plasma atomic emission spectrometry (ICP-OES or ICP-AES), discussed in Chapter 7, and ICP-MS, discussed in Chapters 9 and 10. These techniques can identify almost all the elements in the periodic table, even when only trace amounts are present, but often require that the sample be in the form of a solution. If the sample is a rock or a piece of glass or a piece of biological tissue, the sample usually must be dissolved in some way to provide a solution for analysis. We will see how this is done later in the chapter. The analyst can determine accurately what elements are present, but information about the molecules in the sample is often lost in the sample preparation... 

Besides the electrochemical method, other methods such as the chemically initiated polymerization method, the vapor-phase methods, and the Langmuir-Blodgett method have been devised for the preparation of conducting polymers. In the chemical method, a chemical oxidant such as ferric chloride initiates the polymerization. Polymerization usually results in a powdery product and the resultant powder is then compressed into a pellet or dissolved in a suitable solvent such as methylene chloride or chloroform and spin coated on a substrate. In the vapor-phase technique, which is a variation of the chemical method, a monomer film is vacuum sublimed onto a glass substrate and then exposed to a solution or vapor of ferric chloride for oxidative polymerization. Films thus prepared are usually thick, of the order of micrometers. For some applications in which ultrathin and very uniform films are required, the Langmuir-Blodgelt technique for depositing monolayers has also been tried successfully [5]. 

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