Gravimetric analysis, organic

Erdey, L. Gravimetric Analysis, Pergamon Oxford, 1965. Steymark, A. Quantitative Organic Microanalysis, The Blakiston Go. New York, 1951. 

The heavy metal salts, ia contrast to the alkah metal salts, have lower melting points and are more soluble ia organic solvents, eg, methylene chloride, chloroform, tetrahydrofiiran, and benzene. They are slightly soluble ia water, alcohol, ahphatic hydrocarbons, and ethyl ether (18). Their thermal decompositions have been extensively studied by dta and tga (thermal gravimetric analysis) methods. They decompose to the metal sulfides and gaseous products, which are primarily carbonyl sulfide and carbon disulfide ia varying ratios. In some cases, the dialkyl xanthate forms. Solvent extraction studies of a large number of elements as their xanthate salts have been reported (19). 

Inorganic Qualitative Analysis Organic Qualitative Analysis Inorganic Gravimetric Analysis Vol. IB Inorganic Titrimetric Analysis... 

A historically important form of gravimetric analysis was combustion analysis, used to determine the carbon and hydrogen content of organic compounds burned in excess 02 (Figure 27-4). Instead of weighing combustion products, modem instruments use thermal conductivity, infrared absorption, or coulometiy (with electrochemically generated reagents) to measure the products. 

A polyvinyl acetate latex prepared by semi-continuous polymerization at 55° using a polymethacrylic acid-nonylphenol-poly-ethoxylate phosphate ester emulsifier and sodium persulfate-sodium formaldehyde sulfoxylate initiator (23). The latex was cleaned by ion exchange and serum replacement using both Nuclepore and Pellicon membranes, and the cleaned latex and serum fractions were analyzed by conductometric titration. In addition, the dried films were extracted with water and organic solvents, and the extracts were analyzed by infrared spectroscopy and thermo-gravimetric analysis. 

The use of organic components increases the discrimination in soils that are otherwise similar. For example, soils that have identical Munsell color values could be discriminated by subtractive FTIR. A new ancillary method using thermal gravimetric analysis in addition to IR analysis on samples prior to and after pyrolysis has been applied to soils and could give additional valuable information for the discrimination of soils (Thermo electron corporation application note 50862). 

There are several laboratory tests available for identifying the type of contaminant and its concentration. If onsite laboratory facilities are not available, these tests can be conducted by an independent laboratory or a water-treatment consultant. Tests include gravimetric analysis, infrared analysis, spot testing, chromatography and measurement of total organic carbon (TOC). 

Conversion of the as-deposited film into the crystalline state has been carried out by a variety of methods. The most typical approach is a two-step heat treatment process involving separate low-temperature pyrolysis ( 300 to 350°C) and high-temperature ( 550 to 750°C) crystallization anneals. The times and temperatures utilized depend upon precursor chemistry, film composition, and layer thickness. At the laboratory scale, the pyrolysis step is most often carried out by simply placing the film on a hot plate that has been preset to the desired temperature. Nearly always, pyrolysis conditions are chosen based on the thermal decomposition behavior of powders derived from the same solution chemistry. Thermal gravimetric analysis (TGA) is normally employed for these studies, and while this approach seems less than ideal, it has proved reasonably effective. A few investigators have studied organic pyrolysis in thin films by Fourier transform infrared spectroscopy (FTIR) using reflectance techniques. - This approach allows for an in situ determination of film pyrolysis behavior. 

The diorgano tellurium dicarboxylates are white, crystalline materials that are soluble in organic solvents and stable towards atmospheric agents. Diaryl tellurium diacetates can be boiled in water without decomposition. However, bis[trifluoromethyl] tellurium bis trifluoroacetate] was reported to be moisture-sensitive. Aqueous sodium hydroxide converts diaryl tellurium dicarboxylates to diaryl tellurium oxides or dihydroxides . Thermal gravimetric analysis of diaryl tellurium dicarboxylates indicated that these compounds lose carbon dioxide at 240-260° and form the tetraaryl tellurium derivatives. The tetraorgano tellurium compounds decompose slowly to the diaryl tellurium compounds and hydrocarbons. ... 

Deprotonation of 8-hydroxyquinoline gives the didentate ligand 12.38 which has a number of applications. For example, Al + may be extracted into organic solvents as the octahedral complex [Al(12.38)3] providing a weighable form of AP for the gravimetric analysis of aluminium. 

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