Wet chemical dissolution

The limitation of ICP-MS in analyzing solid materials (without the need for wet chemical dissolution/digestion methods) led to the development of laser ablation. The principle behind this approach is the use of a high-powered laser to ablate the surface of a solid and sweep the sample aerosol into the ICP mass spectrometer for... 

Generally, wet chemical methods require the availability of compounds which are soluble in water or in another solvent. The dissolution in a solvent allows intimate mixture on an atomic or molecular scale. However, it has to be ensured that no compound precipitates before the others when the solvent is evaporated, or else insoluble products are formed. The importance of wet chemical methods lies in the possibility of simple upscaling to industrial needs. 

While most polymer/additive analysis procedures are based on solvent or heat extraction, dissolution/precipita-tion, digestions or nondestructive techniques generally suitable for various additive classes and polymer matrices, a few class-selective procedures have been described which are based on specific chemical reactions. These wet chemical techniques are to be considered as isolated cases with great specificity. 

For the purpose of the identification and quantification of additives (broadly defined) in polymeric materials extraction and dissolution methods are favoured (Sections 3.3-3.7). However, additives are also made accessible analytically by digestion of the sample matrix (cf. Section 8.2). Such wet chemical techniques, that remove the sample matrix first, are often limited to mg amounts because of pressure build-up in destruction vessels. Another reactive extraction approach to facilitate additive analysis is depolymerisation by acid hydrolysis or saponification, sometimes under pressure. This is then frequently followed by chemical methods such as titrimetry or photometry for final identification and quantification. 

Methodology Six samples were analyzed three passed the dissolution test (good samples) and three failed (bad samples). Several ingredients were used as references Avicel (cellulose), the API, magnesium stearate, and poloxamer. Dissolution was tested after NIR imaging measurement to obtain the wet chemical references. 

The Determination of Selenium. The most difficult trace element to determine in coal by wet chemical methods is selenium. Two alternative dissolution techniques can be used—H. L. Rooks combustion method (7) and the oxygen bomb combustion method (4). Also, two alternative analytical methods can be used—the hydride evolution method (5) and the graphite furnace method. 

Wet chemical methods of analyses of formulations contgaining TNT, as cited above, usually involve the application of preferential dissolution for resolving the mixt into its component parts (Ref 53). Titrimetric methods for the quant determination of the resolved components are also presented (Refs 23,26,11, 66 98)... 

The chemical composition with respect to Si and metallic impurities (mainly Fe, Ca, Al) is generally determined by wet chemical methods in combination with standard spectroscopic techniques (AAS, AES, XRF) (Table 8) [224-226]. A precondition is the dissolution of the powder. Typical dissolving processes are fusion with sodium carbonate or mixtures of sodium carbonate and boric acid, with alkaline hydroxides [225, 226] and special acid treatments [225]. A more effective analysis based on optical emission spectroscopy allows the direct analysis of impurities in the solid state and requires no dissolution step [227]. 

For removal of insoluble and/or water-immiscible inorganics by emulsification with detergent solutions For removal of ester and amide-based organics and inorganic salts by chemical hydrolysis with alkaline solutions For removal of metal ions from solutions and surfaces by chelation or complexation reactions For wetting and dispersion of soils with surfactants, suspension of soil residues in order to prevent resedimentation and recontamination on metal surface For removal of surface contaminations, rust scale, mill scale, and other bound moieties (including surface layers of metal itself) by chemical dissolution with acids or alkaline deoxidation with or without the application of an electric current... 

The chemical dissolution of silicon can be obtained in both liquid and gaseous media. The latter is known as dry etching or reactive ion etching (RIE) and is used in today s microelectronic manufacturing. However, wet processes related to silicon are also very important, as one third of the total number of process steps for the fabrication of today s integrated circuits involve... 

Direct analysis of solids for selenium by XRF has a detection limit of —0.5 mgkg and so is often insufficiently sensitive. Rock, sediment, and soil samples can be dissolved using wet chemical methods (HF-HCl-etc.) followed by La(OH)3 co-precipitation to separate hydride-forming elements including selenium. This is present as Se(IV) following acid dissolution (Hall and Pelchat, 1997). The methods described above for aqueous samples can then be used. 

In this paper, we describe an onsite weathering experiment designed to identify acid-rain increased dissolution of carbonate rock. This experiment is based on the measurement of the change in rainfall-runoff composition from the interaction of a rock surface with incident acid rain 2. The experiment involves conducting long-term exposures of two commercially and culturally important calcium carbonate dimension stones (i.e., Indiana Limestone (commercial name for Salem Limestone) and Vermont Marble (commercial name for Shelburne Marble)) (3-5). This technique appears to give a direct measurement of the chemical dissolution of carbonate rock from the combined reactions of wet and dry deposition. Preliminary results from the initial months of onsite operation are presented to illustrate the technique. 

Flow analysis is associated with wet chemical methods and samples are generally collected and transported to the laboratory for analysis. After optional preparative step(s), e.g., dilution, dissolution, extraction, depro-teinisation, or analyte separation/concentration, the resulting aqueous test sample is accommodated in a cup in the sampler tray of the flow analyser for further handling. This practice has been adopted since the appearance of the first commercially available flow analysers, as shown in Fig. 2.3. 

The deactivated catalyst was studied by several methods scanning electron microscopy (SEM)-energy dispersive spectroscopy (EDS), infrared spectroscopy (IR), and by extracting water-insoluble phosphorus. The SEM-EDS studies gave no useful results. IR absorption was measured on samples that were mulled in mineral oil. Comparisons of IR spectra were made with samples of y -alumina and aluminum phosphate. Determination of total P in the deactivated sample, presumed to be present as water-insoluble aluminum phosphate, was made by standard wet chemical analysis dissolution in hot, dilute HCl followed by colorimetric determination of phosphate. ... 

Metallization of PS by the wet chemical corrosive deposition is a subject of both scientific and applied interests [1-3]. The basic reaction of this process is substitution of silicon atoms by metal ones. Such reaction is an example of silicon corrosive dissolution under the oxidizing agent. The metals with a redox potential more negative than hydrogen may be only used as an oxidizer. 

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