Wet residue method

The composition of the solid precipitate which was found in some of the mixtures of the potassium chloride-water-THF system was determined by using Schreinemakers wet residue method (6) as modified by Hill and Ricci (7). 

The modification of Schreinemakers wet residue method which was used in this part of the investigation is that instead of analyzing the wet residue, a complex is prepared of known composition and the solution only is analyzed. This again gives two points on the diagram the solution point on the curve and the complex point which replaces the wet residue point. Hill and Ricci (7) claim that the complex method is as accurate or more accurate than the residue method if algebraic extrapolation of the tie-lines is used. 

The hydrates of Th(N03)4(cr) and ternary system Th(N03)4(cr)-H20-HN03 were investigated at 298.15 K, by the wet residues method. At this temperature, the stable hydrates are the penta- and tetrahydrate. The ternary system is depicted. The invariant... 

For multi-component systems the composition of the equilibrium sohd phase may be determined indirectly by the so-called wet residues method first proposed by Schreinemakers (1893) in which the need for solid-liquid separation by filtration, etc. is avoided. The experimental procedures, together with those of the alternative synthetic complex method, are fully described in section 4.6.5. 

Rb as Che tetraphenylborate and Cl as AgCl. The composition of the solid phases was determined by the wet-residue method. 

The samples were dissolved at 65°C and equilibrated in a water bath by shaking for several days. P2 5 was determined gravi-metrlcally as Mg2P202 Ammonia was determined by the XJeldahl method. The composition of the solid phases was determined by the wet-residue method. 

Many of these phenomena require very careful, and often prolonged, equilibration for their investigation and elimination. A very general analytical method, the "wet residues" method of Schreinemakers (22),... 

IS often used to investigate the composition of solid phases in equilibrium with salt solutions. This method has been reviewed in (23), where [see also (24)] least-squares methods for evaluating the composition of the solid phase from wet residue data (or initial composition data) and solubilities are described. In principle, the same method can be used with systems of other types. Many other techniques for examination of solids, in particular X-ray, optical, and thermal analysis methods, are used in conjunction with chemical analyses (including the wet residues method). 

Environmental monitoring of chloroacetanilides requires methods that have the capability to distinguish between complex arrays of related residues. The two example methods detailed here for water monitoring meet this requirement, but the method for metabolites requires sophisticated mass spectral equipment for the detection of directly injected water samples. In the near term, some laboratories may need to modify this method by incorporation of an extraction/concentration step, such as SPE, that would allow for concentration of the sample, so that a less sensitive and, correspondingly, less expensive, mass spectral detector can be used. However, laboratories may want to consider purchasing a sensitive instrument rather than spending time on additional wet chemistry procedures. In the future, sensitive instrumentation may be less expensive and available to all laboratories. Work is under way to expand the existing multi-residue methods to include determination of additional chloroacetanilides and their metabolites in both water and soil samples. 

Landers et al. [97] and others [98] have described a wet digestion method for the determination of total sulphur in soils. In this method the sample (1.50-500mg) is placed in a digestion flask and heated in a sand bath to dryness at 250°C with 3ml of sodium hypobromite solution. The residue is resuspended with water, neutralized with formic acid, and then hydriodic acid reduction of the sample is followed to quantitatively recover the inorganic sulphate formed by wet oxidation. 

Note About Cleaning Methods. A number of cleaning techniques can be used. For example, a balance brush could be used to sweep residual powder off the balance and onto a filter paper. However, this method is not ideal because the powder tends to be distributed over the base of the unit. Wet cleaning methods tend to be more... 

Wet cleaning process was the first to be adopted and is still the most commonly used platform for post-CMP cleaning processes for removing leftover surface particles, organic residues, and metallic contaminations. In this section, various wet cleaning methods used in semiconductor process will be reviewed. 

The method of wet residues is superior to the procedure necessary in two-component systems, where the liquid and solid phase must be separated and analyzed individually. It is a practical impossibility to separate the solid phase from the liquid without some of the liquid adhering to the solid and thus contaminating it. For this reason, it is frequently easier to add a third substance to a two-component system, determine the equilibrium lines, as well as the composition of the solid phases by the method of wet residues, and infer the composition of the solid in the two-component system from the features of the triangular diagram. 

From a historical point of view, the analysis of food is performed predominandy using typical chemical or physicochemical methods. These are, for example, wet chemical methods for proximity analysis or chromatographic methods for the analysis of pesticides and veterinary dmg residues. In addition, food chemists use such physics-based methods as viscosity measurement and atomic absorption spectroscopy for the analysis of heavy metals. 

Although extrapolations are commonly made graphically on phase diagrams, algebraic extrapolation is less subjective, more accurate, and lends itself to the application of statistical methods which minimize errors. Mathematical extrapolation procedures for the method of wet residues have been described by Ricci (1966) and Schott (1961). 

Purdon and Slater (1946) give good accounts of the practical difficulties that may be encountered in applying both the wet-residues and synthetic complex methods of solid phase analysis. 

Schott, H. (1961) A mathematical extrapolation for the method of wet residues. Journal of Chemical Engineering Data, 6, 324—325. 

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