Semiquantitative measurements

Common TLC techniques are not suitable for exact quantitative measurements. Semiquantitative measurement of the quantity of analyses in a spot can be performed visually. Each spot of sample is applied between two spots of standard, and after development... 

The Wodicka efal. (1997) paper also defined the performance of fhe Affymetrix chip. Semiquantitative measurement of the absolute abundance of mRNA species was possible. Flybridization of total yeast-genomic DNA to the chips revealed the mean hybridization signal across 6049 probe sets to vary by 25% coefficient of variance (CV). The use of gDNA serves to normalize because most genes are represented only once in the population. In fact, the majority (98%) of the intensities were found to cluster well within two standard deviations. Thus, the concentration of a given mRNA could be estimated af >95% probability to reside within twofold of its actual concentration. Measurement at widely different total gDNA concentrations did not appreciably affect this outcome. 

An analytical method has been developed that allows easy standardless semiquantitative measurements of elemental composition from single shot analysis by LA-ICP-ToFMS to identify alloys of different elemental composition.27 28 This method directly compares adjusted ion signals of... 

To circumvent the above limitations, the morphometric method can be used (Riischoff et al., 1990). It consists of automatic or semiquantitative measurement of the area occupied by the silver-stained structures within the nuclear profile with computer-assisted image analysis (Trerb et al., 1995). This method is faster, more accurate and reproducible, and shows less interobserver variation. Moreover, in contrast to the counting technique, the morphometric method is predictive of patient survival, independent of the clinical stage of the disease (Ofner et al., 1995a,b). 

Testing with a Gieseler plastometer (ASTM D-2639) gives a semiquantitative measurement of the plastic property, or apparent melting of coal when heated under prescribed conditions in the absence of air. The chemical nature of the constituents that account for a coal s plastic properties is not known. The material thought to be responsible for the plastic properties of coal has been removed from coal successfully by solvent extraction, leaving a nonplastic residue. Such residue has been rendered plastic by returning to it the extracts obtained by the solvent extraction. No definite relationship has been established between the amount of extract and the plastic properties of the coal. 

Another part of the Midcontinent Herbicide Project involved nine stream sites equipped with automatic samplers that were monitored for triazine herbicides and their degradation products from April through July 1990. It was found that the use of microtiter plate ELISA provided a good semiquantitative measure of atrazine for concentrations less than 3.0 jg/E. At higher concentrations, the samples had to be diluted. Results from the ELISA screen compared with GC/MS results showed good agreement (Pomes and Thurman, 1991 Scribner et al, 1994). 

Transmissometers in simplest form consist of a light source and a detector located some distance along the axis of the light beam. Among their applications, these devices are commonly used at airports to provide data in visual ranging conditions and are used to measure particle loadings in smokestacks. When calibrated for the type of particles present in this aerosol, a semiquantitative measure of the particulate emissions can be made, with knowledge of the volumetric gas flow. 

To measure the donor power of a solvent, Gutmann18 has proposed that one determines the enthalpy of coordination of the donor solvent toward a standard reference acceptor (SbCl5) in a reference solvent of low donor power such as 1,2-dichloroethane. The quantity — A//D SbClj is easily determined at high dilution and may be considered a semiquantitative measure of the coordinating properties of a donor solvent toward an acceptor molecule. It has been termed... 

In general, it appears likely that a fit to the intermediate species profiles should provide the most sensitive means of model verification, even when the result of direct interest is a bulk parameter such as flame speed or rate of energy release. Laser probe methods can be also extremely useful in the absence of full verification, however. Even a semiquantitative measurement of some species in a flame can constitute the clue to the inclusion within the model of an entire subnetwork of chemical reactions. Coupled closely to model predictions, the laser probe results can pinpoint species and reactions which merit special attention, that... 

Donor number (or donicity), DN — is an empirical semiquantitative measure of nucleophilic properties (-> acid-base theories, subentry Lewis acid-base theory) of a solvent defined as the negative of the standard molar heat of reaction (expressed in kcalmol-1) of the solvent D with antimony pentachloride to give the 1 1 adduct, when both are in dilute solution in the inert diluent 1,2-dichloroethane, according to the reaction scheme ... 

An empirical semiquantitative measure of the nucleophilic properties of EPD solvents is provided by the so-called donor number DN (or donicity) of Gutmann [53, 67] [cf. also Section 7.2). This donor number has been defined as the negative A// values for 1 1 adduct formation between antimony pentachloride and electron-pair donor solvents (D) in dilute solution in the non-coordinating solvent 1,2-dichloroethane, according to Eq. (2-10) f... 

Donor numbers are considered as semiquantitative measures of solute/EPD solvent interactions, and are particularly useful in the prediction of other EPD/EPA interactions in coordination chemistry. Numerous examples of the application of donor numbers have been given by Gutmann [26, 27, 30] cf. also [113, 133]. It has been shown that donor number correlations are parallel with correlations based on the highest occupied molecular orbital (HOMO) eigenvalues of EPD solvent molecules [139], For non-HBD solvents, a fair correlation has been obtained between their donor numbers and their gas-phase proton affinities FA, indicating that the DN values do indeed reflect the intrinsic molecular properties of EPD solvents [140]. 

Electronegativity is a semiquantitative measure of the electron-attracting power of a bonded atom. The greater the electronegativity, the more the atom attracts electrons. Covalent bonding between atoms of different electronegativity yields polar bonds that between atoms of the same electronegativity yields nonpolar bonds (Section 13.3). 

If the necessary results cannot be obtained by other methods, very careful sample preparation may give results with a standard deviation of approximately 10%. In some cases, internal standards, such as bands of naphthalene (780 cm ) or KSCN (2100 cm ) can be used for semiquantitative measurements. 

A semiquantitative measure of the amount of overlap between ligands can be attained using the semivertex angle of overlap, X (49). In Figure 13, if the semivertex angle of atom A is a for atom B is p, and the A-M-B bond angle is Xy then the vertex angle of overlap, X, is... 

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