Quantitative analysis using

Quantitative Analysis Using External Standards To determine the concentration of analyte in a sample, it is necessary to standardize the electrode. If the electrode s response obeys the Nernst equation. 

Quantitative Analysis Using the Method of Standard Additions Because of the difficulty of maintaining a constant matrix for samples and standards, many quantitative potentiometric methods use the method of standard additions. A sample of volume, Vx) and analyte concentration, Cx, is transferred to a sample cell, and the potential, (ficell)x) measured. A standard addition is made by adding a small volume, Vs) of a standard containing a known concentration of analyte, Cs, to the sample, and the potential, (ficell)s) measured. Provided that Vs is significantly smaller than Vx, the change in sample matrix is ignored, and the analyte s activity coefficient remains constant. Example 11.7 shows how a one-point standard addition can be used to determine the concentration of an analyte. 

If there is no band overlap in a spectrum, the absorbance at a characteristic wavelength is proportional to the concentration of chromophores present. This is the basis of quantitative analysis using spectra. With band overlap, things are more complicated but still possible. 

PLS metliod applied to speetral data provides exeellent quantitative analytieal results. It offers more aeeurate and robust predietion eompared with the results obtained by LR method. Therefore, the Ca(OH) determination by FTIR using a PLS model ealibration has demonstrated to be an adequate tool, despite the disadvantages of quantitative analysis using FTIR speetroseopie teehnique. 

Si 2p line, at about 100 eV BE, is also easily accessible at most synchrotron sources but cannot, of course, be observed using He I and He II radiation. On the other hand, the Zn 3d and Hg 4f lines can be observed quite readily by He I radiation (see Table 1) and the elements identified in this way. Quantitative analysis using relative peak intensities is performed exactly as in XPS, but the photoionization cross sections a are very different at UPS photon energies, compared to A1 Ka energies, and tabulated or calculated values are not so readily available. Quantitation, therefore, usually has to be done using local standards. 

Quantitative analysis using the internal standard method. The height and area of chromatographic peaks are affected not only by the amount of sample but also by fluctuations of the carrier gas flow rate, the column and detector temperatures, etc., i.e. by variations of those factors which influence the sensitivity and response of the detector. The effect of such variations can be eliminated by use of the internal standard method in which a known amount of a reference substance is added to the sample to be analysed before injection into the column. The requirements for an effective internal standard (Section 4.5) may be summarised as follows ... 

The problems involved in quantitative analysis using NMR spectroscopy, have been discussed by several authors and it is evident that it still causes a lot of problems as especially pointed out by Hays55 in his excellent review on the subject. Thus in liquid state NMR spectroscopy the quantitative estimation of atoms and groups involves the use of normal analytical method. In the case of solid state NMR spectroscopy, however, the application of the cross-polarization technique results in signal enhancements and allows repetition rates faster than those allowed by the carbon C-13 Tl. Therefore, the distortion of relative spectral intensities must always be considered a possibility, and hence quantitative spectra will not always be obtained. 

Quantitative Analysis using Chromatographic Techniques" (Ed. E. Katz), John Wiley and Sons, Chichester-NewYork-Brisbane-Toronto-Singapore (1987). 

E. Katz (Ed.), "Quantitative Analysis using Chronatographic Techniques", Hiley, New York, NY, 1987. 

P.C. Uden, in Quantitative Analysis Using Chromatographic Techniques (E. Katz, ed.), John Wiley Sons, Ltd, Chichester (1987), pp. 99-155. 

Quantitative analysis using FAB is not straightforward, as with all ionisation techniques that use a direct insertion probe. While the goal of the exercise is to determine the bulk concentration of the analyte in the FAB matrix, FAB is instead measuring the concentration of the analyte in the surface of the matrix. The analyte surface concentration is not only a function of bulk analyte concentration, but is also affected by such factors as temperature, pressure, ionic strength, pH, FAB matrix, and sample matrix. With FAB and FTB/LSIMS the sample signal often dies away when the matrix, rather than the sample, is consumed therefore, one cannot be sure that the ion signal obtained represents the entire sample. External standard FAB quantitation methods are of questionable accuracy, and even simple internal standard methods can be trusted only where the analyte is found in a well-controlled sample matrix or is separated from its sample matrix prior to FAB analysis. Therefore, labelled internal standards and isotope dilution methods have become the norm for FAB quantitation. 

The application of screening methods requires that proper reference samples are available. These must contain the analyte exactly at or close to the specification level. Such reference samples have to be verified by quantitative analysis using reference methods. 

Cahn, F. and S. Compton, Multivariate Calibration of Infrared Spectra for Quantitative Analysis Using Designed Experiments , Applied Spectroscopy, 42 865-872 (July, 1988). 

Alnouti Y. et al., 2006. Method for internal standard introduction for quantitative analysis using online SPE LC/MS/MS. Anal ChemlS 1331. 

For high-throughput analysis, it is important to increase the specihcity of each bioanalytical method. The enhancement of chromatographic resolution presents various limitations. Better selectivity can be obtained with TOF mass analyzers that routinely provide more than 5000 resolution (full width at half-mass or FWHM). The enhanced selectivity of a TOF MS is very attractive for problems such as matrix suppression and metabolite interference. In one report of quantitative analysis using SRM, TOF appeared less sensitive than triple quadrupole methods but exhibited comparable dynamic range with acceptable precision and accuracy.102... 

Quantitative analysis using peak areas. Error estimates are based on experimental reproducibility of duplicate runs. 

In the 4th Edition of Organic Structures from Spectra we have introduced problems dealing with quantitative analysis using NMR spectroscopy and problems 284 - 291 involve the analysis of mixtures of compounds. 

Problems are associated with quantitative analysis using IR. First, deviation from Beer s law affect quantitative analyses profoundly, especially those deviations resulting from saturation effects. Variations in the path length that are not accounted for can also cause problems. Second, specific interactions between components in the sample can influence the quantitation, especially those interactions that are temperature and pressure sensitive. Third, if the quantitation is based on the peak being due to only one absorbance when in reality it is a result of overlapping bands, then there will be a bias in data that is not necessarily linear. Currently available IR spectrometers have software packages containing matrix methods that simplify the operations associated with multicomponent... 

In other cases, however, and in particular when sublattices are occupied by rather immobile components, the point defect concentrations may not be in local equilibrium during transport and reaction. For example, in ternary oxide solutions, component transport (at high temperatures) occurs almost exclusively in the cation sublattices. It is mediated by the predominant point defects, which are cation vacancies. The nearly perfect oxygen sublattice, by contrast, serves as a rigid matrix. These oxides can thus be regarded as models for closed or partially closed systems. These characteristic features make an AO-BO (or rather A, O-B, a 0) interdiffusion experiment a critical test for possible deviations from local point defect equilibrium. We therefore develop the concept and quantitative analysis using this inhomogeneous model solid solution. 

Although there are a number of important food components which are naturally fluorescent (e.g., cereal brans, lignified materials such as pea, soy and cotton fiber, and even proteins and pigments), detection of many food components requires application of specific fluorochromes or diachromes. Therefore, quantitative analysis using microscopic imaging also requires judicious use of sensitive dyes or stains suitable for visualization and rapid measurement. The dyes must be stable, non-toxic to liing cells, easily and inexpensively... 

Liu, Y. M., Akervik, K., and Maljers, L. (2006). Optimized high resolution SRM quantitative analysis using a calibration correction method on triple quadmpole system. In Proceedings of the 54th ASMS Conference on Mass Spectrometry and Allied Topics. ASMS, Seattle, WA. 

Yu, C., Penn, L. D., Hollembaek, J., Li, W., and Cohen, L. H. (2004). Enzymatic tissue digestion as an alternative sample preparation approach for quantitative analysis using liquid chromatography-tandem mass spectrometry. Anal. Chem. 76 1761-1767. 

Pelletier, M.J. Quantitative Analysis Using Raman Spectroscopy Appl. Spectrosc. 2003,57,20A-42A. 

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