Range of linearity

There are various ways to derive a calibration curve. Multi-point calibration curves, for example, include a minimum of three different concentrations of the analyte. For semiquantitative assays, a single-point calibration is common. The single point is usually the threshold concentration used to determine whether a specimen is positive or negative for the analyte of interest. Depending on the validation process and performance characteristics of the assay, a single-point calibration curve may also be used in quantitative applications over a limited range of linearity. A historical (pre-established) multi-point calibration curve may also be used, but only if the stability of the analytical method over time has been well established (Goldberger et al., 1997). 

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The method covers the full dynamic range of linear velocities from a few centimetres/second to over 100 meters/seconds with one and the same instrumental set-up. Only the amount of tracer used per injection is varied. 

The successful development of polyfethylene terephthalate) fibres such as Dacron and Terylene stimulated extensive research into other polymers containing p-phenylene groups in the main chain. This led to not only the now well-established polycarbonates (see Chapter 20) but also to a wide range of other materials. These include the aromatic polyamides (already considered in Chapter 18), the polyphenylene ethers, the polyphenylene sulphides, the polysulphones and a range of linear aromatic polyesters. 

TXRF is an ideal tool for microanalysis [4.21]. The analytical merits are that TXRF has a broad range of linearity (lO -lO atoms cm ) and it is extremely surface-sensitive and matrix-independent. TXRF can be applied to a great variety of different organic and inorganic samples such as water, pure chemicals, oils, body fluids and tissues, suspended matters, etc., down to the picogram range. 

Mechanical properties of plastics are invariably time-dependent. Rheology of plastics involves plastics in all possible states from the molten state to the glassy or crystalline state (Chapter 6). The rheology of solid plastics within a range of small strains, within the range of linear viscoelasticity, has shown that mechanical behavior has often been successfully related to molecular structure. Studies in this area can have two objectives (1) mechanical characterization of... 

Instrumental response ratios (tebuconazole/i NsJtebuconazole) versus concentration of tebuconazole present should be proven in solvent and each matrix analyzed up to the highest undiluted final sample extract concentration expected. Once proven linear, final sample extract residues found to lie above the range of linearity are to be diluted prior to addition of IS solution and re-analyzed. 

The peak symmetry, resolution, and detector response are directly dependent on the concentration of the sample. As the concentration of a sample increases, the retention time, separation, and peak symmetry generally decrease. These phenomena are due to isotherm nonlinearity. The detector response may also be nonlinear above or below certain concentrations. In some cases, small amounts of a dilute component are irreversibly adsorbed to the column, leading to reduced recovery. Above some concentration, the response of any detector will cease to be linear. The UV-VIS is one of the most linear detectors, generally exhibiting at least three decades of linearity, while RI, electrochemical, and fluorimetric detectors have a markedly narrower range of linearity. 

In the range of linearity, Eq. (29) correctly represents the heat transfer within the calorimeter. It should be possible, then, by means of this equation to achieve the deconvolution of the thermogram, i.e., knowing g(l) (the thermogram) and the parameters in Eq. (29), to define f(t) (the input). This is evidently the final objective of the analysis of the calorimeter data, since the determination of the input f(t) not only yields the total amount of heat produced, but also defines completely the kinetics of the thermal phenomenon under investigation. 

The purpose of a detector is to monitor the carrier gas as it emerges from the column and respond to changes in its composition as solutes are eluted. Ideally a detector should have the following characteristics rapid response to the presence of a solute a wide range of linear response high sensitivity stability of operation. 

The ideal HPLC detector should have the same characteristics as those required for GC detectors, i.e. rapid and reproducible response to solutes, a wide range of linear response, high sensitivity and stability of operation. No truly universal HPLC detector has yet been developed but the two most widely applicable types are those based on the absorption of UV or visible radiation by the solute species and those which monitor refractive index differences between solutes dissolved in the mobile phase and the pure mobile phase. Other detectors which are more selective in their response rely on such solute properties as fluorescence, electrical conductivity, diffusion currents (amperometric) and radioactivity. The characteristics of the various types of detector are summarized in Table 4.14. 

Dynode strings can be constructed in many ways and the response time and range of linearity of the detector depend on the configuration. In the Venetian blind configuration (Fig. 2.21c) the dynodes are wide strips of material placed at an angle of 45° with respect to the electron cascade axis. This system offers a large input area to the incident primary particles. The advantage is that the dynodes are easily placed in line and the dimensions... 

In the range of linear adsorption behaviour, whatever the number of site types (see Section 2.3.1 for the merging of parameters of two sites), the surface concentration F is related to via an effective linear coefficient, Ah, while the first-order internalisation processes can also be described by an effective first-order constant, k. Thus, equation (39) can be recast, for instance, in terms of r as ... 

Subsequent condensation of the organofunctionalised silanol intermediates (3, 5, 6) will yield a broad range of linear (7) and cyclic (8) products as shown in Fig. 5.5.4, whilst the condensation of two molecules of TMS-OH to yield (TMS)2-0 is expected to be rapid. 

The data in Figures 2.17 and 2.18 are displayed in terms of the dimensionless centre-to-centre separation of particles, i.e. r/2a — (2a + h)/2a. This has been done to illustrate another important point the range of linear elastic response. In a concentrated system, which is showing solid-like or elastic responses, the structure has to be able... 

The reaction current in the range of linear rates is described approximately by Eqn. 9-10 ... 

Protein A chromatography yields inununoglobulins in very concentrated form. Therefore, the absorbance of the solution should not be measured directly. Dilute the sample into PBS, and take areading using PBS as a blank. The optical density of the diluted sample should not be above 1-1.5 to fall within the range of linearity. 

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