Linear range extension

The upper limit to the linear range was 5000 ngml, hut at concentrations >1000 ngml carry-over from the autosampler was observed. This could be reduced by extensive washing. 

There is a wide range of chain extenders commercially available for PET (Table 14.2). Bifunctional chain extenders promote linear chain extension while tri- and tetra-functional chain extenders promote chain branching. Such reactive compounds are also known as repair additives since they can reverse the molecular weight loss of hydrolytically damaged PET. 

Division of the total tensile strain under conditions of F = const into several components 25,6R,69) produced interesting results (see Fig. 8). It has been found that the behavior of molten low-density polyethylene (Fig. 8a) is qualitatively different from polyisobutylene (Fig. 8 b) the extension of which was performed under temperature conditions where the high-elasticity modulus, relaxation time, and initial Newtonian viscosity practically coincided (in the linear range) in the compared polymers. Flow curves in the investigated range of strain velocities were also very close to one another (Fig. 21). It can be seen from the comparison of dependencies given in Fig. 8a,... 

The flame ionization detector (FID), which, for fluorinated compounds, has the advantage of a greater linearity range in spite of its lower sensitivity in comparison with the electron capture detector (BCD), has been extensively applied to organic metal chelates in particular. Comparisons of the different detectors were carried out (Table 1.2) For special analyses such as the determination of SO2 by reaction to SO2F2 with the radioactive F-isotope or by utilization of H-labelled 3-diketon-ates, radiometric measurements for detection are employed ... 

In the previously mentioned approach, a relatively high flow rate (20 /il/min) was used for the continuous monitoring and this resulted in high time resolution as well as the previously mentioned extension in the linear range of the glucose biosensor. The absolute concentration of the interstitial fluid was not determined, but variations in glucose concentration in the subcutaneous tissue were well correlated with those of the blood values and in general there was no phase lag between the two series of measures. 

Dynamic range extension in GD quadrupole/ion-trap MS based on selective ion-accumulation (e.g. by mass-selective instability, single-frequency resonance ejection, combined rf-dc and entrance end-cap dc methods) allows the selective accumulation of the analyte ions and enables the dynamic range to be increased by a factor of 105 [233]. The linearities and relative trapping efficiencies of the previous methods were assessed with respect to the injection time and the methods were used for the GD ion-trap MS determination of major and minor constituents in NIST SRM 1103 Free Cutting Brass. 

It might appear that peak width merely serves as range extension. Yet, since peak width is related to a time span, which in turn is related through linear flow velocity to volumetric rate, peak width measurements allow flow titrations to be performed in a novel way. Therefore, similarly to classical batch titrations, FIA titrations encompass a domain of determinations, which cannot be performed in any other way, because they are based on consumption of an equivalent amount of reagent and, therefore, titrations yield different information than a direct measurement (pH measurement versus titration of a mixture of a weak and strong acid). 

Assuming developed tension is essentially linear with extension over a certain range during peak isometric contraction, and A = 2 during systole, end systolic pressure-extension relations are given by P, total... 

In a very extensive study of both stress relaxation and dynamic mechanical properties in simple extension, on single crystal mats of fractions of linear polyethylene, Takayanagi and collaborators were able to combine data at different temperatures by reduced variables over most of the range from 16°C up to the temperature of crystallization and also to show that the dynamic and transient data corresponded fairly closely, provided the latter were corrected for nonlinear behavior by an extrapolation procedure to zero strain. It is characteristic of crystalline polymers that departures from linear viscoelastic behavior appear at very small strains, and are sometimes significant in stress relaxation even at a tensile strain of = 0.001. In dynamic measurements, the strains are usually small enough to fall within the linear range. 

Magpaiangalan, D.P. Garrett, T.J. Diexler, D.M. Yost, R.A. Analysis of Large Peptides by MALDI Using a Linear Quadrupole Ion Trap With Mass Range Extension Anal. Chem. 2010, 82, 930-934. 

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