Therefore, reaction series with constant entropy have been accorded great significance and have been investigated thoroughly. The condition in eq. (8) was even considered necessary for any linear free energy relationship to hold (16). However, as experimental data accumulated and precision improved, it was clear that for many theoretically important reaction series, this condition is not fulfilled (1, 17). It was also proved that a LFER can hold if entropy is not constant, but linearly related to enthalpy (18, 19). The linear equation... [Pg.416]

The end of the 1980 s saw the application of TIMS to U-series measurement (Chen et al. 1986 Edwards et al. 1987 Goldstein et al. 1989). This represented a major technological advance. Analysis time was reduced from one week to several hours, sample sizes for many carbonate or volcanic rock samples decreased from -10-100 pg to 0.1-1 ug U or Th, measurement precision improved from percent to permil levels, and for the decay series, the dating range was extended from 350,000 years to... [Pg.32]

We might want to increase a> to generate larger limiting currents in order to increase the precision. Improving the precision by this means is valid at low to medium rotation rates (that is, up to about 100 cycles per second) because the motion of solution over the face of the electrode is smooth and reproducible. We say that the flow is laminar. (The word laminar comes from the Latin root lami, meaning thin layer or plate .) We can then see how laminar flow implies that solution readily flows over itself in a smooth and reproducible way. [Pg.206]

Schmitt-Kopplin, P., Garmash, A. V., Kudryavtsev, A. V., Menzinger, F., Perminova, I. V., Hertkorn, N., Freitag, D., Petrosyan, V. S., and Kettrup, A. (2001a). Quantitative and qualitative precision improvements by effective mobility-.scale data transformation in capillary electrophoresis analysis. Electrophoresis 22,77-87. [Pg.535]

As mentioned before, solubility and mass transfer increase at elevated temperatures. Table 3.8 shows that both recovery and precision improved when the temperature was increased during the extraction of total petroleum... [Pg.159]

Unfortunately, the estimator is fairly imprecise. Figure 19. Here we are plotting N versus V for a given standard error. Once again, precision improves as tne sample size becomes larger, but even for fairly large sample sizes the error is not negligible. [Pg.76]

In practice, the composite rate constant is corrected for the independently-measured rate constant for the probe reaction. The precision improves when the kinetic contribution from the kx path is as large as possible while still retaining an acceptable absorbance change provided by the probe reaction. This approach is used widely in laser-flash photolysis studies of radical reactions, which are described in detail in one of the following chapters. [Pg.494]

The acquisition of the spectral information from each single spark separately is now possible with advanced measurement systems, using integration in a small capacitor and rapid computer-controlled readout combined with storage in a multichannel analyzer. With the aid of statistical analysis, sparks with outlier signals can be rejected and the precision improved accordingly. Furthermore, pulse differential height analysis enables discrimination between a number of elements such... [Pg.215]

The precision improves as the square root of the number of measurements. [Pg.76]

If the analytical imprecision if again halved, reducing its standard deviation from 2 to 1, another significant improvement in clinical performance occurs. In this example, in which the biological overlap between the two groups of patients was small, the precision of the analytical system became the principal factor in determining the clinical performance of the test substantial improvements in clinical accuracy occurred as the analytical precision improved. [Pg.162]

This problem may also be due to a leaking vial. Verify that the cap cannot be turned after sealing and reduce the extraction temperature to see if precision improves. [Pg.643]

Microlithography is a process used specifically for the manufacturing of microchips. It allows a series of circuits to be placed on a hard surface with a tremendous amount of precision. Improvements in technology have made it possible for microchips to carry increasing numbers of circuits in new combinations and patterns. [Pg.1209]

Precision. The level of agreement between independent measurements obtained under defined conditions (repeatability and reproducibility). Precision improves when the number of repeated measurements increases, and it is usually measured as a standard deviation (SD) or a relative standard deviation (RSD). [Pg.221]

Pb and Sr isotope measurements by indudively coupled plasma mass spectrometer efficient time management for precision improvement. Spectrochim. Acta B, S3, 1317-1333. [Pg.74]

Batches of performance assessment samples (section 2.4) were analysed on different occasions. Results for unspiked previously characterised materials are presented in Figure 4 and all results summarised in Table 4. Recovery of technetium from spiked samples showed accuracy over the range 10 - 1000 Bq kg to be 94-104 % for soil, 100-108 % for silt, 97-99 % for sand and 101 - 109 % for sediment with precision (as % RSD) across all sample types between 4 and 24 %. Precision improved to <10 % where Tc activity concentrations were > 100 Bq kg. Detection limits estimated from the replicate analysis of blank soils, silts and sediments according to Currie (Ld = 2t-So) were typically 2Bq kg for a 2 g sample of soil, silt or sediment. [Pg.115]

In its simplest, and in chemistry the most used, form, PLS is a method for relating two data matrices X and Y to each other by a linear multivariate model. PLS stands for projection to latent structures by means of partial least squares. It derives its usefulness from its ability to analyze data with many noisy, collinear, and even incomplete variables in both X and Y. PLS has the desirable property that for the parameters regarding the observations (samples, compounds, objects, items), the precision improves with the increasing number of relevant X variables. This corresponds to the intuitive belief of most chemists that many variables provide more information about the observations than do just a few variables. [Pg.2006]

The precision of this test method is based on three interlaboratory studies involving ten laboratories and several solvents. It was established that, in general, the precision improves with increasing purity and decreasing boiling point of the material being test, while it is poorest for mixtures... [Pg.196]

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