A, secondary standard

Electrostatic and adsorption effects conspire to make aqueous GPC more likely to be nonideal than organic solvent GPC. Thus, universal calibration is often not obeyed in aqueous systems. Elence, it is much more critical that the standard chosen for calibration share with the polymer being analyzed chemical characteristics that affect these interactions. Because standards that meet this criterion are often not available, it is prudent to include in each analysis set a sample of a secondary standard of the same composition and molecular weight as the sample. Thus, changes in the chromatography of the analyte relative to the standards will be detected. 

Z values are obtained from Eq. (8-76) for solvents having Z in the approximate range 63-86. In more polar solvents the CT band is obscured by the pyridinium ion ring absorption, and in nonpolar solvents l-ethyl-4-carbomethoxy-pyridinium iodide is insoluble. By using the more soluble pyridine-1-oxide as a secondary standard and obtaining an empirical equation between Z and the transition energy for pyridine-1-oxide, it is possible to measure the Z values of nonpolar solvents. The value for water must be estimated indirectly from correlations with other quantities. Table 8-15 gives Z values for numerous solvents. 

A secondary standard is a substance which may be used for standardisations, and whose content of the active substance has been found by comparison against a primary standard. It follows that a secondary standard solution is a solution in which the concentration of dissolved solute has not been determined from the weight of the compound dissolved but by reaction (titration) of a volume of the solution against a measured volume of a primary standard solution. 

Thus, information concerning size and arrangement of domains in the cross-sectional plane of the fiber are accessible with classical laboratory equipment. Moreover, since the projection /(s) 2 (sn) is complete and a normalization /(s) 2 (sn) —> /(s) 2 (S12)/V to absolute intensity units is readily established by employment of the moving slit device2 without the need to resort to a secondary standard, the invariant... 

The radiation strength of a single electron is determined by elementary quantities that need not be considered in materials science. These quantities and the characteristics of the detector are automatically considered if the primary beam intensity is directly measured or indirectly determined by means of a secondary standard. 

A proper calibration constant for any beamline geometry is the invariant Q. Thus, the Lupolen standard or any other semicrystalline polymer that previously has been calibrated in the Kratky camera can be made a secondary standard for a point-focus setup, after its invariant Q has been computed in absolute units - based on a measurement of its SAXS in the Kratky camera. 

The prepared NaOH solution is a secondary standard because its concentration is determined by titration against a primary standard. 

A secondary standard is one for which the concentration of the analyte has been determined by analysis using a recognised method. 

The problems with various primary calibration standards are still being resolved. The earlier discussion of DeMore et al, indicates the work undertaken by the carb in comparing oxidant calibration procedures. It was recommended that all oxidant analyzers in the California network be calibrated by a secondary standard consisting of an ultraviolet ozone analyzer. The primary standard recommended is ultraviolet photometry. These recommendations have been adopted by the cars. Potassium iodide, indicated as a second choice, requires the application of a correction factor of 0.78. 

Hodgeson, J. A., R. K. Stevens, and B. E. Martin. A stable ozone source applicable as a secondary standard for calibration of atmospheric monhens, pp. 149-158. In J. Scales, Ed. Air Quality InstrumentatkMi. Vol. 1. Selected Papers from International Symposia Presented by the Instrument Society of America. Pittsburgh Instrument Society of America. 1972. 

Polyacrylic acid (PAA) was obtained from Scientific Polymers, Inc., Ontario, NY, as a secondary standard with a mass-averaged molecular weight of two million. The polyacrylamide (PAM) used was Separan MGL obtained from Dow Chemical Company, Midland, MI. Its reported molecular weight was in the range of 500,000 to 5,000,000. The monomer structures of PAA and PAM are illustrated in Figure 1. 

A sample for which the true response is already known or is established is called a standard. A standard can be a primary standard, which is a standard through which other substances or solutions are made to be standards. It can also be a secondary standard, a solution whose concentration is known accurately either because it was prepared using a primary standard or because it was compared to another standard. All standards must ultimately be traced to a standard reference material (SRM). Standard reference materials are available from the National Institute of Standards and Technology (NIST) and should not be used for any other purpose in the laboratory (Section 5.4). Standardization is an experiment in which a solution is compared to a standard in order for itself to be a standard. The solutions used to establish a standard curve are often called reference standards and these must also be traceable to an SRM. 

Because of the very important role of impurities in determining semiconductor properties, it is desirable to know their concentrations, at least of the electrically active ones. Of course, the techniques we have discussed in this chapter never make a positive identification of a particular impurity without confirmation by one of the established analytical techniques, such as spark-source mass spectroscopy (SSMS) or secondary-ion mass spectroscopy (SIMS). Once such confirmation is established, however, then a particular technique can be considered as somewhat of a secondary standard for analysis of the impurity that has been confirmed. It must be remembered here that an analytical method such as SSMS will see the total amount of the impurity in question, no matter what the form in the lattice, whereas an electrical technique will see only that fraction that is electrically active. 

The most common electrode of this type is the saturated calomel electrode (SCE) which consists of mercury in contact with a layer of insoluble Hg2Cl2 immersed in a saturated aqueous solution of KC1. The SCE is used as a secondary standard reference electrode. At 25°C it has an electrode potential of + 0.2415 V. 

Because of its fundamental nature and superior accuracy and repeatability. this kind of instrument is widely used as a secondary standard (National Bureau of Standards lor calibrating other lower level humidity instruments... 

Thiocyanate standard solns. 1.673 g potassium thiocyanate, KSCN in distilled water, diluted to 1 L. This stock soln. = 1000 mg SCN7L or 1 mL = 1 mg SCN". Prepare a secondary standard from the stock solution by diluting 1 mL stock solution to 100 mL with distilled water. Secondary std = 10 mg SCN-/L or 1 mL = 0.01 mg SCN". Prepare a series of calibration standards by diluting the secondary standard with distilled water as follows ... 

Simoes, M. L. (2005). Study of hydrophobic interactions in humic substances and soil components using spectroscopic methodologies. Ph.D. thesis, University of Sao Paulo-USP, Brazil. Singer, L. S. (1959). Synthetic ruby as a secondary standard for the measurement of intensities in electron paramagnetic resonance. J. Appl. Phys. 30,1463-1464. 

In order to obtain a value for the concentration of a secondary standard, data from each of the standards, zero gas and unknown is collected sequentially from the AGAS system. The concentration of the secondary standard is then obtained from these results using the following formula ... 

All RSMs obtained from secondary sources must be qualified. The Sigma-Aldrich family of companies is an excellent example of a secondary standard source, offering over 200,000 chemical compounds in their standard catalogues and an additional 70,000 in various specialty catalogues. 

In this scheme, the primary reference material is defined as a chemical substance of the highest (and known) purity, or a well-characterized substance in a matrix, This classification of materials is, however, fairly arbitrary. It is ideal when used in connection with standards characterized in terms of biological activity. Primary standards are thus the International Reference Preparations (IRP) produced by the World Health Organization (WHO). In this case the primary standard for a particular antibiotic is the WHO reference preparation which constitutes the unit of that antibiotic. When people wish to use it they have to prepare a large batch of samples calibrated to the primary. This is then called a secondary standard. However, for well-defined chemical parameters, the term certified reference material is preferred. 

Xe NMR spectra were recorded with a Bruker WM-250 NMR spectrometer at 69.19 M Hz. Each spectrum is the accumulation of 500 transients with a relaxation delay of 0.5 seconds. The chemical shifts are reported with respect to bulk xenon gas extrapolated to P=0, using a secondary standard of xenon adsorbed in Na-Y zeolite at 590 Torr(3). Positive chemical shifts are to higher frequency than the reference. 

From the analysis of air pollutants and their effects, the NAAQS described above were developed by the US EPA based on requirements of the Clean Air Act. This was done by defining the criteria pollutants to measure air quality, and then by determining the acceptable concentrations under health protection criteria (known as primary standard) a secondary standard was also defined to protect public welfare and prevent environmental and property damage. The criteria pollutants for air quality thus selected were CO, Pb, N02, O3, PM]0, PM25, and... 

A primary standard is used to establish a secondary standard. A secondary standard is defined as a standard whose value is assigned by comparison with a primary standard of the same quantity ". It is often the secondary standard that the analyst will use. 

It is advisable to periodically calibrate the sensitivity of the spectrometer by measuring the spectrum of a Planck source. For this purpose, an iodine-quartz lamp may be used to irradiate a white email as a secondary standard (D Orazio and Schrader, 1976). Further, the laser power should be monitored periodically. 

Although the so-called saturatedWeston cell, containing a saturated solution of cadmium sulfate, is the ultimate standard for E.M.F. measurement, a secondary standard for general laboratory use has been recommended this is the unsaturated Weston cell, which has an even smaller temperature coefficient than the saturated cell. The form of unsaturated cell generally employed contains a solution which has been saturated at 4 c., so that it is unsaturated at room temperatures its temperature coefficient is so small as to be negligible for all ordinary purposes and its e.m.p. may be taken as 1.0186 volt. ... 

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