Value materials standards

Conversion tables and charts now available make it possible to express I.C.I. data in forms in which a specified color and the significance of measured color differences can be more easily visualized. For example, I.C.I. values calculated from objective instrumental readings can be converted into the Munsell notation which evaluates the three psychological color attributes—hue, lightness (Munsell value), saturation (Munsell chroma)—on scales of approximately equal visual steps. In addition, the Munsell color charts offer one of the most convenient sources of material standards for direct color comparisons. 

Here the concentration range of the analyte in the ran is relatively small, so a common value of standard deviation can be assumed. Insert a control material at least once per ran. Plot either the individual values obtained, or the mean value, on an appropriate control chart. Analyse in duplicate at least half of the test materials, selected at random. Insert at least one blank determination. 

Here we cannot assume that a single value of standard deviation is applicable. Insert control materials in total numbers approximately as recommended above. However, there should be at least two levels of analyte represented, one close to the median level of typical test materials, and the other approximately at the upper or lower decile as appropriate. Enter values for the two control materials on separate control charts. Duplicate a minimum of five test materials, and insert one procedural blank per ten test materials. 

Certified Reference Materials. Certified Reference Materials are materials whose properties have been guaranteed or certified by recognized bodies. The certified analyses of these materials can be used as an estimate of the "true" value for assessment of accuracy. The United States National Bureau of Standards (NBS) provides an inventory of various materials whose compositions (and properties) have been measured using definitive and reference methods. These materials, Standard Reference Materials (SRM s), when used in conjunction with reference methods, i.e., one of demonstrated accuracy, make it possible to transfer accuracy between measurement protocols. 

To check traeness using a reference material, a series of replicate tests is carried out and the mean value and standard deviation are compared with the characterized value for the reference material. Certified matrix reference materials may be purchased and used directly for validation. If this is not possible reference materials for validation may be prepared by spiking... 

Evaluation Methods. In testing paint materials, paints, and other coating materials, the properties or variations in properties often cannot be described quantitatively but must be assessed subjectively. A uniform system of evaluation has been established in the form of a numerical scale to facilitate the assessment of results and mutual understanding. This system should only be used if a result cannot be obtained as a directly measured value. For standards, see Table 1 ( Test evaluation ). 

Key words Traceability chain Metrology in chemistry Reference material Comparisons values of standards... 

The standard for on a particular kind of stainless steel is one containing 18% chromium and 8% nickel. Thus, not only the units of the International System of Units (SI units), such as mass, temperature and density, but also compositional standards can be defined by attributes or represented by reference materials. Any of these measurement standards can be referenced in technology or commerce often as a contractual or mandatory requirement. Traceability and traceable are commonly used in relation to (the value of) a material standard. 

Of importance the sulfatides can be further distinguished by a more sophisticated procedure. This would entail intraperitoneal injection of 35S04 into small animals. A quite rapid incorporation of label into brain lipids, for example, will provide support for the presence of a sulfatide. The isolated sulfatide-containing fraction is subjected to thin-layer chromatography, and the lanes are sectioned and assayed for radioactivity. Location of labeled material migrating at the same Rf value of standards (nonlabeled) would be... 

The distance substances a and b in Figure 11.3 moves compared with how far the solvent, x, moves, i.e. a/x and b/x, is called the Rf value. The Rf values are characteristic for the individual substances using the same type of paper (or thin layer of inert material), same solvent and same method. These values are standard, whether the experiment is repeated in Tokyo or UK, as long as the same conditions are applied. 

Thestandard heat of formation of a material is its value of AH at one atmosphere and 25°C. Values of standard heats of formation may be found in [13], [15]-[18], and [26]-[29], for example [13] and [29] are particularly extensive. Estimates of standard heats of formation for materials not appearing in tables may be derived by the bond-energy procedure described in [17]. 

Quoted density values in standard reference works are of the materials true density. If density is determined using a gas pyknometer, the volume measured would include closed pores but exclude open pores i.e. the measured density would be the apparent density. If the suspending liquid penetrates all the cracks and fissures on the particle surface, the measured volume would be the same as that determined by gas pyknometry but the total mass would be greater due to the included liquid that will remain with the particle as it falls in the liquid, hence its sedimentation density will be intermediate between the apparent density and the true density and greater than the effective density. These differences are usually not highly significant for coarse particles unless they are highly porous. 

Each year, 6 million ha of land in the world undergo desertification, 17 million ha are deforested, and soil erosion exceeds soil formation by 26 billion tons. The ecological footprint is an accounting tool devised by William Rees to measure the productive land area needed to supply the resource consumption and waste assimilation of a given human population.23 Twenty percent of the world s population, largely in industrialized nations, consumes 80% of its resources. Some typical values of the productive land or water needed to support a person at a given material standard indefinitely are shown in Table 17.1. 

Figure 3.1 Normal distribution showing a result (a) that falls between the 95% and 99% limits. In the example given in the text, x = 0 corresponds to the value of the certified reference material and the axis shows values of standard deviations of the mean from this value.

Current attitudes on the use of chemical ingredients in human food preparations make it imperative to master the utmost potential values in standard food components. This is particularly true of such a material as starch, which has a structural function in foods as well as a nutritional role. The expanding concepts of starch molecules and granules have made possible a more effective adaptation to intended end uses. The authors believe this elaboration of purely scientific knowledge has not reached its zenith. 

This should not be considered as a drawback when one realizes that FIA is a technique essentially performed under physically and chemically non-equilibrium conditions, and that reproducibility of the reaction process rather than its completeness is the key issue of the technique. With proper calibration, good results may be obtained under nonequilibrium conditions for the precipitation. This has been pfewen experimentally in the coprecipitation of cobalt and nickel with Fe(lI)-HMDTC [22]. Although the analyte collection efficiency was onl approximately 50%, good sensitivity and precision were achieved. with excellent agreement of analytical results with certified values of standard reference materials, covering a large variety of different sample matrices. 

Good agreement of analytical results with certified values of standard reference materials has been reported for CASS-1, CASS-2 coastal sea waters, NASS-2 open ocean seawater and SLRS-1 riverine water. 

The next phase that came about was called raw material standards, which were a material balance, also called a mass balance, applied aroimd the entire operation, with standard yields that were based on a five-year history of the operation. Again, these yields were developed by using historical data and applying an improvement factor. Hypothetical values were also calculated for chemical reactions so an assmned number was the theoretical standard. Process results could be evaluated as to how close they come to the theoretical best possible performance. 

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