Base Reference

Table 5.4 gives the specific energies of selected organic liquid compounds. Compared with the isooctane chosen as the base reference, the variations from one compound to another are relatively small, on the order of 1 to 5%, with the exception of some particular chemical structures such as those of the short chain nitroparaffins (nitromethane, nitroethane, nitropropane) that are found to be energetic . That is why nitromethane, for example, is recommended for very small motors such as model airplanes it was also used in the past for competitive auto racing, for example in the Formula 1 at Le Mans before being forbidden for safety reasons. 

If time and circumstances permit, data should be recorded when the compressor is run on process gas to establish a new base reference point. During operation, all monitoring equipment should be observed to establish a signature of vibration and temperature, and to be sure these data are all within permissible limits. 

Most organic compounds are bases, that is, they are capable of accepting a proton. The best-studied organic bases are the moderately strong ones, which will receive a proton in dilute aqueous solutions amines are the most important examples. The pKa value of the protonated base, referred to the infinitely dilute aqueous solution, is the usual measure of base strength, and the pH of the solution is a quantitative measure of solvent acidity, or ability to transfer a proton. 

Tables 2-16, 2-17, 2-18, and 2-19 are setup with base reference conditions. In order to correct or change any base condition, the appropriate multiplier(s) must be used.

The Bronsted-Lowry theory of acids and bases referred to in Section 10.7 can be applied equally well to reactions occurring during acid-base titrations in non-aqueous solvents. This is because their approach considers an acid as any substance which will tend to donate a proton, and a base as a substance which will accept a proton. Substances which give poor end points due to being weak acids or bases in aqueous solution will frequently give far more satisfactory end points when titrations are carried out in non-aqueous media. An additional advantage is that many substances which are insoluble in water are sufficiently soluble in organic solvents to permit their titration in these non-aqueous media. 

Wolf WR and Iyengar V (1996) Nutritional metrology Food-based reference materials. Food Testing Analysis 2(6) 27-3i. 

See other oxosalts of nitrogenous bases (reference 1), OXIDANTS... 

H.J. Yoon, J.H. Shin, S.D. Ixe, H. Nam, G.S. Cha, T.D. Strong, and R.B. Brown, Solid-state ion sensors with a liquid junction-free polymer membrane-based reference electrode for blood analysis. Sens. Actuators B. 64, 8-14 (2000). 

The observations on which thermodynamics is based refer to macroscopic properties only, and only those features of a system that appear to be temporally independent are therefore recorded. This limitation restricts a thermodynamic analysis to the static states of macrosystems. To facilitate the construction of a theoretical framework for thermodynamics [113] it is sufficient to consider only systems that are macroscopically homogeneous, isotropic, uncharged, and large enough so that surface effects can be neglected, and that are not acted on by electric, magnetic or gravitational fields. The only mechanical parameter to be retained is the volume V. For a mixed system the chemical composition is specified in terms of the mole numbers Ni, or the mole fractions [Ak — 1,2,..., r] of the chemically pure components of the system. The quantity V/(Y j=iNj) is called the molar... 

NaN3 + 0.1 M NaClO. Base (reference) potential was -0.97 V vs. SCE sample potentials (mV vs. SCE) are as indicated. Spectra were obtained by acquiring 1024 interferometer scans at the base and sample potentials, the potential being altered after every 32 scans (see references 7 and 10 for further details). 

It is important that the ocean science community be encouraged to investigate the various proposed matrix-based reference materials so as to establish their properties with consensus-based values for the concentrations of a variety of constituents. 

Chapter 3 discusses the analysis of seawater constituents and reiterates the scientific problems that necessitate a number of seawater-based reference materials. 

The preparation of a reference material requires substantial planning prior to undertaking a specific project (see Box 5.1). The process begins with the definition of the material to be produced, for example, preparation of a seawater-based reference material containing the nutrient elements N03, P04, and Si(OH)4 at concentration levels appropriate to oceanic samples and certified for these constituents." Such definitions arise either from internal decisions by reference material producers (such as NIST or NRC-Canada) typically in response to perceived needs, or through external pressure on these producers from potential users. (This report, for example, explicitly identifies a number of pressing needs for reference materials for the ocean sciences.)... 

Approaches to the Preparation of Algal-Based Reference Materials... 

Each of the sediment based reference materials recommended in Chapter 4 should be certified for both inorganic and organic carbon concentration, total nitrogen concentration, S13C of both the inorganic and the... 

In the case of the acquisition of large-scale data sets, the benefits of using reference materials are self-evident. In the past, whenever such data sets have been acquired without using suitable reference materials, a great deal of effort has subsequently been needed to adjust the data to a common scale. But the benefit of comparability is not restricted to large programs. Matrix-based reference materials that can be exchanged between different laboratories will enable researchers to better understand their own techniques and the information they provide. 

The committee recommends the development of a seawater-based reference material containing the nutrient elements nitrogen (as N03), phosphorus (as P04) and silicon (as Si(OH)4) at concentrations similar to those in oceanic deep waters (40 pM for N03, 3 pM for P04, and 150 pM for Si(OH)4) and certified for these constituents. 

A seawater-based reference material with concentrations of metals corresponding to oceanic deep water, certified for total iron concentration. 

The committee recommends the development of three types of algal-based reference materials ... 

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