Comparative references

We use HT for all voltage systems above l.l kV unless a comparative reference is necessary. 

Proving test hardware, comparative references, and test software (4.11.1.1)... 

Where test software or comparative references such as test hardware are used as suitable forms of inspection, the standard requires that they be checked to prove that thep are capable of verifying the acceptabilify of product prior to release for use during production, installation, and servicing and shall be rechecked at prescribed intervals. The standard also requires the supplier to establish the extent and frequency of such checks and to maintain records as evidence of control. 

Comparative references are devices which are used to verify that an item has the same properties as the reference. They may take the form of materials such as chemicals which are used in spectrographic analyzers or those used in tests for the presence of certain compounds in a mixture or they could be materials with certain finishes, textures, etc. Certificates should be produced and retained for such reference materials so that their validity is known to those who will use them. Materials that degrade over time should be dated and given a use by date. Care should be taken to avoid cross contamination and any degradation due to sunlight. A specification for each reference material should be prepared so that its properties can be verified. 

What documented procedures have you established to control and maintain comparative references ... 

Standard Ton Conditions. These are taken by industry to represent the refrigeration tonnage of a system when operating with an 86°F condenser temperature and a 5°F evaporator temperature. This is a comparative reference condition and does not need interpolation for effective evaluation of other tonnage requirements and conditions. 

Metal/molten salt interfaces have been studied mainly by electrocapillary833-838 and differential capacitance839-841 methods. Sometimes the estance method has been used.842 Electrocapillary and impedance measurements in molten salts are complicated by nonideal polarizability of metals, as well as wetting of the glass capillary by liquid metals. The capacitance data for liquid and solid electrodes in contact with molten salt show a well-defined minimum in C,E curves and usually have a symmetrical parabolic form.8 10,839-841 Sometimes inflections or steps associated with adsorption processes arise, whose nature, however, is unclear.8,10 A minimum in the C,E curve lies at potentials close to the electrocapillary maximum, but some difference is observed, which is associated with errors in comparing reference electrode (usually Pb/2.5% PbCl2 + LiCl + KC1)840 potential values used in different studies.8,10 It should be noted that any comparison of experimental data in aqueous electrolytes and in molten salts is somewhat questionable. 

The above also shows that even in the cases where a well-defined initial act, such as dissociation, is necessary, we may not expect to find a sharp photochemical threshold. (Compare reference (2), page 249.) And for other than monochromatic radiation the restriction mentioned at the outset must evidently be that a photochemical temperature coefficient due to the influence of temperature on light absorption can appear to its full extent only in cases where there is small fractional reduction in the intensity of the active radiation. 

The results show that DE-MS alone provides evidence of the presence of the most abundant components in samples. On account of the relatively greater difficulty in the interpretation of DE-MS mass spectra, the use of multivariate analysis by principal component analysis (PCA) of DE-MS mass spectral data was used to rapidly differentiate triterpene resinous materials and to compare reference samples with archaeological ones. This method classifies the spectra and indicates the level of similarity of the samples. The output is a two- or three-dimensional scatter plot in which the geometric distances among the various points, representing the samples, reflect the differences in the distribution of ion peaks in the mass spectra, which in turn point to differences in chemical composition of... 

The difference between hydrophobicities of the hydroxyethyl (HE) grouping and the hydroxypropyl (HP) unit is evident in the relative aqueous solution surface tensions(7,8) of the two cellulosic polymers in these comparative references the M.S. of the products is not equal. The dramatic influence of the more hydrophobic HP groupings on surface pressures is illustrated in Figure 2. 

Fig. 2.1. Chemical structure of several SERMs in triphenylethylene group. The estradiol molecule is also included as a comparative reference...

These biological factors also affect the reference materials. It is easy to envisage that different reference materials, all certified with respect to their mass fractions, could be derived from different cultivars or derived from different tissues (processed fractions) and would differ in their genetic make-up. This would result in different relative amounts of DNA for an identical mass fraction. Due to these biological factors these uncertainties can only be avoided if all producers of certified reference materials establish a system of comparable reference materials, accounting for the underlying biological factors. 

The following are bare bones protocols of the general format specified by Toneguzzo et al.46 and Liszewski et al.49 They are primarily offered for comparative reference, and the reader is referred to additional indicated references that specify more elaborate isolation techniques. 

Straight line Correlation Number of Comparative References... 

Straight line equation Correlation coefficient Number Comparative of samples method compared References... 

Straight line equation Correlation Number Comparative References coefficient of samples method compared ... 

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