Individual component calibration levels

As shown in the Level column of Figure 10, the various injected volumes can be designated as individual component calibration levels. By doing this, experiments 10-27 can also be used to help validate multilevel, multi-replicate calibration algorithms on a chromatographic data system. 

Measurements by photographic photometry require careful calibration due to the nonlinear response of photographic plates saturation effects can lead to erroneous values. Line profiles can be recorded photoelectrically, if the stability of the source intensity and the wavelength scanning mechanism are adequate. Often individual rotational lines are composed of incompletely resolved spin or hyperfine multiplet components. The contribution to the linewidth from such unresolved components can vary with J (or TV). In order to obtain the FWHM of an individual component, it is necessary to construct a model for the observed lineshape that takes into account calculated level splitttings and transition intensities. An average of the widths for two lines corresponding to predissociated levels of the same parity and J -value (for example the P and R lines of a 1II — 1E+ transition) can minimize experimental uncertainties. A theoretical Lorentzian shape is assumed here for simplicity, but in some cases, as explained in Section 7.9, interference effects with the continuum can result in asymmetric Fano-type lineshapes. 

Calibration is performed on a mass basis, using mixtures of specified pure aromatic hydrocarbons. Volume percent data is calculated from the densities of the individual components and the density of the sample. A multipoint calibration consisting of at least five levels and bracketing the expected concentrations of the specified individual aromatics is required. Specified deuterated hydrocarbons are used as the internal standards, for example, d6-benzene for quantitating benzene. Unidentified aromatic hydrocarbons present which have not been specifically calibrated for are quantitated using the calibration of an adjacent calibrated compound and summed with the other aromatic components to obtain a total aromatic concentration of the sample. 

These components can be individually computed from measurements at a site after proper calibration to establish specific attenuation factors. For example, from a series of sites that differ in DOC concentration and having low or constant levels of phytoplankton pigments, total and [DOC] are measured... 

One of the main purposes of measuring NIR data is the determination of chemical composition or physical properties in a quantitative way. The principle of the measurement procedure for quantitative analysis is based on recording the NIR spectra of reference samples (the number depending on the number of components or parameters to be determined) of known composition. The levels of the constituents or the physical parameters are determined by independent, conventional analytical or physical methods. Then the set of reference spectra and the independently determined values of the parameters under investigation are used by a selected statistical method to build a calibration. This enables unknown samples to be evaluated with regard to the individual parameters of interest. The accuracy of the NIR technique depends upon the validity of the calibration data set, which must incorporate the entire range of concentrations that will be determined by the instrument. This set must contain samples with varying ratios of each component. NIR calibrations do not typically extrapolate or interpolate well across concentrations. Typical calibration sets include more than... 

A Level II infrared thermographer shall be qualified to set up and calibrate equipment, conduct inspections, and to interpret inspection results in concordance with procedure requirements. The individual shall be familiar with the limitations and scope of the method employed and shall have the ability to apply techniques over a broad range ofapplications within the limits of their certification. The Level II shall be able to organize and report inspection results. A Level II must have the ability to correctly identify components and parts of components within the scope of the IR inspection. 

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