And background correction

Multichannel instruments are capable of measuring the intensities of the emission lines of up to 60 elements simultaneously. To overcome the effects of possible non-specific background radiation, one or more additional wavelengths may be measured and background correction (see Section 21.12) can be achieved. 

For USAXS and SAXS studies in normal-transmission geometry it is more convenient to carry out this step later - after the absorption and background correction. 

Moreover, the intensity is additionally increasingly dampened with increasing scattering angle. The corresponding absorption and background correction... 

Q. Why are fast response electronics and background correction essential when using furnace... 

P. Zhang and D. Littlejohn, Peak purity assessment by matrix projection for spectral line selection and background correction in inductively coupled plasma optical emission spectrometry, Spectrochim. Acta, Part B, 50(10), 1995, 1263-1279. 

Ag, At, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Tl, V, and Zn ETAAS Metals are measured by ETAAS using the manufacturer s recommended conditions and an injection volume of 20 pL Applicable to surface, ground, tap, and waste water. A high CE concentration interferes. To minimize the matrix effect, the chemical modification, standard addition method, and background correction systems may be used. 105... 

FIGURE 4.17 Two-dimensional scattering patterns after sample volume and background corrections corresponding to (a) CF, (b) CFC29, (c) CFC50, and (d) CFS48. (From Lozano-Castello, D., et al., Carbon, 40, 2727, 2002. With permission.)... 

Karstang, T.V. and Kvalheim, O., Multivariate prediction and background correction using local modeling and derivative spectroscopy, Anal. Chem., 63, 767-772, 1991. 

Zinc. AAS analysis of zinc by P CAM 173 is a standard application of the method as seen in NIOSH PAT. Zinc in the divalent state has been analyzed by dithiozonate (13). This colorimetric method suffers interferences from many other dithi-zone complexing metals. Zinc is easily determined after nitric acid wet ashing with an oxidizing air-acetylene flame using the 213.9 nm analytical line and background correction. The AAS analysis for Zn is as sensitive as more complex activation or plasma techniques. 

Certain systems also have an artificial intelligence software that can be used to optimise the operating conditions without user intervention. As in this case, for a given sample type, settings such as generator output, gas flow rates and background correction points can be determined depending on the objective of the analysis, in terms of accuracy and detection limits. 

Inductively coupled plasma-atomic emission spectrometry was investigated for simultaneous multielement determinations in human urine. Emission intensities of constant, added amounts of internal reference elements were used to compensate for variations in nebulization efficiency. Spectral background and stray-light contributions were measured, and their effects were eliminated with a minicomputer-con-trolled background correction scheme. Analyte concentrations were determined by the method of additions and by reference to analytical calibration curves. Internal reference and background correction techniques provided significant improvements in accuracy. However, with the simple sample preparation procedure that was used, lack of sufficient detecting power prevented quantitative determination of normal levels of many trace elements in urine. 

Figure 8.40. Spectra of sucrose solution illustrating several processing steps A is the raw spectrum of 1 M sucrose in water in a quartz cuvette B is after the 1000 e bias and dark signal was subtracted C is after the instrument response correction (described in detail in chapter 10) D is the water/cuvette background after the same processing steps E is spectrum C minus spectrum D, and is the final spectrum after bias, dark, response, and background corrections.

Furthermore, tuning of the primary source enables off-peak measurements and background correction to be made directly. 

The data in Table 11.1 demonstrate that the combination of standard additions and background correction successfully overcomes matrix effects to give accurate results. Similar excellent agreement has been obtained between HVAA and neutron activation data, as discussed below. 

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