Integration baseline correction

The purpose of sample acceptance criteria is to confirm that the run for a test article is suitable for quantification. The corrected peak area of the sample should be within linear range of the assay the baseline should be suitable for integration the corrected peak percentage should be in a reasonable range. Again, for a purity assay, migration time is usually not a critical parameter. 

Selected entries from Methods in Enzymology [vol, page(s)j Boundary analysis [baseline correction, 240, 479, 485-486, 492, 501 second moment, 240, 482-483 time derivative, 240, 479, 485-486, 492, 501 transport method, 240, 483-486] computation of sedimentation coefficient distribution functions, 240, 492-497 diffusion effects, correction [differential distribution functions, 240, 500-501 integral distribution functions, 240, 501] weight average sedimentation coefficient estimation, 240, 497, 499-500. 

Note Equal slopes of the integral baseline may by corrected with the Bias option. It is recommended to apply a spectrum baseline correction (see chapter 5) or to simply activate the Basline Correction option in the integral Options dialog box prior to integration. 

Unequal slopes of the integral baseline may be corrected either by the Slope option or a combined application of the Slope/ Bias options. 

Repeat the integration but activate the Baseline Correction mode in the Options... dialog box, and compare the two results. 

After processing in the time domain, Fourier transformation, phasing and basic processing (calibration, peak picking, integration) ahs been performed, additional processing steps to improve spectral quality are at your disposal. This includes operations common to both ID and 2D spectra e.g. baseline correction in the frequency domain, as well as operations specific to these different type.s of data sets. 

Samples and digitizes the detector signal at up to 40 Hz performs peak area integration or peak height measurement with baseline correction and deconvolution of incompletely resolved peaks. 

Thus, the derivative can be evaluated at any temperature by dividing the baseline-corrected excess heat capacity, ACP(T), by the integrated enthalpy A /f. By substituting this result into equation (16.19) one obtains... 

The choice of the reference band (or bands), however, influences less the results than the reproducibility of the baseline construction and the correct reading of the maxima. Modern software in FTIR spectroscopy are useful in automatic and reproducible location of baselines, maxima, integral values, and baseline-corrected absorbances. 

For both the isothermal series of runs on samples 1 throngh 6 and the temperatnre-dependence rnns on sample 1, make a table of yonr resnlts. For each rnn, specify the Fl concentration and/or temperatnre and list for both methyl band A (pyrnvic acid) and band B (dihydroxypropanoic acid) the band position, the FWHM width W (Hz), and the integrated area. If possible, obtain an ASCII file of I(v) intensity data, which will allow a least-sqnares fit to the peaks with a Lorentzian form with baseline corrections see Exp. 43. This permits a check on the actual line shape and an independent determination of area and width values. 

For accurate integrations, zero-fill the FIDs, baseline correct the spectra, and correct the slope and bias of the integrals individually. 

Use baseline corrections on each integral cut if spectral tilt is noticeable. Extensive zero filling (see step 2) is useful, because it provides more data points to define line shapes better (Section 2-5b). Slight line broadening produces smoother spectral and integral lines with less baseline noise. 

Most integrators are developed for use in GC and have sophisticated routines for peak detection and for baseline corrections if there are negative slopes. They are able to detect small peaks even in the descending part of a solvent peak. How-... 

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