Sample chromatogram

Where SA R is the specific area of the reference peak, and SA is the specific area of component x. AR is the GC peak area of the reference, Ax is the GC peak area of component x, WR is the weight of the reference, and Wx is the weight of component x. The weight percent of component x can be obtained from the sample chromatogram by using the relative response factors in the following equation ... 

The diameter averages calculated from the mixt ire rule are given in Table VI. While the first row entries for each mixture are the true values, the values that would be obtained from the analysis of the bimodal chromatograms should be compared with the third row entries since these account not only for the less than satisfactory calculations for the 183 nm sample chromatogram, but also for the incomplete recovery of the l83 nm particles. 

The calibration technique used in conventional SEC does not always give the correct MWD, however. The molecular size of a dissolved polymer depends on its molecular weight, chemical composition, molecular structure, and experimental parameters such as solvent, temperature, and pressure ( ). If the polymer sample and calibration standards differ in chemical composition, the two materials probably will feature unequal molecular size/weight relationships. Such differences also will persist between branched and linear polymers of identical chemical composition. Consequently, assumption of the same molecular weight/V relation for dissimilar calibrant and sample leads to transformation of the sample chromatogram to an apparent MWD. 

Axial dispersion characterization is a valuable by-product of coupling GPCs. By sampling chromatograms with the second GPC, extremely monodisperse fractions can be obtained and the concentration of misplaced molecules in any chromatogram slice revealed. 

Figure 1 Example of a sample chromatogram with the analyte peak (11) eluting at 18.23 min, solvent peaks (1-3), matrix component peaks (4, 7-10, 12), and instrumental noise (5, 6,13)...

Figure 2 Sample chromatogram from turf clipping.

Figure 4 Sample chromatogram from cloth dosimeter.

With the jt/PI. C system connected to a MS, sample identity could easily be confirmed. If the sample chromatograms shown in Figure 6.29 were to be considered, MS spectra for all compounds could be obtained after all runs were completed, as shown in Figure 6.36. The MS capability... 

Fig. 11.2 Sample chromatogram obtained using worst case column. Source Own files...

Chromatographic Evidence Sample chromatograms often contain evidence that natural attenuation has occurred. If chromatograms of fresh petroleum that was released can be obtained, then a solid comparison can be made between fresh and weathered samples relatively soon after being released in many circumstances. 

Fig. 2.34. Sample chromatogram of light-adapted Z. marina leaf sample. Peak identification 1 = neoxanthin, 2 = violaxanthin, 3 = antheraxanthin, 4 = lutein, 5 = zeaxanthin 6 = chlorophyll b, 1 = chlorophyll a, 8 = / -carotene. Reprinted with permisson from P. J. Ralph et al. [76].

The modulator is the heart of the GCxGC system, and is positioned at the confluence of the coupled chromatography columns. The role of the modulator is to trap or isolate compounds present in a given time fraction eluting from the first-dimension column and reinject these components rapidly into the second column. This essentially yields a time-sampled chromatogram, from the first dimension ( D) to the second dimension ( D). It is critical that the modulator is capable of representatively and faithfully sampling peaks eluting from onto D. This can be achieved by either complete or partial transfer of the first-column eluent, however, both techniques are considered comprehensive. 

The LOQ can be determined by a signal-to-noise ratio of 10 1, or approximated by mnltiplying the LOD by 3.3. As with LOD, this fnnction is easily obtained from current data-acquisition software. Similarly, LOQ can be estimated by the equation LOQ = 10(SD/S) and by hand calculation as well. LOQ should be reported as a concentration and the precision and accuracy of this value should also be reported. As for LOD, measurement of the actual LOQ value may not be necessary if the method is shown to perform at a level that is sufficiently low (e.g., 0.1%). Figure 4 shows an example of an estimate of LOQ for an HPLC sample chromatogram. 

Miniaturizing the column i.d. is of great benefit to the sensitivity of ESl-MS, which behaves as a concentration-sensitive detection principle, because the concentration of equally abundant components in the LC mobile phase is proportional to the square of the column internal diameter. Column diameters from 150 to 15 jm with flow rates 20-200nL improve detection limits of peptides 1-2 orders magnitude over microliter flow rates. Several references referred to in other sections of this chapter discuss the use of LC-ESI MS to characterize separation products. and a sample chromatogram from Ito and coworkers. is seen in Figure 3.8. Table 3.4 provides additional and references that have used this technique. 

The resolution between each peak and its nearest eluting peak in the sample chromatogram where Rs can be calculated as follows ... 

Where Cone, is concentration, s is sample chromatogram, IS is the internal standard and std. is the standard chromatogram. 

The concentrations of each analyte can be calculated by relating the peak area in the sample chromatogram to the peak area in the standard chromatogram as follows peak area in sample... 

Figure 4.12—Analysis using an external standard. Sample chromatogram. This basic method can be improved by using several reference solutions varying in concentration to create a calibration curve. In certain cases, peak height can be used instead of peak area.

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