Evaluation of peak areas

The estimation of the peak area is particularly recommended when the shape of the signals is not symmetrical. One of the simplest way to measure the peak area is to cut out the plotted peak and to weigh the paper in comparison with a well-known area. It is also practicable to plot the curve on a squared graph paper and to count out the number of squares if the peaks have no horizontal basis, aberration must be taken into consideration (Fig. 2-35). 

Nowadays, there are many algorithms to calculate the area below the peaks [74] and also for baseline correction and the correction of overlapping signals. Nevertheless, quantitative results must be reviewed critically because of possible artifacts [75], 

French, C. S., Church, A. B., Carnegie Inst. Wash. Yearbook 1955, 54, 162-165. 

Botton, D, Honkawa, T., Tohyama, S., Perkin-Elmer Corp. Norwalk, C.T., US.A. Application Data Sheet Second Derivative Spectroscopy. Perkin-Elmer Corp. Norwalk, C.T., US.A., 1977 22 p. 

Talsky, G., Risti6-Solaji6, M., Anal Chim. Acta 1987, 196, 123-134. 

---

With the multitude of transducer possibilities in terms of electrode material, electrode number, and cell design, it becomes important to be able to evaluate the performance of an LCEC system in some consistent and meaningful maimer. Two frequently confused and misused terms for evaluation of LCEC systems are sensitivity and detection limit . Sensitivity refers to the ratio of output signal to input analyte amount generally expressed for LCEC as peak current per injected equivalents (nA/neq or nA/nmol). It can also be useful to define the sensitivity in terms of peak area per injected equivalents (coulombs/neq) so that the detector conversion efficiency is obvious. Sensitivity thus refers to the slope of the calibration curve. 

To evaluate linearity, calibration curves were generated for the values of peak areas obtained for analytes of interest against their concentrations in solutions prepared from serial dilutions of a standard mixture. In the case of methyl paraben, solutions with concentrations varying from 0.3 to... 

FIGURE 6.49 Time course obtained for evaluation of product formation in a protein A kinase and Kemptide system. Values of peak areas obtained for product are plotted against corresponding time points used during evaluation. 

Prepare a graph of peak area ratio (C 0Hg/C,oD8) versus concentration ratio [CI0H8]/[CI0D8] and find the slope, which is the response factor. Evaluate F for each of the three samples and find the standard deviation of F to see how constant" it is. 

Quantitative evaluation of the total amounts of T and D units, found in the pyrolyzate, gives a T/D ratio corresponded to that in the original polymer. For the conversion of peak area values into weights authors used reflex factors for the Flame Ionization Detector [81],... 

Figure 5.1-5 Illustration of various baseline options in spectral evaluation by peak area measurements (a) no baseline (b) horizontal single-point base-line (c) two-point baseline (d) common tangent baseline.

A typieal two-eolumn setup featuring two six-port switching valves (Ch. 1.5.5 and Figure 1.4) was evaluated. To support the claim that no sample pretreatment prior to analysis is required with the TFC system, Herman [113] analysed 1000 eompounds in plasma, urine, intestinal perfusates, brain homogenates, and eerebrospinal fluid. Similar results in terms of peak area were obtained for the five different matriees. 

Certain evaluation methods were examined based on the quantification processes. These can be divided into three groups, employing only the values of peak normalization (PN). The effect of the use of IS and certain evaluation methods, such as correction of peak area (normalization), was calculated by dividing the related peak area into on which the precision was examined. These can be divided into three groups a) employing only the area values of PN (PN no IS), b) computing the ratio values (IS no PN), and c) using the area values of peak normalized IS and ENX (IS and PN). The precision of the peak areas was calculated as shown in Table 1. 

Integration of peak areas in routine analysis is mostly achieved with electronic integrators. Two main problems arise from this evaluation technique first the definition of the baseline, and second, the determination of the time constant of the TLC-scanner and the integrator electronics. 

Fig. 10. Recorded reflectance curve with evaluation of fractionalized areas for determination of overlapping peaks 19>...

In another application, Sturm et al. (44) evaluated CE-mass spectrometric (capillary electrophoresis-mass spectrometry [CE-MS]) data from different Corydalis species, that is, Corydalis cava from two different regions (CM and CB), Corydalis pumila (PU), Corydalis intermedia (IN), and Corydalis solida from two different regions (SG and SE). Exploring the CE-MS data with PCA succeeded in distinguishing the six Corydalis species samples. In this example, only a comprehensive list of peak areas of analytes was chosen as initial data... 

Using peak heights in XPS instead of peak areas speeded up the analysis and evaluation of data. A comparison of peak height ratios with peak area ratios on a selected series of samples showed that only a very small error was introduced by using peak heights. The XPS ratio of carbon to tin was calibrated with TMT vapors solidified at the sample stage at -112°C. A conversion... 

The peak areas of all relevant bands are evaluated as a function of the time to analyze the kinetics of the pyrolysis process. In Fig. 69 the normalized changes of peak areas of several bands are shown for a temperature of 812 K. Four different behaviors can be identified. The bands assigned to the imide system (bands D and F in Fig. 67) decrease rapidly (seeA in Fig. 69 the out-of-plane bending vibration of the imide ring is shown). The bands... 

The effect of water volume on SPME efficiency was evaluated using three different volumes 2, 4, and 8 mL, while the concentration of analytes remained flie same. As shown in Table 2, the peak area ratio (the peak area of analyte divided by the peak area of the internal standard) increased about 10 times when the volume was increased from 2 to 4 mL. However, when water volume further increased from 4 to 8 mL, only slight enhancement of peak area ratios was found. Since the volume of water extracts after flie hot water extraction of rosemary was 5 mL, the 4 mL of water voliune was chosen in this work. 

The use of peak area integration instead of the peak height evaluation may eliminate kinetic interferences. 

The local site effects play an important role in the evaluation of seismic hazard. The proper evaluation of the local site effects will help in evaluating the amplification factors for different locations. This article deals with the evaluation of peak ground acceleration and response spectra based on the local site effects for the study area. The seismic hazard analysis was done based on a probabilistic logic tree approach and the peak horizontal acceleration (PHA) values at the bed rock level were evaluated. Different methods of site classification have been reviewed in the present work. The surface level peak ground acceleration (PGA) values were evaluatedfor the entire study area for four different site classes based on NEHRP site classification. The uniform hazard response spectrum (UHRS) has been developed for the city of Bangalore and the details are presented in this work. 

The success of the CE experiments from an analytical point of view depends on the conditioning of the capillary surface. Therefore, cleaning and conditioning processes, as explained in the experimental part, must be repeated after each injection to provide optimum resolution and reproducibility. The precision of the peak area was also assessed by considering certain evaluations, such as the effects of correction of peak area (normalization), which were found by the division of the related peaks into the corresponding migration times the use of an internal standard was studied. 

In general, the transmission integral (O Eq. (25.31)) can be used to evaluate the peak area that depends nonlinearly on the effective thickness, which, in turn, is proportional to the concentration of the resonant atoms. 

Figure 2 The principle of (a) ACE-/x for weak binding and (b) for tight binding systems by evaluating the peak area (S, reference molecule P (protein), solute L, ligand). (Reproduced from Ref. 5. Springer, 1998.)...

---