Peak area using

The effect of solvent polarity on the injection conditions for the determination of nitro-PAH by capillary GC with splitless injection was investigated LOD was 129 pg of 2-methyl- 1-nitronaphthalene (228), at SNR 2, RSD 1.8-6.7% when measuring by peak area using FID474. 

The previous method can be improved by preparing a number of standard solutions that contain the sample to be analysed plus increasing quantities of that same compound. Using the NMR spectra obtained from these solutions, a plot can be made of the peak areas used for quantification. The intercept of the plot with the concentration axis will give the required sample concentration (Fig. 9.26). 

This method avoids overlap in the peak areas used in the former method. 

Lauric acid and mono-, di-, and trilaurin were analyzed by capillary GC according to the method described by Langone and Sant Anna (9). All concentrations were calculated as molar fractions from the peak area using calibration curves. 

Procedure Inject the volume of Sample Preparation as designated in the monograph into the column. Determine the concentration of intermediates and side reaction products from the peak areas using the slope, m, and intercept, b, calculated under Calibration by the equation... 

Polyphenol Analyses. Skin and seed extracts were prepared as described elsewhere (4,15). Flavonol and anthocyanin composition of grape skin extracts and wines were determined by direct reversed-phase HPLC analysis with diode array detection. The chromatographic conditions were the same as described earlier (16) but the formic acid concentration in the elution solvents was raised to 5% to improve anthocyanin resolution. Quantitations were based on peak areas, using mdvidin-3-glucoside (at 530nm) and quercetin-3-glucoside (at 360 nm) response factors, respectively, for anthocyanins and flavonols. 

Corrected peak area using photoelectric cross-sections relative to C Is. 

The accuracy of the determination will depend upon the accuracy of peak areas used in the calculation, perhaps 2% - . For a crystalline complex, a single crystallization of material of >95% ee will almost certainly bring it to complete optical purity, in which case the absence of NMR signals for the minor diastereomer of the complex to within the limits of sensitivity of the NMR spectrometer will be the criterion for complete optical purity of the arsine. Since the displacement of an arsine from a configurationally homogeneous complex of this type is stereospecific with retention of configuration at arsenic and can be carried out under mild conditions, the arsine liberated will also be optically pure. However, to be certain of the optical purity of the arsine the diastereomer should be re-prepared on a small scale and checked once again for purity by NMR spectroscopy. 

In a system with slow kinetics, the Ag and Ab need to be preincubated before injection into the capillary (45,46). Fixed concentrations of Ag or Ab are then incubated with different concentrations of Ab or Ag. The quantity of free Ab or Ag can be determined by the peak area using a calibration plot. Scatchard analysis is made by plotting the total amount of Ab or Ag vs. bound Ab or Ag. For the intermediate kinetics system, separation conditions, such as applied voltage, length of the capillary, pH, and other factors, can be changed so that the system can be analyzed using one of the final experimental protocols. 

Emmerich and Bayreuther (75) found that in their simultaneous TG-EGD apparatus, the EGD peak area was proportional to the sample mass for the evolution of EUO.CO. and COz from the thermal decomposition of CaC204-UNO. This proportionality is shown by the curves in Figure 8.24, which have a linearity of wiihin — 2%. They also studied the effect of gas flow quantity and peak height, half-width, and peak area using calibrated amounts of air injected into the carrier gas stream. The peak area and half-width decreased, whereas the peak height increased with an increase in gas flow. Thus, better... 

Fractional Precipitation of Amylose-lodine Solutions. Fairly concentrated amylose solutions containing a mixture of two to five components (DP 90-56CXJ) were precipitated by successive addition of KI2 solution. The purified fractions were converted into tricarbanilate derivatives and were then separated over a high performance GPC column. The ratio of the components was obtained from careful evaluation of the peak areas using the concentration dependence of the single components and various mixtures of known composition. Figure 9 shows the elution curves of fractions a-d obtained from a two component system (DP 90 and DP 1800, 1 1). 

Differential scanning calorimetry A Perkin-Elmer DSC-2 calorimeter with Thermal Analysis Data Station was used. The calorimeter was calibrated according to manufacturer s specifications. Heats of reaction were calculated from the peak areas using indium as a standard (AH=6.80 cal/g). Tg was taken as the onset of the endothermic deflection. The heating rate was set to 20 /min. For DSC analysis, samples were prepared by two techniques a) vacuum drying of varnish and b) by flaking off resin from prepreg. 

XPS measurements were carried out on an AXIS NOVA photoelectron spectrometer (Kratos Analytical, Manchester, UK). The surface atomic concentration was determined firom peak areas using sensitivity factors. Spectrum background was subtracted according to Shirley. The XPS peaks of the Ti species were analyzed by spectra deconvolution software (CasaXPS-Vision 2, Kratos Analytical, UK). 

Detectors can be classified as mass- or concentration-sensitive detectors. The chromatographic peak area using a mass-sensitive detector is independent of the flow rate used, while the peak area using a concentration-sensitive detector depends on the flow rate. Hence, for quantitative determinations, good flow control is needed with the concentration-sensitive detectors. 

Figure 5.5 Calculation of peak area using the Coveil method...

Figure 5.6 Calculation of peak area using extended background regions...

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