Chromatographic peak areas, calculation

Chromatographic peak areas are calculated automatically by the data system by reference to the response obtained from certain specified, compound-dependent ions. From the peak areas of the target compounds, quantification is achieved by comparison with the internal standards, which are present in known concentration. The laboratory responsible for the analysis must report the target compounds and all tentatively identified (nontarget) compounds. Standard EPA forms must be completed and submitted. A laboratory is said to be in compliance when it has satisfied all aspects of its CLP contract. 

Fig. 3.99. Examples of the evolution of the chromatographic peak areas corresponding to the dye metabolites during SBR 1 cycles in periods 2 (a) and 3 (b). Metabolites 1 ( ) and 3 ( ) correspond to the benzene-based and naphtalene-based amines, respectively. Metabolite 2 (o) is apparently in equilibrium with metabolite 1. The violet dye concentrations calculated form spectrophotometric analysis ( ) are also presented. Reprinted with permission from N. D. Lourenco et al. [156],...

Fractions of total addition products observed, calculated assuming equal gas chromatographic peak, area responses. b Extrapolated values for infinite pressure. c Small amounts of acetone formed are included. d Perhaps contains small amount, of diethyL ketone. 

The carbon and hydrogen contents were calculated on the basis of calibration constants and chromatographic peak areas. It can be inferred from the results [48] that the accuracies were 0.3% for carbon and 0.15% for hydrogen. 

The TVOC value of a sample is determined by the integration of the chromatographic peak area between C6 and C16 with 100 ng total integrated area toluene peak comparison calculated. The two standards hexane and w-hexadecane determine the retention time position of the C6 and C16 peak (see Figure 4.158). For the test samples the peak area between the calibrated retention times of n-hexane and n-hexadecane is determined as a total peak area. Representative chromatograms of a leather and a sponge sample are shown with the total ion current in Figures 4.159 and 4.160. 

Determine the chromatographic peak area for components and use the response factors obtained from the calibration run to calculate amounts of sulfuR present Example ... 

In the second case monitoring is performed on the column outlet with the main objective of identifying when the individual fractions elute. Post column detection is a very importemt part of analytical chromatographs where sophisticated diode array detectors may be utilized, and base line correction and peak area calculations are used for concentration determination of individual fractions. In contrast, in process chromatography, post column detection tends to be used purely qualitatively and may even be absent. 

Quantitative Calculations In a quantitative analysis, the height or area of an analyte s chromatographic peak is used to determine its concentration. Although peak height is easy to measure, its utility is limited by the inverse relationship between the height and width of a chromatographic peak. Unless chromatographic conditions are carefully controlled to maintain a constant column efficiency, variations in... 

To day peak widths are rarely used in chromatographic analysis except for the purpose of calculating peak areas. Peak widths, however, can provide a means of measuring the diffusivity of a solute which is a function of the molecular weight. Consequently, if a reliable relationship between diffusivity and molecular weight can be identified, then the molecular weight of the solute can be assessed. Peak widths of solutes eluted from an open tube can give very precise values of diffusivity. There are a number of equations that purport to relate diffusivity to... 

Figure 9 shows the result of injecting 10 gA of the total low molecular weight fraction from GPC 1 (Column Code A2) into GPC 2 (Column Code Bl). With this column code, GPC 2 is performing as a High Performance Liquid Chromatograph (HPLC). Separation is based upon solubility (i.e. composition differences) rather than upon molecular size. Methyl methacrylate monomer was used as a reference and added to the solution injected into GPC 1. Concentrations of n-butyl methacrylate, styrene and conversion are readily calculated from the peak areas and initial concentrations. 

The reaction mixtures of isophorone were analysed with a gas chromatograph. The GC analyses were carried out with gas chromatograph equipped with a p-cyclodextrine capillary column (analysis temperature dihydroisophorone at 110 °C) and FID. The chromatograms were recorded and peak areas were calculated with Chromatography Station for Windows CSW32 v. 1.2 (DataApex Ltd. 2001, Prague). 

An accurately known amount of a standard is added to the sample before it is chromatographed. The ratio of peak area of standard to that of the component of the sample to be determined is calculated. 

Both gas chromatographic instruments were connected with a PDP 11/45 computer via an analog-to-digital converter. The peak areas were calculated from the digitalized chromatographic data by means of software developed at Delft University of Technology. 

GC-Computer System Nowadays, a large number of data-processing-computer-aided instruments for the automatic calculation of various peak parameters, for instance relative retention, composition, peak areas etc., can be conveniently coupled with GC-systems. A commercially available fairly sophisticated computer system of such type are available abundantly that may be capable of undertaking load upto 100 gas-chromatographs with ample data-storage facilities. In fact, the installation such as multi GC-systems in the routine analysis in oil-refineries and bulk pharmaceutical industries, and chemical based industries have tremendously cut-down their operating cost of analysis to a bare minimum. 

This test uses the entire HPTC system with a specific chromatographic method and validated Cl8 column that should be <10 cm and commercially available. Validated means that the individual column was performance tested before being shipped and that a certified test chromatogram is included with each column. Injection precision testing is typically performed by replicate injections of a test standard (at least six replicates are suggested). One then calculates the peak area %RSD of a stable component in the test standard. Most LC... 

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