Chromatogram integration

Solvent extracts are passed through Florosil compounds to remove the aliphatic and resin fractions. The resulting eluate is analysed through a GC-FID system and the chromatogram integrated to give either speciated or total PAHs. The method is sensitive and specific, to a detection limit of 1 mg/kg, for each PAH. 

Hisatomi H, Nishimoto Y, Ozawa T, Kawasaki H, Ute K. ArakawaR. Polymer analysis utilizing psuedo 2D liquid chromatogram integrated with LC-ESI-MS data using two different columns. Bunseki Kagaku 2011 60 245-51. 

A2.2.1.3 Record the partial pressure and operate the gas sampling valve to place Ae sample onto the column. Record the chromatogram, integrator/computer peak areas, and peak retention times. 

Procedure. Inject 1 fiL of the sample solution and obtain a chromatogram. Under the above conditions the compounds are separated in about 3 minutes, the elution sequence being (1) aspirin (2) phenacetin (3) caffeine. Measure peak areas with an integrator and normalise the peak area for each compound (i.e. express each peak area as a percentage of the total peak area). Compare these results with the known composition of the mixture discrepancies arise because of different detector response to the same amount of each substance. 

Figure 3.28 Representative reconstructed ion chromatograms obtained from the LC-MS analysis of a pesticide mixture, showing integrated peak area and height measurements. From applications literature published by Micromass UK Ltd, Manchester, UK, and reproduced with permission.

Figure 4.18. Peak-size correlation in an HPLC-chromatogram. The impurity profile of a chemical intermediate shown in the middle contains peaks that betray the presence of at least two reaction pathways. The strength of the correlation between peak areas is schematically indicated by the thickness of the horizontal lines below the chromatogram. The top panel gives the mean and standard deviation of some peak areas (n = 21) the two groups of peaks immediately before and after the main peak were integrated as peak groups.

Table II. Carbohydrate compositions (weight percentage) of individual oligomer peaks purified (QAE-Sephadex or HPLC ion-exchange separation, respectively) from mixtures of citrus pectin oligomers or B fruit extracts Compositions shown are for peaks whose biological activity is described in Figure 4. Uronic acid values are based on colorimetric assay. Proportions of neutral sugars were determined by GC and adjusted so that totals equal 100%. In fact, some oligomers (G7 peaks 8, 9 and 10. B extract peak 10) produced small (less than 1 % of the total integrated area), unknown peaks in the GC chromatograms.

In order to cadculate a particle size distribution directly from the output chromatogram for a polydisperse system, the integral, dispersion equation for the chromatogram signal, F(V), as a function of elution volume, V, needs to be evaluated (27) ... 

In equation (8), G(V,y) is the normalized instrumental, spreading fxinction for the component with a mean retention volume y and W(y) is the area under the chromatogram due to that species. The integral is evaluated over the limits of the chromatogram, to V2. The area W(y) is related to the number density of the particles by... 

Theory. We will outline theory developed earlier (11,12) for converting the detector response F(v) from a turbidity detector into particle size information. F(v) is related to the dispersion-corrected chromatogram W(y) by the integral equation... 

Integrator on and off times Lets the computer know the time range of interest within the chromatogram [elution time range of the analyte(s) of interest]. 

The equipment consisted of two Waters (Waters Corp. Milford, MA) M-45 pumps, a Waters 481 UV detector, a six-port Valeo sampling valve (A2L6P) with 0.08" holes in the valve body and rotor, a Rheodyne Model 7413 injection valve with a 1-pl loop, a valve interface box, and a Digital Equipment LSI-11/23-based microcomputer system. The microcomputer was used to control all valves, collect raw data from the UV detector, integrate the chromatogram, and store and plot results. 

In HPLC-TLC coupling, the crucial aspect is the maintenance of the chromatographic integrity during the deposition process. The chromatogram is preserved after LC separation, and is available for further separation and/or investigation. LC-TLC coupling increases the separation efficiency, and allows detection modes which are incompatible with LC (e.g. spectroscopic techniques... 

Peak areas on the chromatogram were measured with an integrator. The integrator prints out the retention time for each peak, together with a number that is proportional to the peak area. 

Because online separations provide such a wealth of information about target proteins, interpretation becomes of critical importance in order to make full use of the data. The first step in any analysis of LC-MS data involves integration and deconvolution of sample spectra to determine protein mass and intensity. In manual analysis (Hamler et al., 2004), users identify protein umbrellas, create a total ion chromatogram (TIC), integrate the protein peak, and deconvolute the resulting spectrum. Deconvolution of ESI spectra employs a maximum entropy deconvolution algorithm often referred to as MaxEnt (Ferrige et al., 1991). MaxEnt calculates... 

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