Peak height sample collection

Concentration in the sample (c). This is normally calculated using both peak areas and peak heights as it is a good idea to postpone the selection of a calibration technique until after the ruggedness study. Mean number of theoretical plates, N, there are several methods to calculate N. The following calculation is often employed due to its convenience as it uses values which are previously collected as part of the data handling. 

With the Chromalytics Model MC-2 mass chromatograph, a sample is introduced into the unit, split into two portions, collected onto traps, and then analyzed simultaneously with two gas density detectors as shown in Figure 1. The peak height or area ratios from each detector are measured and the molecular weights calculated from Equation 3. 

Data Collection Devices Modem data stations receive and store detector output and print out chromatograms complete with peak heights, peak areas, sample identification, and method variables. They are also used to program the liquid chromatograph, controlling most variables and providing for long periods of unattended operation. 

The peaks between 291.6 eV and 284.6 eV, are attributed to carbons bound to one fluorine atom or other electronegative species (e.g., 0 or N). Spectra obtained for sample collected in very active regions of the plasma with a high power input show much less prominent peaks indicative of carbons bound to fluorine and a very prominent carbon peak at 284.6 eV. An obvious qualitative numerical indicator of these characteristic peak shapes is the ratio of the peak height at 291.5 eV (CF2) to that at 284.6 eV. The use of this ratio as a means of identifying trends, 1. ., the conditions that will yield a fluorine rich polymer as opposed to those that will yield a fluorine poor polymer, is clearly justified. However, it should not be thought of as being directly proportional to... 

The basic operation of the instrument (3) consists of the Ionization of the sample in the cell by a timed electron beam which Is followed, after a short Interval, by an RF pulse applied to the plates of the cell. This pulse coherently excites all ions In the cell into cyclotron motion. The motion continues after cessation of the pulse, and the resonance is detected by the plates of the cell, amplified and the data stored In the computer. The excltatlon/detection cycle is repeated numerous times and the collected data summed. The data Is then subjected to fourler transformation and the frequency spectrum resulting converted into a mass spectrum. The spectrum Is normalized to the major peak. For quantitative work, the calibration can be based either on peak height or peak area. Here, major considerations will Include the resolution chosen and the relative concentrations of the constituents under Investigation. 

The classical manifold architecture in Fig. 8.22, upper was exploited in the pioneering work incorporating GD in flow injection analysis for the spectrophotometric determination of total carbon dioxide in blood plasma [265]. Details of the separation unit are shown in Fig. 8.23, left. The donor stream with the sample zone was acidified and the released CO2 diffused through the membrane towards the acceptor stream, which was an alkaline cresol-red indicator solution. Analyte collection resulted in a transient lowering of the pfi of this stream and hence a transient modification to the monitored absorbance. The recorded peak height was proportional to the CO2 content in the injectate. 

Peak height ratios for different detectors or, e.g., ultraviolet detection at several wavelengths, can be used. Another method is to observe the change in retention times upon derivatization of the sample either by chemical or enzymatic methods. With continuous wavelength detectors stopped flow scanning of ultraviolet or fluorescence spectra is a possibility. Isotopic labelling can be used and, finally, fractions can be collected and characterized by, e.g., spectroscopic methods. 

Data from the analyses are collected by a PC running "Mercury MD-1" data analysis software. This software can store multiple calibration curves and raw data finm the samples. The mercury response can be measured using either peak height or integration over time. The PC software is strictly for data acquisition and does not control the instrument start or any operating parameters. 

Sulphonamides in pharmaceutical preparations and urine were determined indirectly using flame AAS by continuous precipitation with copper or silver, as proposed by Montero et al.[22]. The copper method exhibited a better selectivity, and only this was used for determinations in urine. The precipitate, formed by injecting one of the cations into a carrier containing the sample, was collected on an on-line filter, and the peak absorbance of the residual metal in the stream passing through the filter was measured. The decrease in peak height compared to a blank was then related to the sulphonamide... 

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