Peak height from chart recorder

The mixture is identical in each example. The peaks are shown separated by 2, 3, 4, 5 and 6 (a) and it is clear that a separation of 6a would appear to be ideal for accurate quantitative results. Such a resolution, however, will often require very high efficiencies which will be accompanied by very long analysis times. Furthermore, a separation of 6o is not necessary for accurate quantitative analysis. Even with manual measurements made directly on the chromatogram from a strip chart recorder, accurate quantitative results can be obtained with a separation of only 4a. That is to say that duplicate measurements of peak area or peak height should not differ by more than 2%. (A separation of 4a means that the distance between the maxima of the two peaks is equal to twice the peak widths). If the chromatographic data is acquired and processed by a computer, then with modem software, a separation of 4a is quite adequate. 

Perfluoroalkane-225 (PGR, Gainesville, FL) was admitted through a glass inlet system to provide reference peaks. Analytical and reference peaks for the nitrosamines studied are shown in Table I. Sample and reference peaks were scanned alternately at a repetition rate of approximately 1 sec and were monitored on an oscilloscope. When the nitrosamine peak appeared, the oscillographic recorder chart drive was engaged and remained on until the peak disappeared. Nitrosamine quantities were estimated by comparing the sum of sample peak heights measured from the chart (usually 10 to 20 values) with values derived from injection of standard solutions. 

Strip-chart recorders are still the least expensive option, but areas and retention times have to be manually calculated from the tracing. The more expensive integrators, using small memories, give us a time-noted trace followed by a report of areas (or peak heights) versus retention times. The computer requires much more memory to store the one point per second (or more) required for an HPLC run. However, it has much more flexibility in manipulation, redisplay, calculation, and report generation. Data processing will be covered in detail in Chapter 14. 

The determination of Dp involves the measurement of H at several relatively high flow rates, where the term B/u is negligible. The slope obtained in a plot of H versus u enables one to calculate Dp, since K is known in these experiments. The plate height, H, is determined from the eluted peaks displayed on a chart recorder by... 

Duplicate samples are placed on the column, the sample solution is diluted by a factor of 3 and duplicate samples are again placed on the column. This procedure is repeated, increasing the detector sensitivity setting where necessary until the height of the eluted peak is commensurate with the noise level. If the detector has no data acquisition and processing facilities, then the peaks from the chart recorder can be used. The width of each peak at 0.607 of the peak height is measured and the peak volume can be calculated from the chart speed and the mobile-phase flow rate. Now,... 

Weigh about 12 mg of barium chloride crystals into an empty sample tube and obtain chromatograms as indicated under Procedure. Repeat with 9. 6. 3 and 1 mg amounts of barium chloride crystals. Add the values for the two peaks obtained for water in each determination and correct for the blank. Construct a calibration graph relating milligrams of water to the corrected total peak height (or peak area) measured from the recorder chart. 

A) Measure the positions and amplitudes of all the lines in the spectrum and list them in order in a table (a spreadsheet program is convenient for this purpose). A well-defined measure of position in a complex spectrum is the x-axis point halfway between the maximum and minimum of the first-derivative line. The amplitude is the difference in height between the maximum and minimum. If convenient, measure the line positions in gauss if this is inconvenient, use arbitrary units such as inches, centimeters, or recorder chart boxes measured from an arbitrary zero. In your table, also provide headings for the quantum numbers (m1 m2, etc.) for each of the line positions, for the coupling constants (a, a2, etc.), and for the theoretical intensity (degeneracy) of each peak. 

The Testlab takes a few seconds to save and analyze the data. Peak pulse height is read by pressing the Testlab Setup MENU button and reading the last test data column and recording in the log. (Integrated power is also indicated, but not recorded). The maximum fuel temperature is read from the Speedomax 25000 recorder chart and recorded in the log. 

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