Height, measurement

Viggiano A A and Arnold F 1981 The first height measurements of the negative ion composition of the stratosphere Pianet. Space Sc/. 29 895-906... 

Fig. 19-1. Wind variation with height—measured (solid lines) and one-seventh power law (dashed lines).

V = volume a = length of base edge b = width of base measured perpendicular to a h = height measured perpendicular to plane ab d = diameter... 

There have been a few reports of column efficiency and reduced plate height measurements in several unified chromatography techniques. These have been based on the apparent plate height observed at the column outlet. In the notation used by Giddings (32) the apparent plate height, H, is given by the following ... 

Start the vapour generator cycle so that the absorption cell is flushed with argon gas and the pre-set volume of NaBH4 (1 mL) is pumped into the sample vessel. After the pre-selected reaction time (0.5 minute), AsH3 vapour is flushed into the absorption tube. Record the value of each arsenic signal as a peak height measurement. Read off the arsenic concentration of the sample, which is displayed on the instrument video screen. 

Wave-height-concentration plot 604 Wave height measurement of, 605 Wavelengths approximate of colours, 646 limits of various types of radiation, 647 units for, 647 Wave numbers 646... 

Nuclear Magnetic Resonance. The sampie is dissolved in anhyd (0.02% w) dimethylformamide and the NH4 peak width at half-height measured at 7.38t and compared with a graph prepd from samples of AP contg known amts of w. 

It is seen that there is not a great difference between the use of peak heights or peak areas for quantitative analysis, except possibly for very early peaks, where the results seem to indicate that peak height measurements might be more precise. However, it again must be emphasized that the measurements made by Scott and Reese were overall precision measurements that will include all variations in the chromatographic system. The difference between the two methods of measurement may well be significant, but the absolute values for precision will not, by any means, be solely dependent on the method of peak measurement. 

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.

Data Normalization Since the general trend for every set of numbers is obviously similar, a simple normalization was applied for each plate, the mean over all height measurements at 5 jal/spot was set equal to 100%, yield-... 

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. 

Figure 4 Chromatogram of Cr(VI) and Cr(III) in the range 1-5 Xg/L (correlation coefficients >0.999 based on peak height measurements). Cr(VI) appears at 2.8 min, Cr(III) appears at 4.6 min. (From Ref. 92, with permission.)...

Figure 12.17 Mean dendrimer diameter and height measured by AFM from particle s profiles, as a function of generation. The error bars for AFM data represent one standard deviation...

Wh = Width of the peak of interest at half peak height, measured in the same units as VR. 

The relationship between the concentration of the solute and the peak produced in the chromatogram is, strictly speaking, only valid for peak area measurements, but in most instances it is more convenient to measure peak height. Such peak height measurements should only be used when all the peaks are very narrow or have similar widths. The tedium and lack of precision associated with non-automated methods of peak area measurements may be overcome using electronic integrators, which are features of most modern instruments. 

Figure 6.12. Particle stream functions, ty(e = 0.65) (Radial position is expressed as fraction of radial distance from centre line, and axial position as fraction of bed height measured from the bottom)(43 ...

Asymmetry <3.5 (T = W5%/2f), where T is the tailing factor, W5% is peak width at 5% peak height, and f is the width at 5% peak height measured from the leading edge to a vertical line extrapolated from the apex of the peak. 

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