Peak height percentage

There are two basic methods used in quantitative analysis one uses a reference standard with which the peak areas (peak heights) of the other solutes in the sample are compared the other is a normalization procedure where the area (height) of any one peak is expressed as a percentage of the total area (heights) of all the peaks. There are certain circumstances where each method is advantageous, and providing they are used carefully and appropriately all give approximately the same accuracy and precision. 

If peak heights are used, the percentage x(p)% of any specific polymer (p) in a given polymer mixture can be expressed by similar equations,... 

An easy way to quantify the adsorptive and acid/base characteristics of a column is to measure the peak height as a percentage of that expected for complete and undisturbed elution. The two alkanes and three fatty acid methyl esters (non-adsorbing peaks) are connected at their apexes to provide the 100% line as shown in Figure 2.8 [190]. The column activity is then quantified... 

Figure 2.8 Test chronatograa of an open tubular coluen according to the method of Grob. A line is drawn over the peaks of the non-adsorbed solutes. The peak height of the remaining peaks is determined as a percentage of the ideal peak height. In the absence of adsorption all peaks should reach the dotted line.

Table XII lists the relative peak heights (and the percentage of iron in the M2 site obtained from these heights) together with the relative areas (and the same percentage as obtained from these areas). In either method the percentage of iron was taken to be the average of the M2 values, (L2 + R2)/2, divided by the sum of averages of the Mi and M2 values —i.., (ZI/2 R2)/(I i 1 Ri...

Calculation. Draw a baseline on the chart under all the sample peaks by connecting the baseline from aspirating wash at the start, between trays and at the end. Read the concentration of the sample solutions by comparing the peak heights of the samples with the standards using a chart reader (see Chapter 1, Chart reader ). Divide the concentration in pg mb of soluble carbohydrate in the sample solution by 10 to get the % water soluble carbohydrate in the freeze-dried sample. Multiply by 100/(100 - % moisture) to give the percentage water soluble carbohydrate in the sample DM. 

Fulvic acid from the Suwannee River was used to calibrate peak-height ratios for aromatic carbon content. The application of this method to fulvic acid samples with known aromatic plus olefinic carbon content from various environments is shown in Table II. Aromatic plus olefinic carbon percentages calculated by the peak-height ratio method using lH NMR data closely agree with these percentages computed from 13C NMR data, with the exception of the Big Soda Lake samples. 

H NMR data from these seven sites are presented by spectral peak-height ratios in Table III. The sites were listed in order of increasing aromatic plus olefinic carbon percentages. Fulvic acids from all the lake samples are much lower in aromatic plus oleflnic carbon content than those from river samples. These results confirm the hypothesis that autothonous inputs result in dissolved humic substances that have a low aromatic plus oleflnic carbon content. The lake samples also are lower in the ratios of peak 2 (carboxylated chains and aliphatic ketones), peak 3 (carbohydrates), and peak 4 (phenolic tannins and lignins) to peak 1 (branched methyl groups and alicyclic ali-phatics) than are the river samples. 

Determined from peak heights in GC/MS traces. Percentages are probably good to 3%, in most cases. 

This error can be represented as a percentage of the mean E% = 100 (E/x) = 24.1% in this case. It is always useful to check the original graph (Fig. 1) just to be sure, which appears a reasonable answer. Note that classical calibration is slightly illogical in analytical chemistry. The aim of calibration is to determine concentrations from spectral intensities, and not vice versa yet the calibration equation in this section involves fitting a model to determine a peak height from a known concentration. 

Sometimes die width at a different percentage of the peak height is cited rather than the half-width. A further common measure is when the peak has decayed to a small percentage of die overall height (for example 1 %), which is often taken as the total width of the peak, or alternatively has decayed to a size that relates to die noise. 

The drawings incorporate also points and arrows. The points show the true peak height (and the true retention time as well). In cases of poor resolution it is impossible to set this point intuitively to the true position which is often below the sum curve. The arrows show the positions at which both peaks are separated into fractions of equal purity by preparative chromatography. The number above each arrow indicates the percentage purity level attained. These numbers, however, are only true if the ratio between the amount of material and the signal (peak height as... 

ED (ESI optimization). Factorial design and CCD. Factors isopropanol percentage in the sheath liquid, flow rate, nebuhzer gas pressure, dry gas temperature, dry gas flow rate. Response sum of peak heights. 

The concentration of theophylline per tablet is calculated from the peak heights of sample spots and a calibration curve generated from three standard concentrations. Then, the percentage of the nominal value is calculated (200 mg = 100 %). 

Four techniques are commonly used to convert peak heights or areas into relative composition data for the sample. These are the normalization method, the external standard method, the internal standard method and the method of standard additions [264,284]. In the normalization method the area of all peaks in the chromatogram are summed and then each analyte is expressed as a percentage of the summed areas. All sample components must elute from the column and their responses must fall within the linear operating range of the detector. This method will always lead to totals representing 100%. If the detector response is not the same for all compounds then response factors are required to adjust the peak areas to a common scale. Response factors are usually determined as the slope of the calibration curve and converted to relative response factors since these tend to be more stable than absolute values. 

A mass spectrum is a plot or table of the mass-to-charge ratio, m/z, of detected ions vs. their relative abundance (relative concentration). A typical mass spectral plot for a small organic molecule, benzene, is presented in Fig. 10.1. The m/z values are plotted on the x-axis relative abundance is plotted on the y-axis. The most abundant peak in the spectmm is called the base peak. The base peak is assigned an abundance of 100% and the other peak heights are plotted as percentages of that base peak. A tabular form of benzene mass spectral data is given in Table 10.1. The tabular data have the advantage that very low abundance ions can be listed, such as the ions at m/z = 64 and 80 which are too small to be seen on the normalized plot. 

The amount of extractable monomer was estimated using GC (HP 5890 Model with a FID detector and a phenylmethylsilicon fused silica 10 m capillary column). Before extraction, FT-IR spectra were obtained using an IBM IR-32 Model with a DTGS detector. The percentage conversion of double bonds was calculated from the 1640 cm (6) peak height. 

Pyrolysis product Percentage ratio of each peak height to the summation of all peak heights ... 

---