Peak size measurement

Since the peak size is directly proportional to concentration, one may think that one could prepare a series of standard solutions and obtain peak sizes to be used for a standard curve of peak size vs. concentration, a method similar to Beer s law in spectrophotometry, for example. But since peak size also varies with amount injected, there can be considerable error due to the difficulty in injecting consistent volumes, as discussed above and in Section 12.3. A method that does away with this problem is the internal standard method. In this method, all standards and samples are spiked with a constant known amount of a substance to act as what is called an internal standard. The purpose of the internal standard is to serve as a reference for the peak size measurements, so that slight variations in injection... 

Figure 4.9. Constructions for peak size measurements on sloping base line.

TABLE 4.3 CONDITIONS FOR LEAST ERROR IN PEAK SIZE MEASUREMENT. 

Attention has already been given to the errors associated with peak size measurement and with standardization. There are many other places in the chromatographic process where errors enter into quantitative analytical GC. Detailed analysis of most of these error sources is not possible, especially in the confines of this chapter, but they should and will be mentioned and briefly discussed. Most of the error sources are generally obvious it may indeed seem even ridiculous that some have to be mentioned. However, the mere fact that they are obvious tends to slowly place them in the overlooked category. One has to be constantly reminded of these errors until the consideration of them becomes habitual with each problem. 

TABLE 8.4 Conditions for Least Error in Peak Size Measurements... 

In evaluating all of these observations and current practices, the following conclusions regarding peak size measurements seem evident ... 

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