The Instrumental Chromatogram

FIGURE 11.15 An illustration of the tracing of an instrumental chromatogram as separated mixture components elute from the column and pass through an electronic sensor. 

FIGURE 11.16 Retention time is the time from when the sample is injected into the flowing mobile to the time the apex of the peak appears on the chromatogram. 

Other parameters sometimes obtained from the chromatogram, which are mostly measures of the degree of separation and column efficiency, are resolution (R), the number of theoretical plates (N), and 

FIGURE 11.18 The measurement of width at the base, used in resolution and theoretical plate calculations. 

In this equation, tR(B) is the retention time for peak B, tR(A) is the retention time for peak A, WB(A) is the width at the base of peak A, and Wb(B) is the width at the base of peak B. 

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