Response factor.html



Response factor, usually in chromatography and spectroscopy, is the ratio between a signal produced by an analyte, and the quantity of analyte which produces the signal. Ideally, and for easy computation, this ratio is unity (one). In real-world scenarios, this is often not the case.

Expression

The response factor f_i can be expressed on a molar, volume or mass¹ basis:

where A is the signal (e.g. peak area) and the subscript i indicates the sample and the subscript st indicates the standard.² The response factor of the standard is assigned an arbitrary factor, for example 1 or 100.

Examples

As a positive example, the response factors of each hydrogen atom in a sample analysed by proton NMR is unity, or very nearly so. Thus, by comparing the integrals of each peak observed in a proton NMR spectrum, one can determine composition of an arbitrary analyte mixture. Alternatively, one can determine the ratios of protons in various chemical environments in a single pure analyte.

On the other hand, for gas chromatography-mass spectrometry, the total ion counts of different species in a mixture may not produce peaks of similar area per unit of analyte due to the different susceptibilities of fragmentation. As a result, comparing the peak areas of different compounds in a chromatogram, one may not determine the relative proportions of each compound in the mixture.

References