Analysis of Output in Gas chromatography:
In Gaschromatographic AnalysisThe Response factor is one of the limitation of the Analysis as explained below ::
Less than ideal spectral peaks may indicate less than ideal analytical procedures or equipment. The technician can readily observe whether the output exhibits unsatisfactory results. Ideally, the spectral peaks should be symmetrical, narrow, separate (not overlapping), and made with smooth lines. GC evidence may be suspect if the peaks are broad, overlapping, or unevenly formed. If a poorly shaped peak contains a steep front and a long, drawn-out tail, this may indicate traces of water in the specimen.
The GC technician should inject the specimen into the septum rapidly and smoothly to attain good separation of the components in a specimen. If the technician injects the specimen too slowly, the peak may be broad or overlap. A twin peak may result from the technician hesitating during the injection. A smoothly performed injection, without abrupt changes, should result in a smoothly formed peak. A twin peak may also indicate that the technician injected two specimens consecutively.
The size of a spectral peak is proportional to the amount of the substance that reaches the detector in the GC instrument. No detector responds equally to different compounds. Results using one detector will probably differ from results obtained using another detector. Therefore, comparing analytical results to tabulated experimental data using a different detector does not provide a reliable identification of the specimen.
A "response factor" must be calculated for each substance with a particular detector. A response factor is obtained experimentally by analyzing a known quantity of the substance into the GC instrument and measuring the area of the relevant peak. The experimental conditions (temperature, pressure, carrier gas flow rate) must be identical to those used to analyze the specimen. The response factor equals the area of the spectral peak divided by the weight or volume of the substance injected. If the technician applies the proper technique, of running a standard sample before and after running the specimen, determining a response factor is not necessary.