2. Principle and System Configuration of HPLC (2)
Philosophy of Qualitative analysis and Quantitative analysis by chromatography
Qualitative analysis
A standard sample of aspartame was measured, yielding a peak at 12.5 minutes. This peak corresponds to aspartame, itself.
Next, a sample prepared from a beverage was measured under the same conditions, yielding a number of peaks. The peak appearing at 12.5 minutes can be regarded as that of aspartame (Figure 1).
The following conditions were the same: the type of fillers, column sizes, column temperature, composition of the mobile phase, and flow rate.
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Quantitative analysis
The height and area of a peak are proportional to the concentration of the corresponding component. A calibration curve is created using the standard sample. The concentration of aspartame in the beverage can be determined from the peak area of the detected aspartame.
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Attention should be given to the fact that a qualitative analysis includes many uncertainties. Other components may have been eluted together with aspartame. LC and GC systems are good at determining the content of a certain component in a sample, rather than the types of the components of a sample. Performance of a quantitative analysis requires the preparation of a calibration curve. It is very difficult to perform the qualitative or quantitative analysis of a component for which a standard sample is not available.