Читать книгу Process Gas Chromatographs - Tony Waters - Страница 22

The injector valve must inject the measured sample volume all at once, in the form of a compact plug. If the injection is slow and the sample starts to mix with the carrier gas, the sample molecules will start to spread out in time even before they reach the column. This would not be good because it's more difficult to separate a wide band of molecules than it is to separate a narrow band. Separation is easier when the injected molecules tightly pack together.

The sample volume is determined by the application. It's crucial to inject the same volume of sample each time because the detector output signal is proportional to the number of molecules it sees. Should the injected volume change, so would the output signal, even if the concentration of the analyte remained the same.