Gas standards dynamic

It is with gaseous materials that preparation of extremely dilute standards presents real difficulties. For example how can one be certain that a syringe pulled back to 1 cm3 volume in fact contains 1 cm3 of the test gas and not 0.5 cm3 of that gas, plus 0.5 cm3 of air or 1 cm3 of the gas at reduced pressure Furthermore, since the concern is for quantities in the parts-per-million range, a 1-cm3 volume of a standard gas is not a reasonable volume to be considered since it would imply the use of a 1000-liter container. Therefore, a variety of alternative methods has been devised, though the serial dilution of a known gas volume is also used. This is defined as a static gas standard, while methods for the preparation of dynamic flowing concentrations of trace levels of the sample gas in a carrier have also been well defined. The variety of techniques for preparation of gas or vapor standards is fully covered in Chapter 4. 

This question is closely related to the coherent-incoherent transition problem absent from the standard situation in the gas phase namely, a true rate constant can be defined only when the tunneling dynamics is incoherent, i.e., once prepared in the initial state (reactant valley), the system... 

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