The phrase "a necessary quantity of" is correct and usable in written English.
It can be used when discussing the amount of something that is required for a specific purpose or task.
Example: "In order to complete the experiment successfully, we need to ensure that we have a necessary quantity of reagents on hand."
Alternatives: "an essential amount of" or "a required volume of".
An open issue for fusion power reactor is to design a suitable breeding blanket capable to produce the necessary quantity of the tritium and to transfer the energy of the nuclear fusion reaction to the coolant.
The sample of cDNA obtained from the RT was incorporated into the necessary quantity of DEPC-treated water to get a final concentration of 40 ng approximately (range: 10 100 ng).
A sufficient quantity of protein was removed from the fraction containing the highest concentration of protein [now in 100 mM NH4HCO3 buffer (pH 8.0)] to give ∼27 μg of enzyme, which was diluted into the necessary quantity of 100 mM NH4HCO3 buffer to yield a final volume of 45 μL.
Why does it matter if we achieve the necessary quantity of emission abatement at $2 per tonne of CO2 or at $50 per tonne?
Whether the necessary quantity of radioactivity would allow for PET imaging remains to be determined in patients.
The use of 1-methyl-3-octylimidazolium tetrafluoroborate as potential solvent for separation of thiophene from n-alkanes is feasible using the necessary quantity of solvent.
The most important criterion for design is the ability to transfer the necessary quantity of various solids within the required time interval.
The necessary quantity of initial lift gas was estimated and optimized, so that ensures no ballast consuming during the ascending process.
At TV.com, Noel Kirkpatrick commented favorably on how the second season of "one of television's best programs" handled the necessary quantity of exposition, and on its introduction of the theme of conflict between spiritualism and secularism.
