The phrase "an equivalent quantity" is correct and usable in written English.
It can be used when discussing amounts or measures that are equal or comparable in value or significance.
Example: "In order to maintain balance in the equation, we must ensure that we have an equivalent quantity of both reactants."
Alternatives: "a comparable amount" or "an equal measure".
It is the ratio of the amount of heat trapped by a certain quantity of the gas to the heat trapped by an equivalent quantity of carbon dioxide over 100 years.
The North Carolina team announced a breakthrough in 1966 in the form of a concentrate for the blood factor, known as Factor VIII, that could be stored at room temperature, was far more potent than an equivalent quantity of plasma and could be manufactured at low cost.
Nuclear waste retains its very intense level of radioactivity for several hundred years, but after a thousand years have passed, the remaining radioactivity, while persistent, is at a level comparable to (though still greater than) that of an equivalent quantity of natural uranium ore.
Generally, it is considered that all the nodes generate an equivalent quantity of network traffic.
A pellet prepared with an equivalent quantity of pure KBr powder was used as control.
Performing a measurement could reduce the thermodynamic entropy of a system, but to do so requires the creation of an equivalent quantity of bound information in the device which holds the outcome of the measurement.
The dilution effect is a result of replacing a part of cement by the equivalent quantity of MK.
The corresponding grading functions are obtained solving an underlying optimization problem that minimizes a predefined objective function characterized by an equivalent stress quantity.
A glycerol solution of 50% (v/v) was added to the fermentor for 4 hrs to reach an equivalent total quantity of 60 g·L-1 in the culture medium.
Five micrograms of aRNA from each sample (21 SLE patients and 45 healthy individuals) and the equivalent quantity of reference aRNA from a mixture of RNA extracted from peripheral blood of 45 healthy individuals were subjected to Cy3 and Cy5 labeling, respectively.
Equivalent quantity of non-stimulated HMEC was used as a negative control.
