English to Russian Medical Medical (general)

Triplicate samples were prepared and assayed at each spiking level according to the procedure described in protocol. The mean % recovery from the set of three sample solutions at each spiking level ranged from 98.5% to 100.1%.

Я понимаю методику использования добавок, но не могу никак подобрать термин. Уровень добавок звучит глупо.