English to Russian Medical Biology (-tech,-chem,micro-) Immunoassay

Customer reported that instrument has given about 15 initial reactive results for HBsAg this morning which is higher that they would normally expect. Customer reran samples in duplicate per package insert and both replicates were ***non-reactive***. Customer to run assay on second instrument tomorrow with the same reagent to see if they still get an increased rate of initial reactive results for HBsAg.

Подскажите, пожалуйста, каким термином принято переводить ***non-reactive samples***

инертные
не реактивные
отрицательные, др. ?

Спасибо!