serial dilution
The progressive dilution, by the same factor, of standard or sample in a row of tubes so that the first tube contains the highest concentration of test substance
The term "serial dilution" was found in the following pages:
Speciation of Germanium in Environmental Water Reference Materials by Hydride Generation and Cryotrapping in Combination with ICP-MS/MS | EVISA's News
Instrument database: EquiLab Inc. - AIM 1250 sample Preparation System