Sometimes used to mean a test or test result, but other times as a synonym for the analytical method.

The term "assay" was found in the following pages:

Speciation analysis by LC-ICP-MS finds new application area in clinical chemistry: Ceruloplasmin | EVISA's News
Instrument database: GBC Scientific Equipment Ltd. - LC 1210 Programmable Scanning dual wavelength UV-vis Detector
Journals database: Journal of Food Composition and Analysis
Journals database: Bioanalysis
Determination of Vitamin B12 in human milk | EVISA's News
Instrument database: Foss A/S - Direct Contact Analyzer
Instrument database: Varian Inc. - Cary 50 UV-Vis spectrophotometer
Material database: SUPELCO by Sigma-Aldrich - Thioredoxin Reductase from rat liver
Material database: Canadian Certified Reference Materials Project (CCRMP) - MA-1b Gold Ore
Journals database: Journal of Physics Part D: Applied Physics
Instrument database: Oxford Instruments - X-MET3000TX
Instrument database: Aurora Biomed - VERSA 1000 Workstation
Journals database: Molecular Imaging and Biology
On-column internal standardisation as an alternative calibration strategy for speciation analysis | EVISA's News
Link database: EFSA: Chromium nitrate as a source of chromium added for nutritional purposes to food supplements
Instrument database: Spectradyn Technologies LLC - MGA-915 Atomic Absorption Spectrometer
Instrument database: Rigaku Corporation - Alchemist™ II automated liquid formulation system
Company database: Caliper Life Sciences
Instrument database: Spectrolab Analytical - S10-DB
Instrument database: Thermo Scientific - TSQ Vantage™ Triple Quadrupole Mass Spectrometer