Yes, assays is a Scrabble word!

Verb

1. Analyze (chemical substances)

2. Make an effort or attempt

Noun

1. An appraisal of the state of affairs

2. A substance that is undergoing an analysis of its components

3. A written report of the results of an analysis of the composition of some substance

4. A quantitative or qualitative test of a substance (especially an ore or a drug) to determine its components; frequently used to test for the presence or concentration of infectious agents or antibodies etc.