Aspirin is outdated tech. It was used to foil only one type of test - the original EMIT screen. Since then, a second-generation EMIT (aka EMIT II) was introduced to tackle the aspirin issue. As a result, the first-gen EMIT is seldom used anymore (if, at all).

B2 is used for coloring but it must be understood that with the advent of specimen validity checks as SOP, color became the least aspect in determining an overdiluted sample. Even samples with a nice yellow color can still fail the creatinine and specific gravity checks which are the two checks the labs perform to determine an overdiluted sample.