Can you pass a hair follicle test if you only used a very small amount of cocaine?

Depends: Hair follicle tests are tricky--metabolites are deposited and can show up--but the real issue is not how much you did, since I assume you did enough to have an effect; if so you dosed enough to show up. It was how long ago you did it that is the factor and how often. 90 days is the recommended wait time; however, if you have a problem, go for treatment before you get caught. Honesty is best.