Yes, I'm sure of this. The only way to get an accurate ammonia reading within 48 hours of using prime is to buy a seachem ammonia tester. ALL other tests are effected.
Prime works "instantly" and at recommended dosages is available for 48 hrs (increased from 24hrs originally). However, the bond that it makes is permanent--so it will always effect your test kit. What you want is a free-ammonia test kit. Seachem's does both, and their ammonia alerts read free-ammonia...