QF can be heated and reheated without hurting it. What is worrying me here is... where is the box? You should always leave the QF in the box. Exposing QF to sunlight has adverse effects... Also, how old is the QF? In the box was a piece of paper that gave its creation date... and I wouldn't use it if it was over 2 years old. If it was exposed to sunlight, it may not pass the creatinine or specific gravity tests. The only way I'd use this bottle is if it passed a home adulteration test (which tests for those two items). An adulteration test can be expensive, so investing in a new bottle of QF might be the best idea.