Hi Steve,

I used QF 4.0 in June and passed with flying colors (LabCorp). I still have 2 bottles of 4.0 and plan to use them if I have to. If I have no tests for another year or so, I probably will invest in 4.2... since I think 2 years is a good estimate for shelf life.

I got one of those child temp strips for about $2-$3 at Walgreens. I would practice with the QF (actually practiced with water) and pour it into a small plastic cup and then test the temp with the temp strip by wrapping it around the cup. The temp strip on my bottle of QF was close to being accurate. By pouring the sample in the cup, it loses temperature (cold cup, hitting the air, etc)... so you should expect that.

When I handed the sample to the tech, it was around 96 degrees. PERFECT! Of course, I held the sample where you guys can't, so its good that you are practicing. Figure out how long the temp will stay while under your balls (oh the mental image!) and if it drops too low, read more about hand warmers and other methods to help it keeps its temp.

Good luck!
suzieque Reviewed by suzieque on . QF 4.0 vs. 4.2? Temperature strip accuracy? Hello, my name is Steve, and this is my first post after several months of "lurking". I've looked through the substitution sticky and I appreciate all the advice that everyone has posted. I have a test coming up, and a few months ago I purchased some QuickFix 4.0. I've noticed that there is now a 4.2, and I have seen people recommend switching to 4.0 if they have 3.0, but not so much about the difference between 4.0 and 4.2. The only thing I could really find is that 4.2 is less proven than Rating: 5