What are the best tubes to use with the premate test and a centrifuge? Do the vacutainers with the gel separator affect the results? Where is the best place to order?
TIA

I use regular tubes, no separator.

with separator. Used it for years. Let it sit after drawing blood for about 5 minutes while the test is still coming to room temperature. Then spin the blood down. Really makes it easy to work with.

No separator. It will affect the true progesterone level. Use a red top with no separator.

FYI Separator does not affect the results of pre mate testing, not at all. If your personal experience is such that you found differences, perhaps something changed in the process of testing. Same as some saying you have to use distilled water vs tap water. Makes no difference which water you use, it's the temp of water that makes the difference!! I'm talking years of using this successfully. I also know what works for some does not work for others so im strictly speaking from a factual perspective. If using a red top without separator works better for you, that's fine. It just does not have an affect on the actual results nor does distilled vs tap have an affect..... TEMPERATURE changes results.

used separators for years with great results.
you can spin them down in a centrifuge or let stand for few hours until completely separated.

Try an experiment next time. It will cost you a few bucks, but it will show you that a separator DOES change the result. Draw blood, and put half in a separator, and half without. Do it each time. As the progesterone rises, you will see the difference. It is not as obvious when the numbers are low.

To answer the OP's question, PreMate instructions state that you use a heparanized tube or draw into a heparanized syringe if using a centrifuge. If you don't have a centrifuge, according to the instructions, it states to put the blood into a test tube, (no differentiation of what type), and let the blood cells settle for about 45 minutes and then draw the clear serum off the top. If you are letting your sample sit out, the directions state that you need to draw 3ml's of blood. If using a heparanized tube or syringe, you only need to draw 1 ml of blood. I have used PreMate for years up until the end when I pull the quantative test. I have always used the heparanized tubes because I spin my collection with a centrifuge. I have had great results with this method. I use lavender top tubes, (heparanized), for my draws.

I have spoke with many folks at IDEXX and Antech along with many repro vets and they have all told me that to have accurate results for a quantative progesterone assay test, you need to draw into a red top tube and do not use a serum separator tube.

Hope this helps.