For sample extraction, there are two ways to proceed - all require opening the carboy.
There is a device called the "Wine Thief" that works well. It is a plastic tube
with a one way check valve at the bottom. It fits through the carboy neck and allows a
small sample to be quickly removed. It is clear and black plastic. I am not sure if
there are any metal parts on the valve. One of the nice features is the ability to touch
the plastic needle valve on a cylinder allowing the liquid to be dispensed for your test.
The other nice thing is the remaining liquid can be dumped into a glass for further
testing.
Most wine and beer shops carry them.
Other location is the scientific supply company in St. Paul. It is a real
"dangerous" spot to visit especially with cash! They are located on the north
side University Avenue just on the St. Paul side of 280. Sorry but I don't have
their address or name but the last name is "scientific." They have Pipettes,
microscopes, test tubes, glass tubing, earlymeyer, beaker........... Like I mentioned,
really dangerous to the budget.
Best of luck.
Rick Oftel