Floating in Kraken Mare and looking for life has its own issues.
What would you look for? You'd filter out any solids prior to analyzing the liquid so you dont gunk stuff up. Back to only looking at a handful of soluble molecules (srsly. I prepared this list for the Oceanus Calypso probe. These are not exciting molecules.)
At low T, you'd want to look for molecular associations. Need in situ NMR, not destructive GC.
I'm a very wet blanket regarding methane-based life.