Quote Originally Posted by Colin Robinson
He says: " a biological distribution of molecules would be a series of relatively sharp spikes while an abiotic distribution would be smooth." Note that he doesn't just say "spikes", he says "relatively sharp spikes". By "relatively" he means: in comparison to an abiotic distribution.
Its still double-talk.
‘Biotic’ and ‘abiotic’ molecules aren’t defined by their relative abundances (ie: ’spikes’ or no ‘spikes’, ‘smooth’ or not ‘smooth’). We’re talking about organic chemistry here.
He’s trying to impose his fantasies onto the outcome of yet another fantasised hypothetical measurement, whilst ignoring already known chemistry.

Quote Originally Posted by Colin Robinson
You mention the diversity of molecules produced on Titan by abiotic processes.
No .. the diversity of amino acids and their isomers is an outcome of organic chemistry in a natural environment.

At the stage this becomes relevant during the detection/sample treatment process, ‘abiotic’ and ‘biotic’ is unknown.

Quote Originally Posted by Colin Robinson
That diversity would indeed mean lots of little spikes, but the broad outline would still be smooth. If McKay's hypothesis is correct, a series of relatively sharp spikes, corresponding to molecules favoured by Titan biology, would be present if there are biological processes happening, even if there were abiotic processes happening as well.
Pure codswallop.

Isomers have the same molecular weight as biomolecules.
A subset of amino acids are classified as biomolecules.
The distributions of amino acids and their isomers will look the same as a biomolecule distribution in a tholin dominated landscape.

Quote Originally Posted by Colin Robinson
The molecules showing up as relatively sharp spikes would not necessarily be those which are biologically significant on Earth, such as amino acids and lipids. They would be molecules which in Titan conditions have biologically useful properties such as functioning as catalysts (as amino acid polymers do in Earth conditions) or forming membranes (as lipids do in Earth conditions).
They’re still organic chemicals behaving as per known physical chemistries (which can be simulated).

The question is not how biology can use physical properties of compounds.
The question is: Is there biology in the first place?