Proposed method for non-invasive head gasket failure detection

TLR: Why has no one developed a cheap test to check for burnt coolant in tailpipe residue? A Google search says the chemistry exists.

I am in the market for another Gen 3 Prius. I checked out the Gen 5s, and as beautiful as they are and as good as the specs are, the lower seating height is just too difficult for me to get into and out of comfortably. I am 54, with a bad knee, and I tend to keep cars for 15+ years. If I have this much difficulty getting in and out now, it ain't getting better when I'm pushing 70 . I think Toyota made a mistake with this new design, but that is a rant for a different thread!

I don't like the Gen 4s, so I am looking for a Gen 3. As we all know from this forum, blown head gaskets (and sellers making every attempt to hide blown head gaskets) are a big concern. Aside from experiencing the morning death rattle with your own senses (which is easy for a seller to hide by just running the car before you see it), all of the common ways to detect the failure are quite invasive. Pretty much every test I have seen (checking for residue on spark plug, washed cylinder head, boroscope looking for leak, cylinder leak down test, etc.) involve removing at least one spark plug. As I found when I was doing the EGR cleaning on my current Gen 3, this involves significant dissassembly of the engine compartment just to get access. This also ignores the damage you might do when removing the spark plug. Not many Facebook Marketplace sellers are going to let you do that amount of dissasembly when you haven't paid for the car yet. We know that the block testers that check for exhaust gasses in the coolant don't usually work, because that is not typically the way Gen 3 engines fail.

This got me to thinking. Block testers work by checking for exhaust gasses in the coolant, where they have no business being. Well, coolant, or more specifically burnt coolant, has no business being in exhaust gas. I know if you see white smoke out of the tailpipe or if it smells sweet, that is a sign of burning coolant. The problem is this is also too easy for a seller to hide. Just run the engine long enough for the smoke / smell to go away.

So I am thinking that coolant burned in the cylinder has to go somewhere. Detecting it on the spark plug visibly is possible, so why should it not also be detectable, at least in trace amounts chemically, on tailpipe residue? I started doing some searches, and it should be possible with a $75,000 gas chromatograph machine, which is clealry not practical. But there are other tests, that are much cheaper, that can detect the pressence of burnt glycol. Sure, they may have a huge false positive outcome, but is that really a problem?

This seems like a good business opportunity for anyone who has the desire to explore.