While it seems interesting, I have no idea how one gets a trustworthy supply of such micro doses, not to mention that fact that LSD is a schedule 1 drug. Caffeine seems much easier to obtain.
Aside from subjecting the source tabs to the 'acid test', as it were, you would use some lab testing to verify a purchase such as on the DNMs. EnergyControl if you're in the US, possibly some of the national testing programs if you're in the EU. (EnergyControl was not available when I ran my self-experiment.) Another possibility for quality control is moving to the gray market: the analogue 1P-LSD is available from RC vendors and currently is minimally prosecuted, although it's so chemically similar to LSD that it'll probably happen eventually; to the extent that you trust legal sellers more than illegal ones for purity, 1P-LSD would be an improvement. Or you could do both, why not.
Avoiding a drug because of it's scheduled status makes a lot of sense, and because of what it might be cut with, but I am not sure why someone, or how someone would cut LSD with fentanyl given how small I thought the effective dose of LSD is comparatively and how different the effects are.
Without gc/ms you just don't know what's in your tab/liquid/etc. That being said iirc it takes milligrams to OD on fent which means you'd be pretty safe with tabs. Liquid is another story.
[REDACTED] acquired LSD tartrate, made solution w/ everclear, and then diluted it such that one sip is roughly 4-8ug based on volume. That's the only real way to microdose yourself, although you could cut a tab into 20 pieces (depends on the lay but a skilled lay is evenly distributed. An unskilled lay will have massive hotspots and thus one would need to dissolve the tab in a solvent or cut it into n->infty pieces)
