First live quarter: the purity ceiling
Live submission opens. The purity distribution turns out to be compressed at the top, which makes purity a poor discriminator and content a good one.
The first quarter of live submission produced enough records to look at the shape of the purity distribution rather than individual results, and the shape was the quarter's finding: it is compressed at the top and has a long left tail.
What a compressed distribution means
For the high-volume, easy compounds — BPC-157, TB-500, the secretagogue hexapeptides — the interquartile range is under 0.6 pp and the median sits above 98.8 %. Nearly every lot is good and the differences between suppliers are inside the measurement uncertainty. A purity figure on those compounds does not discriminate between suppliers and reporting one as though it does is misleading.
That is not true across the board. The acylated incretins have interquartile ranges two to three times wider, and retatrutide's is the widest of any high-volume compound. There, purity discriminates strongly.
Where the discrimination actually is
The measurements that separate suppliers on the easy compounds are the ones almost nobody orders.
| Measurement | Spread across suppliers, this quarter | Ordered on |
|---|---|---|
| Purity (BPC-157) | 0.6 pp IQR | Nearly every report |
| Water content | 4.1 pp range of supplier medians | About a third of reports |
| Counter-ion | 5.8 pp range of supplier medians | Under a fifth |
| Recovered mass vs label claim | 14 pp range of supplier medians | About a third |
| Endotoxin | Two orders of magnitude | About a quarter |
Recovered mass has a spread more than twenty times wider than purity on the same compounds, and it is the quantity a buyer is actually paying for. This observation is the reason the supplier scorecards weight documentation and recovered mass rather than presenting purity alone, and the reason the purity-to-mass calculator exists.
Rules added
Rule AX-R06 — recovered mass outside ±10 % of label claim — was added this quarter and immediately became the most frequently firing rule in the index. It has remained so.