In a Canadian research-peptide context, the HPLC purity floor is the single quality-control number that most affects batch-to-batch reproducibility. This post explains why we set the floor at 99.0%, what each percentage point above it means for assay drift, and how to read the figure on a lot's COA — drawn from public literature and Pure North's published lot history.
Why the purity floor matters
Why we set the floor at 99.0% and what each percentage point above means for your assay drift and batch-to-batch consistency. The reproducibility gap on most catalogs comes from one place: lots that don't hit ≥ 99% HPLC purity get sold at lower price points instead of being rejected. Pure North's published purity floor is 99.0%, with the average across the catalog at 99.18%. Every lot we ship has a Janoshik-Analytical-verified COA archived publicly at /lab-results/ from synthesis onwards.
The protocol short-version
For Canadian research labs working with any reference standard, the lifecycle is: receive the vial (dispatched within 2 business days, ~4 days in transit via Canada Post Xpresspost), transfer immediately to a research-grade −20 °C freezer, reconstitute in sterile bacteriostatic water at the working concentration your protocol specifies, and use within the storage window noted on the lot's COA. Avoid repeated freeze-thaw cycles — every cycle introduces measurable assay drift even on lots that meet the purity floor.
Cross-batch reproducibility
Pure North holds a 5-year retain sample on every lot. If your assay drifts, we run our retain against your in-hand material and pinpoint whether the variance is in the peptide or upstream in your reagent pipeline. This is the most-requested feature labs cite when asked why they reorder.
Where to source it in Canada
Pure North Peptides is Canadian-based and ships across Canada via Canada Post Xpresspost — orders are dispatched within 2 business days, with typical transit around 4 days. Free shipping over $250 CAD; flat $25 below that. Browse the catalog at /products/. Read more on storage and handling in our storage guide, our shipping policy, lot verification at /coa-verify/, or the public lot archive at /lab-results/.