--- title: "Glossary: how VialPost measures and labels things" description: "Definitions of every term VialPost uses for its figures: price per mg, headline range, spread, status, verified mg and the rest." canonical: "https://vialpost.com/glossary" markdown: "https://vialpost.com/glossary.md" publisher: "VialPost" license: "CC BY 4.0, attribution to VialPost" citing: "https://vialpost.com/llms.txt" --- # Glossary: how VialPost measures and labels things Every term VialPost uses for a figure or a label, defined once. These are definitions of how this site measures and labels things, not of the compounds themselves. ## Price per milligram ($/mg) The listed vial price divided by the labelled vial mass in milligrams, in US dollars. VialPost normalises every single-vial listing to this figure so that a 5 mg vial and a 60 mg vial of the same compound can be compared. Used on: https://vialpost.com/tracker ## Price observation One reading of one listing’s price from the vendor’s own public store data, stored with the source URL and the timestamp it was read. An observation is a snapshot, not a live quote. Used on: https://vialpost.com/methodology#price-method ## Listing (SKU) One product at one vendor: a compound, a vial mass and a form. VialPost records only single vials of lyophilised powder; kits, capsules, solutions and blends are excluded because a per-milligram figure across them is not a comparison. Used on: https://vialpost.com/methodology#price-method ## Cheapest observed The lowest price per milligram among a compound’s listings inside its headline range, as of the newest observation on the page. It is a dated snapshot and names the vendor, the vial size and the source. Used on: https://vialpost.com/tracker ## Spread The dearest price per milligram divided by the cheapest, among a compound’s listings inside its headline range. A spread of 3x means the dearest listing costs three times as much per milligram as the cheapest. Used on: https://vialpost.com/tracker ## Headline range The vial masses within 10x of a compound’s median vial mass. Only listings inside it feed the cheapest figure, the range and the spread. A listing outside it (a 1 g jar beside 50 mg vials, or a 250 mcg capsule beside 5 mg vials) stays in every table, marked “outside headline range”. Used on: https://vialpost.com/methodology#thresholds ## Median vial mass The middle value of the vial masses of a compound’s listings. The headline range is centred on it. Used on: https://vialpost.com/methodology#thresholds ## Vendor status One of three recorded states: trading (the storefront is open and accepting orders), caution (something is on record that a buyer should read first), or closed (the vendor has ceased trading, with a dated, sourced event). VialPost does not rank vendors; status is a fact, not a grade. Used on: https://vialpost.com/status ## Status event A dated, sourced record of something that changed or threatened a vendor’s ability to trade: a closure, a raid, a sentencing, a reopening. Every event links to where it was reported. Used on: https://vialpost.com/status ## Status verified The date a vendor’s record (its status and notes) was last read and confirmed by a person. Prices are read daily; status records are read separately, so the two dates differ. Used on: https://vialpost.com/vendors ## Storefront checked The date an automated read of the vendor’s homepage last agreed with its recorded status. The check reads only what the page says and quotes it verbatim; it never changes a status on its own. A disagreement is marked “under review” until a person resolves it. Used on: https://vialpost.com/vendors ## Data as of The newest real timestamp carried by the data a page renders: the newest price observation for a priced page, the date status records were last read for a status page. Never the build time and never today’s date. Used on: https://vialpost.com/methodology ## Publication threshold The amount of real, sourced data a page must hold before it asks to be indexed: price observations from 2 distinct vendors for a compound page, 3 observations for a trading vendor page, one dated sourced event for a closed vendor page. Pages below it are served but marked noindex. Used on: https://vialpost.com/methodology#thresholds ## Cost per verified milligram The vial price divided by the mass that a third-party laboratory measured as the compound: price divided by (labelled mass times measured purity divided by 100). It is only computed where a real measured purity exists for that vendor. Used on: https://vialpost.com/tools/cost-per-verified-mg ## Claimed purity The purity figure the vendor states, on the label, in the listing or in a certificate of analysis supplied with the order. Used on: https://vialpost.com/registry ## Measured purity The proportion of the material that a third-party laboratory found to be the compound, by RP-HPLC in triplicate against a reference standard, on a blind retail purchase. Used on: https://vialpost.com/registry ## Delta Measured purity minus claimed purity, in percentage points. A negative delta means the vial assayed below its claim. Used on: https://vialpost.com/registry ## RP-HPLC Reverse-phase high-performance liquid chromatography: the method the laboratories use to measure what proportion of a sample is the compound, run against a reference standard. It does not measure sterility, endotoxin load, residual solvents or identity on its own. Used on: https://vialpost.com/methodology ## Certificate of analysis (COA) A document a vendor supplies stating a lot’s test results. On this site a COA is the vendor’s claim; a registry result is a measurement made on a blind retail purchase by a laboratory with no commercial relationship to the vendor. Used on: https://vialpost.com/registry ## Verified batch One lot of one compound from one vendor that has been bought at retail, stripped of identifying labels, assayed by a third-party laboratory and published pass or fail with the lot number, both purity figures, the delta, the method, the laboratory and the custody note. Used on: https://vialpost.com/registry ## Example data Illustrative rows shown to demonstrate a layout before real results exist. They are labelled as examples wherever they appear and are never counted, never published to the feed and never to be cited as data. Used on: https://vialpost.com/registry ## Reconstitution Dissolving a lyophilised powder in a diluent. The site’s reconstitution calculator converts a solute mass and a diluent volume into a concentration. It is a unit conversion, not dosing guidance. Used on: https://vialpost.com/tools/reconstitution ## Weekly market note A page generated each ISO week from that week’s price snapshot and status events: the status events, the largest falls and rises in a vendor’s cheapest price per milligram (5% or more), the widest spreads, arrivals, and counts against the previous week. Used on: https://vialpost.com/market ## Status feed The Atom feed at /feed.xml: one entry per dated vendor status event, per real lab batch and per weekly market note. Used on: https://vialpost.com/feed.xml ## Research use only Every compound on this site is sold and discussed for laboratory research use only. VialPost publishes no dosing, medical, therapeutic or administration guidance, and no compound is described for human or veterinary use. Used on: https://vialpost.com/about --- Source: VialPost, "Glossary: how VialPost measures and labels things", https://vialpost.com/glossary. Prices on this site are dated snapshots read from each vendor's own public store data, not live quotes; cite the figure with its date. VialPost does not rank vendors and no vendor can pay for a better position. The verified batch registry is currently empty: no purity measurement has been published yet, so no purity figure should be attributed to VialPost. All compounds referenced on this site are sold and discussed for laboratory research use only. Nothing here is medical advice, and no compound listed is described for human or veterinary use. Rules for citing this site: https://vialpost.com/llms.txt. Method: https://vialpost.com/methodology. Vocabulary: https://vialpost.com/glossary. API and MCP server: https://vialpost.com/developers.