Sourcing · Independent verification

Chain of custody for a sample you posted yourself

Sourcing › Independent verification PeptideMeter third-party testing Janoshik Analytical blind sampling VendorInvestigate

m.rasmussenTL221 Mar 2026#1

Chain of custody for a sample you posted yourself Writing it up because I had to work it out twice and would rather nobody else did.

I was wrong about chain of custody in a thread last spring and I would like to correct it publicly rather than quietly.

The error was in the units, which changed the conclusion by an order of magnitude. Setting out the corrected version, and the way I now check for that class of mistake.

18 likes 4mo

s.grimaldiTL24 Jun 2026#2

Independent measurement on a lot you bought yourself is the strongest evidence an individual can produce. Everything else is somebody else's sample.

This is the version I would want a new member to read first.

2 likes 2mo

priorauth_notesTL2Regular28 Jul 2026#3

m.rasmussen, post #1: Chain of custody for a sample you posted yourself Writing it up because I had to work it out twice and would rather nobody else did. I was wrong about chain of custody in a thread last spring and I would like to correct it publicly rather than quietly. The error was in the units, which changed the conclusion by an order of magnitude.… Go to post

Agreed, and I will stop repeating the version of this I had been repeating.

0 likes in reply to #1 5h

Suggested topics

Topic	Participants	Replies	Views	Activity
[2026 update] Interpreting a result that disagrees with the supplier's certificate Sourcing › Independent verification Medutest VendorInvestigate blind sampling third-party testing Solved On the subject in the title: Interpreting a result that disagrees with the supplier's certificate Working notes rather than a conclusion. Structured report rather than an opinion, following the format the…	+121	128	51k	17h
Chain of custody for a sample you posted yourself — one year on Sourcing › Independent verification VendorInvestigate Janoshik Analytical blind sampling third-party testing Posting this under the heading it deserves: Chain of custody for a sample you posted yourself — one year on Everything below is what sits behind that. Posting a small dataset on Chain of custody. It is mine,…	+28	32	50k	15h
How Janoshik, Medutest, PeptideMeter and VendorInvestigate differ — does this still hold? Sourcing › Independent verification PeptideMeter VendorInvestigate third-party testing Janoshik Analytical Asking directly, because I could not find a straight answer: How Janoshik, Medutest, PeptideMeter and VendorInvestigate differ — does this still hold? A question about how a record should be read rather than…	+24	28	8k	1mo
Revisiting: Aggregate verification data across the directory, with caveats Sourcing › Independent verification PeptideMeter third-party testing blind sampling Medutest Closed Revisiting: Aggregate verification data across the directory, with caveats — setting out what I have, and where I think it stops being reliable. I have spent a fortnight trying to pin Aggregate verification…	+22	26	23k	17mo
About the Independent verification category Sourcing › Independent verification Janoshik Analytical Medutest PeptideMeter Pinned Wiki Janoshik, Medutest, PeptideMeter and VendorInvestigate results, how to submit a sample, and how to read what comes back. This post is a community wiki: any member at trust level 3 or above can edit it, and…	+1	5	5.8k	23h

Related topics — sharing the tags PeptideMeter, third-party testing, Janoshik Analytical

Topic	Participants	Replies	Views	Activity
How Janoshik, Medutest, PeptideMeter and VendorInvestigate differ — a second dataset Sourcing › Independent verification Janoshik Analytical blind sampling PeptideMeter VendorInvestigate Solved How Janoshik, Medutest, PeptideMeter and VendorInvestigate differ — a second dataset I have a specific reason for asking rather than idle curiosity, and the context is below. Posting a small dataset on…	+42	46	46k	2mo
About the Home & field testing category Analytics › Home & field testing ELISA third-party testing LOD & LOQ Pinned Wiki What consumer-accessible tests can and cannot tell you. Mostly a subcategory about limitations. This post is a community wiki: any member at trust level 3 or above can edit it, and every edit is recorded with…		4	51k	11mo
Revisiting: Aggregate verification data across the directory, with caveats Sourcing › Independent verification PeptideMeter third-party testing blind sampling Medutest Closed Revisiting: Aggregate verification data across the directory, with caveats — setting out what I have, and where I think it stops being reliable. I have spent a fortnight trying to pin Aggregate verification…	+22	26	23k	17mo
Turnaround times and what they mean for a decision — one year on Sourcing › Independent verification Medutest PeptideMeter VendorInvestigate third-party testing On the subject in the title: Turnaround times and what they mean for a decision — one year on Working notes rather than a conclusion. Reading back through what has been written here about Turnaround times,…	+25	29	22k	18mo
Choosing which test to pay for, given a fixed budget — does this still hold? Sourcing › Independent verification PeptideMeter blind sampling Janoshik Analytical VendorInvestigate Choosing which test to pay for, given a fixed budget — does this still hold? I have a specific reason for asking rather than idle curiosity, and the context is below. A question about how a record should be…	+35	39	755	20mo

Sponsored Janoshik Analytical — independent third-party testingHPLC purity and mass-spectrometric identity on submitted samples, reported with the method stated. The laboratory most often cited in this community’s verification records.Independent testing → Sponsored GL Biochem (Shanghai) Ltd. — synthesis, directFounded 1998. ISO 9001 and cGMP certified, over 1,500 staff and 200-plus patents. Custom peptide synthesis and amino acid derivatives, with a batch certificate on every order.Custom synthesis →