Topic summary

[2026 update] What a purity-only report leaves out

Sourcing › Independent verification PeptideMeter third-party testing Janoshik Analytical

This is a generated summary. It shows the 9 most-liked posts from a topic of 104, in their original order, with the accepted answer included where one exists. It is a reading aid and it will miss nuance — the full topic is the record.

DKwiatkowskiTL3Regular26 Jan 2026#9

Right — I had this wrong and I am glad to have read it before it mattered.

28 likes 6mo

b.jansenTL22 Feb 2026 · edited#14

Where I part company with post #10, and it is a narrow parting.

The record shows what was measured. Everything beyond that is inference and this site tries to keep the line visible.

32 likes 6mo

e.roosTL23 Mar 2026#42

Practical note on purity-only: write down what you expect before you look. The number of times I have found what I went looking for is higher than chance would allow.

28 likes 5mo

OTeixeiraTL3Regular10 Mar 2026#49

I changed my mind about purity-only after someone here asked me for the source and I could not produce one. That is worth saying out loud because it is the ordinary way it happens.

29 likes 5mo

a.pereiraTL215 Mar 2026#54

Reporting rather than recommending, on purity-only. What happened is above. Whether it should have is a different question and not one I am qualified to answer.

30 likes 4mo

j.restrepoTL229 Mar 2026#70

The version of purity-only that I was taught turned out to be a teaching simplification. Useful, and not true in the way I had assumed it was.

32 likes 4mo

BirkelandTL3Regular4 Apr 2026#78

t.nardone, post #25: Post #23 describes the usual case. This is about the unusual one. Repeat determination on the same product line months apart is the measurement that speaks to consistency, and consistency is what most buyers actually want. Go to post

Adding a null result on purity-only. I looked, carefully, and found nothing, and null results deserve posting precisely because they never are.

29 likes in reply to #25 4mo

a.schaefferTL2Member15 Apr 2026#91

I would put moderate confidence on the mainstream reading of purity-only and no more. That is not scepticism for its own sake; it is where the sourcing actually stops.

28 likes 3mo

r.sobczakTL222 Apr 2026#100

Taking purity-only seriously for a moment rather than deflecting: the honest position is that the community has observations and no controlled comparison, and those two things support very different sentences.

29 likes 3mo

Read the full topic (104 posts)

This topic was referenced in

Turnaround times and what they mean for a decisionSourcing › Independent verification · 4 replies
How Janoshik, Medutest, PeptideMeter and VendorInvestigate differ — does this still hold?Sourcing › Independent verification · 28 replies
Turnaround times and what they mean for a decision — one year onSourcing › Independent verification · 29 replies

Suggested topics

Topic	Participants	Replies	Views	Activity
Submitting a sample: the process end to end Sourcing › Independent verification blind sampling PeptideMeter VendorInvestigate third-party testing On the subject in the title: Submitting a sample: the process end to end Working notes rather than a conclusion. Submitting a sample keeps being re-asked here and I think that is because the answer is…	+99	114	29k	21h
Blind submission and why it changes minds Sourcing › Independent verification Janoshik Analytical VendorInvestigate PeptideMeter Solved Blind submission and why it changes minds — setting out what I have, and where I think it stops being reliable. What changes if the standard account of blind submission is wrong? I ask because I have been…	+91	96	1.1k	21mo
Publishing an inconvenient result: a case study Sourcing › Independent verification Medutest VendorInvestigate third-party testing Janoshik Analytical Wiki On the subject in the title: Publishing an inconvenient result: a case study Working notes rather than a conclusion. Publishing an inconvenient result, and specifically the version of it that the…	+59	70	992	11mo
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
Chain of custody for a sample you posted yourself Sourcing › Independent verification PeptideMeter third-party testing Janoshik Analytical blind sampling 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…		2	7.3k	5h

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

Topic	Participants	Replies	Views	Activity
Revisiting: The report format the maintainers ask for, and why each field is there Sourcing › Vendor reports batch & lot numbers Janoshik Analytical documentation quality third-party testing Posting this under the heading it deserves: Revisiting: The report format the maintainers ask for, and why each field is there Everything below is what sits behind that. Structured report rather than an…	+100	108	57k	1d
What consumer-accessible tests can and cannot determine — a second dataset Analytics › Home & field testing ELISA LOD & LOQ third-party testing documentation quality Solved What consumer-accessible tests can and cannot determine — a second dataset I have a specific reason for asking rather than idle curiosity, and the context is below. Posting a small dataset on…	+117	131	45k	10h
One lot is one lot: when a report becomes a pattern — the long version Sourcing › Vendor reports third-party testing Janoshik Analytical certificate of analysis batch & lot numbers Closed One lot is one lot: when a report becomes a pattern — the long version — setting out what I have, and where I think it stops being reliable. Structured report rather than an opinion, following the format the…	+137	152	46k	16mo
A comparison of home results against a laboratory result on the same vial — does this still hold? Analytics › Home & field testing ELISA third-party testing LOD & LOQ documentation quality Solved A comparison of home results against a laboratory result on the same vial — does this still hold? I have a specific reason for asking rather than idle curiosity, and the context is below. Comparison of home…	+2	6	15k	11h
What a simple presence test is genuinely useful for Analytics › Home & field testing documentation quality ELISA third-party testing LOD & LOQ Solved What a simple presence test is genuinely useful for — that is the question, and I have not found it answered plainly anywhere I have looked. Trying to work out what would count as evidence on simple presence…		2	58	1d