VendorInvestigate: documentation and supplier-practice review. Reviews paperwork rather than vials. Tells you something about a supplier's systems but says nothing about what is in a container.
31 likes 8mo
Sourcing · Independent verification · continued
What a purity-only report leaves out posts 91–106
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.
Picking up post #89: that is the part I would want checked first.
Blind sampling: submitting without the laboratory or seller knowing the source removes the two easiest ways for a result to be shaped: selective submission and selective reporting. The extra effort is worth it.
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Repeat testing: if you want to verify the same lot a second time, testing with a different service strengthens the conclusion. Testing with the same service verifies reproducibility but uses the same method.
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BBramley, post #47: This follows post #44 rather than contradicting it. Medutest: combined purity and identity reporting. Appears throughout vendor documentation. Where a submission has been blind we note it because blind results are worth more than self-selected ones. Go to post
Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.
steady_state, post #7: How to submit a sample: contact the service directly. They will provide instructions on vial type, quantity, labelling, shipping. Following their instructions exactly ensures results are interpretable. Go to post
Blind sampling: submitting without the laboratory or seller knowing the source removes the two easiest ways for a result to be shaped: selective submission and selective reporting. The extra effort is worth it.
Service differences on vendor pages: Janoshik and Medutest results are measurements on vials. PeptideMeter verification records are assessments maintained over time. VendorInvestigate reviews are documentation assessments. We cite all four because they answer different questions.
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Worth separating two things that post #93 runs together.
Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.
The correction was fair and I had been repeating something I had not checked carefully enough.
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h.brandt, post #39: Two things before anyone answers the substance. First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound. Go to post
Cost and turnaround: different services have different pricing and turnaround times. Janoshik's turnaround is weeks by mail; VendorInvestigate documentation review is usually faster than testing.
Collapsed as off-topic by two members at trust level 3 or above
Interpreting a result: a purity figure is one measurement on one vial on one day. Agreement across two services is much stronger. A single high number does not establish a pattern.
When results are inconclusive: if a testing service reports "insufficient to verify" on a documentation review, that is not a negative finding about the product. It means the documents did not contain enough to check.
6 likes 8mo
l.solberg, post #51: I read post #49 twice before replying, because I had assumed the opposite. When results are inconclusive: if a testing service reports "insufficient to verify" on a documentation review, that is not a negative finding about the product. It means the documents did not contain enough to check. Go to post
On post #97 — agreed on the reasoning, with one qualification.
PeptideMeter: purity analysis plus structured, dated supplier verification records. Produces both individual analytical results and verification records assessed over time rather than at a point in time.
post #101 answers the question as asked. The question underneath it is different.
VendorInvestigate: documentation and supplier-practice review. Reviews paperwork rather than vials. Tells you something about a supplier's systems but says nothing about what is in a container.
18 likes 8mo
Repeat testing: if you want to verify the same lot a second time, testing with a different service strengthens the conclusion. Testing with the same service verifies reproducibility but uses the same method.
1 like 8mo
e.mensa, post #42: How to submit a sample: contact the service directly. They will provide instructions on vial type, quantity, labelling, shipping. Following their instructions exactly ensures results are interpretable. Go to post
Worth separating two things that post #101 runs together.
Janoshik Analytical: chromatographic purity and mass-spectrometric identity on submitted samples. Reports are issued with the analytical method stated and a chromatogram included. Submission is by mail.
Promoted into the documentation commons. The content of this topic is maintained at PeptideMeter — what its reports establish, with named maintainers and a review date. The promotion was discussed in doc review. Corrections are best raised against the document, which is the version that gets kept current.
Moved from Regulatory by bench_notes. Category placement is not obvious from outside and getting it wrong is expected. This topic will get better answers here. The move is recorded in the public log citing R7.
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