Blind submission and why it changes minds posts 31–60

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.

Coming back to post #45, because the follow-up matters more than the original answer.

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.

Picking up post #45: that is the part I would want checked first.

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.

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.

post #49 is right about the mechanism and I think understates the practical bit.

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.

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.

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.

post #52 is right about the mechanism and I think understates the practical bit.

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.

Worth separating two things that post #50 runs together.

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.

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.

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.

On post #54 — agreed on the reasoning, with one qualification.

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.

This follows post #56 rather than contradicting it.

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.

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.