Blind submission and why it changes minds — the long version posts 91–114

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.

Picking up post #89: that is the part I would want checked first.

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.

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.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

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.

Worth separating two things that post #93 runs together.

Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive.

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.

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.

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.

On post #97 — agreed on the reasoning, with one qualification.

Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive.

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.

Picking up post #101: that is the part I would want checked first.

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.