Sample handling between despatch and injection posts 61–69

Transfer between laboratories: a method can be transferred from one lab to another, but the receiving lab needs to demonstrate that they can achieve the same performance. This requires comparative testing and sometimes small method refinements.

The general answer and the answer for your case may diverge here.

Offering a way to settle sample handling between despatch rather than another opinion about it. Two measurements, taken the same way, a fortnight apart. If the difference is within the noise, the question was not answerable at this precision.

Worth separating two things that post #61 runs together.

I have three months of notes on sample handling between despatch and the honest summary is that the trend is real and the week-to-week numbers are noise. I nearly drew the opposite conclusion from the first fortnight.

This follows post #61 rather than contradicting it.

Why two laboratories may disagree: after validating the same method, they may still report different purity on the same sample due to integration differences, column age differences, subtle differences in mobile phase pH or temperature. This is normal and not a sign that one is wrong.

Old habit: I write down the expected answer before I calculate it.

Sample handling between despatch has a well-known answer and a correct answer, and the interesting work is establishing that they are the same. Nobody has done that here yet.

Something worth flagging about sample handling between despatch: the strongest-sounding claims in this thread are the ones with no source attached, which is the usual pattern and not a coincidence.

Picking up post #65: that is the part I would want checked first.

Adding what did not work for me on sample handling between despatch, since the failures never get written up and they are half the useful information.

I had written a reply contradicting post #65 and deleted it. Here is what survived.

If you are new and reading this thread for the answer to sample handling between despatch: the answer is conditional, the conditions are in the third reply, and the rest of the thread is worth skipping.