Revisiting: Sample handling between despatch and injection

Posting this under the heading it deserves: Revisiting: Sample handling between despatch and injection Everything below is what sits behind that.

Reading back through what has been written here about Sample handling between despatch, three questions come up every time and only one has ever been answered properly.

Listing all three, with what I think the state of the answer is for each, so the thread can start further along than the last one did.

Sample stability during analysis is part of validation and is routinely ignored. A preparation that degrades in the autosampler over eight hours produces a sequence-dependent result.

A guess, clearly labelled as one.

This follows the opening post rather than contradicting it.

The most useful single question about a method: what would it fail to detect? Every method has an answer and few documents state it.

For what it is worth, the same held on the two occasions I checked.

I read post #2 twice before replying, because I had assumed the opposite.

Range and working range are different things and a certificate rarely distinguishes them. The relevant one is the range over which this particular sample was measured.

I would call the community position on Sample handling between despatch likely rather than established, and I would be comfortable defending that hedge.

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

Picking up post #4: that is the part I would want checked first.

The distinction between a qualified instrument and a validated method is worth keeping. Both are needed and they fail in different ways.

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.

Post #8 is right about the mechanism and I think understates the practical bit.

A method transferred between laboratories needs a demonstration that it performs equivalently, not just a document describing it. Transfer is where a great many between-laboratory disagreements originate.

Worth separating two things that post #7 runs together.

Adding a reference point for Sample handling between despatch. Mine is a single case, collected without controls, and I am posting the method alongside it so it can be discounted appropriately.