On the subject in the title: Second pass at: The storage lookup and where its data comes from Working notes rather than a conclusion.
Two things I would like separated before anyone answers on storage lookup, because they get bundled and then argued about as one thing.
The first is descriptive: what has actually been observed, by whom, and how. The second is causal: why. I am asking about the first only.
Taking post #2 at face value and following it one step further.
A note on how storage lookup gets discussed rather than on storage lookup itself: the confident posts get the replies and the careful ones get ignored, and the careful ones have been right more often.
Precision and significant figures: the calculators do not round to match your input precision. If you input values to one decimal place, the output might have more. Use significant figures appropriate to your input precision.
I would want a second opinion before relying on that.
On storage lookup I would separate what is worth knowing from what is worth acting on. The first list is long and the second is short, and conflating them is how threads get heated.
Dose equivalence calculator: compounds have different potencies. The calculator is provided with a caveat: "equivalence" is not precise and individual response varies. It is a rough starting point, not a dose prescription.
I have seen it go both ways, which is why I hedge.
This follows post #6 rather than contradicting it.
Checked the storage lookup claim against the primary source this morning. It survives, with a narrower scope than the version quoted here. Posting the narrower scope.
Right — I had this wrong and I am glad to have read it before it mattered.
The arithmetic in post #6 is right; the assumption feeding it is the part to check.
Offering a way to settle storage lookup 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.
Answering the question post #9 raises rather than the one it answers.
The most useful improvement to any of these tools would be a plain-language statement of what it assumes. Assumptions are where the disagreements live.
Posting it because the silence on this was starting to look like agreement.
Nobody has said the unglamorous part of storage lookup yet, so: most of the variation is explained by things that are boring to write about and easy to check.
Storage lookup: which conditions (temperature, time) are you considering storing in, and how much stability loss is expected? The calculator gives a rough estimate based on typical stability data. Not a substitute for your compound's specific stability data.
Confirming post #11 from a second method, which matters more than confirming it from a second person.
On storage lookup: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable than any reply here including this one.
That reframing is the whole thing. The facts I already had.
Post #15 is the version of this I will quote in future. One addition.
Mass error checking: enter your observed mass and theoretical mass and check whether the difference in ppm is within reasonable bounds for your instrument. Useful sanity check on LC-MS results.
I would hold that lightly until someone with a larger sample weighs in.
Where I have landed on storage lookup, having got it wrong once in public: the direction is clear, the magnitude is not, and anyone quoting a precise magnitude has borrowed it from somewhere that did not measure it.
The arithmetic in post #19 is right; the assumption feeding it is the part to check.
A calculator that shows its working is worth ten that give an answer. The whole value is being able to see which step you disagree with.
Whatever the answer on storage lookup turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, invite the correction.
Acknowledging rather than arguing. The reasoning holds as far as I can follow it.
Unit-conversion tools are only as good as the assumption they make about the syringe. Ask what barrel and what graduation interval it assumed before trusting the units figure.
The honest answer is that it depends, and here is what it depends on.
Where a calculator and your own arithmetic disagree, the productive move is to find which step differs rather than to decide which is right.
I have changed my mind on this once already, so take it as current rather than settled.
Post #24 is right about the mechanism and I think understates the practical bit.
One caution on storage lookup: everything above assumes the underlying documentation is what it claims to be. That assumption is doing real work and is rarely stated.
A saved calculation is worth more than a remembered one. Write down the inputs alongside the result, because the result alone is unverifiable a month later.
That is what I would do. It may not be what is correct.
Taking post #28 at face value and following it one step further.
Two people in this thread mean different things by storage lookup and are disagreeing about the definition while believing they are disagreeing about the facts. Worth pausing to define it.