My understanding of mass-error checker is a few years old and may have been superseded. If it has been, I would genuinely like to know rather than keep repeating it.
Posting this under the heading it deserves: Second pass at: The mass-error checker and its intended scope Everything below is what sits behind that.
Posting a small dataset on mass-error checker. It is mine, it is uncontrolled, and the method is stated so it can be discounted appropriately.
What I would like is not agreement but a second dataset collected by someone with no stake in mine. If one exists I would rather read it than argue for this one.
The opening post and I disagree about the size of the effect, not about the direction.
A definition problem is doing most of the work in this mass-error checker discussion. Once the term is pinned down I suspect the disagreement mostly goes away and what is left is small.
Two sentences on mass-error checker and then I will stop, because the rest is speculation and the thread is better without mine.
What is documented is narrow. What is inferred from it is broad. The gap between them is where every argument here lives.
This follows post #3 rather than contradicting it.
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.
That is the version I use. It may not be the version that is correct.
My understanding of mass-error checker is a few years old and may have been superseded. If it has been, I would genuinely like to know rather than keep repeating it.
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.
Whatever the answer on mass-error checker turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, invite the correction.
Worth separating two things that post #9 runs together.
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.
Adding it in case it saves somebody the afternoon it cost me.
Mass-error checker is worth one more sentence than it usually gets, and the sentence is the one about how the number was arrived at.
An update on my earlier mass-error checker post: the pattern held for another six weeks and then stopped, which I did not predict and cannot explain.
Post #13 answers the question as asked. The question underneath it is different.
The most common input error is entering the vial mass in the concentration field. It produces a plausible number, which is why it survives.
The claim is narrower than it sounds, and deliberately so.
Nothing to add on the substance. Thank you for taking the question at face value.
Coming back to post #13, because the follow-up matters more than the original answer.
An honest declaration on mass-error checker: I have a prior here and it is strong enough that you should weight what I say downward. Stating it rather than hiding it.
Post #17 is right about the mechanism and I think understates the practical bit.
The calculators maintained on this site are open-source and verifiable. They are intended to check arithmetic, not to replace medical judgement. Using them is optional and they are provided for convenience.
I would not lead a decision with this, but I would not ignore it either.
I think the mass-error checker question is answerable and has not been answered, which is a more optimistic position than most of this thread.
Adding a null result on mass-error checker. I looked, carefully, and found nothing, and null results deserve posting precisely because they never are.
Adding the measurement that post #18 says would settle it.
Significant figures in the output should not exceed what the inputs support. A concentration calculated from a nominal vial mass is not known to four decimal places.
Mass-error checker came up in a thread eighteen months ago and was answered well. I cannot find it, which is itself the problem, so here is the reconstruction.
Thank you for the correction. I would rather find out here than later.
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.
I have separated what I observed from what I concluded, which does not always happen.
Reporting rather than recommending, on mass-error checker. What happened is above. Whether it should have is a different question and not one I am qualified to answer.
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.
A qualification I should have led with rather than closed on.
Where I part company with post #24, and it is a narrow parting.
The honest answer on mass-error checker is that it depends, and the useful part is the list of what it depends on. Four items, in rough order of how much they matter.
Most people get the first two right and then argue about the fourth.
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.
Old habit: I write down the expected answer before I calculate it.
Everything in post #28 holds. The case it does not cover is the one I have.
The parts-per-million mass-error calculation is simple enough to do mentally to one significant figure, which is a good habit because it catches an order-of-magnitude slip immediately.
I would put this at better than even and not much better.