The mass-error checker and its intended scope posts 121–150

Worth separating two things that post #131 runs together.

The most common input error is entering the vial mass in the concentration field. It produces a plausible number, which is why it survives.

I have no interest in any supplier named above.

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

What I would want before treating mass-error checker as settled: the method, the sample, and whether anyone tried to find the opposite result. Two of the three are usually missing.

Tools that run entirely in the browser send nothing anywhere, which matters more to some people here than others and is worth stating either way.

Picking up post #139: that is the part I would want checked first.

Mass-error checker is well covered in the tag pages, and the older discussions are better than the recent ones because they were argued out properly. Worth twenty minutes before adding to this one.

Posting my mass-error checker numbers with the method attached so they can be discounted properly. Uncontrolled, unblinded, and collected by someone who wanted a particular answer.

Worth separating two things that post #139 runs together.

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.

If anyone can point at the primary source I would be grateful.

Post #140 is right about the mechanism and I think understates the practical bit.

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.

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.

Picking up post #144: that is the part I would want checked first.

On mass-error checker the community has more anecdote than the confidence in this thread implies, and I include my own contribution in that.

On post #142 — agreed on the reasoning, with one qualification.

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.

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.

Small methodological point on mass-error checker: repeating a measurement is cheap and resolves most of what is being argued about here at no cost to anyone.

Useful. I had the fact and not the reason, which turns out to be the important half.

The reason mass-error checker keeps being re-asked is that the answer is conditional and people quote it without the condition. It is not that the answer is unknown.