The one-quarter rule, and the paper that took it apart
Grading six widely repeated claims against the studies actually behind them.
Laboratory Notebook in 2025
Page 4 of 5 of this archive, newest first.
What PeptideMeter can tell you about a vial by weighing its water
The physics of the drying cycle explains why some cakes are matte and full-volume and others are glassy discs, and why the difference is not cosmetic.
Calibrated, qualified, accredited: three words that are not synonyms
An assay against a quantitative reference standard measures how much is present. Area per cent measures what proportion of the visible material is the parent. Only the first…
How much water: the question with no single right answer
The diluent choice affects preservation and in-use period rather than the arithmetic — but the wrong choice for a multi-dose vial is a sterility decision, not a convenience…
Choosing a needle for a subcutaneous peptide
A 4 mm needle at ninety degrees without a skin pinch is adequate for essentially all adults. The persistence of 12.7 mm needles in this market is habit, not reasoning.
The cake tells you something, and it is not purity
Dye ingress and microbial immersion are probabilistic. Vacuum decay, high-voltage leak detection and helium mass spectrometry are deterministic and far more sensitive.
The cake is a record of the cycle that made it
Lyophilisation does not stop degradation. It slows every pathway by removing the solvent that most of them require, and the residue of solvent that remains sets the rate.
Five lines that would change what a certificate is worth
The Journal wrote to twenty companies asking five specific questions about sterility assurance. We report the response rate, the substance and the refusals.
How a correct calculation becomes a wrong dose
We have catalogued what readers report, ranked by the size of the dosing error each produces.
Storage after reconstitution, and the evidence behind the numbers
Sharps disposal is a legal obligation in most jurisdictions and a safety obligation everywhere. Household waste is not a route.
Five lines that would change what a certificate is worth
None of what this piece asks for is commercially sensitive, and all of it is already known to whoever released the batch.
A few hundred participants carry the whole body-composition argument
What was pre-specified, what was exploratory, and what was calculated afterwards by people who did not run the trial.
Turnaround, cost and accreditation across the services this trade relies on
Endotoxin is the more tractable of the two questions, and a kinetic chromogenic determination is neither slow nor exotic. It is simply not on the menu.
Vitamin D, adiposity, and a volume-of-distribution problem
Reduced intake is a plausible mechanism for deficiency. Reduced absorption is not, and the two are conflated in most of the advice.
The 0.22 micron filter does the work, and it is the last line
Bioburden entering the filter, filter integrity, environmental monitoring and aseptic process simulation are the four pillars. The trade documents none of them.
Five things a purity figure cannot tell you
An orthogonal method separates on a different physical principle, so that species co-eluting in the first are likely to resolve in the second. Two runs of the same method at…
A spectrum is a photograph of an ion, not of a molecule
The two ionisation techniques in general use produce different charge distributions, different adducts and different failure modes. Certificates almost never say which was…
Deamidation, oxidation, and the two shifts worth memorising
What would be needed to catch each of these, and what it would cost.
Why Janoshik may run electrospray where another laboratory runs MALDI
The two ionisation techniques in general use produce different charge distributions, different adducts and different failure modes. Certificates almost never say which was…
A few hundred participants carry the whole body-composition argument
A substudy powered to describe a mean is not a substudy powered to detect a clinically meaningful individual change.