What column temperature does to selectivity
A shallow gradient resolves impurities that a steep one runs into the parent peak. Both methods are legitimate; only one of them can see the small stuff.
Laboratory Notebook in 2025
Page 3 of 5 of this archive, newest first.
The out-of-range flag is a statistical convention with a printer attached
A twelve-analyte panel in a perfectly healthy person has roughly even odds of producing at least one flagged result.
How to read the silence on a certificate you already hold
Our position is about documentation practice. It is not an allegation about anybody’s honesty, and we are explicit about the difference.
What a diode array adds, and why the certificate never shows it
A diode-array detector records the whole spectrum at every time point and can confirm that a peak is spectrally homogeneous. Almost nobody prints that information.
Which results should be repeated before they are investigated
What the pivotal programmes measured and how often, which is a more defensible template than most published monitoring schedules.
The one randomised trial that combined an incretin with supervised exercise
Mass and function are different endpoints and training affects them differently. Most coverage treats them as one.
Which results should be repeated before they are investigated
What the pivotal programmes measured and how often, which is a more defensible template than most published monitoring schedules.
Storage after reconstitution, and the evidence behind the numbers
A needle blunts on first use. Reuse is uncomfortable, and it is a documented contributor to lipohypertrophy.
Bacteriostatic water, sterile water, and the 0.9 per cent that makes the difference
We set out what is known, what is inferred and what is simply assumed about the fortnight after a vial is opened.
Why a dry powder is a chemical reactor with the volume turned down
Residual moisture is measured routinely in regulated manufacture, is reported almost nowhere in this trade, and predicts long-term stability better than any other single…
The ionisation line on a report is the most informative line on it
The ionisation method determines the charge states you see, the adducts you must account for, and the modifications you might destroy in the process.
Units, millilitres, milligrams: three scales on one small object
We work through the arithmetic in full, because it is short, and because the errors it prevents are order-of-magnitude errors.
Hydrolysis, isomerisation, and the arithmetic of a broken bond
Deamidation, oxidation, aggregation and hydrolysis account for nearly all of what happens to a peptide over time. Each has a characteristic residue, a characteristic…
Twenty-eight days is a number from somebody else’s product
Every degradation pathway accelerates by orders of magnitude on reconstitution, because the solvent that lyophilisation removed is the reagent most of them need.
One measurement, twenty companies, forty compounds
The Journal has read several hundred certificates from twenty companies. The number is almost always there; the method behind it almost never is.
The instrument was calibrated on Tuesday. Your sample ran on Friday.
Parts per million sound impressive until they are converted into daltons at the molecular weight of the thing being measured.
Bone density during rapid weight loss: what is known, which is less than you would hope
The evidence base is one secondary analysis, several small studies and a large amount of extrapolation from bariatric surgery.
Change the pH and the co-elution moves
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…
Resolution, tailing, repeatability: the arithmetic before the result
Matching a retention time against a standard is evidence of consistency, not proof of identity. Two different species can elute at the same time on one method.
Load, not cardio: the distinction the general advice keeps losing
The recommendation survives scrutiny. The reasoning offered for it frequently does not.