The arithmetic behind every identity confirmation, worked in full
A peptide has a monoisotopic mass and an average mass, they differ by several daltons at this molecular size, and a certificate that does not say which it quotes cannot be…
Laboratory Notebook — 2024
Bench methods, bloodwork, stability, sterility.
The specification sheet says 500,000. The report says conforms.
Every instrument specification quoted in an advertisement is a best case obtained on a calibration mixture, not on a submitted vial.
HbA1c and its lag: what a result three months old is telling you
What the SURPASS and STEP programmes reported, with the estimands and the baseline values stated.
Errors ranked by how much dose they move
A pharmacist catches most of these in licensed practice. In this market there is no pharmacist, so the checks have to be structural.
A reference interval is not a target, and a result outside one is not a diagnosis
The arithmetic of the reference change value, worked for the analytes that matter here.
A guide to the results that will resolve themselves
The panel drawn during a week of vomiting is measuring the vomiting.
What changed after we published the first version of this
A reader holding a certificate can work out what it does not cover in about ninety seconds, and that is a useful ninety seconds.
What happens in solution that does not happen in the cake
Every degradation pathway accelerates by orders of magnitude on reconstitution, because the solvent that lyophilisation removed is the reagent most of them need.
What the older diet-and-exercise trials found in the hip
Weight loss reduces bone mineral density at load-bearing sites. Whether that translates into fractures in this population is unmeasured.
The question no chromatogram has ever answered
Purity, content, identity, sterility and endotoxin are five separate determinations. A single sheet of paper carrying one of them is not evidence about the other four.
The reproducible spectrum: the single most useful thing a report can carry
None of what a checkable identity statement requires is commercially sensitive, and all of it is known to whoever produced the document.
The out-of-range flag is a statistical convention with a printer attached
A flag is a probability statement about a population. It is not a statement about the person holding the printout.
Sarcopenia is a diagnosis, not a synonym for losing lean mass
The gap between a defensible recommendation and a confident one is where most of the harm in this subject lives.
The supplement trade found this drug class quickly, and the citations did not improve
A survey of what the meta-analyses support, with the populations named.
Two sessions a week, and the evidence behind the prescription
The recommendation survives scrutiny. The reasoning offered for it frequently does not.
The retest date and the expiry date are not the same document
We asked twenty companies three questions about stability data and print every answer, refusal and non-response.
Two sessions a week, and the evidence behind the prescription
The recommendation survives scrutiny. The reasoning offered for it frequently does not.
What a mass spectrometer does to a peptide before it measures anything
A brief and unromantic tour of the interface between a liquid sample and a vacuum.
Mapping a rotation that you will actually follow
Repeated injection into the same small area produces lipohypertrophy — thickened, rubbery subcutaneous tissue with blunted and erratic absorption. It is common, it is…
A part per million, in context
Every instrument specification quoted in an advertisement is a best case obtained on a calibration mixture, not on a submitted vial.