Mean kinetic temperature is not the average temperature
The compendial definitions of cold, controlled cold and controlled room temperature permit specified excursions, and knowing the permitted band is the difference between an…
Laboratory Notebook
Page 4 of 12 of this archive, newest first.
Page 4
Two sessions a week, and the evidence behind the prescription
Mass and function are different endpoints and training affects them differently. Most coverage treats them as one.
Freezing a reconstituted vial: the ice-water interface problem
Bacteriostatic water contains benzyl alcohol at 0.9 per cent, which inhibits microbial growth in a preserved multiple-dose presentation. It does not sterilise a contaminated…
Tandem mass spectrometry, and the difference between weighing and reading
The Journal’s standing position: a mass that matches is necessary evidence of identity and nowhere near sufficient.
Leucine, isoleucine, and a difference no balance can measure
Deamidation adds 0.98 daltons. On a low-resolution instrument at incretin molecular weights, that is inside the noise.
Container closure integrity, and the tests that actually probe it
A sterile product is sterile only for as long as its container closure system excludes the outside world. Integrity is testable, and the tests are cheap by the standards of…
What Medutest charges to answer the pyrogen question
The masking phenomenon known as low endotoxin recovery means a formulation can return a clean result while containing endotoxin the assay cannot see.
EGFR, cystatin C, and the check on the check
The reference interval for alanine aminotransferase in most laboratories is derived from a population that included people with undiagnosed fatty liver.
Fat mass fell more than lean mass. That is the finding, and it is not the headline.
What was pre-specified, what was exploratory, and what was calculated afterwards by people who did not run the trial.
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 cake tells you something, and it is not purity
Multiple-dose vials are designed for a defined number of punctures. Nobody counts, and the elastomer does not care whether anybody counts.
In-use periods, and the ones nobody can give you
Sharps disposal is a legal obligation in most jurisdictions and a safety obligation everywhere. Household waste is not a route.
Priming a pen is not optional
Aseptic technique here is four steps and none of them are difficult. They are, however, routinely compressed to two.
The out-of-range flag is a statistical convention with a printer attached
Two sources of noise sit under every number: how reproducible the assay is, and how much the analyte varies within the same person on the same day.
The shelf life ends when the diluent goes in
At low concentrations a measurable fraction of peptide can adsorb to glass and plastic surfaces, and the loss is largest exactly where it is least expected.
Asparagine, glycine, and the two residues that decide a shelf life
We describe each pathway in enough chemical detail to explain why it is invisible to the method the trade uses, because that is the part which has practical consequences.
A reference interval is not a target, and a result outside one is not a diagnosis
Two sources of noise sit under every number: how reproducible the assay is, and how much the analyte varies within the same person on the same day.
Reading the semaglutide composition data without the press release
A substudy powered to describe a mean is not a substudy powered to detect a clinically meaningful individual change.
The substudies, read properly: who was scanned, when, and with what
The composition data comes from imaging substudies enrolling a few score participants at selected sites. It is the best evidence available and it is thin.
What VendorInvestigate would need in order to certify sterility, and why it does not
We asked all four services what they can determine, on what timescale, at what price, and under what accreditation. The answers are printed in full.