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.
Laboratory Notebook
Page 6 of 12 of this archive, newest first.
Page 6
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.
The one-quarter rule, and the paper that took it apart
Grading six widely repeated claims against the studies actually behind them.
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.