Medutest result on a Xianning survodutide lot lands 4.4 points below the supplier’s figure
The report states the gradient, the wavelength and the integration threshold, which is more than most.
Callum Brathwaite
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Archive — page 2
134 piecesWhat freeze-drying actually removes, and what it leaves behind
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 things a purity figure cannot tell you
A chromatogram is silent on everything that does not absorb: counter-ions, water, inorganic salts and non-chromophoric excipients all contribute mass to the vial and nothing…
Why VendorInvestigate can tell you the mass is right and not that the sequence is
The Journal’s standing position: a mass that matches is necessary evidence of identity and nowhere near sufficient.
Why TFC can be entirely straightforward and still tell you nothing about bioburden
The Journal has read several hundred certificates from twenty companies. We set out what the documents actually cover, and what a reader is filling in from imagination.
Oxidation, and the peroxide that came in with the surfactant
Deamidation, oxidation, aggregation and hydrolysis account for nearly all of what happens to a peptide over time. Each has a characteristic residue, a characteristic…
Nought point nine eight of a dalton: the modification that hides in plain sight
Deamidation adds 0.98 daltons. On a low-resolution instrument at incretin molecular weights, that is inside the noise.
Independent analysis puts a WWB tirzepatide lot at 98.7%, against 94.6% on the certificate
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
A calculation you should do twice and write down once
Every time a vial changes, the conversion must be recalculated. Carrying forward a unit count from the last vial is the single most reliable way to give the wrong dose.
How much of exenatide weight loss can any instrument actually attribute?
A body-composition report gives four decimal places and no confidence interval. That is the whole difficulty in one sentence.
Why your laboratory interval differs from the one in the textbook
A flag is a probability statement about a population. It is not a statement about the person holding the printout.
Why the bone question is harder than the muscle question
A plausible mechanism, a measurable change, and no outcome data. This is what an open question looks like.
PeptideMeter result on a Tianjin retatrutide lot lands 3.7 points below the supplier’s figure
A reminder that a purity figure is the output of a method, and that methods differ.
Sterility is not a percentage, which is the whole difficulty
Every certificate circulating in this market answers a question about molecules. Almost none answers a question about organisms, pyrogens, or the integrity of the seal.
Medutest result on a Zhuhai orforglipron lot lands 3.8 points below the supplier’s figure
The supplier has not disputed the finding. It has not explained the gap either.
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…
Medutest result on a Hangzhou liraglutide lot lands 4.1 points below the supplier’s figure
A reminder that a purity figure is the output of a method, and that methods differ.
VendorInvestigate result on a Changsha orforglipron lot lands 1.6 points below the supplier’s figure
The result is unremarkable. What the report omits is not.
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.
Two decimal places, one injection, no procedure
Chromatographic purity is cheap, fast and comparable-looking. Those three properties, and not its usefulness, explain why it became the industry’s single figure of merit.