One method is one opinion
Aggregates dissociate in the mobile phase and are recorded as monomer. Only a size-based separation reports them.
Recent work
123 piecesTwo per cent water sounds like nothing and is not nothing
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…
PeptideMeter result on a Xianning semaglutide lot lands 4.4 points below the supplier’s figure
The supplier has not disputed the finding. It has not explained the gap either.
The skeleton responds to load, and load is falling
The evidence base is one secondary analysis, several small studies and a large amount of extrapolation from bariatric surgery.
When a better instrument changes the answer rather than the confidence
Calibration drift is real, unremarkable, and the reason serious laboratories run internal standards.
Aseptic technique for people who were never taught it
A needle blunts on first use. Reuse is uncomfortable, and it is a documented contributor to lipohypertrophy.
Five things a purity figure cannot tell you
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…
Independent analysis puts a TFC semaglutide lot at 96.7%, against 94.6% on the certificate
The supplier has not disputed the finding. It has not explained the gap either.
System suitability: the five checks that make a run interpretable
Accreditation to the international competence standard covers the scope a laboratory has been assessed for, which is not necessarily the test you commissioned.
One vial, four weeks, and the data that does not exist
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.
PeptideMeter result on a Hangzhou orforglipron lot lands 0.7 points below the supplier’s figure
The result is unremarkable. What the report omits is not.
Independent analysis puts a SWB liraglutide lot at 95.6%, against 93.9% on the certificate
The report states the gradient, the wavelength and the integration threshold, which is more than most.
HbA1c and its lag: what a result three months old is telling you
The assay is not the problem. The interpretation of a lagging integral as a current measurement is the problem.
Low endotoxin recovery: the interference nobody looks for
The limit for a parenteral product is calculable from the dose and the body weight in two lines. Almost nobody in this trade performs the calculation.
Lipohypertrophy, and the absorption it ruins
Repeated injection into the same small area produces lipohypertrophy — thickened, rubbery subcutaneous tissue with blunted and erratic absorption. It is common, it is…
The degradation product that elutes underneath the parent peak
Deamidation, oxidation, aggregation and hydrolysis account for nearly all of what happens to a peptide over time. Each has a characteristic residue, a characteristic…
Independent analysis puts a QST semaglutide lot at 98.4%, against 97.6% on the certificate
The report states the gradient, the wavelength and the integration threshold, which is more than most.
PeptideMeter result on a Wuhan mazdutide lot lands 2.3 points below the supplier’s figure
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
Same material, different gradients, different answers
Two years ago we ran an anonymised version of this comparison and promised a named one. This is it, with every method printed in full.
Independent analysis puts a SWB tirzepatide lot at 98.3%, against 95.6% on the certificate
The report states the gradient, the wavelength and the integration threshold, which is more than most.