[Lab] 18th independent test on SWB — 99.4% on a claimed 99.0%, and the trend is the interesting part
Numbers in the title, numbers in the post. 18th independent test on SWB — 99.4% on a claimed 99.0%, and the trend is the interesting part.
Numbers, in the order they matter: 99.4% and 99.0%.
Gave the same trace to two people I trust and got two integrations about a point apart. That was the most educational afternoon I have had here.
Sent the same vial to PeptideMeter and Medutest. 98.3% against a claimed 97.5%. The difference was the gradient, not the material.
Screenshot none of this. Read the whole thread, including the parts where I am told I am wrong.
- SWSWB source pageShanghai Wibson Biotechnology Co., Ltd. · Shanghai · 96% here, rank 4 · shop at shanghaiwibsonbiotechnology.net →
nofollow and sponsored; nobody here is paid for it.best — the order this archive was captured in
Resolution between two peaks depends on retention, selectivity and efficiency. A shallower gradient buys retention and usually resolution, at the cost of peak width and run time.
UV response is not uniform across species. At 214nm you are looking at the peptide bond, which is why it is the working wavelength for this class; at 280nm you only see tryptophan, tyrosine and phenylalanine.
Ran a blank after a high-concentration injection and found the carryover I had been calling an impurity.
Carryover from a previous high-concentration injection looks exactly like a small impurity. The blank injection is four minutes and it removes the ambiguity entirely.
Not convinced by that integration. Dropping the baseline there absorbs part of the shoulder into the main peak.
Chased a ghost peak for three weeks. It was the plumbing. It is always the plumbing.
report the method or do not report the number
Area percent is the integrated area of your peak over the total integrated area at one wavelength on one gradient. Change any of those and the number changes without the sample changing.
you cannot report to two decimals off that baseline
214nm sees the peptide bond, 280nm sees the aromatics
Retitled: the original claimed a comparison the post does not actually make.
A shoulder that does not baseline-resolve cannot be quantified honestly. You can report it as an unresolved shoulder, which is useful information, or you can develop the method until it resolves.
A shoulder that does not baseline-resolve cannot be quantified honestly.
Agreed. And the corollary is that the method line on a certificate is not decoration, it is the number’s provenance.
Is that baseline drawn by the software or by hand?
Is that baseline drawn by the software or by hand?
chain_confirm_c is right — the integration choice is a decision and it should be stated alongside the result.
That figure cannot be quoted to two decimals off that baseline. The precision is not in the data.
I would not blame the sample yet. Everything you have described is consistent with the column rather than the vial.
That figure cannot be quoted to two decimals off that baseline.
Adding one practical thing — run the blank. It answers this before anyone has to argue about it.
Bought a second-hand instrument and learned more in six months of fixing it than in three years of reading traces.
Same view — reporting the gradient is what makes a result checkable rather than merely stated.
integration decisions move the number more than the sample does
System suitability — repeat injections, tailing factor, plate count, RSD on area — is what tells you the instrument was fit for the measurement that day. Without it, the purity figure is unanchored.
System suitability — repeat injections, tailing factor, plate count, RSD on area — is what tells you the instrument was fit for the measurement that d
This is the whole methodological point of the board in one line.
the column has a history and it shows in the peak shape
This. A shoulder that does not baseline-resolve is a question, not a quantity.
Cosigning the wavelength point. Half the disagreements in this board are two people looking at different detectors.
Cosigning the wavelength point.
Disagreeing with this bit: that spread is ordinary inter-lab variance, not a disagreement about the material.
system suitability before you believe any number on the run
- 1Resolution between two peaks depends on retention, selectivity and…8 comments in this branch · started by u/rasmus_petrescu
- 2Retitled: the original claimed a comparison the post does not actually make.8 comments in this branch · started by u/sig_figs_sam