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Single comment threadYou are looking at one branch of [Lab] split one vial across VendorInvestigate and PeptideMeter — 98.0% and 97.9% — 26 comments in the full submission. View in context.
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c/hplc·submitted 27 days ago by u/insulin_syringe_ian

[Lab] split one vial across VendorInvestigate and PeptideMeter — 98.0% and 97.9%

Labbranch of 8 comments

Result first, context after: split one vial across VendorInvestigate and PeptideMeter — 98.0% and 97.9% . Everything below is how it was ordered, stored and sent. To save the first four comments: 98.0% and 97.9%. Chased a ghost peak for three weeks. It was the plumbing. It is always the plumbing. Carryover from a…

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8 comments, started 26 days ago
u/honest_syringe_pls-36 points·26 days ago

The system suitability argument, since it comes up whenever somebody posts a number without one.

Before the sample result means anything, the instrument has to be shown to be fit that day: replicate injections with an acceptable RSD on area, a tailing factor inside limits, adequate plate count, and a resolution check between the pair you care about.

None of that is exotic and all of it is routine in a laboratory that reports for a living. Its absence does not mean a number is wrong; it means the number is unanchored, and unanchored numbers should not be quoted to two decimal places on this board.

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u/careful_gradient1 point·25 days ago

I would not blame the sample yet. Everything you have described is consistent with the column rather than the vial.

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u/step_count_stan1 point·25 days ago

What did system suitability look like on that sequence?

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[removed]1 point·25 days ago

[removed by moderator]

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u/insulin_syringe_ianOP1 point·25 days ago

Bought a second-hand instrument and learned more in six months of fixing it than in three years of reading traces.

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u/rina_bergstrom1 point·25 days ago

the column has a history and it shows in the peak shape

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u/rina_bergstrom1 point·25 days ago

Correcting myself upthread: I said the gradient was linear and looking again it has a hold in the middle.

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u/insulin_syringe_ianOP1 point·25 days ago

Small fix — 214nm, not 210. It matters for the comparison you are making with the other run.

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