Tags · Technique
peak integration
Where the integrator drew the baseline, and how much that changes the number.
Related in this group: HPLC · LC-MS · high-resolution MS · MALDI-TOF · UV & DAD detection · system suitability · gradient method · water content · amino acid analysis · ELISA · endotoxin testing · sterility testing
26 topics
| Topic | Participants | Replies | Views | Activity |
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What a reversed-phase purity number actually is
The question in the title: What a reversed-phase purity number actually is I will give what I have already checked below so nobody repeats it. I would like to understand what this number means before I repeat…
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+87 | 101 | 27k | 4h |
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Follow-up: Comparing two chromatograms from different laboratories, properly
Comparing two chromatograms from different laboratories, properly — setting out what I have, and where I think it stops being reliable. I would like to understand what this number means before I repeat it…
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+62 | 67 | 12k | 9h |
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Why 99.2% and 97.8% on the same lot can both be correct
Why 99.2% and 97.8% on the same lot can both be correct I have a specific reason for asking rather than idle curiosity, and the context is below. I would like to understand what this number means before I…
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+16 | 20 | 3.1k | 11h |
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Shoulders, tangent skims, and defensible integration
Posting this under the heading it deserves: Shoulders, tangent skims, and defensible integration Everything below is what sits behind that. Posting the method first, because I know what the first three…
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+16 | 20 | 11k | 13h |
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About the HPLC & UHPLC category
Reversed-phase separations, gradients, columns, integration, and reading a chromatogram properly. This post is a community wiki: any member at trust level 3 or above can edit it, and every edit is recorded…
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4 | 137 | 18h | |
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System suitability injections: if they failed, the run did not happen — the long version
System suitability injections: if they failed, the run did not happen — the long version — setting out what I have, and where I think it stops being reliable. A documentation question rather than an…
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+2 | 6 | 6.2k | 1d |
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[2026 update] Why 99.2% and 97.8% on the same lot can both be correct
Why 99.2% and 97.8% on the same lot can both be correct — that is the question, and I have not found it answered plainly anywhere I have looked. I would like to understand what this number means before I…
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+1 | 5 | 719 | 2d |
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[2026 update] Area percent versus weight percent: the confusion that causes most arguments
On the subject in the title: Area percent versus weight percent: the confusion that causes most arguments Working notes rather than a conclusion. Posting the method first, because I know what the first three…
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+65 | 70 | 1.1k | 16d |
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Resolution and tailing factor: real acceptance criteria
Resolution and tailing factor: real acceptance criteria Writing it up because I had to work it out twice and would rather nobody else did. I would like to understand what this number means before I repeat it…
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2 | 15k | 1mo | |
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Injection volume, overload, and peak distortion
Posting this under the heading it deserves: Injection volume, overload, and peak distortion Everything below is what sits behind that. A documentation question rather than an analytical one. I have a…
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+43 | 47 | 36k | 2mo |
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Area percent versus weight percent: the confusion that causes most arguments
Posting this under the heading it deserves: Area percent versus weight percent: the confusion that causes most arguments Everything below is what sits behind that. Posting the method first, because I know…
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+10 | 14 | 2.1k | 2mo |
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[2026 update] Reading a chromatogram someone posted without axes
Posting this under the heading it deserves: Reading a chromatogram someone posted without axes Everything below is what sits behind that. A documentation question rather than an analytical one. I have a…
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2 | 59 | 2mo | |
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Shoulders, tangent skims, and defensible integration — the long version
Shoulders, tangent skims, and defensible integration — the long version Writing it up because I had to work it out twice and would rather nobody else did. Posting the method first, because I know what the…
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+16 | 20 | 27k | 3mo |
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Injection volume, overload, and peak distortion — one year on
Injection volume, overload, and peak distortion — one year on Writing it up because I had to work it out twice and would rather nobody else did. A documentation question rather than an analytical one. I have…
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+4 | 8 | 1.2k | 4mo |
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Comparing two chromatograms from different laboratories, properly
Posting this under the heading it deserves: Comparing two chromatograms from different laboratories, properly Everything below is what sits behind that. I would like to understand what this number means…
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+35 | 40 | 22k | 7mo |
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Detection wavelength and why 214 nm and 280 nm disagree
On the subject in the title: Detection wavelength and why 214 nm and 280 nm disagree Working notes rather than a conclusion. Posting the method first, because I know what the first three replies will…
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+78 | 84 | 1.7k | 8mo |
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Coming back to: Resolution and tailing factor: real acceptance criteria
Posting this under the heading it deserves: Resolution and tailing factor: real acceptance criteria Everything below is what sits behind that. Posting the method first, because I know what the first three…
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+93 | 112 | 5.7k | 9mo |
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Coming back to: Where the integrator drew the baseline, and how much it moved the number
On the subject in the title: Where the integrator drew the baseline, and how much it moved the number Working notes rather than a conclusion. Posting the method first, because I know what the first three…
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+20 | 24 | 2.7k | 10mo |
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Revisiting: Why I ask for the gradient before I discuss the number
Posting this under the heading it deserves: Revisiting: Why I ask for the gradient before I discuss the number Everything below is what sits behind that. I would like to understand what this number means…
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+15 | 19 | 43k | 10mo |
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Column chemistry choices for a 40-residue peptide
Column chemistry choices for a 40-residue peptide — setting out what I have, and where I think it stops being reliable. Posting the method first, because I know what the first three replies will otherwise be.…
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+39 | 43 | 1.1k | 10mo |
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System suitability injections: if they failed, the run did not happen
Posting this under the heading it deserves: System suitability injections: if they failed, the run did not happen Everything below is what sits behind that. A documentation question rather than an analytical…
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+23 | 27 | 6k | 11mo |
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Second pass at: What a reversed-phase purity number actually is
On the subject in the title: Second pass at: What a reversed-phase purity number actually is Working notes rather than a conclusion. I would like to understand what this number means before I repeat it…
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2 | 7.4k | 11mo | |
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Reading a chromatogram someone posted without axes
Reading a chromatogram someone posted without axes — setting out what I have, and where I think it stops being reliable. A documentation question rather than an analytical one. I have a certificate in front…
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+47 | 55 | 9.4k | 13mo |
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Carryover and the ghost peak from last week's standard
On the subject in the title: Carryover and the ghost peak from last week's standard Working notes rather than a conclusion. Posting the method first, because I know what the first three replies will otherwise…
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+80 | 92 | 16k | 16mo |
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Coming back to: Column chemistry choices for a 40-residue peptide
On the subject in the title: Column chemistry choices for a 40-residue peptide Working notes rather than a conclusion. Posting the method first, because I know what the first three replies will otherwise be.…
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2 | 43k | 16mo | |
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Gradient steepness and apparent purity: a worked comparison
On the subject in the title: Gradient steepness and apparent purity: a worked comparison Working notes rather than a conclusion. A documentation question rather than an analytical one. I have a certificate in…
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2 | 51k | 22mo |