Analytics · subcategory

HPLC & UHPLC

Reversed-phase separations, gradients, columns, integration, and reading a chromatogram properly.

35 topics1,237 posts10 solved Moderators: KLindqvist, bench_notes About this category

HPLC peak integration gradient method UV & DAD detection system suitability data table

35 topics · page 1 of 2

Topic	Participants	Replies	Views	Activity
About the HPLC & UHPLC category HPLC peak integration gradient method Pinned Wiki 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…		4	137	18h
What a reversed-phase purity number actually is HPLC system suitability data table peak integration Solved 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…	+87	101	27k	4h
[2026 update] Detection wavelength and why 214 nm and 280 nm disagree HPLC system suitability gradient method Detection wavelength and why 214 nm and 280 nm disagree — 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…	+69	76	920	6h
Follow-up: Comparing two chromatograms from different laboratories, properly gradient method system suitability HPLC peak integration 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…	+62	67	12k	9h
Why 99.2% and 97.8% on the same lot can both be correct system suitability peak integration gradient method data table Solved 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…	+16	20	3.1k	11h
Shoulders, tangent skims, and defensible integration peak integration UV & DAD detection HPLC gradient method 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…	+16	20	11k	13h
Gradient steepness and apparent purity: a worked comparison — the long version HPLC system suitability gradient method Gradient steepness and apparent purity: a worked comparison — the long version — setting out what I have, and where I think it stops being reliable. A documentation question rather than an analytical one. I…		2	32k	1d
System suitability injections: if they failed, the run did not happen — the long version gradient method UV & DAD detection system suitability peak integration 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…	+2	6	6.2k	1d
Revisiting: Theoretical plates: useful number or ritual? system suitability UV & DAD detection gradient method data table Solved Asking directly, because I could not find a straight answer: Revisiting: Theoretical plates: useful number or ritual? I would like to understand what this number means before I repeat it anywhere. A…	+16	21	1.2k	1d
[2026 update] Why 99.2% and 97.8% on the same lot can both be correct UV & DAD detection system suitability peak integration gradient method Solved 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…	+1	5	719	2d
[2026 update] Area percent versus weight percent: the confusion that causes most arguments gradient method UV & DAD detection peak integration data table 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…	+65	70	1.1k	16d
Carryover and the ghost peak from last week's standard — what changed since gradient method data table HPLC UV & DAD detection Solved Carryover and the ghost peak from last week's standard — what changed since 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…	+98	114	37k	22d
Resolution and tailing factor: real acceptance criteria HPLC gradient method peak integration system suitability 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…		2	15k	1mo
Injection volume, overload, and peak distortion peak integration system suitability HPLC data table Solved 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…	+43	47	36k	2mo
Area percent versus weight percent: the confusion that causes most arguments system suitability UV & DAD detection HPLC data table 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…	+10	14	2.1k	2mo
[2026 update] Reading a chromatogram someone posted without axes peak integration HPLC UV & DAD detection data table 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…		2	59	2mo
Shoulders, tangent skims, and defensible integration — the long version HPLC system suitability peak integration data table 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…	+16	20	27k	3mo
Injection volume, overload, and peak distortion — one year on system suitability peak integration gradient method data table Under review 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…	+4	8	1.2k	4mo
Comparing two chromatograms from different laboratories, properly peak integration system suitability UV & DAD detection gradient method Solved Closed 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…	+35	40	22k	7mo
Where the integrator drew the baseline, and how much it moved the number system suitability gradient method UV & DAD detection data table Solved Where the integrator drew the baseline, and how much it moved the number — setting out what I have, and where I think it stops being reliable. Posting the method first, because I know what the first three…	+20	24	1.6k	8mo
What a reversed-phase purity number actually is — the long version gradient method system suitability HPLC UV & DAD detection Solved What a reversed-phase purity number actually is — the long version 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…		2	15k	8mo
Detection wavelength and why 214 nm and 280 nm disagree peak integration UV & DAD detection system suitability HPLC 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…	+78	84	1.7k	8mo
Coming back to: Resolution and tailing factor: real acceptance criteria peak integration data table UV & DAD detection 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…	+93	112	5.7k	9mo
Theoretical plates: useful number or ritual? system suitability data table HPLC UV & DAD detection Solved Theoretical plates: useful number or ritual? 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 repeat it…		2	284	9mo
Coming back to: Where the integrator drew the baseline, and how much it moved the number peak integration gradient method UV & DAD detection data table 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…	+20	24	2.7k	10mo
Revisiting: Why I ask for the gradient before I discuss the number UV & DAD detection data table peak integration system suitability 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…	+15	19	43k	10mo
Column chemistry choices for a 40-residue peptide gradient method system suitability HPLC peak integration 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.…	+39	43	1.1k	10mo
System suitability injections: if they failed, the run did not happen peak integration HPLC data table gradient method 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…	+23	27	6k	11mo
Second pass at: What a reversed-phase purity number actually is peak integration UV & DAD detection system suitability 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…		2	7.4k	11mo
Reading a chromatogram someone posted without axes HPLC UV & DAD detection gradient method data table 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…	+47	55	9.4k	13mo

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