Analytics · subcategory

Impurities & related substances

Deletion sequences, oxidation, deamidation, aggregates, residual solvents, and counter-ion content.

30 topics1,177 posts9 solved Moderators: bench_notes, hana.sato About this category

forced degradation counter-ion content water content endotoxin testing HPLC data table

30 topics

Topic	Participants	Replies	Views	Activity
About the Impurities & related substances category forced degradation counter-ion content water content Pinned Wiki Deletion sequences, oxidation, deamidation, aggregates, residual solvents, and counter-ion content. This post is a community wiki: any member at trust level 3 or above can edit it, and every edit is recorded…	+6	10	50k	15h
Named, unnamed and unspecified impurities as regulatory categories — the long version HPLC data table forced degradation counter-ion content Wiki Named, unnamed and unspecified impurities as regulatory categories — the long version — setting out what I have, and where I think it stops being reliable. A documentation question rather than an analytical…	+112	120	7.6k	5h
Deletion sequences: expected mass shifts by residue — the long version water content endotoxin testing data table forced degradation On the subject in the title: Deletion sequences: expected mass shifts by residue — the long version Working notes rather than a conclusion. Working through the identity arithmetic and I would like it checked.…	+21	25	6.9k	10h
Endotoxin and why it is a separate question from purity — what changed since HPLC endotoxin testing data table forced degradation On the subject in the title: Endotoxin and why it is a separate question from purity — what changed since Working notes rather than a conclusion. A documentation question rather than an analytical one. I have…	+78	91	1k	10h
Impurity thresholds: where the common numbers come from water content data table forced degradation counter-ion content Impurity thresholds: where the common numbers come from — 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…	+11	15	825	2d
Racemisation and why it is invisible to a mass measurement — what changed since forced degradation water content counter-ion content Racemisation and why it is invisible to a mass measurement — what changed since Writing it up because I had to work it out twice and would rather nobody else did. Working through the identity arithmetic and I…	+11	15	42k	16d
Deamidation and the close-eluting pair it produces — the long version counter-ion content endotoxin testing data table Posting this under the heading it deserves: Deamidation and the close-eluting pair it produces — the long version Everything below is what sits behind that. I would like to understand what this number means…		3	347	24d
Second pass at: Where impurities in solid-phase peptide synthesis come from HPLC water content counter-ion content endotoxin testing Second pass at: Where impurities in solid-phase peptide synthesis come from Writing it up because I had to work it out twice and would rather nobody else did. A documentation question rather than an…	+4	8	7.2k	1mo
Racemisation and why it is invisible to a mass measurement counter-ion content endotoxin testing HPLC Closed Posting this under the heading it deserves: Racemisation and why it is invisible to a mass measurement Everything below is what sits behind that. Working through the identity arithmetic and I would like it…	+120	127	41k	1mo
Residual solvents and scavengers: what is looked for — what changed since forced degradation water content data table HPLC Solved Residual solvents and scavengers: what is looked for — what changed since — setting out what I have, and where I think it stops being reliable. Posting the method first, because I know what the first three…	+37	41	7k	2mo
Named, unnamed and unspecified impurities as regulatory categories counter-ion content endotoxin testing water content On the subject in the title: Named, unnamed and unspecified impurities as regulatory categories Working notes rather than a conclusion. Working through the identity arithmetic and I would like it checked.…	+10	14	504	3mo
Impurity thresholds: where the common numbers come from — what changed since counter-ion content HPLC endotoxin testing water content Solved Posting this under the heading it deserves: Impurity thresholds: where the common numbers come from — what changed since Everything below is what sits behind that. A documentation question rather than an…		2	61k	3mo
Deletion sequences: expected mass shifts by residue water content endotoxin testing forced degradation HPLC Deletion sequences: expected mass shifts by residue — setting out what I have, and where I think it stops being reliable. Working through the identity arithmetic and I would like it checked. semaglutide has a…		2	59	3mo
Where impurities in solid-phase peptide synthesis come from water content data table HPLC endotoxin testing Solved Where impurities in solid-phase peptide synthesis come from 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 a…	+54	59	14k	3mo
Endotoxin and why it is a separate question from purity water content counter-ion content forced degradation HPLC Endotoxin and why it is a separate question from purity 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	22k	4mo
Second pass at: Where impurities in solid-phase peptide synthesis come from counter-ion content data table endotoxin testing HPLC Closed Posting this under the heading it deserves: Second pass at: Where impurities in solid-phase peptide synthesis come from Everything below is what sits behind that. A documentation question rather than an…	+47	51	3.3k	5mo
[2026 update] A rising related-substance total over six months: degradation or method drift? forced degradation water content endotoxin testing HPLC Solved Wiki The question in the title: A rising related-substance total over six months: degradation or method drift? I will give what I have already checked below so nobody repeats it. Posting the method first, because…	+71	78	34k	5mo
Trifluoroacetate content and its consequences water content data table forced degradation counter-ion content Trifluoroacetate content and its consequences — 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 of me…	+123	134	31k	5mo
Aggregates and why a purity assay may miss them entirely water content counter-ion content forced degradation HPLC Aggregates and why a purity assay may miss them entirely 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 a…	+61	69	2.9k	6mo
Revisiting: Aggregates and why a purity assay may miss them entirely endotoxin testing HPLC counter-ion content water content Solved Posting this under the heading it deserves: Revisiting: Aggregates and why a purity assay may miss them entirely Everything below is what sits behind that. I would like to understand what this number means…	+48	53	918	8mo
Particulates in a reconstituted solution: identifying the likely source counter-ion content data table HPLC water content Posting this under the heading it deserves: Particulates in a reconstituted solution: identifying the likely source Everything below is what sits behind that. Posting the method first, because I know what the…	+15	19	13k	9mo
Particulates in a reconstituted solution: identifying the likely source — what changed since water content HPLC forced degradation counter-ion content Particulates in a reconstituted solution: identifying the likely source — what changed since — setting out what I have, and where I think it stops being reliable. Posting the method first, because I know what…		2	129	14mo
Residual solvents and scavengers: what is looked for counter-ion content HPLC data table forced degradation Solved On the subject in the title: Residual solvents and scavengers: what is looked for Working notes rather than a conclusion. Posting the method first, because I know what the first three replies will otherwise…	+19	23	39k	14mo
Coming back to: Oxidation pathways for methionine and tryptophan HPLC counter-ion content water content data table Oxidation pathways for methionine and tryptophan Writing it up because I had to work it out twice and would rather nobody else did. Working through the identity arithmetic and I would like it checked.…	+1	5	36k	15mo
Deamidation and the close-eluting pair it produces forced degradation HPLC water content data table Deamidation and the close-eluting pair it produces 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…	+33	37	46k	15mo
Follow-up: Attributing a new peak: degradation product or excipient? water content HPLC forced degradation endotoxin testing Solved Attributing a new peak: degradation product or excipient? I have a specific reason for asking rather than idle curiosity, and the context is below. Posting the method first, because I know what the first…	+15	19	671	17mo
Attributing a new peak: degradation product or excipient? counter-ion content HPLC data table forced degradation Solved Closed Asking directly, because I could not find a straight answer: Attributing a new peak: degradation product or excipient? Posting the method first, because I know what the first three replies will otherwise be.…		2	15k	18mo
Oxidation pathways for methionine and tryptophan counter-ion content data table HPLC water content Posting this under the heading it deserves: Oxidation pathways for methionine and tryptophan Everything below is what sits behind that. Working through the identity arithmetic and I would like it checked.…	+58	63	1k	19mo
Follow-up: Trifluoroacetate content and its consequences counter-ion content endotoxin testing HPLC data table Solved Closed On the subject in the title: Trifluoroacetate content and its consequences Working notes rather than a conclusion. Posting the method first, because I know what the first three replies will otherwise be.…	+12	16	5.7k	21mo
A rising related-substance total over six months: degradation or method drift? data table endotoxin testing HPLC Closed Asking directly, because I could not find a straight answer: A rising related-substance total over six months: degradation or method drift? Posting the method first, because I know what the first three…	+37	42	37k	23mo

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