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purity

Page 11 of 33 · 788 questions tagged purity.

788 questions · sorted by votes · page 11 of 33

25 votes 3 answers23k views
What counter-ion should I expect on an FGP a GLP-1 receptor agonist lot?

Setup, so nobody has to ask: FGP · a GLP-1 receptor agonist. I would like help reading this properly rather than being told what conclusion to reach. I have the full…

acetate-content
acetate-content

Counter-ion content, most often acetate or trifluoroacetate, and why it matters: the counter-ion and residual water are part of the gross mass you…

87 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

438 questions
asked by b_delacroix 48k · 22 months ago
25 votes 5 answers22k views
Is 97.6% a realistic purity ceiling for mazdutide given its chain length?

What I am working with: 97.6% · mazdutide. The units are where I keep going wrong, so please be explicit about them. I have sanity-checked the order of magnitude and…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

466 questions
peptide-mapping
peptide-mapping

Enzymatic digestion followed by LC-MS/MS to confirm sequence rather than just mass. The method that catches a scrambled sequence or a D-amino-acid…

83 questions
asked by rosa_mendieta 13k · 17 months ago
25 votes 5 answers22k views
Is 214 nm or 280 nm the right detection wavelength for a purity number?

The method section is present, which is unusual enough that I want to make use of it. These are treated as interchangeable and I do not think they are. If both are…

hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

466 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
coa
coa

Certificates of analysis: what fields a useful one carries, how to tell a real analytical report from a marketing document, batch and lot…

749 questions
asked by jo_vandeberg 19k · 9 months ago
25 votes1 answer19k views
How do I compute the +4 charge state m/z for a peptide of 4731.3 Da?

For reference: +4 · 4731.3 Da. I would rather understand the derivation than memorise the outcome. Two people I asked gave two answers that differ by a factor of ten,…

mass-spec
mass-spec

Mass spectrometry for identity confirmation: electrospray ionisation, multiple charge states, monoisotopic versus average mass, deconvolution, and…

38 questions
dosing-math
dosing-math

The arithmetic itself: milligrams to millilitres to insulin units, concentration after reconstitution, dose per draw, and vial-days per vial. Show…

811 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
asked by gradient_slope 41k · 13 months ago
25 votes3 answers19k views
Is 97.6% a realistic purity ceiling for cagrilintide given its chain length?

Stated plainly: 97.6% · cagrilintide. The units are where I keep going wrong, so please be explicit about them. I have sanity-checked the order of magnitude and it…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

466 questions
peptide-mapping
peptide-mapping

Enzymatic digestion followed by LC-MS/MS to confirm sequence rather than just mass. The method that catches a scrambled sequence or a D-amino-acid…

83 questions
asked by ayo_fadipe 19k · 2.4 years ago
25 votes 3 answers18k views
What does 97.1% purity on a C4 column actually tell me about an orforglipron vial?

Concretely: 97.1% · a C4 column · orforglipron. I would like to know the limits of what can be inferred from this. What I am trying to avoid is over-reading a single…

hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

466 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
coa
coa

Certificates of analysis: what fields a useful one carries, how to tell a real analytical report from a marketing document, batch and lot…

749 questions
asked by ekaterina_volk 16k · 11 months ago
25 votes5 answers17k views
Does dimerisation of cagrilintide at 4 °C show up as a loss of content or of purity?

Stated plainly: dimerisation · cagrilintide · 4 °C. I keep seeing this stated as a fact with no explanation attached, and unexplained facts make me suspicious. My…

peptide-stability
peptide-stability

The chemistry of peptide degradation: deamidation, oxidation, hydrolysis, aggregation and fibrillation, and how temperature, pH, ionic strength,…

832 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

438 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
asked by tabular_nums 47k · 16 months ago
25 votes5 answers17k views
What does a 99.4% purity with a purity figure attached let me conclude?

Details up front: 99.4% · purity figure. I can parse the result. I am less sure what it licenses me to conclude. I have deliberately not looked at anyone else’s…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
coa
coa

Certificates of analysis: what fields a useful one carries, how to tell a real analytical report from a marketing document, batch and lot…

749 questions
hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

466 questions
asked by rukhsana_iqbal 14k · 6 months ago
25 votes 5 answers17k views
Is a 96.8% result from PeptideMeter comparable to 96.4% from PeptideMeter?

The specifics, since they change the answer: 96.8% · PeptideMeter · 96.4% · PeptideMeter. The comparison I want does not seem to exist anywhere in a form I can…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
batch-testing
batch-testing

Testing at the batch or lot level: sampling plans, how many vials from a lot need testing to say anything about the lot, and the difference…

865 questions
reference-standard
reference-standard

Certified reference materials and in-house standards: traceability, the certificate of the standard itself, system suitability, and why every…

179 questions
asked by Dr_Jonas_Halvorsen 41k · 5 months ago
25 votes 5 answers15k views
Does racemisation of orforglipron at 40 °C show up as a loss of content or of purity?

Details up front: racemisation · orforglipron · 40 °C. I can predict the outcome but I cannot explain it, which means I will get the next case wrong. I would like to…

peptide-stability
peptide-stability

The chemistry of peptide degradation: deamidation, oxidation, hydrolysis, aggregation and fibrillation, and how temperature, pH, ionic strength,…

832 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

438 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
asked by mala_venkatesh 21k · 7 months ago
25 votes 4 answers14k views
Does racemisation of retatrutide at 4 °C show up as a loss of content or of purity?

Details up front: racemisation · retatrutide · 4 °C. I can predict the outcome but I cannot explain it, which means I will get the next case wrong. I would like to…

peptide-stability
peptide-stability

The chemistry of peptide degradation: deamidation, oxidation, hydrolysis, aggregation and fibrillation, and how temperature, pH, ionic strength,…

832 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

438 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
asked by lipid_panel_q 44k · 8 months ago
25 votes0 answers13k views
Would you accept 99.4% on cagrilintide from TFC without a content assay?

What I am working with: 99.4% · cagrilintide · TFC. I would like to set this up properly once, rather than adjust it repeatedly. My budget is real but not tight, and…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

438 questions
vendor-vetting
vendor-vetting

Evaluating a supplier on evidence rather than reputation: testing history across batches, whether certificates are batch-specific, how failures…

436 questions
asked by two_two_micron 15k · 17 months ago
25 votes 2 answers12k views
Would you accept 98.2% on tirzepatide from WXT without a content assay?

Concretely: 98.2% · tirzepatide · WXT. The failure mode I am trying to avoid is making this decision emotionally. I have twelve months in view and I would like the…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

438 questions
vendor-vetting
vendor-vetting

Evaluating a supplier on evidence rather than reputation: testing history across batches, whether certificates are batch-specific, how failures…

436 questions
asked by p_mkhize 41k · 9 months ago
25 votes0 answers11k views
Would you accept 98.2% on survodutide from WWB without a content assay?

The specifics, since they change the answer: 98.2% · survodutide · WWB. I am at the decision point and I would rather think it through than improvise. I would rather…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

438 questions
vendor-vetting
vendor-vetting

Evaluating a supplier on evidence rather than reputation: testing history across batches, whether certificates are batch-specific, how failures…

436 questions
asked by unit_math 13k · 15 months ago
25 votes 3 answers11k views
Does aggregation of cagrilintide at 2–8 °C show up as a loss of content or of purity?

Stated plainly: aggregation · cagrilintide · 2–8 °C. The empirical answer seems settled. The explanation does not. If the honest answer is that nobody knows, I would…

peptide-stability
peptide-stability

The chemistry of peptide degradation: deamidation, oxidation, hydrolysis, aggregation and fibrillation, and how temperature, pH, ionic strength,…

832 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

438 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
asked by swab_and_wait 15k · 5 months ago
25 votes5 answers10k views
Does a phosphate-buffered mobile phase change the purity number I get for semaglutide on a C18 column?

The specifics, since they change the answer: a phosphate-buffered mobile phase · semaglutide · a C18 column. I would like the mechanism, because I want to be able to…

hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

466 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
reference-standard
reference-standard

Certified reference materials and in-house standards: traceability, the certificate of the standard itself, system suitability, and why every…

179 questions
asked by s_kalniete 47k · 13 months ago
25 votes0 answers9.5k views
How do I reconcile 98.8% from PeptideMeter with 98.4% from the supplier?

The specifics, since they change the answer: 98.8% · PeptideMeter · 98.4%. An unexpected observation, and I would like a differential rather than reassurance. The…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
batch-testing
batch-testing

Testing at the batch or lot level: sampling plans, how many vials from a lot need testing to say anything about the lot, and the difference…

865 questions
coa
coa

Certificates of analysis: what fields a useful one carries, how to tell a real analytical report from a marketing document, batch and lot…

749 questions
asked by Dr_Nadia_Farsi 90k · 8 months ago
24 votes5 answers45k views
Why would VendorInvestigate report 97.9% where the supplier certificate says something higher?

The specifics, since they change the answer: VendorInvestigate · 97.9%. An unexpected observation, and I would like a differential rather than reassurance. The…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

466 questions
batch-testing
batch-testing

Testing at the batch or lot level: sampling plans, how many vials from a lot need testing to say anything about the lot, and the difference…

865 questions
asked by triple_agonist_q 37k · 2.3 years ago
24 votes 5 answers44k views
Is 97.6% a realistic purity ceiling for ecnoglutide given its chain length?

The specifics, since they change the answer: 97.6% · ecnoglutide. I would rather understand the derivation than memorise the outcome. Two people I asked gave two…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

466 questions
peptide-mapping
peptide-mapping

Enzymatic digestion followed by LC-MS/MS to confirm sequence rather than just mass. The method that catches a scrambled sequence or a D-amino-acid…

83 questions
asked by ines_delacruz 16k · 20 months ago
24 votes 5 answers25k views
How does reference-standard error propagate into a liraglutide content figure?

I have the report as a PDF with the chromatogram on page two, so I can quote specifics. I would like the arithmetic checked rather than the conclusion asserted. I…

reference-standard
reference-standard

Certified reference materials and in-house standards: traceability, the certificate of the standard itself, system suitability, and why every…

179 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

438 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
asked by fill_volume 13k · 23 months ago
24 votes 5 answers24k views
Is a 98.2% result from Janoshik comparable to 97.9% from Janoshik?

What I have: 98.2% · Janoshik · 97.9% · Janoshik. I have used one of these for a while and I am considering switching, which requires a reason. What I care about is…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
batch-testing
batch-testing

Testing at the batch or lot level: sampling plans, how many vials from a lot need testing to say anything about the lot, and the difference…

865 questions
reference-standard
reference-standard

Certified reference materials and in-house standards: traceability, the certificate of the standard itself, system suitability, and why every…

179 questions
asked by Dr_Otto_Lindqvist 38k · 9 months ago
24 votes 5 answers23k views
What does a 96.8% purity with a method section attached let me conclude?

Concretely: 96.8% · method section. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the specifics…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
coa
coa

Certificates of analysis: what fields a useful one carries, how to tell a real analytical report from a marketing document, batch and lot…

749 questions
hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

466 questions
asked by kirsi_lahtinen 45k · 10 months ago
24 votes 5 answers22k views
Is a 98.4% result from PeptideMeter comparable to 97.1% from PeptideMeter?

The particulars: 98.4% · PeptideMeter · 97.1% · PeptideMeter. The comparison I want does not seem to exist anywhere in a form I can evaluate. I have read the…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
batch-testing
batch-testing

Testing at the batch or lot level: sampling plans, how many vials from a lot need testing to say anything about the lot, and the difference…

865 questions
reference-standard
reference-standard

Certified reference materials and in-house standards: traceability, the certificate of the standard itself, system suitability, and why every…

179 questions
asked by olu_babatunde 14k · 2.1 years ago
24 votes5 answers19k views
Does aspartimide formation of tirzepatide at 30 °C show up as a loss of content or of purity?

Concretely: aspartimide formation · tirzepatide · 30 °C. This is one of those things that everyone repeats and nobody derives. This matters practically, not just…

peptide-stability
peptide-stability

The chemistry of peptide degradation: deamidation, oxidation, hydrolysis, aggregation and fibrillation, and how temperature, pH, ionic strength,…

832 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

438 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

788 questions
asked by yuki_morishita 19k · 8 months ago