Topic
Mass spectrometry
Monoisotopic versus average mass, multiply-charged ions and the arithmetic, and why MS/MS is the only real identity test.
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2024-05first seen
2026-06last seen
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retention_timesemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2024-05-25retention_timedoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2024-05-25retention_timeoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2024-05-25area_percenttirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2024-09-29quiet.hourssorry to jump in is monoisotopic or average mass the one on most certificates#hplc-massspec · 2024-09-29retention_timedoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2024-11-17area_percentms/ms or it isnt identity#hplc-massspec · 2024-11-17rotate_the_sitedeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2024-11-17month_six_meif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2024-11-17salt_bridgetirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5 214nm sees the amide backbone so it sees everything.…#hplc-massspec · 2024-11-17area_percentthats a charge state#hplc-massspec · 2024-11-17area_percentoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2024-11-17monoisotopicoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2024-11-24monoisotopictirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2024-11-24drawup_deei have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2024-11-24ms_ms_mirafollow up if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2024-12-08swirl_not_shakems/ms sequencing is the only thing i would call identity. everything else is circumstantial, your mileage will differ#hplc-massspec · 2024-12-08swirl_not_shakeif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2024-12-08HPLC_Hanktirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2024-12-08fibre_firsti have a number at about a third of what i expected, is that a charge state shallow gradients hide related substances behind…#hplc-massspec · 2024-12-08salt_bridgems/ms or it isnt identity#hplc-massspec · 2025-01-15low_and_slowi have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-01-24low_and_slowdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-01-24snac_and_waterwhile im here if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-01-25area_percentsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-01-25void_volumethats a charge state#hplc-massspec · 2025-01-29area_percentis monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-01-29pbs_pipdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-01-29void_volumems/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-01-29pbs_pipms/ms or it isnt identity#hplc-massspec · 2025-01-29pbs_pipdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-01-29peak_splittirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-02-07mag_citrateif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-02-07ms_ms_mirafor the archive oxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2025-02-07sunday_shotdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-02-09area_percentthats a charge state#hplc-massspec · 2025-02-09van_isle_vialoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2025-02-09void_volumeright so if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-02-15quiet.hoursdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant, happy to be corrected#hplc-massspec · 2025-02-15two_lifts_a_weekis monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-02-15gradient_gregms/ms or it isnt identity#hplc-massspec · 2025-02-20monoisotopicfollow up if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic,…#hplc-massspec · 2025-02-20monoisotopicoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2025-02-20salt_bridgegenuine question if somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2025-02-20wrong_networksemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-02-24karl_fischermonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-02-24forty_unitsthats a charge state#hplc-massspec · 2025-02-24forty_unitsi have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-02-24ms_ms_miraupdate on the earlier thing ms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-02-24wrong_networktirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5, ill dig out the number#hplc-massspec · 2025-02-24ms_ms_miraif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-02-24HPLC_Hankdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-03-02private_script_prims/ms or it isnt identity#hplc-massspec · 2025-03-04private_script_prideamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-03-04cagri_curiousif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2025-03-04taper_tessif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-03-04taper_tessdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-03-04truncation_trums/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-03-04acetate_ashoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2025-03-04steady_state_suethats a charge state#hplc-massspec · 2025-03-10