Topic
Mass spectrometry
Page 4 of 15 — Monoisotopic versus average mass, multiply-charged ions and the arithmetic, and why MS/MS is the only real identity test.
Messages — page 4 of 15
mcg_not_mgms/ms or it isnt identity#hplc-massspec · 2025-06-21third_shiftmonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-06-21no_chargebackmonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-06-22tail_factorif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-06-22first_and_last_fourms/ms or it isnt identity#hplc-massspec · 2025-06-22area_percentthats a charge state#hplc-massspec · 2025-06-22tail_factorcoming back to this semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-06-22vial_ledgerif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-06-26retention_timetirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-06-26nhs_pathway_nellms/ms sequencing is the only thing i would call identity. everything else is circumstantial, anyway#hplc-massspec · 2025-06-26vial_ledgeri have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-06-26vial_ledgersorry to jump in oxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2025-06-26triple_ag_tomdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-07-05retention_timems/ms or it isnt identity#hplc-massspec · 2025-07-05retention_timethats a charge state#hplc-massspec · 2025-07-05nine_nine_onei have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-07-05nine_nine_oneif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic, ill dig out…#hplc-massspec · 2025-07-05hiccup_hollisif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2025-07-05hiccup_hollismonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-07-05peak_splitms/ms or it isnt identity#hplc-massspec · 2025-07-06hk_hplcfor the archive is monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-07-08LC_MS_Lenams/ms or it isnt identity#hplc-massspec · 2025-07-08reta_resting_hrmonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-07-08tarpit_tamquick one deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-07-08deamidationfollow up if somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2025-07-13ghent_gradientms/ms or it isnt identity#hplc-massspec · 2025-07-13gip_glp_gilms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-07-15warsaw_vialthats a charge state#hplc-massspec · 2025-07-15salt_bridgegenuine question is monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-07-15cricket_or_footydeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-07-19cricket_or_footyms/ms sequencing is the only thing i would call identity. everything else is circumstantial, anyway#hplc-massspec · 2025-07-19area_percentis monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-07-19blank_runthats a charge state#hplc-massspec · 2025-07-23retention_timeoxidation is about plus 15.99 Da and is usually methionine or tryptophan truncations show as a mass deficit matching one or…#hplc-massspec · 2025-07-23yyz_vialms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-07-23LC_MS_Lenaif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic, ill dig out…#hplc-massspec · 2025-07-24pinch_not_stretchdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-07-25LC_MS_Lenasemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2, i think#hplc-massspec · 2025-07-25monoisotopictirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-07-25karl_fischerunrelated but i have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-07-27karl_fischerslightly off topic but is monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-07-27karl_fischertirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-07-27cold_chain_cmdrdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-07-27cold_chain_cmdrthats a charge state#hplc-massspec · 2025-07-27vial_ledgersemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-07-28vial_ledgerif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-07-28halifax_hplcdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-07-28deamidationdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant i have had a lot where the mass was exactly…#hplc-massspec · 2025-07-28void_volumems/ms or it isnt identity#hplc-massspec · 2025-07-28void_volumemonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-07-28HPLC_Hankif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-07-31HPLC_Hankis monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-07-31c18_columntirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-07-31c18_columnms/ms or it isnt identity#hplc-massspec · 2025-07-31c18_columndeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-07-31hydrate_hanai have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-08-02hydrate_hanaoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2025-08-02HPLC_Hankif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result, ill dig out the number#hplc-massspec · 2025-08-02HPLC_Hankms/ms or it isnt identity#hplc-massspec · 2025-08-02knees_firstok so monoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-08-02