Topic
Mass spectrometry
Page 11 of 15 — Monoisotopic versus average mass, multiply-charged ions and the arithmetic, and why MS/MS is the only real identity test.
Messages — page 11 of 15
salt_bridgeis monoisotopic or average mass the one on most certificates#hplc-massspec · 2026-03-27karl_fischerif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2026-03-27fake_trackingms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-03-27fake_trackingmonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2026-03-27c18_columni have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2026-03-27lisbon_lotdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2026-03-27ghk_giams/ms or it isnt identity#hplc-massspec · 2026-03-28ghk_giaif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2026-03-28dexa_or_biaoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2026-03-28ghk_giadoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2026-03-28dexa_or_biamonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2026-03-28first_month_fiunrelated but deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant, ymmv#hplc-massspec · 2026-03-28bpc_scepticms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-03-28cold_chain_cmdrif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2026-03-28monoisotopictirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2026-03-29patent_2026if somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2026-03-29lot_number_loums/ms or it isnt identity#hplc-massspec · 2026-03-29coa_or_copems/ms or it isnt identity#hplc-massspec · 2026-03-30coa_or_copetirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2026-03-30dexa_or_biagenuine question is monoisotopic or average mass the one on most certificates#hplc-massspec · 2026-03-30hair_month_foursemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2, we shall see#hplc-massspec · 2026-03-30hair_month_fourthats a charge state#hplc-massspec · 2026-03-30month_six_mei have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2026-03-30month_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 · 2026-03-30marrow.modms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-03-30impersonator_ipsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2026-03-31blank_runthats a charge state#hplc-massspec · 2026-03-31impersonator_ipms/ms or it isnt identity#hplc-massspec · 2026-03-31blank_runsorry to jump in tirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2026-03-31manila_meniscuswhile im here if somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2026-04-04ghent_gradientif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic, for what…#hplc-massspec · 2026-04-04ghent_gradientoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2026-04-04manila_meniscusthats a charge state#hplc-massspec · 2026-04-04acetate_ashis monoisotopic or average mass the one on most certificates#hplc-massspec · 2026-04-04lead_time_larsms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-04-04HPLC_Hanktirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2026-04-05step_one_sianif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2026-04-05bac_water_billis monoisotopic or average mass the one on most certificates#hplc-massspec · 2026-04-05peak_spliti have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2026-04-05back_from_awayunrelated but does ms/ms actually prove identity or just make it very likely#hplc-massspec · 2026-04-09HPLC_Hanksemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2026-04-09hydrate_hanaoxidation is about plus 15.99 Da and is usually methionine or tryptophan, from memory#hplc-massspec · 2026-04-09back_from_awayif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic co-elution…#hplc-massspec · 2026-04-09ms_ms_mirams/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-04-10tarpit_tamms/ms or it isnt identity#hplc-massspec · 2026-04-10swirl_not_shakemonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2026-04-10juniper_joinsmonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2026-04-11juniper_joinstirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2026-04-11juniper_joinsthats a charge state#hplc-massspec · 2026-04-11monoisotopicif 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 · 2026-04-12monoisotopicms/ms sequencing is the only thing i would call identity. everything else is circumstantial semaglutide is about 4113.6 Da.…#hplc-massspec · 2026-04-12triple_ag_tomsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2026-04-13maple_mathsms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-04-13spreadsheet_stuthats a charge state#hplc-massspec · 2026-04-13maple_mathsms/ms or it isnt identity#hplc-massspec · 2026-04-13maple_mathsdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2026-04-13retention_timeis monoisotopic or average mass the one on most certificates#hplc-massspec · 2026-04-13retention_timeif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2026-04-13alt_ast_alislightly off topic but if the number you are staring at is a third of what you expected, do the charge state arithmetic before…#hplc-massspec · 2026-04-15salt_bridgethats a charge state#hplc-massspec · 2026-04-15