Topic
Mass spectrometry
Page 12 of 15 — Monoisotopic versus average mass, multiply-charged ions and the arithmetic, and why MS/MS is the only real identity test.
Messages — page 12 of 15
alt_ast_alims/ms or it isnt identity#hplc-massspec · 2026-04-15salt_bridgeoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2026-04-15forty_five_kgif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result a shoulder on a peak is…#hplc-massspec · 2026-04-15ferritin_faytirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2026-04-16ms_ms_miraoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2026-04-16two_lifts_a_weekmonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2026-04-16food_noise_offms/ms or it isnt identity#hplc-massspec · 2026-04-16spreadsheet_stuis monoisotopic or average mass the one on most certificates#hplc-massspec · 2026-04-16gus_chartsdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2026-04-18fridge_thermoms/ms or it isnt identity#hplc-massspec · 2026-04-18fridge_thermoif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result, still working it out#hplc-massspec · 2026-04-18gus_chartsthats a charge state#hplc-massspec · 2026-04-18ghent_gradienttirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2026-04-22blank_runi have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2026-04-22batch_bandittirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5, happy to be corrected#hplc-massspec · 2026-04-23same_chromatothats a charge state#hplc-massspec · 2026-04-23same_chromatoms/ms sequencing is the only thing i would call identity. everything else is circumstantial, n of 1 obviously#hplc-massspec · 2026-04-23same_chromatoif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2026-04-23food_noise_offms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-04-24freeze_thawtirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5, someone check my working#hplc-massspec · 2026-04-24split_the_costif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2026-04-24hk_hplcthats a charge state#hplc-massspec · 2026-04-25LC_MS_Lenamonoisotopic and average diverge more the bigger the molecule. say which one you are quoting a dimer usually shows up late and…#hplc-massspec · 2026-04-25LC_MS_Lenams/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-04-25back_from_awayif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2026-04-27marrow.modif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic, n of 1…#hplc-massspec · 2026-04-27rowan_readsthats a charge state#hplc-massspec · 2026-04-28LC_MS_Lenamonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2026-04-28rowan_readstirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2026-04-28LC_MS_Lenais monoisotopic or average mass the one on most certificates#hplc-massspec · 2026-04-28nettle_notesok so oxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2026-04-28rowan_readsms/ms or it isnt identity#hplc-massspec · 2026-04-28gradient_gregsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2026-04-28reship_ritadeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant, i think#hplc-massspec · 2026-04-28retention_timeif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2026-04-28retention_timems/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-04-28impersonator_ipms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-04-30LC_MS_Lenathats a charge state#hplc-massspec · 2026-04-30LC_MS_Lenams/ms or it isnt identity#hplc-massspec · 2026-04-30LC_MS_Lenafor the archive if the number you are staring at is a third of what you expected, do the charge state arithmetic before you…#hplc-massspec · 2026-04-30motivation_goneif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2026-04-30food_noise_offoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2026-04-30motivation_goneoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2026-04-30rotterdam_recondoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2026-05-02thistle_testsi have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2026-05-02ten_percent_offms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-05-02vik_verifiesms/ms or it isnt identity#hplc-massspec · 2026-05-02ring_size_downif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2026-05-02monoisotopicis monoisotopic or average mass the one on most certificates#hplc-massspec · 2026-05-02thistle_testsdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2026-05-02travel_coolersemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2026-05-03HPLC_Hankdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2026-05-03HPLC_Hanktirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2026-05-03bench_notesoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2026-05-03marrow.modms/ms or it isnt identity#hplc-massspec · 2026-05-03HPLC_Hankms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-05-03deamidationi have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2026-05-03reship_ritaif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2026-05-04reship_ritams/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2026-05-04peak_splitsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2026-05-04