Topic
Mass spectrometry
Page 5 of 15 — Monoisotopic versus average mass, multiply-charged ions and the arithmetic, and why MS/MS is the only real identity test.
Messages — page 5 of 15
two_four_ceilingsorry to jump in if the number you are staring at is a third of what you expected, do the charge state arithmetic before you…#hplc-massspec · 2025-08-02yyz_vialms/ms or it isnt identity#hplc-massspec · 2025-08-07swirl_not_shakedoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-08-07swirl_not_shakedeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-08-07HPLC_Hankthats a charge state#hplc-massspec · 2025-08-15two_ml_twotirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-08-17two_ml_twodeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-08-17HPLC_Hankms/ms or it isnt identity#hplc-massspec · 2025-08-21two_four_ceilingtirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-08-23two_four_ceilingis monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-08-23gus_chartsdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-08-23madrid_mgms/ms or it isnt identity#hplc-massspec · 2025-08-23madrid_mgif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result, happy to be corrected#hplc-massspec · 2025-08-23madrid_mgthats a charge state#hplc-massspec · 2025-08-23a1c_lagms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-08-23VialBotArchive lookup: monoisotopic first appears in this channel on 2025-03-12.#tirzepatide · 2025-08-26HPLC_Hankms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-08-26mhra_unlicensedms/ms or it isnt identity#hplc-massspec · 2025-08-27mhra_unlicensedsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2, still working it out#hplc-massspec · 2025-08-27mhra_unlicensedthats a charge state#hplc-massspec · 2025-08-27ms_ms_miradeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-09-01alt_ast_aliif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2025-09-02alt_ast_alifor 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 · 2025-09-02sulphur_burpthats a charge state#hplc-massspec · 2025-09-02ms_ms_mirathen MS/MS if you actually want identity. fragment the parent ion and read the fragment ladder against the expected sequence.…#hplc-massspec · 2025-09-02vial_ledgerwe ran a mass spec is a sentence, not a result#hplc-massspec · 2025-09-02peak_splitmonoisotopic and average diverge more the bigger the molecule. say which one you are quoting a warm transit can put a visible…#hplc-massspec · 2025-09-06non_scale_windoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-09-06fridge_thermosemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-09-06peak_splitoxidation is about plus 15.99 Da and is usually methionine or tryptophan, for what its worth#hplc-massspec · 2025-09-06fake_trackingsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-09-09fake_trackingquick one monoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-09-09advance_fee_althats a charge state#hplc-massspec · 2025-09-09advance_fee_alunrelated but ms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-09-09cat_on_the_trayi have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-09-12cat_on_the_trayms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-09-12cat_on_the_traycoming back to this tirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-09-12area_percentthats a charge state#hplc-massspec · 2025-09-14rezept_rolfsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-09-14meniscus_meltirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5, i have it written down somewhere oxidation is about…#hplc-massspec · 2025-09-14charge_stateif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-09-14appetite_backms/ms or it isnt identity#hplc-massspec · 2025-09-14ruo_onlydoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-09-14swirl_not_shakesorry to jump in if somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2025-09-16power_through_nodeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant, thats one data point#hplc-massspec · 2025-09-16hiccup_hollisthats a charge state#hplc-massspec · 2025-09-16salt_bridgeis monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-09-16void_volumedoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-09-16hiccup_hollisms/ms or it isnt identity#hplc-massspec · 2025-09-16split_the_costms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-09-23split_the_costdeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-09-23no_escrow_nateoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2025-09-23madrid_mgunrelated but does ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-09-23logrotateok so monoisotopic and average diverge more the bigger the molecule. say which one you are quoting, anyway#hplc-massspec · 2025-09-23oasis_olatirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-09-23pinch_not_stretchthats a charge state#hplc-massspec · 2025-09-24gip_glp_gilif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result if the number you are…#hplc-massspec · 2025-09-24seoul_swirlmonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-09-24pinch_not_stretchsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2, from memory#hplc-massspec · 2025-09-24shame_and_medsms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-09-26