Topic
Mass spectrometry
Page 6 of 15 — Monoisotopic versus average mass, multiply-charged ions and the arithmetic, and why MS/MS is the only real identity test.
Messages — page 6 of 15
bengaluru_bacwhile im here deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-09-26bengaluru_bactirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-09-26bengaluru_bacthats a charge state#hplc-massspec · 2025-09-26sharps_comedyi have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-10-05nhs_pathway_nellthats a charge state#hplc-massspec · 2025-10-05void_volumei have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-10-08HPLC_Hankis monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-10-08gradient_gregfor the archive tirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5, for what its worth#hplc-massspec · 2025-10-08mg_per_mlif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result, ymmv#hplc-massspec · 2025-10-10first_and_last_foursemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-10-10bea_reconstitutesdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-10-12tenpenceif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-10-12ghent_gradientoxidation is about plus 15.99 Da and is usually methionine or tryptophan, ask me again in a month#hplc-massspec · 2025-10-14ghent_gradientdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-10-14ghent_gradienttirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-10-14blank_rundeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-10-15knees_firstthats a charge state#hplc-massspec · 2025-10-15knees_firstdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-10-15blank_runif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result integration choices move…#hplc-massspec · 2025-10-15blank_runsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-10-15blank_runwhile im here is monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-10-15knees_firsti have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-10-15endotoxin_edtirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-10-17area_percentthats a charge state#hplc-massspec · 2025-10-17split_shipmentright so if the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic, ymmv#hplc-massspec · 2025-10-17endotoxin_edis monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-10-17endotoxin_edwhile im here semaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-10-17HPLC_Hankif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2025-10-22point_two_fivedeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-10-23gall_bladder_gavi have a number at about a third of what i expected, is that a charge state#hplc-massspec · 2025-10-23area_percentthats a charge state#hplc-massspec · 2025-10-23two_four_ceilingdoes ms/ms actually prove identity or just make it very likely#hplc-massspec · 2025-10-23two_four_ceilingtirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-10-23area_percentif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-10-23peak_splitsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-10-23tail_factoris monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-10-23half_life_halsemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-10-29fasting_insulindeamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant#hplc-massspec · 2025-10-29mag_citratethats a charge state#hplc-massspec · 2025-10-30mag_citrateoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2025-10-30oasis_olamonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-10-30ms_ms_mirams/ms or it isnt identity#hplc-massspec · 2025-10-30monoisotopicif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-10-30HPLC_Hanksemaglutide is about 4113.6 Da. [M+2H]2+ lands near 2057.8, [M+3H]3+ near 1372.2#hplc-massspec · 2025-11-01septum_salms/ms sequencing is the only thing i would call identity. everything else is circumstantial#hplc-massspec · 2025-11-01VialBotReminder for monoisotopic: dose day is today. Set 8 days ago.#eu · 2025-11-01gradient_gregthats a charge state#hplc-massspec · 2025-11-04first_month_fims/ms sequencing is the only thing i would call identity. everything else is circumstantial if the lab reports area percent…#hplc-massspec · 2025-11-04peak_splitif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result#hplc-massspec · 2025-11-04karl_fischerms/ms or it isnt identity#hplc-massspec · 2025-11-04orfor_watchtirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2025-11-04karl_fischerthats a charge state#hplc-massspec · 2025-11-04first_month_fideamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant, n of 1 obviously integration choices move…#hplc-massspec · 2025-11-04karl_fischerif the number you are staring at is a third of what you expected, do the charge state arithmetic before you panic#hplc-massspec · 2025-11-04low_and_slowsorry to jump in does ms/ms actually prove identity or just make it very likely update from 21 months ago: switched to asking…#hplc-massspec · 2025-11-04low_and_slowunrelated but monoisotopic and average diverge more the bigger the molecule. say which one you are quoting, still working it out#hplc-massspec · 2025-11-04triple_ag_tommonoisotopic and average diverge more the bigger the molecule. say which one you are quoting#hplc-massspec · 2025-11-07triple_ag_tomis monoisotopic or average mass the one on most certificates#hplc-massspec · 2025-11-07no_appetite_niaif somebody says they ran a mass spec and does not show you a spectrum, that is a claim, not a result, from memory#hplc-massspec · 2025-11-08shame_and_medsoxidation is about plus 15.99 Da and is usually methionine or tryptophan#hplc-massspec · 2025-11-08