Topic
Retention time
Page 12 of 15 — Why retention time is a hint and not a fingerprint, and what co-elution can hide behind a beautiful single peak.
Messages — page 12 of 15
night_pinsingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-04-06meniscus_melthe retention time on this one is different from the last lot, problem#coa-reading · 2026-04-08taper_or_notretention time shifts between runs are normal. relative retention time is the number to compare, we shall see#coa-reading · 2026-04-08HPLC_Hankthats co-elution#hplc-massspec · 2026-04-09HPLC_Hankcoming back to this how do you tell co-elution from a clean single peak#hplc-massspec · 2026-04-09HPLC_Hankrelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-04-09tarpit_tambaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-04-10swirl_not_shakeretention time is a hint#hplc-massspec · 2026-04-10cold_pack_carlashallow gradient#hplc-massspec · 2026-04-10same_chromatothe retention time on this one is different from the last lot, problem#coa-reading · 2026-04-11salt_bridgeretention time is a hint#hplc-massspec · 2026-04-11juniper_joinsquick one retention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-04-11freeze_thawhow do you tell co-elution from a clean single peak#hplc-massspec · 2026-04-11ivy_injectsthe retention time on this one is different from the last lot, problem#coa-reading · 2026-04-12monoisotopicdoes retention time on its own tell you what the compound is#hplc-massspec · 2026-04-12monoisotopicretention time is a hint#hplc-massspec · 2026-04-12salt_bridgeretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-04-12area_percentthe retention time on this one is different from the last lot, problem#coa-reading · 2026-04-13salt_bridgesingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-04-13tga_noticedo you trust an area percent from a shallow gradient#hplc-massspec · 2026-04-13maple_mathsbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-04-13maple_mathshow do you tell co-elution from a clean single peak#hplc-massspec · 2026-04-13assay_not_puritydoes retention time on its own tell you what the compound is#hplc-massspec · 2026-04-13ms_ms_miraretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-04-15alt_ast_alibaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-04-15alt_ast_alihow do you tell co-elution from a clean single peak#hplc-massspec · 2026-04-15thirty_min_waitwhile im here how do you tell co-elution from a clean single peak#hplc-massspec · 2026-04-16gradient_gregupdate on the earlier thing does retention time on its own tell you what the compound is#hplc-massspec · 2026-04-16ms_ms_miraretention time is a hint#hplc-massspec · 2026-04-16ms_ms_mirathats co-elution#hplc-massspec · 2026-04-16seven_five_sweetretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-04-17orfor_watchthe retention time on this one is different from the last lot, problem the honest summary is that a certificate tells you what…#coa-reading · 2026-04-18gus_chartsshallow gradient#hplc-massspec · 2026-04-18fridge_thermowhats a normal gradient for a peptide this size#hplc-massspec · 2026-04-18retention_timeretention time shifts between runs are normal. relative retention time is the number to compare, n of 1 obviously#coa-reading · 2026-04-19area_percentretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-04-21blank_runrelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-04-22maple_mathsretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily, ask me again in a month#hplc-massspec · 2026-04-23same_chromatodo you trust an area percent from a shallow gradient#hplc-massspec · 2026-04-23same_chromatoshallow gradient#hplc-massspec · 2026-04-23evidence_or_notsingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-04-24deamidationhow do you tell co-elution from a clean single peak#hplc-massspec · 2026-04-24cold_start_cythats co-elution#hplc-massspec · 2026-04-24LC_MS_Lenashallow gradient#hplc-massspec · 2026-04-25cold_pack_carlaretention time shifts between runs are normal. relative retention time is the number to compare residual solvents matter more…#coa-reading · 2026-04-26flint_fillssingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-04-26back_from_awayretention time is a hint#hplc-massspec · 2026-04-27marrow.modshallow gradient#hplc-massspec · 2026-04-27marrow.modbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-04-27karl_fischerdo you trust an area percent from a shallow gradient#hplc-massspec · 2026-04-28karl_fischerunrelated but does retention time on its own tell you what the compound is#hplc-massspec · 2026-04-28gradient_gregbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-04-28freeze_thawretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-04-28freeze_thawco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-04-28reship_ritahow do you tell co-elution from a clean single peak#hplc-massspec · 2026-04-28noct.titratefor the archive single wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-04-29dog_person_devdo you trust an area percent from a shallow gradient nobody runs enough blanks, including me#hplc-massspec · 2026-04-30LC_MS_Lenarelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-04-30motivation_gonethats co-elution#hplc-massspec · 2026-04-30motivation_gonebaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column, i have it written down somewhere#hplc-massspec · 2026-04-30