Topic
Retention time
Page 14 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 14 of 15
a1c_lagbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-05-15void_volumeretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-05-15quiet.hoursco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-05-15verify_or_dontbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column, from memory#hplc-massspec · 2026-05-16myrrh_measuressingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-05-17seven_five_sweetslightly off topic but the retention time on this one is different from the last lot, problem#coa-reading · 2026-05-17lisbon_lotretention time shifts between runs are normal. relative retention time is the number to compare, your mileage will differ#coa-reading · 2026-05-17monoisotopichow do you tell co-elution from a clean single peak#hplc-massspec · 2026-05-17brisbane_bacthe retention time on this one is different from the last lot, problem#coa-reading · 2026-05-18dexa_or_biabaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column, still working it out#hplc-massspec · 2026-05-18deamidationretention time is a hint#hplc-massspec · 2026-05-18willow_waitsco-elution is the failure mode that a beautiful single peak is most likely to be hiding, still working it out#hplc-massspec · 2026-05-18LC_MS_Lenathats co-elution#hplc-massspec · 2026-05-18karl_fischershallow gradient#hplc-massspec · 2026-05-18plum_plotsrelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-05-18ghent_gradientbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-05-19LC_MS_Lenaretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-05-19LC_MS_Lenaretention time is a hint#hplc-massspec · 2026-05-19zoya_zerosdo you trust an area percent from a shallow gradient#hplc-massspec · 2026-05-20taper_or_notretention time is a hint#hplc-massspec · 2026-05-20blank_runone: co-elution. an impurity with the same retention behaviour lands inside the main peak, so the integrator counts it as…#hplc-massspec · 2026-05-20blank_runchange the selectivity and see if the peak splits. shallower gradient, or a different stationary phase, or swap TFA for formic…#hplc-massspec · 2026-05-20thirty_min_waithow do you tell co-elution from a clean single peak#hplc-massspec · 2026-05-23monoisotopicbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column a certificate with a number and no…#hplc-massspec · 2026-05-23batch_banditretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-05-24yara_yieldsshallow gradient#hplc-massspec · 2026-05-24yara_yieldsrelative retention time against a standard is comparable between labs. absolute minutes are not a certificate with a number…#hplc-massspec · 2026-05-24cross_border_cambaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column, happy to be corrected#hplc-massspec · 2026-05-24monoisotopicretention time is a hint#hplc-massspec · 2026-05-24coa_or_copethats co-elution#hplc-massspec · 2026-05-25chlorhexrelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-05-25sgp_subqretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-05-25HPLC_Hankthe retention time on this one is different from the last lot, problem#coa-reading · 2026-05-28shame_and_medsthe retention time on this one is different from the last lot, problem#coa-reading · 2026-05-29identity_shiftshallow gradient#hplc-massspec · 2026-05-29tarpit_tamco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-05-29tarpit_tamthats co-elution#hplc-massspec · 2026-05-29a1c_laghow do you tell co-elution from a clean single peak#hplc-massspec · 2026-05-29nordic_price_nilsdo you trust an area percent from a shallow gradient#hplc-massspec · 2026-05-30nordic_price_nilswhats a normal gradient for a peptide this size#hplc-massspec · 2026-05-30ivy_injectshow do you tell co-elution from a clean single peak#hplc-massspec · 2026-05-30salt_bridgeco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-05-30nordic_price_nilsshallow gradient, for what its worth the first peak is the solvent. it is always the solvent#hplc-massspec · 2026-05-30turnaround_tamretention time shifts between runs are normal. relative retention time is the number to compare, not advice obviously#coa-reading · 2026-05-31seven_five_sweetupdate on the earlier thing single wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-05-31chlorhexdoes retention time on its own tell you what the compound is#hplc-massspec · 2026-05-31rotate_the_siteco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-05-31back_from_awayretention time is a hint#hplc-massspec · 2026-05-31chlorhexretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-05-31back_from_awayhow do you tell co-elution from a clean single peak#hplc-massspec · 2026-05-31comment_fatigueshallow gradient#hplc-massspec · 2026-05-31gus_chartsthats co-elution#hplc-massspec · 2026-05-31triumph_watchsingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-06-03lisbon_lotthe retention time on this one is different from the last lot, problem#coa-reading · 2026-06-03zoya_zerosretention time is a hint#hplc-massspec · 2026-06-03no_appetite_niarelative retention time against a standard is comparable between labs. absolute minutes are not, anyway#hplc-massspec · 2026-06-04gus_chartsretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily, thats just me#hplc-massspec · 2026-06-04void_volumesingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-06-05void_volumethe retention time on this one is different from the last lot, problem#coa-reading · 2026-06-05fasting_insulinsingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-06-06