Topic
Retention time
Page 10 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 10 of 15
dexa_or_biaretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-02-19auckland_aliquotthe retention time on this one is different from the last lot, problem#coa-reading · 2026-02-20shame_and_medsretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-02-23impersonator_ipretention time is a hint#hplc-massspec · 2026-02-23impersonator_ipretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-02-23knees_firstthats co-elution#hplc-massspec · 2026-02-23salt_bridgewhats a normal gradient for a peptide this size#hplc-massspec · 2026-02-23impersonator_ipdoes retention time on its own tell you what the compound is#hplc-massspec · 2026-02-23nordic_price_nilsretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-02-25see_a_cliniciando you trust an area percent from a shallow gradient#hplc-massspec · 2026-02-25gip_glp_gilretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily, ask me again in a month#hplc-massspec · 2026-02-25month_six_merelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-02-25vial_ledgerwhats a normal gradient for a peptide this size#hplc-massspec · 2026-02-25luerlokco-elution is the failure mode that a beautiful single peak is most likely to be hiding, i have it written down somewhere#hplc-massspec · 2026-02-25luerlokthats co-elution#hplc-massspec · 2026-02-25karl_fischerretention time is a hint#hplc-massspec · 2026-02-25karl_fischerbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-02-25bengaluru_bacthats co-elution#hplc-massspec · 2026-02-26night_pinwhile im here single wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-02-27nine_nine_onebaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-02-28peak_splitretention time is a hint#hplc-massspec · 2026-02-28alcohol_hitswhile im here relative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-02-28fasting_insulinshallow gradient#hplc-massspec · 2026-03-01fasting_insulindoes retention time on its own tell you what the compound is#hplc-massspec · 2026-03-01no_appetite_niaco-elution is the failure mode that a beautiful single peak is most likely to be hiding, i think#hplc-massspec · 2026-03-01lena_lotsretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-03-02karl_fischersingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-03-02area_percentwhats a normal gradient for a peptide this size#hplc-massspec · 2026-03-02two_four_ceilingretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-03-02two_four_ceilingshallow gradient#hplc-massspec · 2026-03-02freeze_thawco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-03-02coa_or_coperetention time is a hint#hplc-massspec · 2026-03-02hk_hplcco-elution is the failure mode that a beautiful single peak is most likely to be hiding, thats one data point#hplc-massspec · 2026-03-04non_scale_winthats co-elution#hplc-massspec · 2026-03-04assay_not_puritydo not read identity into it. a purity test with a matching retention time is consistent with tirzepatide, it does not confirm…#test-results · 2026-03-04assay_not_purityretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-03-06baseline_driftshallow gradient#hplc-massspec · 2026-03-06plateau_penretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily, ill dig out the number#hplc-massspec · 2026-03-06HPLC_Hankthe retention time on this one is different from the last lot, problem#coa-reading · 2026-03-07reta_resting_hrslightly off topic but single wavelength detection can miss a co-eluting impurity that does not absorb there sterility and…#coa-reading · 2026-03-08area_percentthe retention time on this one is different from the last lot, problem#coa-reading · 2026-03-08ollie_orderswhats a normal gradient for a peptide this size#hplc-massspec · 2026-03-08peak_splitthats co-elution#hplc-massspec · 2026-03-08area_percentretention time shifts between runs are normal. relative retention time is the number to compare, i could be wrong#coa-reading · 2026-03-10rowan_readsshallow gradient#hplc-massspec · 2026-03-11triple_ag_tomshallow gradient#hplc-massspec · 2026-03-12zoya_zerosbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-03-12lyophile_livretention time is a hint#hplc-massspec · 2026-03-12lyophile_livrelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-03-12yyz_vialsingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-03-13stack_scepticbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-03-13gradient_gregretention time is a hint#hplc-massspec · 2026-03-13iris_importsretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-03-14per_mg_petethats co-elution#hplc-massspec · 2026-03-14per_mg_peteupdate on the earlier thing baseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-03-14protein_floordoes retention time on its own tell you what the compound is#hplc-massspec · 2026-03-14per_mg_peteretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily, not advice obviously#hplc-massspec · 2026-03-14reship_ritaunrelated but retention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-03-15peak_splitretention time shifts between runs are normal. relative retention time is the number to compare, still working it out#coa-reading · 2026-03-16gus_chartsthe retention time on this one is different from the last lot, problem#coa-reading · 2026-03-17