Topic
Retention time
Page 11 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 11 of 15
split_dose_samrelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-03-18split_dose_samshallow gradient#hplc-massspec · 2026-03-18split_dose_samco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-03-18a1c_lagretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-03-21deamidationdoes retention time on its own tell you what the compound is#hplc-massspec · 2026-03-23karl_fischerdoes retention time on its own tell you what the compound is#hplc-massspec · 2026-03-24karl_fischerbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-03-24salt_bridgethe retention time on this one is different from the last lot, problem#coa-reading · 2026-03-25typosquat_tayretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-03-25residual_solventsingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-03-25karl_fischerdo you trust an area percent from a shallow gradient#hplc-massspec · 2026-03-27fake_trackingretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-03-27fake_trackingdoes retention time on its own tell you what the compound is#hplc-massspec · 2026-03-27fake_trackingthats co-elution#hplc-massspec · 2026-03-27lisbon_lotquick one relative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-03-27void_volumethe retention time on this one is different from the last lot, problem#coa-reading · 2026-03-28deamidationsingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-03-28the_bet_2026retention time shifts between runs are normal. relative retention time is the number to compare, n of 1 obviously#coa-reading · 2026-03-28truncation_truthats co-elution#hplc-massspec · 2026-03-28low_and_slowretention time is a hint#hplc-massspec · 2026-03-28ghk_giaco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-03-28ghk_giado you trust an area percent from a shallow gradient#hplc-massspec · 2026-03-28bpc_scepticshallow gradient#hplc-massspec · 2026-03-28ms_ms_miradoes retention time on its own tell you what the compound is#hplc-massspec · 2026-03-28cold_chain_cmdrrelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-03-28cold_chain_cmdrshallow gradient#hplc-massspec · 2026-03-28LC_MS_Lenasorry to jump in retention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-03-29assay_not_purityrelative retention time, impurity RT divided by main peak RT. it travels between labs better than raw minutes because it…#coa-reading · 2026-03-29assay_not_puritynot perfectly. different gradient, different selectivity, RRT shifts too#coa-reading · 2026-03-29still_here_2024agreed, give me the gradient every time#coa-reading · 2026-03-29bram_beginswhats a gradient table#coa-reading · 2026-03-29still_here_2024and a vendor who wants a big number picks a fast gradient. nobody has to lie#coa-reading · 2026-03-29adelaide_assayhow do you tell co-elution from a clean single peak#hplc-massspec · 2026-03-29luerlokbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column a shoulder on a peak is…#hplc-massspec · 2026-03-29patent_2026co-elution is the failure mode that a beautiful single peak is most likely to be hiding, anyway#hplc-massspec · 2026-03-29HPLC_Hanksingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-03-30two_ml_twowhats a normal gradient for a peptide this size#hplc-massspec · 2026-03-30two_ml_tworetention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-03-30coa_or_coperelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-03-30dexa_or_biashallow gradient#hplc-massspec · 2026-03-30marrow.moddoes retention time on its own tell you what the compound is#hplc-massspec · 2026-03-30void_volumehow do you tell co-elution from a clean single peak#hplc-massspec · 2026-03-30travel_coolerretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-03-31mcg_not_mgslightly off topic but retention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-03-31impersonator_ipthats co-elution#hplc-massspec · 2026-03-31monoisotopicco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-03-31taper_tessthats co-elution#hplc-massspec · 2026-04-02taper_tessshallow gradient#hplc-massspec · 2026-04-02noct.titrateslightly off topic but relative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-04-04noct.titrateretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily, ymmv#hplc-massspec · 2026-04-04LC_MS_Lenabaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-04-04lead_time_larsthats co-elution#hplc-massspec · 2026-04-04lead_time_larsshallow gradient#hplc-massspec · 2026-04-04lead_time_larsretention time is a hint#hplc-massspec · 2026-04-04acetate_ashdoes retention time on its own tell you what the compound is#hplc-massspec · 2026-04-04snac_and_watersingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-04-05HPLC_Hankgenuine question whats a normal gradient for a peptide this size#hplc-massspec · 2026-04-05triple_ag_tomdo you trust an area percent from a shallow gradient#hplc-massspec · 2026-04-05bac_water_billco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-04-05night_pinthe retention time on this one is different from the last lot, problem#coa-reading · 2026-04-06