Topic
Retention time
Page 9 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 9 of 15
never_for_saleco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-01-23assay_not_purityshallow gradient#hplc-massspec · 2026-01-23peak_splitrelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-01-24seven_five_sweetdoes retention time on its own tell you what the compound is update from 5 months ago: switched to asking for the chromatogram…#hplc-massspec · 2026-01-24vienna_vialwhats a normal gradient for a peptide this size#hplc-massspec · 2026-01-25fridge_thermoretention time is a hint#hplc-massspec · 2026-01-25tail_factorright so relative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-01-25acetate_ashbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column, from memory#hplc-massspec · 2026-01-25fake_trackingdo you trust an area percent from a shallow gradient#hplc-massspec · 2026-01-25ms_ms_miraretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-01-25acetate_ashthats co-elution#hplc-massspec · 2026-01-25maintenance_mosingle wavelength detection can miss a co-eluting impurity that does not absorb there, ask me again in a month#coa-reading · 2026-01-28non_scale_winretention time shifts between runs are normal. relative retention time is the number to compare purity is what fraction of the…#coa-reading · 2026-01-29kev_measuresco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-01-29no_appetite_niadoes retention time on its own tell you what the compound is#hplc-massspec · 2026-01-29kev_measuresrelative retention time against a standard is comparable between labs. absolute minutes are not, i think#hplc-massspec · 2026-01-29slow.taperretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-01-30group_buy_gwenrelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-01-30group_buy_gwendo you trust an area percent from a shallow gradient tirzepatide is about 4813.5 Da, so 2+ is near 2407.8 and 3+ near 1605.5#hplc-massspec · 2026-01-30factory_direct_fidoes retention time on its own tell you what the compound is#hplc-massspec · 2026-01-30HPLC_Hankco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-01-31assay_not_puritythats co-elution#hplc-massspec · 2026-01-31assay_not_puritydo you trust an area percent from a shallow gradient#hplc-massspec · 2026-01-31ten_of_tenrelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-01-31gradient_gregupdate on the earlier thing does retention time on its own tell you what the compound is#hplc-massspec · 2026-01-31VialBotReminder for coelution_cai: dose day is today. Set 7 days ago.#food-and-training · 2026-01-31group_buy_gwenthe retention time on this one is different from the last lot, problem#coa-reading · 2026-02-01fern_freezesco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-02-01ms_ms_miracoming back to this the retention time on this one is different from the last lot, problem#coa-reading · 2026-02-02oasis_olaco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-02-02void_volumeretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-02-06knees_firstdoes retention time on its own tell you what the compound is#hplc-massspec · 2026-02-06assay_not_purityretention time shifts between runs are normal. relative retention time is the number to compare the honest summary is that a…#coa-reading · 2026-02-07reship_ritaretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-02-08reship_ritathe retention time on this one is different from the last lot, problem#coa-reading · 2026-02-08HPLC_Hankunrelated but do you trust an area percent from a shallow gradient#hplc-massspec · 2026-02-08HPLC_Hankbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-02-08assay_not_purityco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-02-08ms_ms_mirathats co-elution#hplc-massspec · 2026-02-08pioneer_piashallow gradient#hplc-massspec · 2026-02-08lower_frequencyretention time shifts between runs are normal. relative retention time is the number to compare#coa-reading · 2026-02-09monoisotopicdo you trust an area percent from a shallow gradient#hplc-massspec · 2026-02-09HPLC_Hankwhats a normal gradient for a peptide this size#hplc-massspec · 2026-02-09HPLC_Hankdoes retention time on its own tell you what the compound is#hplc-massspec · 2026-02-09peak_splithow do you tell co-elution from a clean single peak#hplc-massspec · 2026-02-09peak_splitthats co-elution#hplc-massspec · 2026-02-09bac_water_billdoes retention time on its own tell you what the compound is#hplc-massspec · 2026-02-10lot_number_loushallow gradient#hplc-massspec · 2026-02-10cold_chain_cmdrco-elution is the failure mode that a beautiful single peak is most likely to be hiding#hplc-massspec · 2026-02-10HPLC_Hankbaseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-02-10amber_vialretention time is a hint#hplc-massspec · 2026-02-12amber_vialshallow gradient#hplc-massspec · 2026-02-12area_percentok so baseline drift on a gradient is normal. baseline drift on an isocratic hold is your column#hplc-massspec · 2026-02-12void_volumerelative retention time against a standard is comparable between labs. absolute minutes are not#hplc-massspec · 2026-02-12truncation_truretention time is a hint, not a fingerprint. two different peptides can co-elute perfectly happily#hplc-massspec · 2026-02-12see_a_clinicianco-elution is the failure mode that a beautiful single peak is most likely to be hiding, your mileage will differ#hplc-massspec · 2026-02-15void_volumeretention time is a hint#hplc-massspec · 2026-02-15assay_not_puritythe retention time on this one is different from the last lot, problem#coa-reading · 2026-02-16amylin_amyfollow up retention time shifts between runs are normal. relative retention time is the number to compare, thats just me#coa-reading · 2026-02-17amylin_amysingle wavelength detection can miss a co-eluting impurity that does not absorb there#coa-reading · 2026-02-17