Retention time: difference between revisions

Diff·revision 6 → 7·13:25, 10 Nov 2024

Difference between revision 6 and revision 7 of Retention time. 12 lines changed; the page grew by 618 bytes.

Revision 6 — 12:26, 14 Oct 2024 HypoHildur (talk) add category for method validation 2,283 bytes +256	Revision 7 — 13:25, 10 Nov 2024 Retention_Time_Rae (talk) add the counterion determination method by name 2,901 bytes +618
1	{{Infobox concept	1	{{Infobox concept
2	\| name = Retention time	2	\| name = Retention time
+		3	\| image = chromatogram.svg
3	\| Symbol = t_R	4	\| Symbol = t_R
4	\| Depends on = Column, mobile phase, gradient, flow, temperature	5	\| Depends on = Column, mobile phase, gradient, flow, temperature
⋮		⋮
18		19
19	The strongest form combines retention matching with an orthogonal determination — [[Mass spectrometry\|mass confirmation]] or a second chromatographic mode with different selectivity. This is what pharmacopoeial identification tests specify.{{r\|usp621}}	20	The strongest form combines retention matching with an orthogonal determination — [[Mass spectrometry\|mass confirmation]] or a second chromatographic mode with different selectivity. This is what pharmacopoeial identification tests specify.{{r\|usp621}}
+		21
+		22	== Drift and its causes ==
+		23	\| Cause \| Effect \|
+		24	\|---\|---\|
+		25	\| Column ageing \| Progressive shift, usually earlier \|
+		26	\| Temperature change \| Shift in either direction \|
+		27	\| Mobile-phase preparation \| Small shifts, run to run \|
+		28	\| Instrument dwell volume \| Systematic offset between instruments \|
+		29	\| Gradient delay \| Same, for gradient methods \|
+		30
+		31	Dwell-volume differences are the reason a method transferred between instruments often needs adjustment: the delay between the pump forming a gradient and it reaching the column differs, so retention shifts even with identical settings.{{r\|usp621}}
20		32
21	== References ==	33	== References ==