Mobile phase gradient elution

Mobile-phase Gradient elution-2 minutes, from 20% B to 37% B in 15 minutes, where, A =... 

Mobile-phase Gradient elution of A (o-Hcxanc) and B (Isopropanol) ... 

Mobile phase Gradient elution dependent on column e.g., elute iso-a-acids with methanol water phosphoric acid (75 24 1 v/v/v), then increase proportion of methanol Water ion pair methanol acetonitrile THF (320 9.9 580 40 50 v/v/v/v/v) Methanol water + ion pair b (725 275 v/v) or methanol water + ion pairb (780 220 v/v) Methanol water phosphoric acid 0.1 M EDTA (aq) (812 184 2.5 1 v/v/v/v)... 

Figure 7.11 Separation of four of the compounds of interest employing a mobile-phase gradient. Elution order (1) permethrin, (2) zidovudine, (3) trifluridine, (4) mercaptopurine. Flow = 2 ml/min C02, 150 /xl/min methanol for 1.5 min, 150-450 /d/min in 2.0 min, hold at 450 /d/min column. Deltabond CN (250 x 4.6 mm ID). Oven temperature 60°C UV detection at 254 nm. (Reprinted from Ref. 9, with kind permission of Dr. Alfred Huthig Verlag, GmbH, Heidelerg.)...

Column Zipax SCX 37-44 um (1000x2.1 mm ID), mobile phase gradient elution with A 0.2 M boric acid adjusted to pH 9.3 with 403 sodium hydroxide and B 0.2 M boric acid - acetonitrile -n-propanol (86 12 2) adjusted to pH 9.8 with 40 sodium hydroxide, linear gradient from 0-100 B in 6 min, flow rate 2 ml/min, detection UV 270 nm. Peaks 1, barbitone 2, caffeine 3, morphine 4, 0-acetylmorphine 5, strychnine 6, heroin 7, quinine 8, cocaine. 

Figure 10.12 Chromatogram of tranquillizers (reproduced with permission of Hewlett-Packard). Conditions column, 25cm x 4mm i.d. stationary phase, LiChrosorb RP-8,10pm mobile phase, gradient elution, 30% acetonitrile in water up to 90% acetonitrile in water, 16 min UV detector, 254 nm. Peaks 1 = bromural 2 —carbromal 3 —acetocarbromal 4- — benzyl mandelate.

Why is mobile-phase gradient elution used in HPLC ... 

Figure 2 HPLC elution profile of I and d-amino acids from freshly prepared apple juice (Golden Delicious) derivatized as the isoindoles with (A) o-phthaldialdehyde-W-isobutyryl-l-cysteine (B) o-phthaldialdehyde-Af-isobutyryl-d-cysteine Column Hypersil ODS (250 X 4 mm 5 pm mobile phase, gradient elution (A) = 23 mmol I" sodium acetate (pH 5.95) (B) methanol-acetonitrile (600 50 v/v), linear gradient from 0% B to 53.5% B in 75min flow rate 1 ml min"fluorescence detection (230nm excitation, 445nm emission). (Reprinted with permission from Bruckner H, Haasmann S, Langer M, Westhauser T, and Wittner R (1994). Journal of Chromatography A 666 259-273 Elsevier.)...

LC/MS methods have been published for the analysis of as the mobile phase. Gradient elution was used to increase the ... 

Figure 22 Chromatogram of a reference mixture of pyridine compounds. Conditions column, ODS-2 Spherisorb (125 X 4.6 mm, i.d.) mobile phase, gradient elution with 0.1 M KH2PO4, containing 6 mM tetra-n-butylammonium hydrogen sulfate, at pH 5.5 (eluant A), and methanol (eluant B). Initial conditions 96% A and 4% B, increasing stepwise to 10% B in 5 min, 12% B at 10 min, and 30% B from 13 to 15 min, followed by a return to initial conditions (96% A and 4% B) from 19 to 20 min. Flow rate, 1 mL/ min detection wavelength, 254 nm column temperature, ambient. (From Ref 59.)...

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