Memory effect of mobile phase additives in chiral separations on a Chiralpak AD column

Ye, Yun K.; Lord, Barbara S.; Stringham, Rodger W.

doi:10.1016/s0021-9673(01)01491-1

Cited by 62 publications

(30 citation statements)

References 8 publications

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“…27 When developing rapid chiral methods for pharmaceutical compounds with automated column and several mobile phases screening in sequence, the need of an appropriate equilibration time for a column must be taken into account.…”

Section: Resultsmentioning

confidence: 99%

Direct high‐performance liquid chromatographic separation of the enantiomers of an aromatic amine and four aminoalcohols using polysaccharide chiral stationary phases and acidic additive

2007

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The HPLC enantiomeric separation of N-benzyl-alpha-methyl-benzylamine, phenylalaninol, tryptophanol, 2 (diphenylhydroxymethyl)pyrrolidine, and isoproterenol was accomplished in the normal-phase mode using two polysaccharide-derived chiral stationary phases (CSPs) and various n-hexane/2-propanol mobile phases with acidic (TFA) or basic (DEA) additive. The compounds were separated without any derivatization and separation factor range between 2.09 and 1.09 with resolution factor 3.4 and 0.4, respectively. The best separation of the enantiomers of the amine was achieved on amylose tris (3, 5-dimethylphenylcarbamate) CSP with TFA additive in the mobile phase; in acidic conditions, instead, the best enantioseparation of the aminoalcohols was achieved on cellulose tris (3, 5-dimethylphenilcarbamate). A long equilibration time of the CSP when switching from an undoped mobile phase to a doped one is required to obtain reproducible results.

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Section: Resultsmentioning

confidence: 99%

Direct high‐performance liquid chromatographic separation of the enantiomers of an aromatic amine and four aminoalcohols using polysaccharide chiral stationary phases and acidic additive

2007

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“…22 This finding is consistent with a dedicated study on the memory effect of the mobile phase additives on a Chiralpak AD column. 29 Chromato- Table 2.…”

Section: Results Obtained Using Chiralpak Ad Csp With Ethanol As Modimentioning

confidence: 99%

Direct high‐performance liquid chromatographic separation of the enantiomers of venlafaxine and 11 analogs using amylose‐derived chiral stationary phases

2008

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A direct liquid chromatographic enantioselective separation of venlafaxine and 11 analogs was obtained in the normal phase mode using Chiralpak AD. For some compounds, a comparison between the enantioseparation using coated and immobilized amylose tris(3,5-dimethylphenylcarbamate) chiral stationary phases (Chiralpak AD and Chiralpak IA, respectively) was made. The best separations were achieved on Chiralpak AD with ethanol as alcoholic modifier in a mobile phase made basic by DEA addition: separation factor ranges between 2.08 and 1.15 and resolution factor between 7.0 and 1.0. Using the same CSP and 2-propanol doped with TFA as acidic modifier, 10 compounds were enantioseparated with separation factor ranging between 1.40 and 1.04 and resolution factor between 3.1 and 0.3. The use of ethanol as alcoholic modifier also has the advantage of better solubility of the compounds in the mobile phase. The nature of the substituent (electron donating or withdrawing) affects in general the separation factor. A memory effect that involves a long equilibration time of the CSP is present when switching from an acidic mobile phase to a basic one.

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“…Ye et al 4 indicated that a memory effect was not established when both acidic and basic additives were present in the mobile phase. They suggested a cleaning procedure to remove primary amine additives which Fig.…”

Section: Removal Of Memory Effectmentioning

confidence: 99%

“…Separation is obtained on the new column when additives are incorporated in the mobile phase. Ye et al 4 demonstrated a memory effect for acidic additives on CHIRALPAK AD. This demonstration was enabled by a dramatic change in selectivity with ethanesulfonic acid added to the mobile phase.…”

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confidence: 99%

Memory effect of diethylamine mobile phase additive on chiral separations on polysaccharide stationary phases

2004

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The existence of a memory effect for amine additives on polysaccharide chiral stationary phases has often been suggested, but not clearly demonstrated. Demonstration of this effect is made difficult by the uncertainty as to which analytes benefit from use of amine additives and, typically, an unclear history of column use. In this work, analytes were selected for differences in their behavior with and without additives. Columns were used with no prior history. A persistent memory effect was demonstrated on a CHIRALPAK AD-H column in hexane-based mobile phases. This effect was short-lived, with polar organic mobile phases. Memory was short-lived on a CHIRALCEL OJ-H column. Flushing with isopropanol was shown to remove most of the memory effect. Compounds expected to require amine additives on CHIRALCEL OD-H column did not. Acid treatment of the AD-H and OD-H columns changed their performance, which was subsequently restored by the incorporation of amine.

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Memory effect of mobile phase additives in chiral separations on a Chiralpak AD column

Cited by 62 publications

References 8 publications

Direct high‐performance liquid chromatographic separation of the enantiomers of an aromatic amine and four aminoalcohols using polysaccharide chiral stationary phases and acidic additive

Direct high‐performance liquid chromatographic separation of the enantiomers of an aromatic amine and four aminoalcohols using polysaccharide chiral stationary phases and acidic additive

Direct high‐performance liquid chromatographic separation of the enantiomers of venlafaxine and 11 analogs using amylose‐derived chiral stationary phases

Memory effect of diethylamine mobile phase additive on chiral separations on polysaccharide stationary phases

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