title: Combination of HPLC "inverted chirality columns approach" and MS/MS detection for extreme enantiomeric excess determination even in absence of reference samples. Application to camptothecin derivatives.
abstract: An original, extremely sensitive and selective HPLC-MS/MS technique for the identification and determination of the minor enantiomer in nonracemic mixtures, even when only one enantiomer is available as reference, is described. The method is based on the so-called "inverted chirality columns approach" (ICCA) and consists of the use of chiral stationary phases (CSPs) available in both enantiomeric forms: in fact, inversion of the elution order for a pair of enantiomers is observed in response to the change in column chirality. This offers two key advantages: first, it is possible to demonstrate the potential enantioselectivity of the system by generating a virtual racemate, and second, it permits the choosing of the right column chirality for trace determination. Combination with MS/MS detection affords high specificity allowing not only high sensitivity (down to 0.0025% of the minor enantiomer) but also unequivocal peak identification in complex mixtures. Applications to semisynthetic derivatives of camptothecin, endowed with antitumor activity, are reported. Moreover, applicability of ICCA is not limited to this class of molecules but generates universal support. Its use might also be extended to other classes of compounds by using other CSPs, available in both enantiomeric forms.
authors.affiliation: Analytical Chemistry Department, R&D, Sigma-Tau S.p.A., Via Pontina Km 30.400, 00040 Pomezia, Rome, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Badaloni
authors.forename: Walter
authors.initials: W
authors.lastname: Cabri
authors.forename: Alessia
authors.initials: A
authors.lastname: Ciogli
authors.forename: Roberto
authors.initials: R
authors.lastname: Deias
authors.forename: Francesco
authors.initials: F
authors.lastname: Gasparrini
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Giorgi
authors.forename: Aristide
authors.initials: A
authors.lastname: Vigevani
authors.forename: Claudio
authors.initials: C
authors.lastname: Villani
mesh_terms: D002166:Camptothecin / Q000031:analogs & derivatives / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002942:Circular Dichroism / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods*; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013237:Stereoisomerism
chemical_list: D002166:Camptothecin