Scope of partial least-squares regression applied to the enantiomeric composition determination of ketoprofen from strongly overlapped chromatographic profiles.
Valuable quantitative information could be obtained from strongly overlapped chromatographic profiles of two enantiomers by using proper chemometric methods. Complete separation profiles where the peaks are fully resolved are difficult to achieve in chiral separation methods, and this becomes a particularly severe problem in case that the analyst needs to measure the chiral purity, i.e., when one of the enantiomers is present in the sample in very low concentrations. In this report, we explore the scope of a multivariate chemometric technique based on unfolded partial least-squares regression, as a mathematical tool to solve this quite frequent difficulty. This technique was applied to obtain quantitative results from partially overlapped chromatographic profiles of R- and S-ketoprofen, with different values of enantioresolution factors (from 0.81 down to less than 0.2 resolution units), and also at several different S:R enantiomeric ratios. Enantiomeric purity below 1% was determined with excellent precision even from almost completely overlapped signals. All these assays were tested on the most demanding condition, i.e., when the minor peak elutes immediately after the main peak. The results were validated using univariate calibration of completely resolved profiles and the method applied to the determination of enantiomeric purity of commercial pharmaceuticals.
LIDMA (Laboratorio de Investigación y Desarrollo de Métodos Analíticos) y División Química Analítica, Universidad Nacional de La Plata, La Plata, Argentina.
Juan M
JM
Padró
LIDMA (Laboratorio de Investigación y Desarrollo de Métodos Analíticos) y División Química Analítica, Universidad Nacional de La Plata, La Plata, Argentina.
Jaiver
J
Osorio-Grisales
Departamento de Química Analítica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Instituto de Química de Rosario (IQUIR-CONICET), Rosario, Argentina.
Juan A
JA
Arancibia
Departamento de Química Analítica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Instituto de Química de Rosario (IQUIR-CONICET), Rosario, Argentina.
Alejandro C
AC
Olivieri
LIDMA (Laboratorio de Investigación y Desarrollo de Métodos Analíticos) y División Química Analítica, Universidad Nacional de La Plata, La Plata, Argentina.
Cecilia B
CB
Castells
D000465:Algorithms; D002138:Calibration; D002845:Chromatography; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D007660:Ketoprofen / Q000032:analysis*; D016018:Least-Squares Analysis; D057230:Limit of Detection; D008962:Models, Theoretical; D015999:Multivariate Analysis; D015203:Reproducibility of Results; D012984:Software; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism
D012997:Solvents; D007660:Ketoprofen
Chiral analysis; Enantioresolution; Ketoprofen; Liquid chromatography; Multivariate calibration