Determination Of Enantiopurity Research Articles

Localized Partitioning of Enantiomers in Solid Samples of Sulfoxides: Importance of Sampling Method in Determination of Enantiopurity.

Localized partitioning of amorphous enantioenriched aryl benzyl sulfoxides in the solid state can lead to substantial variation in enantiopurities, even for sulfoxides which do not show detectable levels of self-disproportionation of enantiomers (SDE) during chromatography on an achiral stationary phase. The importance of preparation of representative samples of enantioenriched sulfoxides for chiral HPLC to enable reproducible results is clear.

Enantiopurity Determination of the Enantiomers of the Triple Reuptake Inhibitor Indatraline

The present study describes the development of two approaches for the determination of the enantiopurity of both enantiomers of indatraline. Initially, a method was developed using different chiral solvating agents (CSAs) for diastereomeric discrimination regarding signal separation in (1)H nuclear magnetic resonance (NMR) spectroscopy, revealing MTPA as a promising choice for the differentiation of the indatraline enantiomers. This CSA was also tested for its ideal molar ratio, temperature, and solvent. Optimized conditions could be achieved that made determination of enantiopurity for (1R,3S)-indatraline up to 98.9% enantiomeric excess (ee) possible. To quantify even higher enantiopurities, a high-performance liquid chromatography (HPLC) method based on a modified β-cyclodextrine phase was established. The influence of buffer type, concentration, pH value, percentage and kind of organic modifier, temperature, injection volume as well as sample solvent on chromatographic parameters was investigated. Afterwards, the reliability of the established HPLC method was demonstrated by validation according to the ICH guideline Q2(R1) regarding specificity, accuracy, precision, linearity, and quantitation limit. The developed method proved to be strictly linear within a concentration range of 1.25-1000 μM for the (1R,3S)-enantiomer and 1.25-750 μM for its mirror image that enables a reliable determination of enantiopurities up to 99.75% ee for the (1R,3S)-enantiomer and up to 99.67% ee for the (1S,3R)-enantiomer.

Determination of L‐ and D‐Enantiomers of Leucine Using Amperometric Biosensors Based on Diamond Paste

Four amperometric biosensors, based on diamond paste, are proposed for the determination of the enantiopurity of leucine. The design of the biosensors used physical immobilization in diamond paste of L‐amino acid oxidase for the assay of L‐leucine and D‐amino acid oxidase for the assay of D‐leucine. The response characteristics of the different diamond paste based biosensors were obtained and compared. The linear concentration ranges for the biosensors were in pmol/L to nmol/L magnitude order. The biosensors showed high reliability for the determination of enantiopurity of leucine as a raw material.