CHIRALPAK® Protein-Based

Columns packed with the immobilized protein stationary phases (PSPs) are successfully utilized by scientists for separation and characterization of chiral compounds in a great number of applications, ranging from drug discovery and quality assurance of marketed drugs to environmental monitoring.

The chiral selector for the CHIRALPAK® AGP is a1-acid glycoprotein (AGP), while human serum albumin (HSA) is the chiral selector for CHIRALPAK HSA. The chiral selector for CHIRALPAK CBH is cellobiohydrolase, a stable enzyme. The three chiral selectors are immobilized on 5-µm spherical silica particles. The PSPs function entirely in the reversed-phase chromatographic mode, using buffers with low organic modifier content and at moderate pH values. Enantioselectivity can easily be controlled or improved by changes in the mobile phase composition: pH, buffer and organic modifier types and concentrations.

All PSP selectors are packed in columns with 3, 4 and 10mm internal diameter to cover separations on both analytical and semi-preparative scales.

 

PSP Enantioselectivity

Enantioselectivity can easily be controlled or improved by changes in the mobile phase composition: pH, buffer and organic modifier types and concentrations. The mobile phases, with which these columns are used, are compatible with MS and MS/MS analyses. However, the previously established guidelines on method development for the PSP columns involved the extensive use of phosphate buffers, which required a lengthy optimization process of identifying a buffer system better suited for the MS analysis. A poster on LC-MS Compatible Reversed-Phase Screening Strategies on Daicel Protein-Based Columns, presented at the Chirality 2010 meeting by T. Zhang, et al., describes approaches to simplify screening and optimization methodology for separation of diverse chiral compounds on CHIRALPAK PSPs.



The approaches to rational and simplified method development were described in detail in the paper New approaches of LC-MS compatible method development on a1-acid glycoprotein-based stationary phase for resolution of enantiomers by HPLC, published by T. Michishita, et al., in the Wiley Journal of Separation Science (J. Sep. Sci. 2010, 33, 3627-3637). One of the goals of this research work was to achieve a high success rate for separating diverse chiral compounds by applying a newly devised method development strategy, which is simple, general and LC-MS compatible. A total of 76 compounds were used for the evaluation of CHIRALPAK AGP. The effect of chromatographic parameters, such as pH, the organic modifier, and buffer types, on enantiomer resolution was carefully considered. The screening methodology, described in the paper, was tested on these 76 chiral compounds. The identified success rate of the enantiorecognition by CHIRALPAK AGP was over 92%.

 

Generic Drug Analysis

 

The PSP columns are successfully applied to enantiomeric purity analyses of bulk drugs and also of finished drug formulations. The United States Pharmacopeia (USP) is the widely used and continuously revised compendium of standardized test methods. The USP sets standards to ensure the quality and safety of medicines and pharmaceuticals. The USP collection offers over 4,000 monographs that contain validated methods of analysis. The USP list the CHIRALPAK AGP brand of L41 column for HPLC methods to test Enantiomeric Purity of the single-enantiomer drug, montelukast sodium (brand name Singulair) and Stereoisomeric Purity of galantamine (Razadyne). CHIRALPAK AGP is also listed by the USP to ascertain Enantiomeric Purity of chiral drugs: ropivacaine ((Naropin) and tenofovir (Viread). HPLC methods are used to ensure that the levels of ropivacaine- and tenofovir-related chiral compounds meet the specified criteria for the impurities being present in the drugs.

 

Drug Monitoring in Wastewater

 

It is the extremely broad applicability and versatility of the PSPs that result in their numerous applications for the analyses of chiral compounds in different matrices. It is important to note that commensurate with the results of a recent study funded by the EPA, the EPA is planning to address potential hazards posed by the presence of pharmaceuticals in domestic water supplies. The results of trace analysis of fluoxetine (Prozac) and its metabolite in wastewater by the combination of the CHIRALPAK AGP and MS were reported by V.K.H. Barclay, et al. in the paper Trace analysis of fluoxetine and its metabolite norfluoxetine. Part I: Development of a chiral liquid chromatography – tandem mass spectrometry method for wastewater samples, published in J. Chromatogr. A. (2011), 1218, 5587-5596. Use of CHIRALPAK AGP allowed the enantiomers of norfluoxetine to be resolved for the first time.

Another example of the use of the PSPs, the CHIRALPAK CBH, was presented by B. Kasprzyk-Hordern, et al. in the paper Enantiomeric Analysis of drugs of abuse in wastewater by chiral liquid chromatography coupled with tandem mass spectrometry, published in J. Chromatogr. A. 1217 (2010) 4575-4586. The authors discussed the importance of enantiomeric analyses of chiral illicit drugs in both the environmental and forensic fields

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