Page 87 - Application Handbook - Liquid Chromatography
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LAAN-A-LC-E271







            Application                  Supercritical Fluid Chromatography

            News                         Automated Optimization of Chiral Separation


                                         Parameters Using Nexera UC Chiral Screening System
            No.L495





            Chiral compounds contain asymmetric carbons in their   n Separation Parameters for the Chiral Screening System
            molecules and are not superimposable on their mirror   Model sample: The structure of omeprazole is shown
            images. HPLC has been the main method used to      in Fig. 1. Daicel CHIRALPAK /CHIRALCEL  series 12
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            separate such chiral compounds, but in recent years, the   columns for chiral analysis were used for the analysis.
            use of supercritical fluid chromatography (SFC) has been   These columns offer a line of complementary stationary
            gaining attention. The main mobile phase used for chiral   phase columns that are able to separate a wide variety
            SFC is supercritical carbon dioxide, with low polarity,   of chiral compounds. When used in combination with
            low viscosity, and high diffusivity, to which polar organic   the Nexera UC chiral screening system, which features
            solvents (modifiers) are added to control solubility and   a method scouting function, optimal chiral separation
            polarity. Therefore, chiral compound separation by   parameters can be determined easily. In addition, three
            HPLC, which generally uses normal phase conditions,   types of modifiers were used, methanol, ethanol, and
            offers the potential for high speed, low organic solvent   a mixture of acetonitrile and ethanol. Details about the
            consumption, low cost, and low environmental impact.  separation parameters are indicated in Table 1. The optimal
            However, chiral SFC requires  selecting  a variety  of   parameters for chiral separation were comprehensively
            separation parameters, such as columns and modifiers,   selected from the total of 36 possible combinations of
            which can involve large amounts of time and effort. This   modifiers (3 types) and columns (12 types).
            article describes using the Nexera UC chiral screening
            system to automatically optimize the large number of
            separation parameters by switching between up to 12
            columns and various mixture ratios of four types of
            modifiers. This can significantly reduce the effort required.
                                                                            Table 1  Analytical Conditions
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                                                                Column     : CHIRALPAK , CHIRALCEL  Series
                                                                             100 mm L. × 3.0 mm I.D., 3 μm
                                                                Mobile Phase   : A; Super critical fluid of CO2
                                                                             B;  Modifier: Methanol, Ethanol, mixture of
                                                                              Acetonitrile: Ethanol = 3:1 (v:v)
                                                                Time Program   :   B Conc. 20 % (0 - 8 min) → 40 % (8 - 10 min)
                                                                            → 20 % (10 - 14 min)
                                                                Flowrate   : 3 mL/min
                                                                Column Temp.   : 40 °C
                              Omeprazole                        Injection Volume  : 2 μL
                                                                BPR Pressure   : 10 Mpa
             Fig. 1  Sample Used to Evaluate the Method Scouting Function  Detector   : Photodiode Array Detector (Max Plot 210 - 400 nm)




























                                     Fig. 2  Method Scouting Solution Operating Screen for Nexera UC
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