Frequently Asked Questions
Advantages of the Pirkle-Type Chiral Stationary Phases is Universal Solvent Capability The entire family of Regis’ Pirkle-Type Chiral Stationary Phases (CSP’s) can be used in BOTH normal and reversed-phase solvents. Due to the fact that all of the Pirkle-Type CSP’s are covalently bonded, the columns can tolerate all commonly used mobile phase combinations. We are listing some of the frequently asked questions from the Regis library, for more information please do write to us.
01 How long does it take your columns to equilibrate?
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The column should equilibrate after about 20 column volumes. When you are switching from normal to reversed-phase solvent systems and vise-versa, flush the column with a miscible solvent for 20 column volumes. It should take another 20 column volumes to equilibrate. The equilibration volumes may vary depending on the composition of the mobile phase.
02 Do you always need a modifier in the mobile phase?
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No modifiers are usually needed for initial method development. Modifiers can be used to improve peak shape and resolution when the samples are extremely basic or acidic in nature. Acetic acid or ammonium acetate are recommended for acidic compounds, and triethylamine, diethylamine or ammonium acetate are recommended for basic compounds. Usually 0.1% of modifier is all that is required. Note: Although TFA may be used as a modifier, its use should be limited. Acetic acid usually works as well as TFA.
03 Can I use your columns for SMB chromatography and SFC?
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Yes, many analytical and preparative chromatographers use Pirkle-Type Chiral columns in both SFC and SMB. Special hardware is necessary for certain column dimensions.
04 Does my compound need an aromatic ring to achieve separation on a Pirkle-Type Chiral column?
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In most cases (not all), yes. Chiral recognition occurs at binding sites. The potential π-π interaction that can occur between the aromatic rings on the Chiral selector and the aromatic ring on the sample is a major factor in achieving selectivity. Binding does occur at other sites such as acidic sites, basic sites and steric interaction sites—this is why you do not always need a ring—but by far, the π-π interaction is the major binding site
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05 Can I use the Pirkle-Type Chiral columns in polar organic mode?
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Yes, even though the success rate is very poor, you can use the columns in polar organic mode. We do not recommend dedicating a slot in your method development station for a Pirkle-Type Chiral column if you are exclusively running in polar organic mode. Add another Pirkle-Type column to your normal-phase system to achieve a higher success rate.