Effects of Various Acids and Acid Concentration on a ChiroSil® Crown-Ether Chiral Stationary Phase

The Application Notebook

The Application Notebook, The Application Notebook-09-01-2010, Volume 0, Issue 0

The Chirosil RCA(+) and SCA(–) chiral stationary phases (CSPs) are specialized chiral phases very effective in separating various natural and unnatural amino acids as well as compounds containing primary amines.

Ted Szczerba, Regis Technologies, Inc.

The Chirosil® RCA(+) and SCA() chiral stationary phases (CSPs) are specialized chiral phases very effective in separating various natural and unnatural amino acids as well as compounds containing primary amines. They are also successfully used for chiral resolution of chiral amino alcohols including therapeutically active compounds such as amphetamine, phenylethanolamine, octopamine, and norepinephrine. The Chirosil® RCA(+) and SCA() are covalently bonded, show high performance and durability, and have the ability to invert elution order.

Figure 1: Chromatogram Set #1: Column: 15 cm × 4.6 mm Chirosil® SCA(–). Mobile Phase: Methanol/Water (70/30) + acid. Flow Rate: 1.0 mL/min.The experimental analysis was performed on the (D,L)-DOPA in order to study the effects of various acids and acid concentration in the method development process.

An Agilent 1200 HPLC system was used for the study. Chromatography was performed on a Chirosil® SCA(–) chiral column, 15 cm × 4.6 mm. The effect of acidic modifiers in the mobile phase was studied using four acids: trifluoroacetic acid (TFA), perchloric acid, phosphoric acid, and acetic acid. The aim of the study is to demonstrate the scope of method development options and propose a simple way to optimize separation methods.

Table I summarizes the effect of different acids. Chromatogram Set #1 (Figure 1) illustrates the chromatograms.

Table I: Summary of the effect of different acids

Table II summarizes the effect of acid concentration. Chromatogram Set #2 (Figure 2) illustrates the chromatograms.

Table II: Summary of the effect of acid concentration

Figure 2: Chromatogram Set #2: Column: 15 cm × 4.6 mm Chirosil® SCA(–). Mobile Phase: Methanol/Water (70/30) + acid. Flow Rate: 1.0 mL/min.

Conclusions

Different acids and acid concentrations play a key role in the method development process on a Chirosil® Crown Ether column. The behavior of each acid is sample dependant. All four acids should be tried to achieve the best separation and resolution of your test analyte. The separation can be further optimized by adjusting the acid concentration. Other parameters that should be explored are organic modifier choices (ethanol, methanol, acetonitrile, etc.) in the mobile phase and column temperature.

Regis Technologies, Inc.

8210 Austin Ave., Morton Grove, IL 60053

tel. (847) 583-7661; fax (847) 967-1214

Email: teds@registech.com; Website: www.registech.com/chiral/