Separation of dithiothreitol and dithioerythritol by an open tubular capillary electrochromatographic column with a MOF modified by histidine as stationary phase

A separation and determination method of dithiothreitol (DTT), as an important small molecule reducing agent, and dithioerythritol (DTE), as a C3-epimer of DTT, was developed by capillary electrochromatography. A functional MOF (His-ZIF-93) was first prepared by using ZIF-93 (synthesized via coordination between 4-methylimidazole-5-carbaldehyde and Zn2+) as the framework and D-histidine (D-His) as a modifier, and then was bonded to the inner wall of the capillary column to obtain His-ZIF-93 column by Schiff base reaction. The results showed that the baseline separation of DTT and DTE was easily obtained under a very wide experimental conditions with a extremely short analysis time with less than 3 min. Separation mechanism was proved by the binding constant experiments. There was a good linearity between concentration (0.10-5.0 mg/mL) and peak area of DTT and DTE (R2 ≥ 0.996), and the relative standard deviations for the peak area and the retention time were less than 0.93%. The average impurity content of DTE in a 5.0 mg/mL DTT were 0.79%. Thus, the method was able to realize for the simple and fast separation and precise quantification of DTT and DTE.