Abstract:

The separation of chiral compounds using common dimension chiral chromatographic columns consumes a large of mobile phase and a long time. This is mainly due to the fact that the inner diameter of common chiral chromatographic column is usually 4.6 mm and the column length is 25 cm. The larger column volume requires more mobile phase to drive the sample through the separation process， and the longer column length increases the migration path of the sample within the column， resulting in an extended separation time. Moreover， the common dimension chiral column is filled more stationary phase which is usually expensive. The micro-packed column， due to their structural characteristics， with inner diameters typically controlled and a few millimeters and significantly shortened column lengths， show broad application prospects in improving separation efficiency， achieving miniaturization of separation instruments， and reducing the consumption of stationary and mobile phases. In this study， amylose tris（3，5-dimethylphenylcarbamate） （ADMPC） was used as the chiral selector. Amylose molecules have a helical structure， and the size of the helical cavity and the chiral environment can be regulated through substituent modification. The introduction of 3，5-dimethylphenylcarbamate groups can enhance the hydrophobic interaction， hydrogen bonding， and π-π stacking between ADMPC and chiral compounds， thereby improving chiral recognition ability. Due to its excellent selectivity and wide applicability， it has become a research hotspot in the field of chiral separation. Two 10-millimeter-long micro-packed columns were prepared by coating ADMPC on silica gel particles with diameters of 500 nm and 1.7 μm， respectively， and were named ADMPC-1 （500 nm silica gel） and ADMPC-2 （1.7 μm silica gel）. On these two micro-packed columns， 23 and 20 racemates， respectively， including various types such as alcohols， esters， ketones， and acids， achieved good separation effects. Notably， there are certain differences in separation selectivity between these two micro-packed columns， showing a certain degree of complementarity. Moreover， these two micro-packed columns also exhibit this complementary property compared with the commercial Chiralpak AD-H chiral column. The most significant advantage of micro-packed columns is the short separation time， most compounds can be separated within 8 min， and many compounds can achieve baseline separation. Commercial chiral columns， due to their longer column lengths， usually require 15-30 min or even longer for sample retention time， and some compounds may not achieve baseline separation due to insufficient resolution. The shorter column length and optimized small size silica gel of micro-packed columns significantly reduce the retention time of samples and improve resolution， which is of great significance for high-throughput screening experiments （such as chiral compound screening in drug development）， and can significantly improve experimental efficiency. At the same time， due to the reduced column volume， the amount of mobile phase used is also very small. Common dimension chiral columns usually consume tens to hundreds of milliliters of mobile phase for one analysis， while the micro-packed columns in this study only require a few milliliters or even less for one analysis. This greatly reduces the generation of organic waste and lowers environmental pollution， in line with the development concept of green chemistry. In addition， compared with common dimension chiral columns， the amount of stationary phase in micro-packed columns is significantly reduced， significantly lowering the cost； at the same time， it can also provide suitable column dimemsion for the development of miniaturized chromatographic systems.

Key words: high performance liquid chromatography, miniature column, amylose tris（3, 5-dimethylphenylcarbamate）, silica gel