Expanding the potential of chiral chromatography for high-throughput screening of large compound libraries by means of sub–2μ Whelk-O 1 stationary phase in supercritical fluid conditions

With the aim of exploring the potential of ultra-​fast chiral chromatog. for high-​throughput anal., the new sub-​2 μ Whelk-​O 1 chiral stationary phase (CSP) has been employed in supercrit. fluid conditions to screen 129 racemates, mainly of pharmaceutical interest.By using a 5-​cm long column (0.46 cm internal diam.)​, a single co-​solvent (MeOH) and a 7-​min gradient elution, 85​% of acidic and neutral analytes considered in this work have been successfully resolved, with resoln. (Rs) larger than 2 in more than 65​% of cases. Moreover, almost a half of basic samples that, for their own characteristics, are known to be difficult to sep. on Whelk-​O 1 CSP, have shown Rs greater than 0.3. The screening of the entire library could be accomplished in less than 24 h (single run) with 63​% of pos. score.For well-​resolved enantiomers (Rs roughly included between 1 and 3)​, we show that method transfer from gradient to isocratic conditions is straightforward. In many cases, isocratic ultra-​fast sepns. (with anal. time smaller than 60 s) have been achieved by simply employing, as isocratic mobile phase, the eluent compn. at which the second enantiomer was eluted in gradient mode.By considering the extension and variety of the library in terms of chemico-​phys. and structural properties of compds. and numerousness, we believe that this work demonstrates the real potential of the technique for high-​throughput enantioselective screening.