Frequency-swept HSQC sequences for high-throughput NMR analysis

This article describes new versions of the DEPT phase-edited heteronuclear single quantum correlation (HSQC) pulse sequence with sensitivity enhancement. The sequences incorporate frequency-swept carbon and proton pulses. The new experiments are inherently robust, well-suited for a high-throughput setting in which sample-to-sample variations may be ignored. The observed signal has the obvious benefit of sensitivity enhancement resulting from the preservation of two magnetization transfer pathways. The two pathways are maintained even in the version of the sequence in which all pulses are frequency-swept. There is an additional signal gain of roughly 10% that derives from the use of both proton and carbon frequency-swept pulses. Furthermore, the sequences use J compensation to provide optimal signal over a range of heteronuclear coupling constants. We demonstrate that the new sequences offer good sensitivity and perform well even when the NMR probe is deliberately mistuned.