Development of an LC-NMR System Using a Diode Array Detector and a Charged Aerosol Detector

Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for structure determination. However, NMR spectra sometimes suffer from severe signal overlaps. To avoid such signal overlaps, LC-DAD-NMR systems have been used. These systems have enabled the separation of components on a column before NMR detection. However, DAD detection alone is insufficient when the sample does not contain chromophores. To increase the detection coverage, we used a corona charged aerosol detector (CAD) that responded to analytes independent of their physical/chemical characteristics. The established LC-DAD/CAD NMR system was evaluated. Its calculated detection and quantitation limits were 0.25 and 1.0 mu g/peak, respectively. This system was used to analyze rubus extract. Along with glucose and fructose, a small amount of rubusoside was detected by corona CAD and identified by NMR without needing a chromophore.