The latest development in the field of hyphenated techniques is the usage of a Solid Phase Extraction (SPE) system as an interface between liquid chromatography (LC) and NMR.
The use of loop collection & transfer (BPSU-36/2) is an established analysis technique in LC-NMR. However, the samples are measured in the original eluent and concentration as provided by the chromatographic system. Interferences with the (protonated) eluents and low concentrations due to limited on-column loading are programmed.
For the process of LC-SPE NMR a chromatographic separation is done and the peaks of interest are trapped on an individual SPE cartridge after the column.
The peak selection is done either by UV detection or by evaluation of the on-line registered MS or MSn spectra. The trapped peaks are prepared for the NMR measurement (washed, dried, ...), the NMR spectrometer is equipped with a special flow probe and connected via capillaries to the SPE system. The peaks are transferred with a suitable (deuterated) solvent through the capillaries directly into the flow NMR probe or into 1.7-3mm NMR tubes in a SamplePro Tube liquid handler.