Solenoidal microcoils

The size of sample required has been reduced by a number of technical developments including micro inverse probes and micro cells (references in Martin et al. 1998), and has been reduced even further using a newly developed 1.7-mm submicro inverse-detection gradient probe (Martin et al. 1998). The combined use of inverse detection probes with solenoid microcoils has also been developed to reduce sample volumes for NMR (Subramanian and Webb 1998). 

Subramanian R, AG Webb (1998) Design of solenoidal microcoils for high-resolution C NMR spectroscopy. Anal Chem 70 2454-2458. ... 

The development of microcoil techniques has been reviewed by Minard and Wind [24, 25] and by Webb [26]. In a more recent publication Seeber et al. reported the design and testing of solenoidal microcoils with dimensions of tens to hundreds of microns [27]. For the smallest receiver coils these workers achieved a sensitivity that was sufficient to observe proton NMR with an SNR of unity in a single scan of 10 pm3 (10 fL) of water, containing 7 x 1011 proton spins. Reducing the diameter of the coil from millimeters to hundreds of microns thus increases its sensitivity greatly, allowing analysis of pL to pL sample volumes. 

FIGURE7.14 Instrumental setup for CE-NMR with online NMR detection using a solenoidal microcoil probe. 

Figure 6.45 Microbore LC-NMR layout. A Microbore HPLC system with a 0.5 mm X 150 mm C18 column is interfaced to a solenoidal microcoil probe. The transfer capfllary is connected to the NMR flow cell with a polyamide resin. Reproduced from [85] with permission. Copyright 1999 American Chemical Society.

Figure 7.3.1.4 Microfabricated RF coils (a) photograph of a 325 pm-diameter solenoidal microcoil fabricated by microcontact printing. Adapted by permission of the American Institute of Physics, from Rogers, J. A., Jackman, R. J., Whitesides, G. M., Olson, D. L. and Sweedler, J. V., Appl. Phys. Lett., 1997, 70, 2464. (b) Scanning electron micrograph of a planar microcoil with an o.d. of 200 pm and an i.d. of 60 pm...

A. M. Wolters, D. A. Jayawickrama, A. G. Webb, and J. V. Sweedler, NMR detection with multiple solenoidal microcoils for continuous-flow capihary electrophoresis, AnaZ. Chem. 74 (2002), 5550-5555. 

The first microbore LC-NMR experimental results were published in 1995 [32]. In this report, a solenoidal microcoil was wrapped around a fiised-silica capillary (50 nL), directly coimected to an LC microbore column, situated in the bore of the... 

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