NMR Spectrometers
The School of Chemical and Physical Sciences hosts one of the largest NMR suites in New Zealand with five magnets operating between 300 MHz and 600 MHz.
The 300, 500 and 600 MHz instruments are used primarily for postgraduate research in chemistry. The other two systems, both operating at 400 MHz, are more commonly used to study physical processes such as rheometry and diffusion.
600 MHz
The 600 MHz instrument is a Varian VNMRS system equipped with a 13C-enhanced cryogenic probe purchased in 2005. Operation at 25 K cools the electronics of the probe to such a degree that the thermal noise of electrons in the antennae, wires and pre-amplifiers is significantly reduced and leads to an increase in the signal-to-noise ratio of the detected signal.
The cryogenic probe is a triple-resonance HCN probe and is capable of collecting indirectly-detected 15N spectra which provide insight into molecular structures that would be difficult to obtain otherwise.
The 600 MHz system is used extensively by the School's natural products research groups to determine the structures of very small amounts (less than 500 ug) of marine metabolites.
500 MHz
The 500 MHz Varian INOVA instrument is our workhorse and was purchased from the Varian Apps Lab in 2005. It is equipped with a tri-axial gradient driver, four RF channels and three waveform generators for created shaped selective pulses. Its Zymark SMS-50 autosampler enables up to 50 samples to be queued ahead of time and run automatically by the software.
The Varian AutoX direct broadband probe is usually installed in the magnet although the indirect version of the same probe is also available. With the Protune automatic tuning system, the spectrometer is capable of automatically tuning to any frequency between 50 and 500 MHz to acquire spectra of 1H, 13C, 19F, 29Si, 31P, 127I and 195Pt for example.
300 MHz
The 300 MHz Varian INOVA system is used when a more hands-on approach is needed. It is equipped with Z-gradients and two RF channels, both with waveform generators. It is fitted with a Varian 4-nucleus AutoSwitchable probe which is simultaneously tuned to 1H and 19F on the high-band channel and 13C and 31P on the low-band channel.
The 300 MHz instrument is generally used for any variable-temperature work with spectra routinely acquired as low as -80°C and as high as 60°C.
400 MHz
The two 400 MHz Bruker Avance II instruments are equipped with Bruker GREAT-60 gradient amplifiers. The magnets are both 89 mm vertical wide-bore cryostats.
These spectrometers are used by researchers in the MacDiarmid Institute, studying the rheology and diffusion of soft materials or the flow dynamics of liquids in porous media. Both micro-imaging (up to 15 G/mm) and diffusion (up to 360 G/mm) probes for both systems are available.