Current Instrumentation

CURRENT

INSTRUMENTATION

Autospec-Q (VG/Micromass) Photo

The hybrid high resolution quadrupole mass spectrometer was purchased in 1992 when the demand for new ionization techniques, elemental composition, high mass, and MS/MS data exceeded the capabilities of our existing quadrupole mass spectrometers. Samples can be introduced into the Autospec-Q from the GC, in-source glass cup, in-source resistively heated platinum wire coil, or from static or dynamic liquid secondary ion mass spectrometry probes (“LSIMS”; similar to fast atom bombardment or “FAB”). Samples are ionized by electron ionization (at energies from 8 to 250eV), chemical ionization or the LSIMS technique. Our system has a mass range up to 4500 Da (“a.m.u.”) at full accelerating potential (8KV) and is quite capable of achieving 5000 resolution at scan speed and range appropriate for use with GC introduced samples. At slower scan speeds or narrower mass range, actual resolutions of more than 20,000 are quite possible. MS/MS is possible either by linked scan techniques, or using the quadrupole stage.

DeltaPlus (Finnigan-MAT) Photo

The stable light isotope mass spectrometer was added in 1997 particularly to provide compound specific d¹³ C isotopic data. In compound specific mode, compounds are separated using an HP 6890 GC with Gerstel PTV/CIS4 injection system and modified for two-dimensional GC then oxidized to CO2 in the Finnigan GC combustion interface before being sent into the MS source. We have significantly modified the combustion interface to increase robustness and serviceability. If isotopic data is desired for bulk samples such as sediments or biological materials, the GC is replaced with the elemental analyzer. Using this mode, and with significant modifications to the EA, we have determined d¹⁵N in pigments at levels as low as 150nM.

Elemental Analyzer Model 1108 (Carlo Erba) Photo

The elemental analyzer allows for the determination of the amount of carbon, hydrogen, nitrogen and sulfur in a bulk sample. Samples are weighed into tin boats, which are then dropped into an oxygen rich gas stream in the combustion tube. As the tin flash-combusts at 1700^°C, the sample is also rapidly and fully combusted. The resulting gases are then separated on a packed GC column and quantified using a TCD.

Avance 400 DPX (Bruker) Photo

This nuclear magnetic resonance spectrometer was acquired by the Facility in 2000 and replaced our vintage 1989 Bruker AC-300. The actively shielded magnet and fully digital electronic brings us once again to the state-of-the-art in NMR. This system is outfitted with three sample probes. The 5mm inverse broadband probe with gradients, tunable from ¹⁰⁹Ag to ³¹P, is our most commonly used probe for ¹H, ¹³C and ¹⁵N. The gradient option is particularly useful with protium spectra from marine or biological samples containing large amounts of water. The 10mm broadband observe probe covers the same spectral range as the 5mm inverse probe, but is optimized to directly observe the non-protium nucleus and holds large volumes of material. The 7mm cross polarization-magic angle spinning (“CPMAS”) probe again covers the same spectral range, but allows for the acquisition of NMR spectra from solid samples.