January 19, 2010.  We unpacked our new Agilent GCMS today. It comes with a container of fine alumina abrasive. I’ve never had to maintain one before so this has been an education. It has a triple MSD (mass selective detector) on it for what amounts to a noise cancellation feature. This increases the signal to noise ratio of the output substantially. I never realized that the MSD was off-axis relative to the quadrapole electrodes. The ion beam is steered 90 degrees into the MSD by a 10 kV post that also accelerates the beam.

Oh yes, the abrasive is for polishing the metal surface that sits against the high vacuum seal of the mass analyzer chamber. It struck me as amusing that a mass spec comes with a supply of abrasives. Now it makes sense.