Can the Agilent Aria MX be connected to a UPS (uninterrupted power supply)?

Yes.   The AriaMX can be connected to a UPS.  However, you do want to make sure that the UPS is rated to deliver at least 1000VA. If the UPS is not rated to deliver at least that much power it will act as a bottleneck to the power the instrument tries to draw and will do more harm than good. Also, If you are connecting multiple Mx instruments to the same UPS you want to make sure that it can deliver sufficient power for each instrument to draw 1000 VA at the same time.