This invention relates to methods and apparatus for detecting, quantifying,
and/or identifying trace quantities of an anion in the presence of an excess of
another anion. One apparatus comprises a sample loop having a first end adapted
to be connected to a sample-injection device and a second end adapted to be connected
to an inlet of a first separator. An outlet of the first separator has connections
to a first waste port and to an inlet of a first anion suppressor. An outlet of
the first anion suppressor is connected to a first end of a concentrator and alternatively
to waste, the concentrator connected at a second end to a second waste port and
alternatively to a pump. The first end of the concentrator is alternatively connected
to a second separator inlet, and the second separator is connected at an outlet
thereof to an inlet of a second anion suppressor; and an outlet of the second anion
suppressor is connected to a mass spectrometer.
