Abstract: The present invention generally provides a leak detector having at least two partial pressure analyzers. The leak detector comprises a pumping system, a trace gas detector, and a residual gas analyzer. The leak detector is attachable to a test object, such as a vacuum system, and the pumping system operates to draw a vacuum therein. The residual gas analyzer determines the presence of oxygen, nitrogen, and other components of air in the test object. A trace gas, such as helium, provided to the exterior of the test system is monitored by the trace gas detector which may be a magnetic sector mass spectrometer. The residual gas analyzer and the trace gas detector may be operated simultaneously or independently.