A detector system that contains two inlet port coupled to a photoionization chamber. One inlet port allows for the introduction of a test sample. The test sample may contain contaminants, drugs, explosive, etc. that are to be detected. The other port allows for the simultaneous introduction of a standard sample. The standard sample can be used to calibrate and/or diagnose the detector system. Simultaneous introduction of the standard sample provides for real time calibration/diagnostics of the detector during detection of trace molecules in the test sample. The photoizonizer ionizes the samples which are then directed into a mass detector for detection of trace molecules. The detector system may also include inlet embodiments that allow for vaporization of liquid samples introduced to a low pressure photoionizer.