Abstract: A phasing system is provided for parallel channel continuous flow systems wherein the individual test channels have different flow times although intersample timing is constant. A phasing sample is introduced and its presence is sensed at the output of each of the parallel test channels. The presence of the phasing sample is detected by means of an analog detector, a digitizer, and a digital computation system. After detection of the phasing sample in a channel the time at which it arrives at the detector is marked. Since intersample timing is constant and the time when the sample is introduced into the parallel channels is known, the time at which subsequent samples should arrive at the detector can be established for each channel. Time zones are opened for each channel and each detector which correspond to the times plus or minus a certain tolerance at which subsequent samples can be expected to arrive.