Automatic on-line chemistry monitoring system having improved calibration unit

A continuous monitoring system for automatically sampling, monitoring and analyzing power plant steam cycle water supplied as samples from various points in a power plant steam cycle includes a control unit with a feedback loop. An ion chromatograph unit provides semi-continuous monitoring of a selected influent fluid sample stream. A calibration unit including a conditioning unit creates a pressure differential in the sample stream and utilizes the pressure differential to inject a mixed standard solution into the influent fluid sample stream, to provide a conditioned influent fluid sample stream having predetermined chemical characteristics; calibration is done with respect to the predetermined chemical characteristics of the conditioned fluid sample stream. The ion chromatograph unit is calibrated with respect to the predetermined chemical characteristics of the selected conditioned fluid sample supplied thereto.