An online monitor for trace sodium in high-purity water, and an online monitoring method and device thereof are provided. Under the control of an embedded industrial computer, an injection-calibration system conveys calibrated water samples and to-be-measured water samples to a flame atomization system continuously and stably. The flame atomization system forms a negative pressure field using a high-purity hydrogen-oxygen mixture as carrier gas, draws in the to-be-measured water samples for atomization, mixing and droplet separation, and then ignites a characteristic spectrum which emits sodium at a high-temperature inner cone. A photoelectric sensor system quickly scans the characteristic spectrum of sodium, and outputs a second-order differential modulation sodium spectrum after removing background interferences. A data acquisition system acquires an analog signal of the second-order differential modulation sodium spectrum, converts the analog signal into a digital signal and outputs the digital signal to the embedded industrial computer for real-time monitoring and control.

An online monitor for trace sodium in high-purity water, and an online monitoring method and device thereof are provided. Under the control of an embedded industrial computer, an injection-calibration system conveys calibrated water samples and to-be-measured water samples to a flame atomization system continuously and stably. The flame atomization system forms a negative pressure field using a high-purity hydrogen-oxygen mixture as carrier gas, draws in the to-be-measured water samples for atomization, mixing and droplet separation, and then ignites a characteristic spectrum which emits sodium at a high-temperature inner cone. A photoelectric sensor system quickly scans the characteristic spectrum of sodium, and outputs a second-order differential modulation sodium spectrum after removing background interferences. A data acquisition system acquires an analog signal of the second-order differential modulation sodium spectrum, converts the analog signal into a digital signal and outputs the digital signal to the embedded industrial computer for real-time monitoring and control.