在线控压消解-串联镉圈去盐法测定海水中溶解态总氮OA北大核心

The measurement of dissolved total nitrogen in seawater by online digestion produces active chlorine,which causes abnormal bubble partition and instability,resulting in poor accuracy and stability of the monitoring data.This study established an automatic method for determining the total dissolved nitrogen in seawater by opti-mizing the digestion reagent formulation.This was achieved by applying online controlled pressure injection from a gas cylinder to separate the liquid flow and using a serial cadmium ring device to remove salinity interference.The method has a good linear relationship in 0-2.00 mg/L,and its detection limit is 0.010 mg/L.The standard deviation of the parallel sample is 5.1%-7.0%,and the spike recovery rate is 93.0%-101%.The relative deviation of the ac-tual sample determination results compared with HY/T 147.1-2013 was 0.33%to 3.7%.Results show that the online controlled pressure digestion and serial cadmium ring desalting method has the following advantages:strong an-ti-interference ability,good consistency of bubble separator flow fragments,good state stability of the instrument,and enhanced and continuous monitoring ability.According to quality control standards,the method's precision and accuracy,as well as measurement results for actual sample results,meet the specified requirements.Further,the detection limit is lower than that of the existing standards.