Improvement of method for semi-automatic determination of nitrate in seawater based on program-controlled injection pump coupled with cadmium-copper reduction column
The cadmium-copper reduction method is widely utilized for determining the nitrate content in seawater,and it is also the recommended standard method in China's marine monitoring specifications.However,this method currently requires manual monitoring to prevent over-emptying of the cadmium column,and have difficulties in flow rate control,while other issues also existing.In this study,we introduce a program-controlled syringe pump at the end of the cadmium-copper reduction column.This innovation effectively eliminates the possibility of over-emptying the cadmium column and enables precise flow rate control ranging from 5-20 mL/min.To evaluate the performance of the new device,we compared its results with the conventional device for determining standard solutions.The improved device exhibited lower relative standard deviation(0.4%),and the time to pass the column(5.0 min).Additionally,it demonstrated a lower detection limit of 0.05 μmol/L.These indicate that the improved device has superior precision,accuracy,and higher efficiency.Furthermore,we conducted a comparison before and after the improvement using seawater samples from the Qingdao coastal area.The results showed no significant differences,demonstrating good consistency.Therefore,the incorporation of a programmed syringe pump brings about a more precise and convenient operation for the Cd-Cu reduction method,rendering it suitable for widespread use in front-line marine monitoring units.
NETL
NSTL
万方数据
维普
