Determination of Heavy Metal Ions in Water by Terahertz Time-Domain Spectroscopy
Terahertz time-domain spectroscopy was used to collect time-domain data of solutions.After de-noising and time-domain analysis,linear models were established for mercury,cadmium and copper ion solu-tions at frequencies of 1.7 THz,0.7 THz and 1.2 THz respectively,and the determination coefficients with the best fitting effect were 0.969,0.896 and 0.932,respectively.The method detection limit were from 0.001 mg/L to 0.002 mg/L,the RSD of 6 measurements of spiked blank samples was 2.0%,and the recoveries were from 94.0%to 102%.Applying this method in monitoring practical water samples from two inlets of a sewage treat-ment plant,mercury ion was not detected.