Inductively coupled plasma emission spectrochemical analysis for trace heavy metals in waste water

Inductively coupled plasma was employed to determine trace heavy metals in waste water by emission spectrometry. Seven iron atomic lines were used to measure the excitation temperature under an analytical condition. From two sets of transition probability values, 5560 K and 6280 K were obtained. Emission intensities of ionic spectral lines were generally stronger than those of atomic lines. Analytical sensitivities for refractory elements were (10100) times as high as those for atomic absorption spectrometry. Ionization interference of coexisting sodium was not marked, but the emission intensity was suppressed when its concentration exceeded 300 ppm, because of the decrease of the amount introduced to the plasma. Coagulant used for the clarification of waste water also lowered the intensity. Variations in a sample introduction rate were corrected by scandium emission intensity (Sc II 361.4 nm) as an internal standard. Chromium, copper, iron, manganese, molybdenum, nickel, tungsten and zinc in waste water were determined without a special sample preparation like solvent extraction. Analytical results by the present method agreed with those by JIS, the difference being only less than 2%.