Development of a multi-elemental determination of ultratrace metals in seawater

A method for the multi-elemental determination of ultratrace metals in seaw ater has been developed based on column extraction using 8-hydroxyquinoline immobilized on fluorinated metal alkoxide glass (MAF-8HQ) and determinatio n by ICP-atomic emission spectrometry (ICP-AES) or high-resolution ICP-mass spectrometry (HR-ICP-MS). A clean technique has been realized in the metho d through selecting the reagents and apparatus, cleaning the apparatus, syn thesizing a chelating adsorbent, and sophisticating sampling procedure, as well as filtration and concentration systems. In a preliminary concentratio n experiment, 34 elements were collected quantitatively from synthetic seaw ater of pH 5 and eluted with 0.5 M nitric acid. The measured concentrations of Co, Cu, Fe, Ni, Zn, Mo in a nearshore seawater reference material by IC P-AES after 10-fold concentration closely agreed with the certified values; the relative standard deviations were less than 8%. Lower concentrations o f ultratrace metals in open ocean water were determined by HR-ICP-MS after a 10-fold concentration. Vertical profiles for Co, Cu, Fe, Ni, Zn observed in the northeast Pacific Ocean were in harmony with previous reports. The b lank values for these elements have been improved to less than 0.1 nM. Sinc e the concentrations of alkaline and alkaline earth metals in the eluate we re less than 0.1% of those in seawater, this method was effective for remov ing sea salt.