Determination of Hg in seawater by inductively coupled plasma mass spectrometry after on-line pre-concentration

A method for the determination of Hg in seawater by inductively coupled pla sma mass spectrometry, after an on-line separation and pre-concentration, i s described. The matrix separation was accomplished by retention of the Hg complex with the ammonium salt of O,O-diethyl dithiophosphoric acid on C-18 immobilized on silica in a micro-column. Before pre-concentration, the sea water sample was acidified with HNO3 to 0.14 mol l(-1). Methanol was used a s the eluent, which was introduced into the conventional pneumatic nebulize r of the instrument. External calibration with aqueous analytical solutions , submitted to the same procedure, was used. An enhancement factor of 16 wa s obtained, and the limit of detection was 5 ng l(-1). The sample consumpti on was 2.3 ml per determination, and the sampling frequency was 21 h(-1). T he accuracy was tested by comparison with vapor generation inductively coup led plasma mass spectrometry. The agreement between the Hg concentrations m easured by the two methods in the seawater samples was good. (C) 2001 Elsev ier Science B.V. All rights reserved.