Mercury and lead in a single strand of pinnule of snow petrel (Pagodroma Nivea) in the Antarctic

Abstract

The direct determination of most trace elements in natural water samples is still very difficult even if the high-sensitivity atomic analytical instrument, such as ICP-MS, is available. The reasons are (1) the natural concentrations of most trace elements in the water samples are extremely low, and (2) the concentrations of major ions (Na, Mg, K and Ca) are very high in some water samples, such as seawater. Therefore, this work presents syringe-driven chelate-minicolumns as a preconcentration method for trace elements in natural water for the determination by ICP-MS. Laboratory-made syringe-driven chelate-minicolumns were constructed with three kinds of parts, i.e., two kinds of syringe filters and a kind of chelating resin (200-400 mesh) with iminodiacetate as functional group. All of these parts are commonly available; therefore the present method may be easily reproduced in any laboratories. The samples were adjusted to a certain pH conditions (pH 5 for fresh water and pH=6 for seawater) and loaded to the minicolumn so that trace elements could be adsorbed on the resin packed in the minicolunm. Thereat~er, trace elements adsorbed on the minicolumn were eluted with 2 M nitric acid. Trace elements in the eluent were measured with ICP-MS instrument, where Ge, In, Re, and TI were added as internal standard. In the case of seawater, 1 M ammonium acetate was passed through the minicolumn to eliminate major ions prior to the elution of trace elements. A common-size minicolumn with bed volume of ca. 0.08 mL and a down-sized minicolumn with bed volume of ca. 0.01 mL were capable for the high-flow-rate (with flow rate of ca. 10 mL/min) preconcentration and for the high-concentration-factor (100-fold preconcentration using only 50 mL of sample) preconcentration of trace elements in na~tral water, respectively. More than 20 trace elements, including all natural rare earth elements, in natural water could be preconcentrated with good recovery values exceeding 80%. The present minicolumns were successfully applied to the analysis of trace elements in river water, lake water, seawater, and submarine hydrothermal fluid. Because the present minicolumns are of the syringe driven type, they are also portable and could be easily applied to the on-site pretreatment of natural water samples.