Stability of dissolved metals in environmental aqueous samples: Rideau River surface water, rain and snow

The stability of nickel, lead, copper, cadmium, aluminium and zinc in the d issolved phase of environmental aqueous samples stored in common containers made of various materials was investigated. The samples were Rideau River surface water, rainwater and snow collected at Carleton University, Ottawa, Canada, and had concentrations of the above metals ranging from 0.5 to 90 ng l(-1), and the samples were not acidified. The container materials studi ed were high-density polyethylene (HDPE), polypropylene (PP) and Teflon. Th e rate and the extent of metal loss were dependent on the container materia l, and the metal. Significant losses were observed in both polyethylene and PP containers even over periods as short as 30 min. The time taken for the concentration of the metals in the dissolved phase to be reduced to half w as in the high-density polyethylene containers: 5, 15, and 20 min, for lead , copper and cadmium, respectively. With PP containers, only 15% lead, 25% copper, and 20% cadmium were lost in 2 h of storage. Teflon containers show no loss of dissolved metals from aqueous environmental samples over period s of 24 h, and hence, Teflon is the most suitable container material for th e storage of environmental aqueous samples for trace metals for periods up to 24 h. The loss was the same for all environmental aqueous samples, river water, rainwater and snowmelt. This study shows the importance of the cont ainer material in preserving the sample integrity of environmental aqueous samples. Dissolved zinc was found to be stable in all the container materia ls studied. This aspect needs further experimental verification before any generalization is justified. (C) 1994 Elsevier Science B.V. All rights rese rved.