Sample integrity is an essential component in understanding the origin of a contaminant. In most cases, elemental speciation is lost during the extraction step through complete dissolution of the sample. This is generally done to decrease potential matrix interferences in the analysis phase. Unfortunately, this also strips most elemental speciation information, making sample attribution (mainly age and form) difficult to impossible. In order to improve current sample extraction protocols, a series of sequential dissolution experiments were undertaken to understand the effects of aging of contaminant sequestration. Dissolutions were conducted using increasingly stringent conditions (weak acid, strong acid, strong oxidizer, and total dissolution). In addition to the sequential dissolutions, geochemical speciation modeling was used to predict the contaminant's speciation in relation to other ions present in solution. Samples were analyzed using a coupled (multi-dimensional) capillary electrophoresis (CE) or liquid chromatography (LC)-inductively coupled plasma-mass spectrometer (ICP-MS).

Early results indicate that solution phase composition has a large effect on speciation of target analytes (as expected); however, their effect on analytical determination was less straightforward with numerous interferences observed. Instrumental interferences were minimized by using co-precipitation techniques and altering dissolution matrix (for example: HCl vs HNO3). Additionally, alternative instrumental techniques such as reversed-phase liquid chromatography and ion chromatography are being investigated to enhance sample separation and quantification.