Fingerprinting of ground water by ICP-MS. Progress report, January 1, 1995--March 31, 1995

This report contains the results of the chemical analysis of water from springs in Ash Meadows National Wildlife Refuge, Nevada. Each spring was sampled two to five times between July, 1992 and March, 1994. Samples were collected and analyzed by the Harry Reid Center for Environmental Studies (HRC) Environmental/Analytical Laboratory, at the University of Nevada, Las Vegas. Chemical analyses included major cations and anions and trace elements. The analyses for the major anions were performed by atomic absorption (AA) spectrophotometry, the anions by ion chromatography (IC) and the trace elements by inductively coupled plasma - mass spectrometry (ICP-MS). The standard operating procedures (SOP) used for each method are included. The concentrations of the analytes range from the part per million (ppm) levels for the major cations and anions to the sub part per trillion (ppt) levels for a number of the trace elements. Approximately nine orders of magnitude are covered from the highest to the lowest concentrations. The formation of molecular species in the ICP-MS, plasma produces false positives for a number of elements. None of the elements reported here, that the HRC is aware of, are subject to these isobaric interferences, with the exception of europium (Eu). Europium values are reported for samplings four and five where the HRC used an extraction procedure that extracted Eu but not barium (Ba), whose oxides cause the interference. In order to overcome matrix effects in the samples from high concentrations of cations and other elements, the method of standard additions was instituted for the analysis of samplings four and five as an alternative to external standardization. It is believed that these data, and those for the Death Valley Spring reported in January, 1995 are the first efforts at such a comprehensive trace element analysis of ground waters. HRC has had to develop, test, and refine sampling and analysis procedures throughout the course of this study