2.3. Analytical methods
Samples were analyzed for antimony using a Thermo
Electron Element 2 single-collector double-focusing magnetic
sector inductively coupled plasma mass spectrometer
(ICP-MS) in low-resolution mode. Analytical accuracy and
precision for the measurements were determined by analyses
of river water standard reference materials NIST 1640, NIST
1643e, and NRC SRLS4. Precisions were within 3% (1s).
Measured and certified values for standards were within the
quoted errors. The limit of detection and method reporting
level are 0.004 and 0.028 ppb, respectively.