F.O. Simon L. P. Greenland F. W. Brown 1975 <p>Arsenic in soil and rock samples may be determined in part-per-million concentrations using a radiochemical-isotope dilution method. Arsenic in the sample plus added As⁷⁶&nbsp;tracer is separated as arsine and determined spectrophotometrically as a molybdenum blue complex. The As⁷⁶&nbsp;activity in the absorbing solution allows corrections for chemical losses. A lower limit of 1 ppm is determinate in a 0.5-g sample.</p> application/pdf en U.S. Geological Survey Spectrophotometric-isotope dilution determination of arsenic in soils and rock article