Capabilities for routine analysis of ¹²⁹I/¹²⁷I have recently been developed at LLNL using the Tandem FN system and the newly deployed heavy-isotope high energy beamline. The low energy FN system employs a cesium sputter source producing high intensity ion beams, and a spherical electrode electrostatic analyzer (ESA) providing energy resolution capable of rejecting high-energy sputter tails. Maximum Tandem transmission (12%) occurs in the +5 charge state and at 8MV accelerator voltage. The high energy beamline consists of a 30° magnetic bend and a 45° electrostatic (cylindrical ESA) bend having a 4.4 meter radius and a 5 centimeter plate gap. An ESA plate voltage of ±110 kV is used for ¹²⁹I. Iodine-127 is measured in an off-axis Faraday cup positioned on the high energy beamline. Beam currents for ¹²⁷I are typically ~20-25µA for 1 mg iodine targets. Stable and reproducible currents can be obtained for targets as low as 1µg (~25nA), and high-quality low-background analyses can be obtained with 100µg targets (~2.5µA). Iodine is precipitated as AgI, oven dried, and mixed with Nb powder in a 5:1 ratio (Nb:AgI). The sample is then loaded into a stainless steel cathode target for sputtering. Stainless steel cathodes were superior to aluminum cathodes, which react with AgI forming Al³⁺ that is extremely hygroscopic and causes visible deliquesence. Sputtering an empty stainless steel cathode resulted in negligible mass-127 current (<0.9nA), with no ¹²⁹I ions detected over counting periods up to 10 minutes. Calibration has been achieved using NIST SRM4949c with a 10^-13 to 10^-10 dilution series for which we obtain linear results. Calibration line extrapolation provides a value of (2.2±0.6)x10^-14 for Woodward iodine on repeated analyses. We have begun systematic analysis of standard reference materials available from NIST and the IAEA. Reference soils are combusted at 1000ºC under oxygen flow using a double-furnace to extract iodine. Analysis of IAEA-375 soil results in (1.00±0.04)x10⁹ atoms-¹²⁹I/g-soil and measured ¹²⁹I/¹²⁷I ratios of (1.32±0.12)x10^-7. Similar analyses of NIST SRM2711 (Montana soil) and SRM2709 (San Joaquin soil) yield (2.03±0.06)x10⁸ and (1.0±0.4)x10⁷ atoms ¹²⁹I/g-soil respectively. A ¹²⁹I/¹²⁷I value of (5.9±0.3)x10^-11 is obtained for Monterey Bay seawater, similar to values obtained from seaweed near Carmel by Kilius et al. (1994). The 10-fold(+) sample-size reduction provided by 100-µg-analysis has permitted us to begin examination of variations in migration styles of anthropogenic ¹²⁹I and ³⁶Cl in semi-arid soils in the Great Basin and in surface-waters in the Sierra Nevada.