The Uranium Series Chronology Laboratory at the Institute of Geology and Geophysics, Chinese Academy of Sciences, has facilities for precisely measuring 238U–234U–230Th isotopes and dating carbonate samples from a wide rage of surface environments, including speleothem, coral, tufa, lake authigenic carbonate and carbonate nodules in loess sequences for applications in oceanography, paleoclimatology, paleoenvironmentology and archeology.

The laboratory has a Thermo-Fisher-Scientific Neptune-Plus, a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS), which provides high precision measurements for uranium series dating using isotopic dilution techniques. The Neptune-Plus has a mass detection range of 4-310 amu (atomic mass units), with a highest resolution (5%, 95%) of ≥ 8000.

Fig.1. Neptune Plus MC-ICP-MS

Equipped with 9 Faraday cups, 3 SEMs, 4 CDDs and 1 RPQ accessory, the machine can optimize the settings of U-Th isotope measurements for different samples. Aridus II is used to reduce solvent interference, improve signal stability, and increase sensitivity by up to 4-10 times. The injection rates of Aridus II can be set to 50, 100 and 200 μL/min, according to sample U-Th concentrations.

The laboratory has clean rooms for both chemical separations and instrumental analysis, including air filtering and water purification systems.

There are six fume hoods and one central working bench in the ultra-clean chemistry room. Fume hoods provide ISO Class 6 conditions, and the remainder of the room is better than ISO Class 5. The temperature of the laboratory is set at 21±2°C with a stability of <2°C/h, and a relative humidity of 55±3%.

Fig.2. The ultra-clean chemical room

The water purification system includes a pretreatment system, the Milli-Q Elix-35 and the Milli-Q Advantage A10. The system has a 200 L tank, which can produce 15 MΩ of water in 35 L/h for a continuous supply of 18.2 MΩ water. The U-Th blank of the water is low and suitable for U-series work.