Lithium assay refers to the process of determining the concentration of lithium in a sample, which may be a geological sample, a mineral concentrate, or a final product. Lithium is a highly sought-after element due to its use in rechargeable batteries, ceramics, glass, and other applications. The accurate determination of lithium concentration is crucial for the mining, processing, and trading of lithium-containing materials.

Various assay methods are available for the determination of lithium, including atomic absorption spectroscopy (AAS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). The choice of assay method depends on the sample type, the required detection limit, and the analytical precision required.

Atomic absorption spectroscopy (AAS) is a widely used and accepted method for the determination of lithium in geological and mineral samples. The method is based on the absorption of light by lithium atoms in a flame or graphite furnace, which is proportional to the concentration of lithium in the sample. ICP-OES and ICP-MS are also commonly used methods for the determination of lithium, offering lower detection limits and the ability to determine multiple elements simultaneously.

X-ray fluorescence (XRF): XRF is a non-destructive method that can rapidly determine the lithium concentration in a solid sample. The method is based on the measurement of the characteristic X-ray emission from the sample. XRF can be used for a wide range of sample types, including geological materials, ores, and concentrates.

In summary, the accurate determination of lithium concentration is crucial for the mining, processing, and trading of lithium-containing materials. Various assay methods are available, including AAS, ICP-OES, XRF, and ICP-MS, and the choice of method depends on the sample type and the required detection limit.

The accepted lithium assay method for a lithium concentrate in trading will depend on the specific requirements of the parties involved in the trade. However, in general, the most commonly used assay method for lithium in a concentrate is atomic absorption spectroscopy (AAS) or inductively coupled plasma optical emission spectrometry (ICP-OES).

AAS is a widely accepted method for the determination of lithium in geological samples, including lithium concentrates. The method is based on the absorption of light by lithium atoms in a flame or graphite furnace, which is proportional to the concentration of lithium in the sample. AAS can detect lithium in the concentration range of parts per million (ppm) to parts per billion (ppb).

ICP-OES is another widely used method for the determination of lithium in geological samples. The method is based on the excitation of the sample with a plasma source and the detection of the emitted light from the excited atoms. ICP-OES can detect lithium in the concentration range of ppm to ppb and is often used for multi-element analysis.