BACKGROUNDSepiolite is a very important non-metallic mineral, which is widely used in aviation, animal husbandry, the chemical industry, environmental protection and other fields. Sepiolite is in great demand and needs a lot of analysis and testing. However, the existing sepiolite reference materials are inadequate and do not satisfy the needs of sepiolite composition analysis. Furthermore, there are no sepiolite reference materials in China, making it necessary to develop one.

OBJECTIVESTo prepare a reference material for composition analysis of sepiolite whose certified value components cover as many elements as possible.

METHODSSepiolite samples were collected from Xiangtan, Hunan Province. The samples were subjected to primary crushing, coarse-grain sieving, inactivation, fine grinding and fine grain sieving. After passing the initial inspection, samples were bottled and numbered. Random samples were taken for homogeneity test, stability test. 24 components were selected for homogeneity and stability test.

RESULTSThe results showed that the RSD of 20 components were less than 3%, and the F value of the variance test was less than the critical value of the listF_0.05(29, 60)=1.65, indicating that the homogeneity of the reference material was good. During the investigation period, the contents of 24 components had no significant change, indicating that the standard material was stable. Nine laboratories cooperated with traditional chemical analysis methods and modern instrumental analysis methods to determine the value. The final values were 63 components, covering major, trace and all rare earth elements. The contents of characteristic components MgO and LOI were 18% and 8.55%, respectively. These two components form a certain ladder with the existing reference materials, which can better satisfy the requirements of sepiolite composition analysis.

CONCLUSIONSThe developed sepiolite reference material can be used as the quality control standards for geological prospecting, geochemical investigation and testing of geological and mineral products, as well as for other industries to analyze similar materials. Moreover, in the process of developing the reference material, improvements and developments to the new methods will provide technical support for the subsequent development of the sepiolite reference material.