Determination of Major Components in Rock Salt by X-ray Fluorescence Spectrometry with Sample Fusion

Abstract

The lack of reference materials, and chlorine loss are two of the problems that need to be solved in order to aid the determination of major components in rock salt by X-ray Fluorescence Spectrometry. It is important to select an appropriate sample pretreatment method to ensure reproducibility and it has been demonstrated that sodium chloride, calcium sulfate and other components in synthetic calibration materials for the pressed pellets method show a tendency of diffusion towards the pellet surface when samples are exposed to X-ray irradiation. Moreover, the decomposition of sodium chloride makes it difficult to obtain a stable calibration curve. The fusion bead method, however, does not exhibit these problems. In the study documented in this paper, samples were prepared by the fusion method. Synthetic calibration materials used for standard curve establishment were prepared by mixing spectrum pure salts/oxides with sediment/soil reference materials. 0.6 g of sample was fused by 10 g of mixing flux of lithium tetraborate and lithium metaborate (12:22) at 1000℃ for 300 s pre-fusion and for another 300 s fusion, followed by 30 s standing. The resulting glass disk was flat and transparent. No extra release agent was added because the samples contained chlorine. Analytical results of the major components in salt rock yielded a precision of less than 1.5% (relative standard deviation). This method shortens the analysis time and reduces the reagent consumption compared with the traditional method, which is an alternative method for analyzing major components in salt rock.

Keywords

• rock salt
• major components
• fusion sampling
• chlorine release agent
• x-ray fluorescence spectrometry