Rapid Determination of Trace Elements in Water by Total Reflection X-Ray Fluorescence Spectrometry Using Direct Sampling

Compared with the complicated enrichment procedure, a rapid, simple and reliable method is urgently needed to determine trace metal elements in drinking water. Total reflection X-ray Fluorescence spectrometry (TXRF) is a convenient and quantitative method for simultaneous analysis of trace multi-metal elements requiring less samples and short measured time and can be analysed directly without samples pretreatment. In this paper, Ga was used as the internal standard. The feasibility of rapid determination of multi-mass concentration gradient and the multi-element metal solution was explored by direct injectionTXRF method and then applied to the low mineral drinking water for the trace metal elements analysis. The experimental results showed that Al, K, Ca, Mn, Fe, Co, Ni, Cu, Zn and Sr can be analyzed immediately. However, the experiment results found that Al, K and Ca, as light elements, are difficult to achieve accurate quantification due to the recovery rate deviating from the standard value, the reason for the high matrix effect and low elements sensitivity. In contrast, other elements achieve the quantitative requirements. It was found that Mn, Fe, Co, Ni, Cu, Zn and Sr showed good accuracy and precision when the concentrations of metal elements were 40 mg center dot L (1), 4 mg center dot L (1), 0. 4 mg center dot L (1) and 40 mu g center dot L (1), respectively. The Recovery Rate (RR) was 80%similar to 112%. The relative Standard Deviation (RSD) was 3. 6 % similar to 10. 5 %, and the Detection Limit (DL) was 0. 001 similar to 0. 07 mg center dot L-1. With the decrease in the concentration gradient, the accuracy and precision appeared to have different degrees of decline. When the mass concentration was at the lowest level of 4 mu g center dot L (1) in this experiment, the RR and RSD of most elements (except Mn) significantly deviated from the standard value. This paper used the direct injection-TXRF method to test the RR of drinking mineral water at low, medium and high levels. The results showed that Mn, Fe, Co, Ni, Cu, Zn and Sr in the samples were basically at the concentration of mu g center dot L-1 levels, the average RR ranged from 90% to 110% and the average RSD was less than 12%, which met the qualification of micro estimation. In summary, Multi-element test results showed that TXRF is more suitable for heavy elements (Z>20) in selecting elements. Water samples with more than ten components of p_g " L (1) level can directly achieve rapid and accurate quantitative analysis without complex pretreatment for enrichment. Preconcentration techniques are needed to improve the accuracy of ultra-trace level samples in the environment.