Methodology for direct quantification of total selenium (Se) concentration in mine water by total-reflection X-ray fluorescence (TXRF) spectrometry was developed and optimized. Inductively coupled plasma – mass spectrometry (ICP-MS), as a recognized standard test method, was used as a benchmark for results verification. Preliminary measurements with aqueous multi-element standard solutions showed that Se concentration can be accurately determined down to 10 ng/g by using a single-drop of solution (10 μL) and a measurement time of 600 s. Quantification of lower Se concentration below 10 ng/g was subsequently optimized, also with aqueous multi-element standard solutions. Improvement in detection limit was accomplished by increasing amount of sample deposition as well as increasing measurement time. TXRF analysis of SRM1640a, Trace Elements in Natural Water, was also performed for accuracy check. The developed methodology was applied to analyze five raw mine water samples (MW-1, MW-2, MW-3, MW-4 and MW-5) collected from anonymous mine site locations. TXRF analysis was performed on the as-received samples directly without filtration, dilution and digestion. Samples were prepared as single-drop specimens and analyzed using a measurement time of 600 s. Se and fifteen other elements were detected in varying degree in the as-received samples. Se concentrations quantified by TXRF were 256.5 ± 22.5, 88.4 ± 1.4 and 61.3 ± 2.8 ng/g for mine water samples MW-1, MW-2 and MW-3, respectively, compared to 255.3 ± 5.6, 87.3 ± 2.6 and 59.7 ± 3.5 ng/g by ICP-MS. No clear Se-Kα peak above background was observed for samples MW-4 and MW-5. Increasing amount of sample deposition by preparing triple-drop specimens and using a longer measurement time of 1800 s, allowed a Se-Kα peak to emerge above the background for MW-4, but not MW-5. Se concentration in MW-4 quantified by TXRF was 4.9 ± 0.5 ng/g, compared to 6.7 ± 0.7 ng/g by ICP-MS, which represents an agreement within three standard deviation values between the two techniques. For sample MW-5, even after using triple-drop specimens and increasing the measurement time to 1800 s, Se concentration could not be determined because a Se-Kα peak was not detected by TXRF, compared to the Se concentration of 0.83 ± 0.1 ng/g obtained by ICP-MS. Overall, our analysis results showed that the TXRF technique can be used for direct analysis of total Se concentration in raw mine water samples down to ng/g range, providing high-quality, accurate and repeatable analysis comparable to ICP-MS while requiring much simpler sample preparation.

开发并优化了通过全反射X射线荧光（TXRF）光谱法直接定量矿井水中总硒（Se）浓度的方法。电感耦合等离子体质谱法（ICP-MS）作为公认的标准测试方法，被用作结果验证的基准。用多元素水溶液标准溶液进行的初步测量表明，通过使用一滴溶液（10μL）和600 s的测量时间，可以精确测定低至10 ng / g的Se浓度。随后，还使用多元素标准水溶液对低硒浓度低于10 ng / g的定量进行了优化。通过增加样品沉积量以及增加测量时间可以提高检测限。SRM1640a的TXRF分析 还对天然水中的微量元素进行了准确性检查。所开发的方法用于分析从匿名矿场所在地收集的五个原矿水样（MW-1，MW-2，MW-3，MW-4和MW-5）。直接对原样进行TXRF分析，无需过滤，稀释和消化。将样品制备为单滴样品，并使用600 s的测量时间进行分析。在收到的样品中检测到不同程度的硒和其他十五种元素。通过TXRF量化的矿泉水样品MW-1，MW-2和MW-3的硒浓度分别为256.5±22.5、88.4±1.4和61.3±2.8 ng / g，而255.3±5.6、87.3±2.6和59.7± ICP-MS测定为3.5 ng / g。对于样品MW-4和MW-5，未观察到高于背景的清晰的Se-Kα峰。通过制备三滴样品并使用更长的1800 s测量时间来增加样品沉积量，使Se-Kα峰出现在MW-4而非背景以上的背景上。通过TXRF定量测定的MW-4中的Se浓度为4.9±0.5 ng / g，而采用ICP-MS则为6.7±0.7 ng / g，这表明两种技术在三个标准偏差值之内的一致性。对于MW-5样品，即使在使用三滴样品并将测量时间增加到1800 s之后，也无法确定Se浓度，因为与0.83±0.1 ng的Se浓度相比，TXRF未检测到Se-Kα峰/ g通过ICP-MS获得。总体而言，我们的分析结果表明，TXRF技术可用于直接分析低至ng / g范围的原矿水样品中的总Se浓度，从而提供高质量，