Development of a novel digestion method utilizing a new PTFE digestor for the rapid and reliable determination of technology-critical elements (TCEs) in granite samples by ICP-OES: A simple approach for the analysis of complex geological matrices.

IF 5.6 1区化学 Q1 CHEMISTRY, ANALYTICAL

Talanta Pub Date : 2025-04-01 Epub Date: 2024-12-20 DOI:10.1016/j.talanta.2024.127426

Venkata Balarama Krishna Mullapudi, Chandrasekaran Krishnan, Venkateswarlu Gumma

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Abstract

A new and high performance polytetrafluoroethylene (PTFE) digestor was designed and fabricated in-house for the total dissolution of granite samples for the determination of technology-critical elements (TCEs) by inductively coupled plasma optical emission spectrometry (ICP-OES). Initially, the granite sample (∼0.25 g) was placed in the PTFE digestor and added 8 mL(v/v) of 20%HF+40%HCl+10%HNO₃ acid mixture. After closing, the digestor was directly heated on a hotplate at ∼250 °C for about 2 h (hotplate digestion step (HDS)). Subsequently, the sample mixture was transferred to a graphite-bottom Teflon beaker for evaporation step (ES) at ∼180 °C to remove silica matrix followed by aqua regia treatment step (ATS) to the sample residue for the transformation of highly insoluble metal-fluoro complexes in to soluble chloro-complexes. After ATS, the sample residue was reconstituted in 3 mL of 60 % (v/v) aqua regia. The final sample digests were very clear and stable with no apparently visible fluoride precipitates indicating complete decomposition of different phases present in the granite matrix. The clear sample digests were analysed for REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Sc and Y), high field strength elements HFSEs (Ta, Ti, Zr, Nb, Hf and Th) by ICP-OES. The key parameters of the proposed digestion protocol were optimized for achieving quantitative recovery (>95 %). The proposed procedure was validated using granite based reference materials viz., NCSDC-73376, SARM-1 and JG-2. Various novelty aspects are involved in the present work which include (a) utilization of in-house PTFE digestor (b) hotplate heating with dilute acid mixtures (c) complete elimination of metal-fluoride precipitates (d) no need of expensive commercial bomb digestion systems and (e) total dissolution of granite sample for the determination of elements of highly technological relevance in ∼3 h which is much faster than what is achievable using prevailing conventional methods.

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利用新型聚四氟乙烯消化器开发一种新型消化方法，用于ICP-OES快速可靠地测定花岗岩样品中的技术关键元素（TCEs）：一种用于分析复杂地质基质的简单方法。

采用电感耦合等离子体发射光谱法（ICP-OES）测定花岗岩样品中的技术关键元素（TCEs），自制了一种新型高性能聚四氟乙烯（PTFE）消解池。最初，将花岗岩样品（~ 0.25 g）放置在聚四氟乙烯沼气池中，并加入8ml （v/v）的20%HF+40%HCl+10%HNO3酸混合物。关闭后，直接在热板上加热~ 250°C约2小时（热板消化步骤（HDS））。随后，将样品混合物转移到石墨底聚四氟乙烯烧杯中，在~ 180°C下进行蒸发步骤（ES）以去除二氧化硅基质，然后对样品残留物进行王水处理步骤（ATS），将高度不溶的金属-氟配合物转化为可溶的氯配合物。ATS后，样品残渣在3ml 60% （v/v）王水中重组。最终样品消化非常清晰和稳定，没有明显可见的氟化物沉淀，表明花岗岩基质中存在的不同相完全分解。用ICP-OES分析样品中稀土元素（La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Yb、Sc和Y）和高场强元素（Ta、Ti、Zr、Nb、Hf和Th）的含量。对所提出的溶出方案的关键参数进行了优化，以达到定量回收率（> 95%）。采用花岗岩基准材料NCSDC-73376、SARM-1和JG-2验证了所提出的程序。目前的工作涉及到各种新奇的方面，包括(a)利用内部聚四氟乙烯消化器(b)用稀酸混合物热板加热(c)完全消除金属氟化物沉淀(d)不需要昂贵的商业炸弹消化系统和(e)花岗岩样品的完全溶解，用于在~ 3小时内测定具有高度技术相关性的元素，这比使用流行的传统方法要快得多。

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来源期刊

Talanta 化学-分析化学

CiteScore

12.30

自引率

4.90%

发文量

861

审稿时长

29 days

期刊介绍： Talanta provides a forum for the publication of original research papers, short communications, and critical reviews in all branches of pure and applied analytical chemistry. Papers are evaluated based on established guidelines, including the fundamental nature of the study, scientific novelty, substantial improvement or advantage over existing technology or methods, and demonstrated analytical applicability. Original research papers on fundamental studies, and on novel sensor and instrumentation developments, are encouraged. Novel or improved applications in areas such as clinical and biological chemistry, environmental analysis, geochemistry, materials science and engineering, and analytical platforms for omics development are welcome. Analytical performance of methods should be determined, including interference and matrix effects, and methods should be validated by comparison with a standard method, or analysis of a certified reference material. Simple spiking recoveries may not be sufficient. The developed method should especially comprise information on selectivity, sensitivity, detection limits, accuracy, and reliability. However, applying official validation or robustness studies to a routine method or technique does not necessarily constitute novelty. Proper statistical treatment of the data should be provided. Relevant literature should be cited, including related publications by the authors, and authors should discuss how their proposed methodology compares with previously reported methods.