Article ID Journal Published Year Pages File Type
1227637 Microchemical Journal 2015 5 Pages PDF
Abstract

•Microwave-induced combustion was applied for graphite digestion.•Graphite is a very difficult matrix to digest due to its stable structure.•Digestion efficiency was higher than 99% (RCC lower than 1%).•Digests were suitable for inorganic impurities determination in graphite by ICP OES and ICP-MS.•Up to seventeen elements were determined using 4 mol L− 1 HNO3 as absorbing solution.

Graphite is extremely difficult to digest even using concentrated acids and quality control of impurities is critical for its industrial application. In this work, microwave-induced combustion is proposed for graphite digestion and further determination of Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Sr, V and Zn by inductively coupled plasma optical emission spectrometry (ICP OES). A relatively high graphite mass (400 mg) was completely burnt using 20 bar O2 and HNO3 (1–14.4 mol L− 1) as absorbing solution. A high digestion efficiency (> 99%) was obtained with recoveries better than 95% for all analytes just using a solution as diluted as 4 mol L− 1 HNO3. Determination was also performed by inductively coupled plasma mass spectrometry (ICP-MS) with an agreement better than 97% with ICP OES results. Additionally, a microwave-assisted acid digestion/extraction method using concentrated HNO3 and high-pressure system was performed and an agreement better than 95% was achieved in comparison to MIC results. Analysis of certified reference materials was also performed (agreement > 95% to certified values). The proposed method allowed using diluted acids, resulting in digests fully compatible with multielemental analysis allowing lower blanks and better limits of quantification.

Related Topics
Physical Sciences and Engineering Chemistry Analytical Chemistry
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