Simultaneous Determination of Major Elements, Si, Al, Ca, Mg, Fe, Ti, Mn and P in Graphite by Inductively Coupled Plasma-Optical Emission Spectrometry with Sodium Carbonate Fusion

Abstract

Graphite is a stable nonmetal and must be decomposed completely by alkali fusion at high temperature (1000℃). In previous methods, different crucibles were used in different phases in order to shorten the utility time of the platinum crucible and avoid damage to the platinum crucible and sample loss. Based on the nature of graphite ore and the character of the crucible, a new method has been developed. The sample was firstly ignited at high temperature in a platinum crucible, which was prepared with 0.50 g potassium carbonate at the bottom. The sample was then directly digested by 0.80 g sodium carbonate in the former platinum crucible. Lastly the melt was dissolved by diluting hydrochloric acid. Eight major elements (Si, Al, Ca, Mg, Fe, Ti, Mn, P) were simultaneously determined by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The proposed method has a detection limit of 13-228 μg/g, precision (RSD, n=12) of 0.7%-7.2%, and whole-process recoveries of 90.5%-105.0%. The analytical results of flake graphite and amorphous graphite by this method are in agreement with those by chemical method. This method avoids sample loss and platinum crucible damage. The whole process of treatment is simple and rapid.

Keywords

• graphite
• major elements
• platinum crucible
• potassium carbonate-sodium carbonate fusion
• inductively coupled plasma-optical emission spectrometry