Determination of halogens and sulfur in high-purity polyimide by IC after digestion by MIC

Publication date: 1 September 2016
Source:Talanta, Volume 158
Author(s): Sindy R. Krzyzaniak, Rafael F. Santos, Flavia M. Dalla Nora, Sandra M. Cruz, Erico M.M. Flores, Paola A. Mello
In this work, a method for sample preparation of high-purity polyimide was proposed for halogens and sulfur determination by ion chromatography (IC) with conductivity detection and, alternatively, by inductively coupled plasma mass spectrometry (ICP-MS). A relatively high polyimide mass (600mg) was completely digested by microwave-induced combustion (MIC) using 20bar of O2 and 50mmolL⁻¹ NH4OH as absorbing solution. These conditions allowed final solutions with low carbon content (<10mgL⁻¹) and suitable pH for analysis by both IC and ICP-MS. The accuracy was evaluated using a certified reference material of polymer for Cl, Br and S and spike recovery experiments for all analytes. No statistical difference (t-test, 95% of confidence level) was observed between the results obtained for Cl, Br and S by IC after MIC and the certified values. In addition, spike recoveries obtained for F, Cl, Br, I and S ranged from 94% to 101%. The proposed method was suitable for polyimide decomposition for further determination of halogens and sulfur by IC and by ICP-MS (Br and I only). Taking into account the lack of methods and the difficulty of bringing this material into solution, MIC can be considered as a suitable alternative for the decomposition of polyimide for routine quality control of halogens and sulfur using IC or ICP-MS.

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