Evaluation of pH and thermal stability of sorbent based on silica modified with polyaniline using high-resolution continuum source graphite furnace atomic absorption spectrometry and Raman spectroscopy

Abstract

The stability of stationary phases on temperature and pH is especially important for separation techniques because it extends the possibilities of applications.In the present paper, the high-resolution continuum source graphite furnace atomic absorption spectrometry HR-CS-GF-AAS and confocal Raman microscopy were successfully used to evaluate stability of silica sorbent modified with polyaniline (Si-PANI) on acidic, neutral and alkaline media and elevated temperature.The solutions at pH range 1–12 were passed through the SPE cartridges, the eluates were collected and an amount of dissolved silica was analyzed. Furthermore, the quality of polyaniline film and its spatial distribution were verified by confocal Raman microscopy.The solubility of silica occurred significantly lower for Si-PANI adsorbent comparing to silica and RP-18. Our research shows that covering the particles of silica with polyaniline protects the surface of support material against the drastic pH value. The results obtained by Raman analyses confirm the high stability of polyaniline layer at a temperature range of 30–70°C and at pH from 1 to 12. The sorbent may be used in separation techniques, e.g. as a stationary phase for liquid chromatography in the wide pH and temperature range.