Amino-Modified Diamond as a Durable Stationary Phase for Solid-Phase Extraction

• Published in: Analytical chemistry (Washington) Vol. 80; no. 16; pp. 6253 - 6259
• Main Authors: Saini, Gaurav, Yang, Li, Lee, Milton L, Dadson, Andrew, Vail, Michael A, Linford, Matthew R
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.08.2008
• Subjects: Adsorption; Amino acids; Analytical chemistry; Chemistry; Diamonds; Exact sciences and technology; Phase transitions; Solids; Spectrometric and optical methods; Solid phase extraction; Fourier transform spectroscopy; Diffuse reflection; X ray spectrometry; Polymer; Diamond; X ray; Cholesterol; Ellipsometry; Chemical enrichment; Reflection spectrometry; Adsorption; Photoelectron spectrometry; Silicon; Aqueous solution; Breakthrough curve; Stationary phase
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac800209c

We report the formation of a highly stable amino stationary phase on diamond and demonstrate its use in solid-phase extraction (SPE). This process consists of spontaneous and self-limiting adsorption of polyallylamine (PAAm) from aqueous solution onto oxidized diamond. Thermal curing under reduced pressure or chemical cross-linking with a diepoxide was shown to fix the polymer to the particles. The resulting adsorbents are stable under even extreme pH conditions (from at least pH 0−14) and significantly more stable than a commercially available amino SPE adsorbent. Coated diamond particles were characterized by X-ray photoelectron spectroscopy (XPS) and diffuse reflectance Fourier transform-infrared spectroscopy (DRIFT). Model silicon surfaces were characterized by spectroscopic ellipsometry and wetting. Solid-phase extraction was demonstrated using cholesterol, hexadecanedioic acid, and palmitoyloleoylphosphatidylcholine as analytes, and these results were compared to those obtained with commercially available materials. Breakthrough curves indicate that, as expected, porous diamond particles have higher analyte capacity than nonporous solid particles.