A molecular imprint-coated stirrer bar for selective extraction of caffeine, theobromine and theophylline

• Published in: Mikrochimica acta (1966) Vol. 181; no. 3-4; pp. 303 - 311
• Main Authors: Zhu, Quanfei, Ma, Chao, Chen, Huaixia, Wu, Yaqi, Huang, Jianlin
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.02.2014; Springer
• Subjects: Adsorption; Analysis; Analytical Chemistry; Beverages; Caffeine; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Coatings; Crosslinking; Desorption; Extraction; High performance liquid chromatography; Microengineering; Nanochemistry; Nanotechnology; Original Paper; Polymerization; Polymers; Solvents; Theophylline; Beverages; Molecularly imprinted polymer; Stirrer bar sorptive extraction; Caffeine
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-013-1117-1

We have prepared a novel caffeine imprinted polymer on a stir bar that can be used for selective extraction of caffeine, theobromine and theophylline from beverages. The polymerization time and quantities of reagents (template, cross-linker, porogenic solvent) were optimized. The morphology of the molecularly imprinted polymer-coating was studied by scanning electron microscopy and Fourier transform IR spectroscopy. A rapid and sensitive method was worked out for the extraction of caffeine, theobromine and theophylline from beverages by using the molecularly imprinted stir bar followed by HPLC analysis. The effects of extraction solvent, stirring speed, desorption solvent, adsorption and desorption time were optimized. The method displays a linear response in the 5–150 μg L −1 caffein concentration range, with a correlation coefficient of >0.9904. The recoveries for three analytes in tea, carbonated and functional beverages were 91–108 %, 90–110 % and 93–109 %, with relative standard deviations ranging from 3.6–5.7 %, 3.5–7.9 % and 3.2–7.9 %, respectively. Figure A molecularly imprinted stir bar was prepared and applied for the selective extraction and sensitive determination of caffeine and its analogues in beverages by coupling with HPLC. The limits of detection were in the range of 1.24–2.25 μg L −1 (S/N = 3) which are lower than those in published papers