1. College of Pharmacy, Liaoning University of Traditional Chinese Medicine, Shenyang 116600, China 2. The State Key Laboratory of Rare Earth Materials Chemistry and Application, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China 3. Linyi Product Quality Supervision and Inspection of Shandong Province, Linyi 276004, China 4. Mongolia Medical College, Inner Mongolia University for the Nationalities, Tongliao 028000, China 5. Shenyang Dootel Biopharmaceutical Research Center, Shenyang 110031, China
Abstract：In situ TLC/FTIR technique has tremendous potential in the analysis of complex mixtures. However, the progress in this technique was quite slow. The reason is that conventional stationary phase has strong absorption in FTIR spectrum and thus brings about severe interference in the detection of samples. To solve the problem, the authors propose to use AgI fine particles as stationary phase of TLC plate. The reasons are as follows: Silver iodide fine particles have no absorbance in an IR region between 4 000 and 800 cm-1, therefore, the interference caused by IR absorption of stationary phase can be removed. Moreover, silver iodide is stable and insolvable in water and organic solvents and thus it will not be destroyed by mobile phase or react with samples during the TLC separation. To improve TLC separation efficiency and quality of FTIR spectra during the TLC/FTIR analysis, the size of AgI particles should be below 500 nm. We used orthogonal design approach to optimize the experimental condition to AgI particles so that the average size of AgI particles is around 100 nm. No absorption of impurity or adsorbed water were observed in FTIR spectrum of the AgI particles the authors used “settlement volatilization method” to prepare TLC plate without using polymeric adhesive that may bring about significant interference in FTIR analysis. Preliminary TLC experiments proved that the TLC plate using AgI fine particles as stationary phase can separate mixtures of rhodamine B and bromophenol blue successfully. Applications of silver iodide fine particles as stationary phase have bright perspective in the development of in-situ TLC/FTIR analysis techniques.
[1] Stahlmann S, et al. European Journal of Pharmaceutical Sciences, 2001, 12: 461. [2] Fuller M P，Griffiths P R. Anal. Chem., 1978, 50: 1906. [3] Gary E Zuber, Richard J Warren, Peter P Begosh. Anal. Chem., 1984, 56: 2935. [4] Lindsay B Lloyld, Randall C Yeates, Edward M Eyring. Anal. Chem., 1982, 54: 549. [5] Robert L. White. Anal. Chem., 1985, 57: 1819. [6] Neil D Danielson, Katon J E, Steven P Bouffard. Anal. Chem., 1992, 64: 2183. [7] Bouffard S P, Katon J E, Sommer A J. Anal. Chem., 1994, 66: 1937.
