Development of high-performance liquid chromatography and nonaqueous capillary electrophoresis methods for the separation of calixarene derivatives

Abstract: In the present work, the separations of calixarene derivatives have been investigated using both high-performance liquid chromatography (HPLC) and nonaqueous capillary electrophoresis (NACE) techniques. HPLC-1 method with LC-318 (pore size=300Å) column and MeCN mobile phase was optimized for the separation of calixarenes. At the flow-rate of 1ml/min p-nitrocalix[6]arene, calix[4]arene and calix[6]arene could be well baseline and symmetrically separated within 5min. For the separation of p-tert-butylcalix[n]arenes (n =4, 6, 8), HPLC-2 and NACE methods have been optimized. The optimal conditions in HPLC-2 method included NH2 column and MeCN mobile phase, and p-tert-butylcalix[n]arenes (n =4, 6, 8) were baseline separated within 10min at 0.8min/min. The optimal conditions for NACE method employed MeCN–H2O (8:2, v/v) as the nonaqueous medium and 120mM Tris/HCl (pH 9.0) as the buffer, and p-tert-butylcalix[n]arenes (n =4, 6, 8) were successfully baseline resolved within 16min. With the detection at 280nm, the calibration lines were linear in the ranges of 1–200μg/ml for calixarene derivatives by HPLC-1 and HPLC-2 methods, and of 2.5–200μg/ml for p-tert-butylcalix[n]arenes (n =4, 6, 8) by NACE method, respectively. The detection limits (S/N=3) and recoveries ranged from 0.5 to 1.4μg/ml and from 98.1 to 102.4% by both HPLC-1 and HPLC-2 methods, and from 1.3 to 2.0μg/ml and from 97.9 to 105.1% by NACE method, respectively. The intra-day reproducibility of the methods was determined with satisfactory results. The proposed HPLC and NACE methods were accurate and reproducible, and could be utilized to separate and determine calixarene derivatives. [Copyright &y& Elsevier]

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