Silica-based ionic liquid coating for 96-blade system for extraction of aminoacids from complex matrixes

1-Vinyl-3-octadecylimidazolium bromide ionic liquid [C(18)VIm]Br was prepared and used for the modification of mercaptopropyl-functionalized silica (Si-MPS) through surface radical chain-transfer addition. The synthesized octadecylimidazolium-modified silica (SiImC(18)) was characterized by thermogravimetric analysis (TGA), infrared spectroscopy (IR), C-13 NMR and Si-29 NMR spectroscopy and used as an extraction phase for the automated 96-blade solid phase microextraction (SPME) system with thinfilm geometry using polyacrylonitrile (PAN) glue. The new proposed extraction phase was applied for extraction of aminoacids from grape pulp, and LC-MS-MS method was developed for separation of model compounds. Extraction efficiency, reusability, linearity, limit of detection, limit of quantitation and matrix effect were evaluated. The whole process of sample preparation for the proposed method requires 270 min for 96 samples simultaneously (60 min preconditioning, 90 min extraction, 60 min desorption and 60 min for carryover step) using 96-blade SPME system. Inter-blade and intra-blade reproducibility were in the respective ranges of 5-13 and 3-10% relative standard deviation (RSD) for all model compounds. Limits of detection and quantitation of the proposed SPME-LC-MS/MS system for analysis of analytes were found to range from 0.1 to 1.0 and 0.5 to 3.0 mu g L-1, respectively. Standard addition calibration was applied for quantitative analysis of aminoacids from grape juice and the results were validated with solvent extraction (SE) technique. (C) 2013 Elsevier B.V. All rights reserved.