Development of silica modified with ionic liquids and their use in sample preparation techniques

Abstract

Antimicrobials are applied to dairy cattle with goal therapeutic, prophylactic and to stimulate growth. Improper use of antimicrobials in dairy cows, particularly sulfonamides, leads to the possibility of residues of these substances in milk. In this context is necessary the use of specific and selective analytical methods in order to achieve the residue limits set by agencies responsible ensuring the quality of the final product. A classical method of quantifying SAs residues in milk is shown by AOAC International, which uses liquid-liquid extraction, and the extracts are analyzed by high performance liquid chromatography (HPLC). Although HPLC presents several advantages such as, high resolution, versatility, amongst others, this in itself does not solve all analytical problems mainly with the increase in the number of residues and contaminants present in complex matrices. Therefore, it is important to use techniques for more efficient sample preparation in order to increase the selectivity. Among the sample preparation techniques stands miniaturized techniques (e.g., a solid phase microextraction (SPME), the solid phase microextraction the tube (in-tube SPME) in the sorptive extraction stirring bar (SBSE) , microextraction by packed sorbent (MEPS), liquid phase microextraction (LPME)) due to lower consumption of solvent, sorbent among other advantages. Currently the use of sorbents for these classical methods of preconcentration have been largely replaced by modified materials such as silica and polymers in order to increase the selectivity. The most recent publications show immobilization of surfaces of various materials such as silica with ILs or polymerizing materials with ILs, that exhibit success as adsorbent materials. Ionic liquids at room temperature (ILs) have been used as "green solvents" to replace traditional organic solvents for chemical reactions. Due to its low stability, high thermal volatility and good solubility for these organic and inorganic. These products have been successfully applied in the field of analytical chemistry, such as extraction liquid-phase liquid-liquid microextraction, solid phase microextraction, electrolyte additives in CE and GC stationary phases. In addition to the advantages of the use of adsorbents with high selectivity when used in preconcentration techniques in hyphenated analytical systems for separation and detection, for obtaining a rapid analysis, low consumption of solvent, lower exposure to toxic solvents analysts, as well as increased analytical accuracy and automation of the analysis. This work will develop a new sorbent (silica surface modified with an ionic liquid) to be applied as sorbent in the sample preparation in online systems such as SPE online and in-tube SPME. The characterization of the synthesized adsorbent will be performed by FT-IR, SEM and BET. Factors optimization of separation and extraction will be evaluated by factorial design. The results of extraction using modified silica IL will be compared with C18 sorbent commercial. The method will be applied for the simultaneous detection of sulfonamides in 10 samples of bovine milk.