Synthesis and use of molecularly printed polymers with miniaturized techniques coupled to liquid chromatography for triazines and sulfonylureas analysis in corn samples

Author(s)

Felipe Nascimento Andrade

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT)
• Defense date: 2015-12-18

Examining board members

Fernando Mauro Lanças; Suzana Lucy Nixdorf

• Advisor: Fernando Mauro Lanças

Abstract

Triazines and sulfonylureas have been much used due to the growing in agricultural production and application of herbicides on crops, which may cause serious risks to human health and the environment. One problem is the low concentration found of these analytes, making it necessary the use of the sample preparation. Thus, the search for miniaturized sample preparation such as techniques simple, low cost, with less risk of environmental contamination and low solvent consumes has great predominance. Among the sample preparation microtechnology we can highlight the microextraction by packed sorbent (MEPS) and bar adsorptive microextraction (BA?E). Another desired aspect for sample preparation is to obtain a higher selectivity concerning the sorbent employed as compared to their conventional format; for example, modified silica (ex. 18), Amberlite XAD resins, and others. In this context, this paper presents the synthesis of two molecularly imprinted polymers (MIPs) and their applications in the selective adsorption of triazines and sulfonylureas molecules being the separation, identification and quantification steps made by LC-TOF-ESI and HPLC-DAD. The first step developed was the synthesis of imprinted polymers using methacrylic acid and ethylene glycol dimethacrylate. After synthesizing, the polymers were characterized by infrared spectroscopy and scanning electron microscopy. The MIP selectivity coefficient was compared with the NIP (non imprinted polymer) selectivity coefficient employing binary mixtures of atrazine / picloram, atrazine / propanil, bensulfuron / betazon and bensulfuron / prometon where the values of relative selectivity coefficients (k \') obtained were 17.2, 3.2, 10.6 and 8.5. Next, we developed two methods for MEPS triazines and sulfonylureas, respectively. The methods were validated based on the recommendations of the National Health Surveillance Agency (ANVISA) and the European Community directives, and presented linearity, selectivity, precision, accuracy and adequate recovery for the triazines and sulfoniuréias. The quantification limits were obtained in the range of 5.0-10.0 μg kg-1 for triazines and 2.5 μg kg-1 for sulfonylureas. Aiming determining these herbicides in corn samples, two new sample preparation methods were developed, using the BAμE. The recently developed BAμE, was combined with molecularly imprinted polymers to evaluate the determination to triazines and sulfonylureas. The BAμE variables were optimized and validated. The quantification limits were obtained in the range of 0.7 μg kg-1 for triazines and 0.4 μg kg-1 for sulfonylureas. The proposed methods were successfully applied for the determination of triazines in different samples of corn, with satisfactory recovery values in the range of 80.0 -120.9%. (AU)

• FAPESP's process: 11/09898-4 - Development of molecularly imprinted polymer and use for the sample preparation and analysis of triazine and sulfonylurea in maize using high performance liquid chromatography (HPLC).
• Grantee: Felipe Nascimento Andrade
• Support Opportunities: Scholarships in Brazil - Doctorate