Desenvolvimento e otimização de metodologia para análise de atrazina e seus produtos de degradação por cromatografia líquida de alta eficiência e eletroforese capilar

Abstract

Atrazine is an herbicide widely used on crops of major economic relevance as corn and sugar cane. The widespread use of this herbicide can cause its accumulation or contamination of environmental matrices. In addition, the degradation products of atrazine also deserve attention. This study aims to develop methodology for the analysis of atrazine and its derivatives by capillary electrophoresis (CE) and high performance liquid chromatography (HPLC). Both methodologies developed during the present work, HPLC and CE, were applied to the detection and quantification of atrazine and its degradation products after treatment using the white-rot fungus Pleurotus ostreatus. The best chromatographic conditions for atrazine, simazine and propazine analysis by HPLC were obtained using as mobile phase ACN/H2O 30/70 (v/v%), with analytical column C18 (150 X 4.6 mm 5µm), flow of 1 mL/min, temperature at 25 °C and detection at 221 nm . Liquid-liquid extractions with ethyl acetate were performed before the HPLC analyses. Analysis of atrazine, desetilatrazina (DEA), deisoprilatrazina (DIA), hidroxiatrazina (HA), desetildeisopropilatrazina (DEDIA), desetilhidroxiatrazina (DEHA) and deisopropilhidroxiatrazina (DIHA) was performed by CE in a nonaqueous medium (NACE) . The electrolyte consisted of Tris-HCl 100 mmol/L in ACN / MeOH 50/50 (v/v%) with total capillary length of 48.5 cm (effective length of 40 cm) Experimental conditions were: cartridge temperature at 25 ° C, voltage applied of +20 kV, injection of 50 mbar.1s, detection at 221 nm and the analysis time of 9 min. Despite the co-elution of three compounds (HA, DEHA, DEDIA), due to the short time of analysis and the use of small quantity of organic solvent, the method is very useful for the screening of atrazine and its degradation products. The HPLC analysis of these compounds was performed using as mobile phase ACN / sodium phosphate buffer 5 mmol/L (pH 7.2) under gradient elution mode, flow of 1 mL/min, temperature at 25 ° C and wavelength at 221 nm. Although the long time required for the analysis (70 min), the methodology allows the quantification of all triazines compounds studied. Therefore, the two methodologies developed can be used in a complementary way, since that the compounds identification can be performed by CE without using large volumes of organic solvents in a short time analysis; and their quantification can be performed by HPLC. The degradation promoted by P. ostreatus during a period of 15 days generated predominantly the DEA derivative. The degradation product obtained was detected by HPLC and confirmed by GC-MS, supporting that the methodologies developed in this work can be used in complex aqueous matrices, successfully.