Development of analytical methods to attend the green chemistry principles in the analysis of veterinary medicines in bovine milk

Author(s)

Adriana Nori de Macedo

• Document type: Master's Dissertation
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT)
• Defense date: 2012-04-20

Examining board members

Eny Maria Vieira; Eduardo Bessa Azevedo

• Advisor: Eny Maria Vieira

Abstract

The use of veterinary medicines is of great importance in animal production, but also can have negative consequences, such as the occurrence of residues in food of animal origin, among which bovine milk stands out. Sulfonamides are an antibiotic class used in animal and human treatments, so it is important to analyze this kind of residue in food of animal origin, such as milk, because it can cause allergic reactions and poisoning, affecting food safety and damaging the manufactory of dairy products. Most of the studies have used solid-phase extraction (SPE) in the extraction of sulfonamides and clean up of the sample. However, the QuEChERS method, introduced in 2003, has been considered promising in the extraction of various compounds in food matrices. Thereby, this research aimed to develop and validate analytical methods comparing the extraction methods SPE and QuEChERS, followed by high performance liquid chromatography with diode array detection for the analysis of sulfonamides (sulfathiazole, sulfamethazine and sulfadimethoxine) in bovine milk. In the optimization of the chromatographic conditions and QuEChERS method, we used experimental design. Chromatographic conditions were optimized, selecting column C18 Luna (100 x 4.6 mm, 5 µm), injection volume of 17 µL, wavelength of 290 nm, flow rate of 0.5 mL min-1, temperature of 20 °C and gradient mode, using water and ethanol as mobile phase. In the QuEChERS method, the optimized procedure used 6 g of milk, 3 mL of water, 6 mL of acetonitrile with 1% of acetic acid, 2.4 g of MgSO4 and 0.6 g of sodium acetate, and in the clean up step it was used 37.5 mg of primary and secondary amine, 25 mg of octadecylsilane and 150 mg of MgSO4. Experimental design was considered efficient in the optimization, since it was obtained good separation of the chromatographic peaks and recovery between 95 and 98% with relative standard deviation below 8.25% for the analytes in the concentration of 0.050 mg kg-1. In the development of the extraction method SPE, it was not possible to obtain good recovery for the analytes and clean up of the sample. It is believed sulfonamides are lost in the sample pre-treatment step, which is important in performing SPE. Therefore, the QuEChERS method was selected for this analysis. The validation tests demonstrate the method is appropriate, within the maximum limit residue (0.1 mg kg-1), established by the National Health Surveillance Agency, with accuracy and precision within the accepted limit, according to the followed validation guides. Moreover, it was possible to use just water and ethanol as mobile phase, what is an advantage in relation to traditional methods, because it uses an organic solvent less toxicant and renewable. Rate flow is also relatively low, which contributes to decrease the required volume of organic solvent and the amount of waste produced. (AU)

• FAPESP's process: 09/12218-5 - Analitic method development to attend the green chemistry to analysis veterinary medicine in cow milk
• Grantee: Adriana Nori de Macedo
• Support Opportunities: Scholarships in Brazil - Master