Experimental Design Methodology to Optimize the Solid Phase Microextraction Procedure Prior to GC/MS Determination of Ethyl Carbamate in Samples of Homemade Cachaça

Abstract

Seeking to improve the quality of cachaça, the Ministério da Agricultura, Pecuária e Abastecimento (Ministry of Agriculture, Livestock and Supply - MAPA), the body responsible for setting and approving regulations governing the Identity and Quality Standards (PIQs) for distilled sugar cane spirits and cachaça, through the Normative Instruction No. 13 of 2005 included some contaminants such as ethyl carbamate (EC), acrolein, lead, and arsenic that must be evaluated in these drinks. Studies on EC, as well as the methods for its determination, are required to evaluate and determine which factors contribute to the formation of this compound in the beverage. An analytical method using gas chromatography/mass spectrometry (GC/MS) with prior sample treatment by solid phase microextraction (SPME) was developed along with the assessment of the principal validation parameters. These two developments lead to the determination of EC with analytical reliability. The optimization of the extraction step was performed via a factorial design involving the selection of parameters such as extraction time, extraction temperature, salt concentration, desorption time, pH, and the method of extraction. The linear range was 5.0 to 200.0 µg L−1 (R2 = 0.9965) with limits of detection and quantification of 1.5 and 5.0 µg L−1, respectively. The recoveries for samples of cachaça containing 10.0 and 80.0 µg L−1 concentrations of EC were 89% and 93%, respectively. The concentrations of EC in the samples of cachaça examined were well below the limits required by Brazilian law.