Monitoring of some pesticides in farmers saliva and exhaled breath condensate using deep eutectic solvent- based liquid-liquid microextraction and GC-MS

Pesticides are organic or inorganic compounds which are extensively used in agriculture worldwide [1]. Commonly, these compounds are highly toxic and stable in the environment. Generally, pesticides were transferred to the human’s body indirectly by consuming foods and drinking waters contaminated with these compounds [4]. But farmers have direct contact with pesticides in period of agriculture activities. Due to toxicity of the pesticides their monitoring is needed in biological fluids. Different biological samples were investigated in several studies such as blood, plasma, urine, saliva, and exhaled breath condensate (EBC). The major aim of the present study was the development of an LPME method performed in a new extraction vessel using a lighter than water green DES for the extraction and preconcentration of some mostly used pesticides in farmer’s saliva and EBC samples and their determination using gas chromatography–mass spectrometry (GC-MS). The microextraction method was performed in an extraction vessel fabricated in our laboratory. It was firstly cleaned with deionized water and then washed with acetone to remove possible impurities adhered to inner wall of the glass and glass filter. Then, 5 mL of aqueous standard solution (spiked with the analytes at 10 ng mL–1, each analyte) or diluted saliva or EBC sample (see Sec. 2.3) containing 0.25 g NaCl (5%, w/v) was transferred into the device on the on the glass filter. The prepared menthol: phenylacetic acid (41 µL) was transferred into the narrow tube of the device and it was forced to pass through the glass filter using air stream with a flow rate of 2 mL min–1 for 2 min. In this step, the DES was dispersed as fine droplets and moved up with the aid of air bubbles due to its low density and the analytes were extracted into the extraction solvent. After collection of the extraction solvent on the top of the sample solution a portion of the DES was removed by a capillary tube and 1 µL of the extraction solvent was injected into the GC–MS system. Validation of the method showed, limits of detection and quantification at the ranges of 2–17 and 10–85 ng L−1 in saliva and 7-59 and 35-295 ng L−1 in exhaled breath condensate, respectively. Extraction efficiency of the present method, expressed as extraction recovery for the target analytes, was in the range of 79–97%.