Application of the mixed-solvent BID-SDME technique for determination of some stilbene hormones in water downstream of a cattle slaughterhouse, using gas chromatography and mass spectrometry

This article reports the application of a mixed-solvent 'bubble-in-drop single drop micro-extraction' method for pre-concentration of stilbene hormones - hexestrol and diethylstilbestrol from the water sample collected downstream of the cattle slaughterhouse. The optimised conditions for extraction included 75% chloroform-toluene mixture, 2:1 drop-bubble ratio, 10% NaCl, pH 5.5 and 20min of static extraction. The extraction demonstrated sufficient linearity (R-2 >= 0.9992), reproducibility and reliability (%RSD<10%). The enrichment factors between 3218 and 3987 were observed under optimised conditions using the real samples. The observed limit of detection values were in the range of 0.025-0.075ng/mL using the S/N ratio approach, while the limit of quantification values were in the range of 0.083-0.25ng/mL. These values are comparable or lower than those reported in the available literature. Application of the method to real samples from the stream did not detect any analytes. These results, however, do not free the slaughterhouse operators from the requirement that they maintain necessary measures to prevent potential pollution of water bodies if these hormones are indeed used, and could still be active in the animal at the time of slaughtering.