2.4. Determination of detoxification enzyme activities and the secondgeneration integrated biomarker response index (IBRv2)
One earthworm was randomly selected from each beaker, weighed,and homogenized with a 50 mM phosphate buffer (pH 7.8; 1:10, W/V). The homogenized mixture was then centrifuged in a cryogenic centrifuge at 9000 rpm for 10 min, and the collected supernatant was analyzed to determine the activities of CYP450, CarE, and GST using a kit provided by ShangHai HengYuan Biological Technology Co., Ltd. (Shanghai, China). The absorbance (optical density value) was determined at a wavelength of 450 nm using a microplate reader, and the activities of CYP450, CarE, and GST in the sample were calculated from the standard curve.
