*2.4. Sample Pretreatment*

Milk: Milk samples can be detected directly without pretreatment. If the sample is rich in fat, the fat can be removed by centrifugation.

Pork: After the pork was chopped with scissors and homogenized, 4 g were accurately weighed into a centrifuge tube, and 4 mL of 0.2 M phosphate buffer (PB, pH 7.4)-methanol solution (*v/v*) were added. The sample was vortexed vigorously for 3 min, sonicated for 3 min, and then centrifuged at 4000× *g* for 10 min at room temperature. The supernatant was transferred out for use.
