Quantification of Methylamphetamine in Biological Samples

The concentration of MA in serum and fecal samples from MA group mice were determined using LC–MS/MS method. In brief, 1 ml serum or fecal suspension was intensively mixed with 2 ml 0.01 mol/L Na2B4O2 and 3 ml diethyl ether. Afterward, mixtures were centrifuged (13,000 r/min, 10 min) to separate the supernatant and then, volatilized to dryness at 45°C. Samples were resolubilized with 200 μl of 70% acetonitrile solution and filtered using a 0.22 μm filter membrane. An LC-20AD Prominence UFLC system (Shimadzu, Japan) coupled with a Z-Spray electrospray interface was used to perform the chromatographic separation. Injections were made onto an Agilent Zorbax SB C18 chromatographic column (150 mm × 2.1 mm, 3.5 μm) in this study (CA, United States). The detailed procedures and parameters were set as described previously (Milesi-Hallé et al., 2015 (link); Zhang et al., 2019 (link)).