Chlorination of SMPs SMPs were chlorinated by adding sodium

Briefly, a sample of SMPs or chlorinated SMPs was acidified to pH 2 with HCl and then passed through a HLB cartridge (Oasis, Waters, USA) that had previously been washed with 10 mL of methanol and 10 mL of deionized water. 100 mL of each sample was loaded on the cartridge at a flow rate of about 5 mL/min, and then the cartridge was dried under a flow of air and eluted with 5 mL of methanol, 5 mL of acetone and 5 mL of acetonitrile in sequence.