Further details of the LC and MSD conditions are provided in the Electronic Supplementary Material, S-1. The peak area of the target chemical relative to that of the internal standard (d5-C10-BAC for C6-, C8-, and C10-BACs, d5-C12-BAC for C12-and C14-BACs, and d25-C12-C12-DADMAC for C8-C8-and C10-C10-DADMACs) was used for quantification. Calibration standards were prepared in the concentration range of 1 to 100 µg/L using acetonitrile.