This disclosure provides quantitative, rapid, and reliable LC-MS/MS methods for analyzing panels of pesticides and mycotoxins in various samples, including very hydrophobic and chlorinated compounds normally analyzed on a GC-MS/MS system. The methods can be carried out using a single instrument and can detect and quantify levels of the pesticides and mycotoxins that are well below action limits specified by U.S. states (e.g., California) and other countries (e.g., Canada) for these compounds in cannabis products.