In other labs’ experience, what is the best methodology for measuring voriconazole and posaconazole? All respondents say that they use LC-MS/MS for TDM of these drugs, especially since LC-MS/MS allows you to build a platform that can easily be expanded to incorporate other drugs in the future. There is also a good immunoassay for voriconazole, but no one is aware of an immunoassay for posaconazole.