“…4,9,10 Most of the reported methods are based on the use of liquid chromatography (LC) coupled with UV spectrophotometry (UV) 11,12,13,14 or mass spectrometry (MS), when there was a need for high selectivity and/or sensitivity. [15][16][17][18][19][20][21][22]23,24,25,26,27,28,29,30,31,32,33,34 Limits of detection 51 In our opinion, ELSD is not recommended for analysing pemetrexed since this molecule is UV-active and ELSD is often less sensitive and selective than the commonly used UV detectors. A methodology including a PP step followed by LC-MS analysis was also developed for the determination of raltitrexed in human plasma with a limit of quantification (LOQ) of 2 ng mL −1 .…”