Detection of trace palladium by direct analysis in real time mass spectrometry (DART-MS)

A detection method for palladium by direct analysis in real time (DART-MS) was developed. The method was used for the detection and semi-quantification of palladium in compound samples for which palladium was used during synthesis from compound collections in early drug discovery. The samples containing palladium were mixed with the chelating agent 4-methyl-piperazine-1-carbodithioate and a palladium chelating complex was subsequently formed and detected by DART-MS. The distinct isotopic pattern of palladium was observed and used for its qualitative identification. Semi-quantification was performed based on the peak areas of the extracted ion currents for the four most abundant isotope peaks at m/z 456, 457, 459 and 461. The limit of detection for this method was observed to be 1.2 mu M (120 ppb). With DART ionization, rapid analysis of 18s per sample was achieved with low carryover. Different solvents and chelating agents were also tested for this analysis, and satisfactory signal intensity was obtained using both volatile and nonvolatile solvents. (C) 2014 Elsevier B.V. All rights reserved.