High sensitivity of ortho-substituted polychlorobiphenyls in negative ion mass spectrometry (NCI-MS): A comparison with EI-MS and ECD for the determination of regulatory PCBs in soils
B. Rothweiler et Jd. Berset, High sensitivity of ortho-substituted polychlorobiphenyls in negative ion mass spectrometry (NCI-MS): A comparison with EI-MS and ECD for the determination of regulatory PCBs in soils, CHEMOSPHERE, 38(7), 1999, pp. 1517-1532
Selected ortho-substituted PCBs (IUPAC no. 28, 52, 101, 118, 153, 138, 180)
were quantified at trace levels in twenty different agricultural soils usi
ng high resolution gas chromatography (HRGC) and negative-ion chemical ioni
zation mass spectrometry (NCI-MS), electron impact mass spectrometry (EI-MS
) and electron capture detection (ECD). In NCI PCBs generated simple mass s
pectra with the molecular ion as base peak. The dissociative electron captu
re mechanism increased for higher chlorinated PCBs. After ion source optimi
zation (pressure, temperature) detection of the tri-and tetrachloro-PCBs be
came possible. NCI-MS showed comparable sensitivity with the ECD for most o
f the PCBs analyzed, excellent linearity and good repeatability. A comparis
on of the PCB soil concentrations obtained with the three detection techniq
ues revealed that NCI-MS gave values closest to the overall mean with the s
mallest deviations.