137 
A triple quadrupole mass spectrometer was applied in the ECNI mode (1200L, Varian, 
Walnut Creek, USA). Regular performance optimisation of both quadrupoles was 
carried out. The temperature of the transfer line was 280 °C, of the ion source 200 °C 
and of the manifold 40 °C. Methane was used as reagent gas (99,995 %, Carbagas, 
Switzerland) at a pressure of 7.3 mbar (5.5 Torr). The dwell time was 0.25 ms per ion 
group. Table 42 and Table 43 summarised the selected masses in the selected ion 
monitoring mode. 
Table 43: Mass-to-charge ratios of ion selected for the internal standards e-HCH and n C w -trans- 
chlordane as well as for other polychlorinated compounds included during method development. The 
ECNI-MS mode was applied. 
Compound 
Ion 
m/z 
m/z most abundant 
isotope 
a-HCH 
[M-Clf 
253 
255 
e-HCH 
[M-Clf 
253 
255 
’ C i o -'' ' v -C h 1 o rd a n e 
[MP 
416 
420 
r/.v-Chlordane 
[M]- 
406 
410 
rz.v-Xonachlor 
[M]- 
440 
444 
Heptachlor 
[M-2C1]" 
299 
302 
Octachloronaphthalene 
[M-2C1]" 
332 
334 
p,p’-DDT 
[M+H-3C1] - 
248 
248 
PCB 153 
[M]- 
358 
360 
Toxaphene #44 
[M-Clf 
373 
377 
Toxaphene #62 
[M-Clf 
373 
377 
rra/z.v-Chlordane 
[Mf 
406 
410 
rra/z.v-\o nach lor 
[Mf 
440 
444 
5.6.6 Quantification of PCAs by ECNI-HRMS 
A comparison between ECNI-HRMS and ECNI-LRMS combined with the newly 
developed clean-up was carried out to ensure, that the latter has the necessary selectivity 
for PCA. The ECNI-HRMS measurements were carried out at the Norwegian Institute 
for Air Research (Kjeller, Norway). Results obtained by LRMS and HRMS were well 
comparable (see chapter 5.3.3.3).