135

temperature  programme  was  employed:  100  °C  isothermal  for  2  min,  with  15  °C/min  to
280  °C,  isothermal  for  8  min  or  alternatively  100  °C  isothermal  for  2  min,  with  10
°C/min  to  260  °C,  isothermal  for  10  min.
An  HP  5989B  mass  spectrometer  was  applied  in  the  ECNI  mode  (Hewlett  Packard,  Palo
Alto,  USA).  Regular  performance  optimisation  was  carried  out  with  perfluorotributylamine
  selecting  the  mass  fragments  m/z  283.0,  414.0  and  453.0.  The  temperature
of  the  transfer  line  was  280  °C,  of  the  ion  source  200  °C  and  of  the  quadrupole  100  °C.
Methane  was  used  as  reagent  gas  (99,995  %,  Carbagas,  Switzerland)  at  a  pressure  of  1-1.6
  hPa  (0.9-1.1  Torr).  Table  42  and  Table  43  summarise  the  selected  masses  in  the
selected  ion  monitoring  mode.  The  most  abundant  chlorine  isotope  signal  was  selected
for  quantification  and  the  second  one  for  confirmation.
Formula  and  congener  patterns  were  determined  on  a  CP-3800  (Varian,  Walnut  Creek,
USA)  gas  chromatograph.  A  fused  silica  capillary  was  employed  of  15  m  length  and
0.25  mm  ID  coated  with  a  0.25  pm  film  of  DB5-MS  (5  %-phenyl-95  %-methylsiloxane,
J&W  Scientific,  Folsom,  USA).  The  injected  volume  was  2.0  pi  in  the  splitless  mode  (3
min  splitless  time)  using  an  autosampler  (Combi  Pal  autosampler,  CTC  Analytics,
Switzerland).  The  injector  temperature  was  275  °C.  He  was  used  as  carrier  gas
(99,999  %  purity,  Carbagas,  Switzerland)  at  a  head  pressure  of  68.9  kPa  (10  psi).  The
following  temperature  programme  was  employed:  100  C  isothermal  for  2  min,  with  10
°C/min  to  260  °C,  isothermal  for  10  min.