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2.2.7  Analytical  problems  and  method  development
The  aim  of  the  project  was  to  develop  methods  for  the  determination  of  these  target
compounds  at  ultra-trace  levels  in  marine  water,  sediments,  and  biota.  Very  sensitive
methods  were  developed  for  chlorpyrifos,  endosulfan  and  trifluralin  with  detection
limits  of  <10  pg/L  for  water,  <10  ng/kg  for  sediment,  and  <0.5  pg/kg  for  biota.  Sea
water  extraction  was  performed  by  solid  phase  extraction.  Sediments  and  biota  were
extracted  by  microwave  assisted  hot  solvent  extraction  with  a  mixture  of
hexane/acetone.  GC-MS  in  the  negative  ion  chemical  ionisation  mode  was  used  for  the
determination.
The  limits  of  detection  (LODs)  for  PCP  and  dicofol  were  not  quite  as  low  but
appropriate  for  this  study  and  comparable  with  LODs  reported  for  terrestrial  surveys.  A
fast  HPLC-MS  method  with  detection  limits  of  0.2  and  0.4  ng/L  was  developed  for  PCP
and  the  chlorpyrifos  degradation  product  trichloropyridinol  (TCPy)  in  sea  water.  This
method  was  sufficient  for  screening  purposes  in  river  estuaries  and  at  coastal  stations,
but  not  selective  enough  for  sediment  and  biota  samples.  Therefore,  additionally  a  GC-NCI-MS
  method  was  developed  for  these  matrices,  which,  however,  required  a
derivation  of  the  phenol  group.
Dicofol  degraded  thermally  very  quickly  during  GC-MS  analysis.  Therefore,  a  limit  of
quantification  (LOQ)  of  only  1  ng/L  could  be  achieved,  which  is  only  sufficient  for  a
screening  of  local  hot  spots.  Since  dicofol  was  found  to  be  unstable  in  sea  water  and  due
to  time  constraints,  no  method  was  developed  for  sediment  or  biota.
2.2.8  Chlorpyrifos  in  the  marine  environment  of  the  North  and  Baltic
Seas
This  is  the  first  time  that  chlorpyrifos  has  been  detected  in  quantifiable  amounts  in  the
marine  environment.  Chlorpyrifos-methyl  was  not  detectable  in  the  North  Sea  and
Baltic  Sea.  However,  the  homologue  ester  chlorpyrifos-ethyl  was  found  in  most  water
and  biota  samples.  It  was  less  frequently  detected  in  sediment  samples.  Observed
concentrations  were  very  low  with  a  median  of  26  pg/L  in  water  samples  and  9  ng/kg