Method development for multi-residue analysis of persistent organic pollutants in seal faecal samples

The toxic effects of Persistent Organic Pollutants' (POPs) in the environment are well documented. Marine mammals ,are particularly vulnerable and there is currently much interest in monitoring POPs levels within their bodies. It is normal practice to use blubber samples for analysis but this can only be obtained from dead animals so availability is limited. In this study, a new method was investigated using seal faecal samples for the analysis of POPs. This matrix was chosen because it can be readily collected without causing undue stress to the animals. The first stage of the project involved chromatographic characterisation of the analytes of interest. A total of 55 compounds were investigated and these originated from four different POPs subgroups (OCPs, PCBs, PCDDs and PBDEs). Analytical standard solutions were initially run on a gas chromatograph equipped with an electron capture detector (GCÆCD) and co¬elution problems were identified. It was demonstrated that these co-elution problems could not be satisfactorily resolved simply by altering the GC parameters and hence compounds pre¬fractionation would be necessary. It was also found that OCPs could not be reliably analysed on the instrument because they were degrading. Significant progress was made in the development of a clean-up method using HPLC with a silica column that separated POPs from seal faecal sample co-extractives. Faecal samples were spiked with the 55 investigated POPs, and very good contaminant recoveries were recorded after clean-up. Additionally, a suitable solvent (acetone) was identified for the backflushing of the column and all lipid content of the injected faecal sample was recovered. Although more development is required they were indications that pre-fractionation of OCPs could be achieved. Additional pre-fractionation of POPs was investigated using the Power-Prep system and elution profiles were established using columns of either alumina or Florisil. Separation of the non-ortho PCBs and dioxins was successfully achieved on Florisil and this was in agreement with published work. However, when all compounds were injected together there were significant changes in elution profile and thus it was concluded that column capacity had been exceeded. Results are discussed in a general manner and possible explanations for the problems experienced are presented. Suggestions for improving the method are also detailed