Environ Sci Pollui Res (2015) 22:19887-19895 
19893 
Springer 
Internal Standards 
Fig. 5 Recovery rates of internal laboratory standards on deployed 
samplers from Fehmarn and Heligoland (n = 2 each) and their 
corresponding lab (n=3) and transport blanks (h=2) 
Removing silicone oligomers from sample extracts 
by HPLC-SEC 
Measurements of PDMS extracts with TXRF showed co 
extraction of silicone oligomers (see “Optimization of the sili 
con rubber pre-cleaning”). Hence, extracts had to be further 
purified to avoid coating of instrumental parts. Smedes and 
Booij (2012) recommend extract purification with C-l 8 bonded 
silica cartridges, which is suitable for methanol or acetonitrile/ 
methanol as solvent. Due to the fact that the ideal solvent for 
PDMS sampler extraction with ASE was found to be non-polar 
(“Optimization of the organic solvent for ASE extraction”), 
alternative purification steps needed to be performed. 
Shahpoury and Hageman (2013) used SEC to remove silicone 
oligomers from sample extracts only for PAH analysis. HPLC- 
SEC can be set up with non-polar solvents and hence no solvent 
transfer from non-polar to polar and back is necessary, which 
can potentially result in lower analyte recoveries by using C-l8 
silica cartridges. In this study, HPLC-SEC was tested for the 
separation of PAH and CHCs from silicone oligomers using a 
mixture of hexane-dichloromethane as eluent in order to keep 
the same extraction solvents during the entire extraction proce 
dure. Monitoring the resulting SEC fractions with TXRF 
showed that the majority of silicone oligomers (mean 98.9 %) 
were present in the first fraction (0-10 min). Less than 1 % 
(average 0.3 %) of the original silicone oligomer content was 
left in the second fraction (10-28 min), in which the target 
CHCs and PAHs were eluted. HPLC-SEC is restricted to a 
certain amount of residual oligomers, e.g. if the pre-cleaning 
step to remove residual oligomers is skipped, the burden for a 
semi-preparative column to separate target compounds from 
oligomers is too high. HPLC-SEC thus proved to be a very 
efficient purification method to remove co-extracted silicone 
oligomers showing the additional advantage that no solvent 
exchange is necessary. 
Additionally to HPLC-SEC, the fast monitoring of the sil 
icone content in each (purified) extract by TXRF avoids ana 
lytical interferences and coating of instrument parts (e.g. GC 
liner and column). 
Field samples 
Recovery rates 
The whole set of deployed sampler, transport and laboratory 
blanks was extracted and purified as described in “Sample 
extraction”. Internal laboratory standard recoveries represent 
the quality of the extraction and purification procedure and 
ranged from 83-114 % for CHCs and PAHs (Fig. 5). De 
ployed PDMS samplers from Heligoland and Fehmam also 
showed good IS recovery rates for CHCs in the range from 85 
to 126 % (Fig. 5), which is within the range of the 
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Fig. 6 a Fits of the proportionality constant B by nonlinear least square regression, b, c Calculated concentrations of CHCs and PAHs in water from 
deployed sampler (n=2) of Fehmarn (Baltic Sea) and Heligoland (North Sea)