19894 
Environ Sci Pollui Res (2015) 22:19887-19895 
Ф Springer 
corresponding lab and transport blanks. In general, PAH re 
covery was good, while 2- and 3-ring aromatic PAHs showed 
lower recoveries than PAHs with higher aromatic rings. 
The recovery rates of PRCs in laboratory blanks can be 
additionally used for QA/QC issues, for example, to ensure 
a successfi.il spiking procedure and storage. The recovery rates 
of PRCs determined in laboratory blanks ranged from 66 to 
101 % demonstrating that the used spiking procedure was 
successful for most of the CHCs and PAHs. Due to its 
physico-chemical properties, y-HCH- 13 C 6 showed the lowest 
recovery as this analyte might be already equilibrated with the 
water phase during spiking, supported by the fact that the 
corresponding internal standard e-HCH. representing the ex 
traction efficiency, showed good recoveries (87 %). 
Overall, the results of the recovery rates proofed that matrix 
of deployed samplers does not affect extraction and purifica 
tion as well as that the used procedure is reliable for PDMS 
extraction, avoiding the interference of silicone oligomers dur 
ing mass spectrometric analysis. Full-scan MS measurements 
revealed no additional background peaks which could be re 
lated to silicone oligomers. 
CHC and PAH concentration 
At the stations Fehmam and Heligoland CHC and PAH con 
centrations in the water phase were estimated according to the 
method of Smedes and Booij (2012). Briefly, the proportion 
ality constant B was calculated by a nonlinear least square 
regression calculated by the PRC fractions retained in the 
exposed sampler compared with the control sampler versus 
log(Ap W M 0 47 ) as presented in Fig. 6a. The proportionality 
constant B was then used to estimate the specific sampling rate 
which is necessary to calculate the water phase concentrations 
of the target compounds. 
Heligoland represents a marine station while Fehmam 
represents a brackish water station. Thus, as expected, 
Fehmam waters generally show higher analyte concentra 
tions than Heligoland waters (Fig. 6b, c). The concentra 
tions of individual CHCs were between 6-54 and 0.4- 
18 pg/L for Fehmam and Heligoland, respectively, with 
hexachlorobenzene having the highest concentration. The 
concentrations of individual PAHs ranged from 3-7145 and 
1-2750 pg/L for Fehmarn and Heligoland, respectively. 
Phenanthrene, fluorene and fluoranthene have the highest 
concentration within the measured PAH compounds. The 
more hydrophobic PAHs (e.g. indenopyrene) have minor 
concentrations. In general, the concentrations are in the 
same range and show the same compound patterns and pro 
portions compared to active water samples of routine mon 
itoring operated by the BSH (Loewe et al. 2013; MURSYS 
2011). Hence, PDMS sampler deployment and extraction as 
described in this study is suitable for routine monitoring of 
non-polar organic contaminants in brackish and seawater. 
Conclusions 
The method presented improves handling and use of silicone 
rubber sheets for passive sampling in several aspects: (1) ASE 
for pre-cleaning and extraction, (2) HPLC-SEC for the remov 
al of residual silicone oligomers and (3) control of oligomers 
by TXRF. 
ASE can perform pre-cleaning and extraction in a fraction 
of time and with much less solvent compared to other extrac 
tion procedures, such as Soxhlet. Furthermore, non-polar ex 
traction solvents show better extraction efficiencies and higher 
analyte recoveries than polar solvents. In combination with 
HPLC-SEC as additional sample extract purification proce 
dure, residual silicone oligomers can be removed before the 
determination of non-polar compounds. By monitoring the 
silica content in the extract with TXRF, interferences of chem 
ical analysis can be avoided. The entire method was success 
fully applied on deployed marine sampler. In conclusion, this 
study optimized the preparation as well as extraction and pu 
rification procedure of PDMS samplers in order to enable 
silicone passive samplers more favourable and robust for rou 
tine monitoring of contaminants in the water phase. 
Acknowledgement This work was part of the NOAH project funded 
by the German Federal Ministry of Education and Research (No. 
03F0670A). We are grateful to Ms. A. Neubauer-Ziebarth and Ms. I. 
Raschke for their help in performing the TXRF measurements. 
Open Access This article is distributed under the terms of the Creative 
Commons Attribution 4.0 International License (http:// 
creativecommons.org/licenses/by/4.0/), which permits unrestricted use, 
distribution, and reproduction in any medium, provided you give appro 
priate credit to the original authorf s) and the source, provide a link to the 
Creative Commons license, and indicate if changes were made. 
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