Environ Sci Pollut Res (2015) 22:19887-19895
19889
Ô Springer
Surrogated and deuterated compounds (Table 1) were used
as performance reference compounds (PRC), compounds that
are spiked into the passive sampler prior to deployment and
whose dissipation rates can be used to estimate sampling rates.
Internal standards (IS) were added prior to extraction of samplers
to compensate for variations during sample preparation.
Silica gel (Chromabond, Macherey&Nagel, Germany) was
used as solid-phase material in the SPE clean-up step.
Instrumentation
Pressurized liquid extraction was performed with an accelerated
solvent extraction system (ASE 350, Dionex, CA, USA).
Ultrapure water was obtained from a Milli-Q water purification
system (Integral 5 Millipore, MA, USA). Gravimetric
analysis were performed on a scale with ¿/=0.001 g (Sartorius,
Germany).
F1PLC-SEC was performed on a system consisting of a
F1PLC pump (L-6200, Merck-Hitachi, Germany), an injection
valve (Rheodyne), a column oven (Techlab, Germany) with a
Phenogel column (5 pm. 50 A, Phenomenex, USA), a fluorescence
detector (JASCO, Japan) and a fraction collector
(Foxy 200 ISCO, USA).
Concentration was performed either with a parallel solvent
concentrator with two backflush cooling zones (Syncore
Q101, BUCHI, Switzerland) or with nitrogen.
The silicone oligomer content was determined using a total
reflection X-ray fluorescence analyzer (TXRF 3 Picotax,
Rontec, Germany).
Analysis of PAFls was performed with a GC-MS system
(GC CP-3800 coupled to Varian 1200, both Varian, CA, USA)
using a Varian Factor Four Capillary Column VF-5 ms separation
column (30-m length, 0.25-mm ID, 0.25-pm film thickness)
(Varian Associates, CA, USA) in selected ion monitoring
mode (SIM). Flelium 5.0 (Linde, Germany) with a flow
rate of 1 mL/min was used as carrier gas. The injection was
performed split/splitless (split opens after 3 min), with an injection
volume of 2 )iL. The temperature gradient for chromatographic
separation was as follows: start 60 °C for
0.2 min, temperature increase to 100 °C in 5 °C/min steps,
temperature increase to 320 °C in 3.5 °C/min steps and a final
constant temperature for 4 min. The injection was carried out
with a cold injection system with a starting temperature of
60 °C, following an increase of 10 °C/s to a final temperature
of 280 °C, The temperatures of transfer line, ion source and
quadrupole were 275, 250, and 40 °C, respectively. The quantification
of target analytes was performed with internal
standards.
Determination of chlorinated hydrocarbons (CFICs) was
performed with a GC-MS ion-trap system (GC CP3800
coupled to a Saturn 2200, both Varian, CA, USA) in the
multi-reaction monitoring mode (MRM). As separation column,
a FIT 8 (0.22 mm ID, 25 m length, 0.22 pm film
thickness) (SGE Analytical Science, Milton Keynes, UK)
was used, with a desactivated pre-column (2- to 5-m length,
0.53-mm ID) (Agilent, Germany).
Flelium 5.0 (Linde, Germany) with a flow rate of 1.3 mL/
min was used as carrier gas. The injection was performed split/
splitless (split opens after 3 min), with an injection volume of
2 pL. The temperature gradient for chromatographic separation
was as follows: start 90 °C for 1 min, temperature increase
to 170 °C in 10 0 C/min steps, temperature increase to 290 °C
in 3 °C/min steps and a final constant temperature for 40 min.
The injection was carried out with a cold injection system with
a starting temperature of 90 °C, following an increase of 5 °C/
s to a final temperature of 250 °C, The temperatures of trap,
manifold and transfer line were 200, 80, and 280 °C, respectively.
The axiale modulation of the ion-trap was 4.1 V. The
quantification of target analytes was performed with internal
standards.
Optimizing ASE parameters for silicone rubber
pre-cleaning
ASE is used for the first time as a pre-cleaning tool for PDMS
strips in this study. The release of small polymers from silicone
rubber (oligomers) by different solvents was tested for
eight solvents and combinations, which are used typically for
pre-cleaning (ethylacetate, acetone, и-hexane, mediano l/л -
pentane (1:1), acetonitrile/methanol (2:1), dichloromethane/
acetone (1:1), n-hexane/acetone (1:1 v/v) and n-hexane/acetone
(3:1 v/v)) (Rusina et al. 2007; Schafer et al. 2010; Ezzell
and Richter 2012; Smedes and Booij 2012; Allan et al. 2013).
Past studies investigated polymer swelling in organic solvents,
which lead to an enhanced fragility of PDMS strips and blockage
of solvent flow through the ASE extraction cell (Rusina
et al. 2007; Shahpoury and Flageman 2013). Thus, oligomer
release and swelling was quantified by gravimetric analysis.
Pre-weighted silicone strips (55x90x0.5 mm) were folded
into extraction cells (22 mL) with glass fibre filters in the
screw cap and extracted with each solvent (-mixture) at
100 °C using the parameters given in Table 2.
After extraction, strips were wiped with a paper tissue
(Kimtech, Kimberly-Clark), quickly wrapped in preweighted
aluminium foil to prevent evaporation of absorbed
Table 2 ASE instrumentation parameters for different experimental
approaches
Temperature (°C)
Static time (min)
Cycles
Solvent tests
100
10
2
Time series
100
10-90 (Ю-min steps)
1
Temperature tests
75; 100; 125
10
5
All extractions were performed with 1500 psi pressure, 50 % flush and
5 min oven heat
