Environ Sei Pollut Res 
Ö Springer 
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This study aimed to present, analyze, and evaluate long 
term results of seawater analysis obtained by the Federal 
Maritime and Hydrographic Agency (BSH) and the Leibniz 
Institute for Baltic Sea Research (IOW) during the last decade 
(2001-2014) to identify spatial hot spots as well as time trends 
of 50 polar organic micropollutants in the Baltic Sea. 
Material and methods 
Chemicals 
Calibration standards for pesticides were purchased from Dr. 
Ehrenstorfer/LGC as neat materials, single solutions, or mix 
tures. Perfluoroalkyl substances were delivered from 
Wellington Laboratories/Campro as single solutions or mix 
tures. Labeled compounds (Deuterium and 13C) were used as 
internal standards. Methanol was used for standard solutions, 
SPE elution, and HPLC mobile phase (MeOH HPLC-ana- 
lyzed. Baker). Ammonium acetate (p.a. Merck) and acetic 
acid (p.a. 96% Merck) were used for buffer solutions. Pure 
water for HPLC separations was prepared by a pure water 
system (Milli-Q academic A10, Millipore) until 2007, follow 
ed by bottled water (HPLC water. Baker). HPLC/MS- 
spectrometer was operated with Nitrogen Gas 5.0 (Air 
Liquide). For further information, see Tab. SI. 
Sampling station 
Most of the sampling was done during routine monitoring of the 
Leibniz Institute for Baltic Sea Research Wamemiinde (IOW) 
from 2009 to 2014 at 7 (until 2009) to 9 (from 2010) stations in 
the western Baltic Sea (Fig. la, b). A similar station net was 
sampled from 2001 to 2005 by the Federal Maritime and 
Hydrographic Agency of Germany (BSH). In addition, the cen 
tral and eastern part of the Baltic Sea was sampled on a research 
cruise during 2008 by R/V Maria S. Merian. The cruises from 
2001 to 2008 were done in summer (June to August), while later 
samplings occurred during wintertime (January and February). 
Sampling details are presented in the supplements in Tab. S2 and 
S3. During all campaigns, a total of 133 water samples were 
taken and analyzed for 50 micropollutants. Some results of the 
perfluoroalkyl substances from the cruises GA442 and ММ03/ 
08 have been published in Theobald et al. (2007) and Kirchgeorg 
et al. (2010), respectively (Tab. S15). 
Water sampling and solid phase extraction 
Samples from 5 m below surface (2001-2008) were collected 
in 10 L glass bottle samplers, and the internal pump system of 
the ship’s inlet was used from 2009 to collect samples at 4 m 
depth. An internal standard solution was added to each sample 
prior to further treatment for quantification calculations. 
Solid phase extraction (SPE) was applied to enrich 
micropollutants for the analysis by high-performance liquid chro 
matography coupled with a tandem mass spectrometer (HPLC- 
MS/MS). Sample volumes of 6 to 9 L were pumped through 
12 mL SPE columns containing 1.7 g polymer adsorber (samples 
from 2001 to 2009); 2.1 L samples were applied since 2009. To 
avoid clogging of the adsorber column, a 12 mL column filled 
with 1 g of glass wool was connected prior to flow direction. SPE 
adsorber material was Chromabond HR-P® (Macherey & Nagel, 
Düren, Germany) for all samples, except Strata-X® 
(Phenomenex, Aschaffenburg, Germany) for the AL430 cruise. 
Loaded SPE columns were eluted with methanol buffered with 
5 mM ammonium acetate and 2.5 mM acetic acid. The solvent 
was vaporized to a final extract volume of 0.5 mL. The reduced 
sample volume since 2009 was an adoption to the higher sensi 
tivity of the new MS/MS spectrometer. Changes in sampling and 
measurement features were checked by internal and external 
quality assurance or regular inter-comparison tests (Tab. S5). 
HPLC-MS/MS analysis 
All samples were analyzed by HPLC-MS/MS, but the device 
configuration was subject to changes during the investigations. 
From 2001 to 2009, an MS/MS API 2000 (AB Sciex, Darmstadt, 
Germany) was used and then replaced by the Model 5500 QTrap 
of the same brand. Both systems were operated with a turbo ion 
spray probe. An HPLC Agilent Series 1100 was used for chro 
matographic separation from 2001 to 2012, which was then re 
placed by an HPLC Ultimate 3000 Series (Dionex/Thermo 
Fisher Scientific, Idstein, Germany). A combination of two 
HPLC columns (Synergi Polar RP, 4 qm particle size, 50 x 2 
mm, and Synergi Hydro RP, 4 qm particle size, 75 x 2 mm, 
Phenomenex, Aschaffenburg, Germany, respectively), with a se 
curity guard column (Aqua Cl8, 4 x 2 mm, Phenomenex, 
Aschaffenburg, Germany), was used for separation with the 
Agilent HPLC system. The Dionex system was operated with a 
Kinetex Cl8 column (2.6 qm particle size, dimension 100 x 2 
mm, Phenomenex, Aschaffenburg, Germany). The mobile 
phases were water (A) and methanol (B), each containing am 
monium acetate and acetic acid. The concentrations of ammoni 
um acetate and acetic acid were 10 mM each for the API 2000 
spectrometer and 5 mM each for the 5500QTrap system. 
Gradient programs were carried out for elution and separation. 
The gradient program started at 15% B was increased up to 95% 
B with 220 to 300 qL/min as flow rates. 
Ionization was carried out in positive and negative 
electrospray ionization mode, and the mass analysis was per 
formed by scheduled multiple reaction monitoring. Ionization 
and mass transition parameters of LC-MS/MS analysis are 
listed in Tab. S4. Certified calibration standards were adopted 
from the routine mass spectrometer analyses of the BSH mon 
itoring program. The calibration ranges of target analytes 
ranged from 0 to 10 ng/mL with average internal standard