Topic
Name
Institution

Outline
Introduction 3
Sampling Methods 3
Active Sampling 4
Passive Sampling 4
Passive Samplers Applied 4
Purpose of the Study 5
Materials and Methods 5
Sampling site 5
Figure 1 6
Materials 6
Standards Applied 6
Methods and Procedures 8
Preparation of the samples and sampling 8
Analysis 8
Results and Discussion 9
Conclusion 13
References 14

Altitude and Seasonally Profiled Air Concentrations of Polycyclic Aromatic Hydrocarbons (PAH) Determined with PDMS (TWISTER®) in Taurus Mountains, Turkey
Introduction
To monitor environmental pollution and its health effects, atmospheric data of persistent organic pollutants (POP) has been collected for some time to help in evaluating the cause. Polycyclic aromatic hydrocarbons (PAH) have been in focus of attention for years. In 1982, the US Environmental Protection Agency (EPA) come forth with a thorough study on the emissions and health effects of benzo (a) pyrene and other PAHs (United States Environmental Protection Agency, 1982). According to the report, the carcinogenetic effect of benzo (a) pyrene was already proven and other PAHs were suspected to have similar effects. The US EPA categorized these PAHs and selected 16 compounds that were found and monitored to prove the claims. They are were named as the sixteen EPA-PAHs.
The emission sources for these compounds that were presented in the study as having an anthropogenic origin. Following this, the European Commission issued a position paper on monitoring PAHs in the air (European Commission, 2001). The effort has been of great importance since PAHs are by-products of nearly every combustion. The strategy have also improved the air quality requirement for the European Union. These standards set by the paper have to be met and complied with by involving tests by government authorities (Goia, 2007).
Sampling Methods
In this case, different methods of measuring the atmospheric concentrations of PAHs are of importance. The main effective approaches to be used are; active and passive sampling.
Active Sampling
Active sampling devices are considered less practicable for a wide spread usage. They usually require a power supply and therefore considered costly and difficult to apply.
Passive Sampling On the other hand, Passive sampling often involves small, simple and light devices that measure average concentrations in a relatively long period of time (Kot-Wasik et al., 2007). Furthermore, choosing passive sampling material e.g. polydimethylsiloxane (PDMS), allows for specific target compounds to be analysed. Changing the sorbent to a more hydrophobic compound enables sorbent’s affinity to PAH increases and vice versa (Seethapathy et al., 2008). However, a great disadvantage applying this is that for each analyses done on the enrichment factors and partition equilibria have to be measured since the exact amount of air that were analysed cannot be determined. Also passive sampling rates vary with influences of air speeds and temperature variations. Also since the sampling rates are not as high, passive sampler are usually not used for short-term measurements.
Passive Samplers Applied
Passive samplers that are currently used for PAH enrichment are: polydimethylsiloxane stir bar samplers (e.g. Twister®), polyurethane foam discs and semi permeable membrane devices (SPMD) (Söderström et al., 2005; Cupr et al. 2006).
The kinetics behind passive sampling are of great interest since they are useful tools determining the atmospheric concentrations. Bartkow, Booij et al. is a good example of an instance that applies first order kinetics to passive sampling (Bartkow et al., 2005). The approach is suitable as it complies with facts recognized about diffusive molecular transport (Whitman, 1923). Based on these kinetics, quantification of measurement data for passive sampling with PDMS coated stir bars has been applied to laboratory experiments (Wennrich, 2002) as well as field experiments (Paschke, Popp, 2005).
With the help of the two film theory, molecular processes can be linked to observed kinetics (Bartkow et al., 2005). Therefore, influences on diffusive processes can directly be correlated to changes in rate constants. Recently, a study was conducted on the influence of ambient air concentration to absorption and the resulting concentration progression (Hawker, 2010). Since the determination of concentrations is difficult in variable environments, performance reference compounds (PRC) are used to quantify desorption and in case of known or estimated partition coefficients to quantify the time-weighted concentrations (Huckins et al., 2002, Booij et al., 1998). PRCs are compounds that are chemically and physically similar and have almost identical properties as the analysed compounds, however they can be detected separately e.g. deuterated or 13C-labeled analytic molecules. This method has been successfully applied to membrane passive sampling devices in liquid sampling matrices (Booij et al., 2002).
Purpose of the Study
The aim of this study was to determine the concentrations of PAHs in Twister between sea level and 1881 m altitude above sea level and to evaluate the levels and possible sources of chemicals by using Twister in Taurus Mountains, Mersin, Turkey.
Materials and Methods
Sampling site
The stir bars that were exposed in Taurus Mountains in 8 different locations (Altitudes; 1: Sea Level, 2: 121 m; 3: 408 m; 4: 981 m; 5: 1225 m; 6: 1373 m; 7: 1639 m; 8: 1881 m).The samples were exposed for 5 months at eight different heights. Sampling location one was situated at sea shore with typically high traffic volume.
The rest of the sampling sites were away from human activities and samplers were placed in legally protected reserves which was particularly possible for sampling points 5. 6. 7 and 8.
Figure 1. Sampling Locations (Altitudes; 1: Sea Level, 2: 121 m; 3: 408 m; 4: 981 m; 5: 1225 m; 6: 1373 m; 7: 1639 m; 8: 1881 m)
Materials
The measurements were conducted with the reusable PDMS coated stir bars Twister® purchased from Gerstel (Mühlheim, Germany). The PDMS coating on the stir bars has a length of 20 mm and a film thickness of 1.0 mm.
Standards Applied
Three different kinds of standards were used in these experiments. The native PAH standards (PAH-mix 9) used for calibration were purchased from Dr. Ehrenstorfer (Augsburg, Germany). For the isotope dilution technique deuterated PAH standards (PAH-mix 9 deuterated) were used in order to quantify the PRC and native PAH concentrations. They were also acquired from Dr. Ehrenstorfer (Augsburg, Germany). The performance reference compounds, 13C-labeled PAH standards, were purchased from Cambridge Isotope laboratories (Andover, MA, USA). Additionally, paper wipes which were used to wipe the stir bars were purchased from Kimberly Clark, (Dallas, TX, USA). All solvents used were purchased from LGC Promochem (Wesel, Germany). They were of trace analysis grade. The 1 µL micro-syringes used for spiking the Twisters® with no dead volume were purchased from Hamilton Company (Reno, NV, USA, model no. 7001 or 7002).
The desorption unit used to desorb the absorbed analysed compound was a TDU model with a KAS 4 cryo-trap both purchased from Gerstel (Mühlheim, Germany). The auto sampler used was a Gerstel Multipurpose sampler MPS 2 with Twister® option purchased from Gerstel (Mühlheim, Germany).
The GC/MS measurements were conducted on a Finnegan MAT 95 mass spectrometer (Finnegan, San Jose, CA, USA) coupled with a HP 5890 Series II gas chromatograph (Hewlett Packard, Santa Clara, CA, USA). The mass configuration was done with the MS standard FC5331 (MasCom GmbH, Bremen, Germany). The software used to quantify the signal was the Quandesk tool of the Qualbrowser version 1.4SR1 (Thermo Electron Corp., Waltham, MA, USA).
The sampling and GC sequences are listed in table 1:
Table 1: GC and TDU program

GC Column Rtx®-Pesticides 2 (30 m, 0,25 mm ID, 0,2 µm) (Restek, Fuldabrück, Germany) Temperature program 1,5 min 60°C, 17 min 10°C/min; 225°C 13 min 5°C/min; 315°C 20 min Carrier gas Helium 90 mL/min splitless TDU Temperature program 5 min: 280°C TDU & -50°C Cryo;
12°C/s; 5 min: 280 °C Cryo

Before use all glassware and tweezers were cleaned in a dishwasher and baked out at 450°C in a heating cabinet (Heraeus Wärmetechnik, type WU 6100).
Methods and Procedures
Preparation of the samples and sampling
For all samples 1 µL of the performance reference standard is applied onto the surface of the stir bar. Due to the small volume, the solvent quickly evaporates leaving 500 pg. of each analysed 13C-labeled PAH standard on the PDMS coating. The sample bars are then sealed in labelled vials and stored at -28°C. The stir bars are then mounted onto racks and exposed to the air inside a mounted compartment outside the institute at Neuherberg. It is open to air flow yet protected against strong winds and sun. After 0 h, 48 h, 96 h, 192 h, 384 h and 768 h four samples are collected and stored at – 28°C until they are analysed (Booij, 2002).
Also spiked twisters are set as references into the compartment in their vials. Four of each are collected after 0 h, 192 h and 768 h. Before measurement and spiking with deuterated standards the stir bars are wiped with paper wipes.
Analysis
Before analysis each stir bar is spiked with 1 ng deuterated PAH standard. This is necessary since the concentrations for each Twister® are quantified with the isotope dilution technique. The stir bars are then put into the auto sampling glass tubes insulated from the room atmosphere. The stir bars are then analysed by GC/MS. Since the analysed compound is still absorbed to the stir bar it has to be desorbed in order to be analysed. After desorption the analysed compound is cryo-focused before it is entered into the GC.
The MS is conducted in SIM mode and the retention time as well as target masses for the quantification of the compounds are listed in table 2. The concentrations per stir bar are calculated based on the deuterated PAH standard. For the quantification five stir bars are spiked with all three standards in order to obtain response factors for the recovery percentages calculated for the PRCs. These are then averaged as well as the obtained real concentrations of the deuterated standards that are used for quantification. As the absolute reference the native standard with accurately known concentration is used.
For all samples, concentrations of native PAHs (in pg. / stir bar) as well as recovery percentages for PRC are calculated. For benzo (g, h, i) perylene no recovery percentages for PRC could be measured since the signals overlapped strongly with other fragments. Only the native concentrations can be calculated indirectly by using response factors applied to the concentration of indeno (1, 2, 3-c, d) pyrene.
Results and Discussion
Measured native PAH stir bar concentrations (pg. /stir bar) concentration (pg / stir bar)
Station Numbers 1 2 3 4 5 6 7 8
Naphthalene 1288,48 299,36 381,34 230,74 184,45 354,25 129,16 168,90
Acenaphthylene 26,20 9,25 6,96 5,57 4,30 4,96 3,81 4,40
Acenaphthene 116,88 32,14 28,27 17,02 24,18 29,44 13,67 19,10
Fluorene n.d. 506,53 561,39 526,62 466,56 1599,19 706,56 426,49
Phenanthrene n.d. 1905,48 1978,84 1359,95 1681,38 1841,68 927,65 1439,73
Anthracene n.d. 49,07 46,95 31,20 20,16 16,31 11,51 20,60
Fluoranthene n.d. 1245,38 1170,86 913,98 623,24 733,13 460,74 515,89
Pyrene n.d. 571,82 630,68 278,00 155,50 188,18 82,15 127,45
Benzo(a)Anthracene 467,90 13,41 10,87 4,40 3,00 3,55 2,91 3,22
Chrysene 481,85 237,02 168,96 82,62 39,89 36,44 30,19 34,26
Benzo(b)Fluoranthene 156,98 77,70 65,22 103,00 23,96 22,35 25,89 21,62
Benzo(k)Fluoranthene 47,02 17,77 16,48 14,58 6,13 7,91 8,35 6,35
Benzo(a)pyrene 6,67 6,75 6,09 3,87 2,75 3,90 3,75 4,48
Indeno(1,2,3-c,d)pyrene 19,84 8,39 10,29 6,88 6,94 7,95 7,87 5,61
Benzo(g,h,i)perylene 25,72 7,47 10,37 9,11 7,87 8,43 10,28 8,93
Dibenz(a,h)Anthracene 6,10 4,74 6,80 6,10 5,41 7,57 5,51 5,30
∑PAH 2643,64 4992,28 5100,37 3593,64 3255,72 4865,24 2430 2812,33
*1: 121m, 2: 408 m, 3: 981 m; 4: 1225 m, 5: 1373 m, 6: 1639 m, 7: 1881 m
n.d. Not detected

Measured PRC recovery percentage
Station Numbers 1 2 3 4 5 6 7 8
Naphthalene-13C6 0,3% 0,1% 0,1% 0,1% 0,1% 0,3% 0,2% 0,2%
Acenaphthylene-13C6 1,3% 0,5% 0,4% 0,3% 0,6% 0,8% 0,7% 0,7%
Acenaphthene-13C6 2,3% 0,8% 0,7% 0,8% 0,8% 0,3% 0,4% 2,2%
Fluorene-13C6 n.d. 0,7% 0,8% 2,4% 26,3% 5,5% 3,6% 2,4%
Phenanthrene-13C6 n.d. 3,4% 5,3% 3,9% 6,4% 5,5% 4,3% 11,3%
Anthracene-13C6 n.d. 1,0% 1,0% 1,1% 1,1% 1,4% 1,5% 1,9%
Fluoranthene-13C6 n.d. 19,5% 27,9% 37,0% 46,2% 51,7% 44,5% 58,0%
Pyrene-13C3 n.d. 3,9% 5,5% 4,5% 4,3% 4,1% 2,3% 5,0%
Benzo(a)Anthracene- 13C6 1,1% 1,1% 1,4% 1,1% 1,7% 2,4% 2,8% 3,3%
Chrysene-13C6 26,5% 19,7% 19,6% 12,7% 14,1% 11,7% 7,1% 12,8%
Benzo(b)fluoranthene-13C6 130,5% 136,5% 148,1% 151,2% 128,1% 111,6% 134,8% 148,2%
Benzo(k)fluoranthene-13C6 48,1% 42,2% 48,0% 43,0% 41,2% 31,8% 30,4% 37,9%
Benzo(a)pyrene-13C4 6,1% 6,0% 5,7% 6,6% 10,8% 6,5% 8,3% 6,5%
Indeno(1,2,3-cd)pyrene-13C6 20,7% 17,7% 20,3% 17,6% 13,5% 15,4% 12,9% 17,9%
Benzo(g,h,i)perylene-13C12 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.
Dibenz(a,h)anthracene-13C6 8,3% 11,1% 8,5% 3,8% 8,9% 6,4% 6,4% 7,8% *1: 121m, 2: 408 m, 3: 981 m; 4: 1225 m, 5: 1373 m, 6: 1639 m, 7: 1881 m
n.d. Not detected
Conclusion
In conclusion, after 0 h, 48 h, 96 h, 192 h, 384 h and 768 h four samples are collected and stored at – 28°C until they are analysed. It is clear that two different aspects play an important role in the accumulation of pesticides in SPMD along the altitudinal profiles: 1) the different performance in the SPMD uptake and 2) the variations in the PAHs concentrations along the altitudinal profiles. Both are influenced by temperature and the physicochemical properties of the compounds studied.
The complementary deployment periods enabled the compound uptake stage to be determined in SPMD and also revealed the differences in the uptake performance (different sampling rates) in periods 1 and 2. These could be related to the change in the total mass transfer resistance below _4 _C due to the change in state. Consequently, we cannot compare the SPMD accumulations directly in deployment periods where temperature changes include the melting point. To calculate and to compare air concentrations directly in these different periods, PRC must be used (Booij, 2002).

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