Determination of PAHs from Sea Water
Using Automated SPE
Brett Holmes, Horizon Technology, Inc., Salem, NH
Introduction
Polycyclic aromatic hydrocarbons (PAHs) are an important
class of environmental contaminants because of their
prevalence and potentially adverse health effects. PAHs
are generated in exhaust from gasoline and diesel engines,
and emissions from the combustion of most organic
compounds.
When people are exposed to some PAHs at levels above the
maximum concentration limit for relatively short periods of
time red blood cell damage, leading to anemia, and a
suppressed immune system can occur. Long-term exposure
is believed to potentially have negative developmental and
reproductive side-effects and cause some forms of cancer.
PAHs released into coastal seawaters have been proven to
be a prevalent problem and are thought to be responsible
for some of the biological effects on marine life such as
chromosomal problems in fish and other marine organisms.
Sources of this include natural seepage, platforms, pipelines,
produced waters, vessel spills, vessel operations, aircraft
dumping, and coastal facilities.
The Horizon Technology SPE-DEX® 4790 Automated
Extraction System provides for the automated extraction of
liquid samples via SPE methods. The SPE-DEX® 4790 can
handle sample volumes ranging from 20 mL to 4 L, and
matrices such as waste water and sea water. The Horizon
Technology Envision® Platform Controller provides a userfriendly, web-based controller, capable of interacting with
up to eight extractors via a standard PC connection.
The Horizon Technology SPE-DEX® 4790 Automated Extraction
®
®
System, Envision Platform Controller, DryVap Automated Drying
and Concentrating System, and the Atlantic™ HLB SPE Disk.
Instrumentation
Horizon Technology
- SPE-DEX® 4790 Automated Extractor System
- Envision® Platform Controller
- DryVap® Concentrator System
- DryDisk® Separation Membrane
- Reclaimer™ Solvent Recovery System
- Atlantic™ HLB SPE Disk (47mm)
•
Agilent
- 6890 GC
- 5973 Mass Selective Detector
• Column: DB 5MS 30 m x 0.25 mm ID, 0.25 um
•
Method Summary
1)
2)
The Horizon Technology DryVap® Concentrator System
provides automated sample drying, with a patented PTFE
membrane technology that automatically removes residual
water from the organic solvent and concentrates each dried
extract by applying heat, vacuum, and sparge flow for up to
six samples at once. The environmentally-friendly Horizon
Technology Reclaimer™ Solvent Recovery System is
designed to condense and collect solvent vapors which are
generated by the DryVap® Concentrator System.
These automated systems are specifically designed to
streamline the sample handling required for the preparation
and analysis of environmental samples. The use of such
systems allows for decreased turn-around-times and
increased productivity of lab personal thereby introducing a
significant cost savings.
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4)
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9)
10)
Horizon Technology, Inc., 45 Northwestern Dr. Salem, NH, 03079 USA
Tel: (603) 893-3663 Fax: (603) 893-4994
Sea water was collected from Salisbury Beach,
Massachusetts and transferred into 1 L sample bottles.
Samples were preserved with 1.0 mL of concentrated
HCl (pH = 2) and refrigerated.
Each sample was spiked with 50 ug of the PAHs of
interest.
Sample bottles were placed on the SPE-DEX® 4790
Extractors and Atlantic™ HLB Disks were placed in
the disk holders.
40 ml VOA vials were placed on the extractors for
extract collection.
Load the PAH method Table 1 start the extraction
procedure.
After the extraction has completed the final extract
was removed from the extractor.
The extract, now in two phases of Acetone/Water and
methylene chloride was poured into the DryDisk®
reservoir.
The sample was dried using and concentrated to 0.9
mL using the DryVap® Concentrator System with the
settings in Table 2.
Rinse the bottom of the concentrator tube with
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AN038-091214
Determination of PAHs from Sea Water Using Automated SPE
11)
12)
methylene chloride to bring the extract up to a final
volume of 1 mL.
Transfer 0.4 mL of extract to a GC vial and add 8 uL
of Internal Standard.
Analysis by GC/MS using the parameters in Table 3.
Table 3: GC/MS Settings
Gas Makeup:
Flow Rate:
Flow Mode:
Inj. Amount:
Inj. Temp:
Split Ratio:
Temperature
(deg C)
45
270
320
Table 1: Extractor Method
Step
Solvent
Soak Time
Dry Time
Methylene
Chloride
Acetone
0:30 min
0:15 min
0:30 min
0:15 min
0:02 min
Prewet #4
Reagent
0:10 min
Water
Reagent
0:10 min
Water
Sample Process
Rinse Step #1
Acetone
3:00 min
0:20 min
Rinse Step #2
Methylene
Chloride
Methylene
Chloride
Methylene
Chloride
Methylene
Chloride
3:00 min
0:20 min
1:00 min
0:20 min
1:00 min
0:20 min
1:00 min
1:00 min
Prewet #1
Prewet #2
Prewet #3
0:02 min
Air Dry 30 s
Rinse Step #3
Rinse Step #4
Rinse Step #5
Table 2: DryVap® Settings
Parameter
Setting
Dry Volume
20
Heat Power
5
Auto Rinse Mode
OFF
Heat Timer
OFF
Nitrogen Sparge
20 psig
Horizon Technology, Inc., 45 Northwestern Dr. Salem, NH, 03079 USA
Tel: (603) 893-3663 Fax: (603) 893-4994
Helium
9 psi
Constant
1 ul
280 C
1:10
Rate
(C/min)
0
15
6
Total Time:
Hold
(min)
1:00
0
0
24:33
Results
Table 4 shows the results for four samples replicates. The
final recoveries of the extraction, drying and concentration
process range from 72.6% on the light ends to 84.8% on
the heavy ends. Also, the relative standard deviation of
each compound was 7% or less. These show not only
excellent recoveries and repeatability, but also show that
there is no affect on the recoveries due to the sea water
matrix.
Conclusions
The resulting data demonstrate that the Horizon
Technology fully-automated extraction, drying and
concentration systems used with the Atlantic™ HLB disk
are capable of extracting PAH compounds from sea water.
Typical extraction times using the SPE-DEX® 4790 range
from 20 to 25 minutes while drying and concentration on
the DryVap® with the DryDisk® took approximately 35
minutes.
The Horizon Technology SPE-DEX® 4790 Automated
Extractor System, coupled with the Envision® Platform,
DryVap® Concentrator System and the Reclaimer™
Solvent Recovery System reduces analyst labor, solvent
usage, turn-around time, and greatly improves accuracy and
precision.
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Determination of PAHs from Sea Water Using Automated SPE
Table 4: Recoveries of PAH Compounds in Sea Water.
Compound
Napthalene
2-Methylnapthalene
Acenapthylene
Acenapthene
Fluorine
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benz (a) anthracene
Chrysene
Benzo (b) fluoranthene
Benzo (k) fluoranthene
Benzo (a) pyrene
Indeno (1,2,3-cd) pyrene
Dibenz (ah) anthracene
Benzo (ghi) perylene
Sample 1
(%)
69.0
75.2
80.0
78.3
81.6
82.2
80.8
83.4
83.0
84.0
80.9
87.3
80.5
83.2
88.4
85.8
84.2
Sample 2
(%)
81.3
83.1
84.5
84.8
85.0
86.2
82.2
88.0
87.4
86.7
80.8
90.1
82.4
84.3
91.7
88.1
86.6
Sample 3
(%)
67.7
70.5
72.5
71.7
75.9
74.6
76.6
76.6
75.9
75.8
74.9
76.3
77.6
75.0
78.4
76.8
77.9
Sample 4
(%)
72.4
75.2
78.0
79.6
81.9
80.4
79.9
80.8
80.0
80.7
81.3
77.3
80.0
77.8
80.5
78.6
81.9
Average
(%)
72.6
76.0
78.8
78.6
81.1
80.9
79.9
82.2
81.6
81.8
79.5
82.8
80.1
80.1
84.8
82.3
82.7
RSD
(%)
6.1
5.2
5.0
5.4
3.8
4.8
2.4
4.8
4.9
4.7
3.1
7.0
2.0
4.4
6.3
5.5
3.7
Figure 1: Typical Chromatogram for PAH Compounds in Sea Water.
Horizon Technology, Inc., 45 Northwestern Dr. Salem, NH, 03079 USA
Tel: (603) 893-3663 Fax: (603) 893-4994
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AN038-091214