Identification of Degradation Products of Sea-Dumped Chemical Warfare Agent-Related Phenylarsenic Chemicals in Marine Sediment

Article abstract of DOI:10.1021/acs.analchem.9b04681

Previously unknown phenylarsenic chemicals that originated from chemical warfare agents (CWAs) have been detected and identified in sediment samples collected from the vicinity of chemical munition dumpsites. Nontargeted screening by ultrahigh-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) was used for detection of 14 unknown CWA-related phenylarsenic chemicals. Methylated forms of Clark I/II, Adamsite, and phenyldichloroarsine were detected in all analyzed sediment samples, and their identification was based on synthesized chemicals. In addition, other previously unknown CWA-related phenylarsenic chemicals were detected, and their structures were elucidated using MS/HRMS technique. On the basis of relative isotope ratios of protonated molecules and measures of exact masses of formed fragment ions, it could be concluded that some of these unknown chemicals contained a sulfur atom attached to an arsenic atom. In addition to that, some of the samples contained chemicals that had formed via addition of an OH group to the aromatic ring. However, it is not possible to say how these chemicals are formed, but the most plausible cause is activities of marine microbes in the sediment. To our knowledge, these chemicals have not been detected from sediment samples previously. Sensitive analytical methods are needed for these novel chemicals to assess the total CWA burden in marine sediments, and this information is essential for the risk assessment.

Full text of DOI:10.1021/acs.analchem.9b04681

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Article
Identification of novel degradation products of sea-dumped chemical
warfare agent-related phenylarsenic chemicals in marine sediment
Hanna Niemikoski, Martin Soderstrom, Harri Kiljunen, Anders Östin, and Paula Vanninen
Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.9b04681 • Publication Date (Web): 03 Mar 2020
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Page 1 of 16
Analytical Chemistry
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Identification of novel degradation products of sea-dumped chemical
warfare agent-related phenylarsenic chemicals in marine sediment
Hanna Niemikoski1*, Martin Söderström1, Harri Kiljunen1, Anders Östin2, and Paula Vanninen1
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1Finnish Institute for Verification of the Chemical Weapons Convention, VERIFIN, Department of Chemistry, P.O. Box 55,
FI-00014 University of Helsinki, Finland
2Swedish Defence Research Agency, FOI, SE-90182 Umeå, Sweden
ABSTRACT: Previously unknown phenylarsenic chemicals originated from chemical warfare agents (CWAs) have been detected
and identified in sediment samples collected from the vicinity of chemical munition dumpsites. Non-targeted screening by ultra-high
performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) was used for detection of 14 unknown
CWA-related phenylarsenic chemicals. Methylated form of Clark I/II, Adamsite and phenyldichloroarsine were detected in all
analysed sediment samples and their identification was based on synthesized chemicals. In addition, other previously unknown CWA-
related phenylarsenic chemicals were detected and their structures were elucidated using MS/HRMS technique. Based on relative
isotope ratios of protonated molecules and measures exact masses of formed fragment ions, it could be concluded that some of these
unknown chemicals contained sulfur atom attached to arsenic atom. Addition to that, some of the samples contained chemicals which
had formed via addition of OH-group to the aromatic ring. Yet it’s not possible to say how these chemicals are formed, but the most
plausible cause is activities of marine microbes in sediment. To our knowledge, these chemicals have not been detected from sediment
samples previously. Sensitive analytical methods are needed for these novel chemicals to assess the total CWA burden in marine
sediments and this information is essential for the risk assessment.
Recently, abandoned chemical weapons (CWs) containing
Cl
CN
As
Cl
Cl
toxic chemical warfare agents (CWAs) manufactured during
World Wars (WWs) have raised concern not only for the
environmental, but also for safety reasons. Until the 1970’s,
chemical munitions and containers filled with CWAs were
disposed worldwide mainly by sea-dumping, and some
countries were trying get rid of these toxic chemicals by burying
them in the ground soil.1 Huge dumping operations took place
in the Baltic Sea area and Skagerrak Strait, where the load of
dumped chemical weapons were approximately 50,000 and
170,000 tons, respectively.2 These dumping operations were
adopted all around Europe; Japanese, North-American coastal
areas and Pacific Ocean were also loaded with chemical
munitions. It has been estimated that the total amount of
chemicals munitions dumped into seas and oceans is as high as
1 million tons including CWAs produced during WWs and
post-war period.1 In the Baltic Sea area dumped munitions
contain mainly sulfur mustard and phenylarsenic CWAs, such
as Clark I and II (DA and DC), and Adamsite (DM).
Furthermore, technical Clark, so-called arsine oil, consisting of
phenyldichloroarsine (Pfiffikus, PDCA), triphenylarsine
(TPA), Clark I and arsenic trichloride (AsCl3), was dumped.
Arsine oil is a tactical mixture and it was used as an additive in
sulfur mustard to lower its freezing point. Structures of these
CWA-related phenylarsenic chemicals are shown in Figure 1.
As
As
As
As
5
Cl
N
H
1
2
3
4
Figure 1. Chemical structures of Clark I, DA (1), Clark II, DC
(2), Adamsite, DM (3), Piffikus, PDCA (4), and triphenylarsine,
TPA (5)
Several
investigations
dealing
with
identification,
determination of exact location sites and corrosion stages of
dumped warfare objects have been accomplished during the last
two decades. Based on the information gained from several
sediment monitoring campaigns the Baltic Sea area and
Skagerrak it has been clearly demonstrated that corroded
ammunitions are leaking into marine environment causing risk
to marine ecosystem.1,3 Moreover, it has been proven that these
CWAs are uptaken by different marine biota species.4,5
All previous sediment monitoring campaigns in the Baltic Sea
and Skagerrak areas have focused on analyzing intact CWAs
and their known primary degradation products either by gas
chromatography-electron impact (tandem) mass spectrometry
(GC-EI/MS, GC-MS/MS) or liquid chromatography tandem
mass spectrometry (LC-MS/MS).6–8 The structures of known
primary degradation products of sea-dumped phenylarsenic
CWAs are presented in Figure 2. These degradation products
are known to be formed via hydrolysis and subsequent
oxidation reactions in the water environment.6,9
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Analytical Chemistry
Page 2 of 16
decomposed into arsenate, PAA, MPAA, and MDPAO.
O
As
OH
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O
OH
O
OH
Moreover, three unknown metabolites were detected but not
identified. These unknowns were eluted after DPA when C18
column was used suggesting that metabolites have more
hydrophobic nature compared to DPA. A paper published a year
later demonstrated the identification of the major metabolite
formed in soil cultures spiked with DPA.17 Time-of-flight high-
resolution mass spectrometry (TOF-HRMS) was utilized for
obtaining the exact mass and proposed elemental composition
for detected degradation product. In HRMS spectrum, a peaks
at m/z 260.97179 with the elemental composition of
C12H12AsSO was detected. This suggested that ion at m/z 279 is
a protonated molecule ion of diphenylthioarsinic acid, but
further structure elucidation of detected metabolite wasn’t
enable by TOF-MS.
OH
O
As
As
As
4
N
H
3
1
2
Figure 2. Primary degradation products of sea-dumped CWAs:
diphenylarsininc acid, DPA (1), phenarsazinic acid (2),
phenylarsonic acid, PAA (3), and triphenylarsine oxide, TPAO
(4)
9
According to the latest published study, 31% of the sediment
samples collected near the CW dumping areas, contained at
least one of the target CWA compounds.7 For example
concentrations such as 210, 1300, and 41 µg/kg dried sediment
were detected by LC-MS/MS for phenarsazinic acid,
diphenylarsinic acid (DPA), and phenylarsonic acid (PAA),
respectively. Results obtained during EU BSR Project
DAIMON (www.daimonproject.com) in 2019, showed that the
CWA pollution level in some sampling sites in Bornholm deep
was as high as 55, 2000, and 5700 µg/kg dried sediment
analysed by LC-MS/MS for phenarsazinic acid, DPA, and
PAA, respectively.10 Similar results have been obtained from
Skagerrak area: 1100 mg/kg from dried sediment for
propanethiol derivatives of Clark I and PDCA analysed by GC-
EI/MS.8
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In this paper, we describe identification of previously unknown
degradation products originated from sea-dumped CWAs based
on synthesized chemicals and Orbitrap high-resolution mass
spectrometry (OT-HRMS) measurements. Selected marine
sediment samples were analysed using non-targeted screening
method in order to investigate whether unknown phenylarsenic
chemicals originated from CWAs are existing in sediments.
These samples were previously analyzed quantitatively for
known primary degradation products of CWA-related
phenylarsenic chemicals containing high concentrations of
target chemicals (see Figure 2). OT-HRMS was utilized for
detection and identification of unknowns. High-resolving
power and high mass accuracy provided by OT-HRMS enables
screening and identification of unknown chemicals without
reference standard from complex matrix, such as marine
sediment.
Kizaki area in Japan is one of those areas where CWs containing
phenylarsenic chemicals were buried in the ground soil. In 2002
people started to get serious central nervous system symptoms
after drinking contaminated well-water.11 Graphite furnace
atomic absorption spectrometry (AAS) analysis revealed that
arsenic level in well-water was 450-times higher than
recommendations of World Health Organization (WHO).12
Further investigations based on GC-MS and inductively
coupled plasma mass spectrometry (ICP/MS) demonstrated that
the source of elevated arsenic concentrations was degradation
products of arsenic-containing CWAs such as DPA, PAA (See
Figure 2) and bis(diphenyl)arsine oxide (BDPAO) originated
from CWs buried in the soil.12 BDPAO is a dimerized
degradation product of Clark I/II.9 Soil samples taken in Kizaki
area showed contamination with these chemicals and
By this far, the investigations has focused only intact sea-
dumped chemicals and their known primary degradation
products. To estimate the total CWA burden in the sea bed,
information provided in this study is crucial. To our knowledge,
there are no previous published studies on methylated, sulfur-
containing, and hydroxylated degradation products of
phenylarsenic CWAs in marine sediment. In addition, this is
first time that these chemicals have been detected and identified
in any sediment samples.
furthermore,
dimethylphenylarsine
methylphenylarsinic
oxide
acid
(MPAA),
and
(DMPAO)
methyldiphenylarsine oxide (MDPAO) were detected.13
Structures of these methylated degradation products of CWAs
are presented in Figure 3.
EXPERIMENTAL SECTION
Chemicals and reagents PDCA, DM and DA were synthesized
at Finnish Institute for Verification of the Chemical Weapons
Convention. Methanol (MeOH) (LC-MS grade) and acetonitrile
(ACN) (HPLC grade) used in sample pre-treatment and
tetrahydrofuran (THF9 (HPLC grade) were obtained from
VWR International (Belgium) and Merck Group (Germany),
respectively. ACN and formic acid (FA) (both LC-MS grade)
was purchased from Merck and hydrogen peroxide (33 %) was
obtained from VWR International. Methyl lithium (MeLi) (99
%) was obtained from Sigma Aldrich. Water was purified using
a Direct-Q3 UV system (Millipore, Germany).
H3C
H3C
H3C
O
O
O
As
As
As
OH
CH3
3
1
2
Figure 3. Methylated degradation products of CWAs:
methylphenylarsinic acid, MPAA (1), dimethylphenylarsine
oxide, DMPAO (2), and methyldiphenylarsine oxide, MDPAO
(3)
It has been suggested that these methylated phenylarsenicals are
formed by bacteria under anaerobic conditions.14,15 Unlike in
the water environment, the behaviour of these chemicals in
terrestrial environment have been studied to some extent.
Transformation of DPA was investigated in the soil cultures
under sulfate-reducing conditions.16 After 5-week incubation
samples were analysed by LC-ICP/MS showing that DPA was
Sediment samples Samples containing high concentrations of
phenylarsenic CWAs collected during the previous
international projects dealing with marine munitions
(CHEMSEA, MODUM and DAIMON projects) were selected
for non-targeted screening by UHPLC-HRMS. The list of the
current target phenylarsenic CWA chemicals18 is presented in
Supporting information (Table S-1) and the concentrations of
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Analytical Chemistry
target chemicals in these sediment samples are given in Detailed synthesis procedure are described below for
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Supporting information (Table S-2). Sediment samples
collected from area were no CWA contamination has occurred
were also analysed as matrix blanks. The samples were shipped
frozen on dry ice and stored at -20 °C prior to reanalysis.
Sample preparation Sediment samples were prepared
according to “Recommended Procedures for Sampling and
Analysis in Verification of Chemical Disarmament” (ROP).18
In generally, sample preparation consisted of removal of pore
water, extraction with ACN, filtration, and solvent exchange
(H2O/MeOH, 50:50, v/v) steps. The sample pre-treatment
controls were done by spiking DA, DM, and TPA in blank
sediment.
synthesized chemicals. Synthesis of MDPAO is presented in
Scheme 1.
CH3
As
Cl
O
CH3
[ox]
As
As
MeLi
THF
H2O
Scheme 1. Synthesis scheme for MDPAO
Methyldiphenylarsine oxide (MDPAO) 12.3 mg of Clark I
(0.047 mmol) was dissolved in dry THF (0.5 mL) under argon
atmosphere. 35 µL of MeLi was added through the septum and
the reaction mixture was strirred for one hour at the room
temperature. Reaction was stopped by adding 0.5 ml of water.
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UHPLC-HRMS analysis The UHPLC-HRMS analysis were
performed on Thermo Scientific Orbitrap Fusion mass
spectrometer (San Jose, USA) connected to Thermo Scientific
Dionex Ultimate 3000 ultra-high performance liquid
chromatograph (Germering, Germany).
UHPLC separation was done using Waters XBridge BEH C18
column (2.1 x 50 mm, 1.7 µm) at 40 °C using a linear gradient
of two mobile phases: 0.1 % FA in water (A) and 0.1 % FA in
ACN (B). The gradient was run from 5 % B at 0 min to 100 %
B at 2 min. After this the B eluent was kept 100% for 1 min and
at 5% for 2 min. The flow rate was 0.5 ml/min and the injection
volume was 5 µl.
The ionization was done using a heated electrospray (HESI)
probe in the positive ion mode. The instrumental parameters
were set as follows: spray voltage 3000 V, source temperature
300 °C, ion transfer tube temperature 350 °C, sheath gas 30,
auxiliary gas 10 and sweep gas 0. Mass measurement in full
scan mode was done with mass range m/z 60–600 using RF lens
at 60% and quadrupole isolation (m/z 60–600) at resolution of
120,000. Mass accuracy of the instrument using external
calibration was specified to be ≤ 3ppm. For MS/HRMS
measurements higher-energy collisional dissociation (HCD)
was used for induce the fragmentation of selected protonated
molecule ions.
10-methyl-5H-phenarsazinine 10-oxide (10-M-5H-PAO)
14.5 mg of Adamsite (0.052 mmol) was dissolved in dry THF
(0.5 mL) under argon atmosphere. 35 µL of MeLi was added
through the septum and the reaction mixture was stirred for one
hour at the room temperature. Reaction was stopped by adding
0.5 ml of water.
Dimethyl(phenyl)arsine oxide (DMPAO) 15.3 mg of PDCA
(0.069 mmol) was dissolved in dry THF (0.5 mL) under argon
atmosphere. 50 µL of MeLi was added through the septum and
the reaction mixture was stirred for one hour at the room
temperature. Reaction was stopped by adding 0.5 ml of water.
The synthesis products were used as an analytical standards
after dilution.
The qualitative identification of the these methylated
phenylarsenic compounds were based on criteria of the
Organisation for the Prohibition of Chemical Weapons
(OPCW).19 In LC analysis, retention time of the identified
compound shall not differ more than ±0.2 min from reference
standard sample (see Figure 4). For HRMS techniques, the
elemental composition has to be obtained and the mass accuracy
with a mass error must be below 2.5 parts per million (ppm).
RESULT AND DISCUSSION
Analysis of sediment samples. All samples were analysed in
full scan mode using non-targeted analysis. An example of total
ion chromatogram (TIC) of a sediment sample is given in
Supporting information (Figure S-1). Matrix blank samples
(sediment extracts and solvent) were analysed before and after
sediment samples analysis. No cross-contamination arose from
sample pretreatment and no carry over occurred during
instrumental analysis. Novel chemicals discussed in this paper
were not detected in matrix blank sediment samples nor sample
pre-treatment controls.
Identification of methylated phenylarsenic chemicals In full
scan mode, unknown peaks were detected in sediment samples
at m/z 199.01034, 274.02084 and 261.02562 with the elemental
composition of C8H12OAs, C13H13ONAs and C13H14OAs,
respectively. This strongly suggests that sediment samples
contained DMPAO, 10-5H-PAO and MDPAO, respectively.
Figure 4: UHPLC–HESI/HRMS total ion chromatograms for
DMPAO, 10-M-5H-PAO and MDPAO in analytical standard (A)
and sediment sample (B)
For reliable qualitative identification, methylated phenylarsenic
chemicals were prepared using MeLi as a methyl group donor.
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For further structure elucidation, HCD was used for generating
fragments from protonated molecule ions of different
methylated phenylarsenicals. Spectrometric parameters for
different methylated phenyl arsenic chemicals are presented in
Table 1.
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Table 1. Mass spectrometric parameters used for the detection
and characterization of methylated phenylarsenic chemicals
Parent ion
[m/z]
HCD
[%]
scan range
Compound
DMPAO
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[m/z]
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274
261
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40
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70-210
70-300
70-280
10-M-5H-PAO
MDPAO
MS/HRMS spectra for different methylated phenylarsenic
chemicals detected in analytical standards and sediment sample
are presented in Figure 5. MS/HRMS spectra A, C and E are
presenting synthesized chemicals and spectra B, D and F are
from original the sediment sample. The elemental composition
of protonated molecules and formed fragments were found to
match with the elemental compositions of protonated molecules
and formed fragments of synthesized chemicals.
As seen in Figure 5, fragmentation of DMPAO (A and B),
generates signals at m/z 168.96291 and 152.96805,
fragmentation of 10-M-5H-PAO (C and D) generates signals at
m/z 241.99458 and 167.07298, and fragmentation of MDPAO
(E and F) generates signals at m/z 226.98369, 168.96283 and
154.07776. These fragments are generally known to be specific
for PAA, phenarsazinic acid and DPA (see Figure 2),
respectively. This indicates undisputable that these detected
chemicals are originated from phenylarsenic CWAs.
Determination of purity and concentrations of synthesized
chemicals wasn’t enabled in the framework of this study,
therefore the quantitative analysis of methylated phenylarsenic
chemicals in sediment samples wasn’t possible. However, peak
areas of these chemicals was compared to peak areas of primary
degradation products found in same sediment sample. Even
though the ionization efficiency of analytes with different
chemical properties varies, the peak areas of methylated
chemicals in some sediment samples are even higher than peak
areas of current target chemicals. Data is shown in Supporting
information (Figure S-2).
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Analytical Chemistry
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Figure 5. MS/HRMS spectra for DMPAO in analytical standard (A) and sediment sample (B), 10-M-5H-PAO in analytical standard ( (C)
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and sediment sample (D) and MDPAO in analytical standard ( (E) and sediment sample (F)
Identification of sulfur containing phenylarsenic chemicals
All analysed sediment samples contained unknown chemicals
which didn’t appear in TICs of blank sediment samples.
Proposed structures for protonated molecule ions, their
elemental compositions, measured masses, mass differences
compared to theoretical masses, retention times, and relative
abundance of isotope34S are presented in Table 2. The presence
of distinct [M+H]++2 peak for detected chemicals indicates that
the structures of these chemicals contain one sulfur atom. In
generally, the relative abundance of [M+H]++2 peak of detected
compounds varied from 3.79 to 4.4 %. Ratios of [M+H]+ and
[M+H]++2 peaks strongly suggests that each compounds
contained 32S and 34S isotopes, which is crucial for elemental
composition elucidation.
in Fig 2). This is seen in retention times: their elution out of C18
column is delayed 1.25-1.79 minutes compared to their oxygen
containing analogues. The structure elucidation of these sulfur-
containing chemicals were done by MS/HRMS using different
HCD energies. MS/HRMS spectra were recorded and the
structures of formed fragments were elucidated based on
measured mass. Proposed fragmentation pathways for
methyldiphenylarsine sulfide, 10-methyl-5H-phenarsazinine
sulfide, dimethylphenylarsine sulfide, and triphenylarsine
sulfide are shown in Figure 6. Masses of the fragments
presented in Figure 6 are theoretical and they all are present in
spectra of corresponding novel compounds within mass
accuracy of 1 ppm. TICs and MS/HRMS spectra for six
detected sulfur-containing chemicals (see proposed structures
in Table 2) are presented in Supporting Information (Figures
S3-S7) and relative ion intensities for detected fragments are
presented in Supporting Information (Table S3).
Very likely polar properties of these phenylarsenic chemicals
are decreasing when sulfur is attached to arsenic atom compared
to their corresponding oxygen analogues (structures presented
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As seen in Figure 6, compounds that have analogous structures,
methylated phenylarsenic chemicals, peak areas of sulfur-
containing
chemicals were compared to peak areas of target chemicals
found in same sediment sample. Data is shown in Supporting
information (Figure S8-S9).
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form same fragments. This indicates very clearly, that structures
of these chemicals are similar to each other. For example
fragment with mass at m/z 151.96017 are generated from
protonated molecules of dimethylphenylarsine sulfide and
triphenylarsine sulfide (See Figure 6 C and D), which have
analogous structures. Same fragment is generated from DPA, a
primary degradation product of DA.
This further supports the assumption, that these sulfur-
containing chemicals are originated from CWAs. As in case of
9
Table 2. Proposed structures of novel sulfur-containing phenylarsenic chemicals in sediment, corresponding elemental composition,
measures masses, mass differences compared to theoretical values, retention times, and relative abundance of [M+H]++2 ion
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Relative
Mass
Proposed structure and elemental
composition
Measured
mass
abundance of
[M+H]++2
difference
[ppm]
Rt [min]
peak (34S )*
PDCA-related chemical
HS
As
CH3
CH3
C8H12AsS+
214.98701
0.02052
1.96
3.97 %
Dimetylpenylarsi
ne sulfide
Adamsite-related chemicals
HS OH
As
N
H
C12H11AsNOS+
291.97723
289.99792
0.05111
0.02315
2.57
2.92
4.44 %
4.16 %
10-hydroxy-5H-
phenarsazinine-
10-acid
HS CH3
As
N
H
C13H13AsNS+
10-methyl-5H-
phenarsazinine-
10-sulfide
Clark-related chemicals
HS OH
As
C12H12AsOS+
C13H14AsS+
278.98196
277.00275
0.10915
0.07746
3.30
3.41
3.82 %
3.93 %
Diphenylthiorsini
c acid
HS CH3
As
Methyldiphenyla
rsine sulfide
Triphenylarsine-related chemical
HS
As
C18H16AsS+
339.01842
0.30191
4.53
4.24 %
Triphenylarsine
sulfide
*Observed interval of 34S isotope-abundance in natural material is 3.96-4.77 %20
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Analytical Chemistry
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Figure 6. Proposed structures for fragment ions in the MS/HRMS spectra of methyldiphenylarsine sulfide (A), 10-methyl-5H-phenarsazine-
32
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60
10-sulfide (B), dimethylphenylarsine sulfide (C), and triphenylarsine sulfide (D)
Mass
differen
ce
Identification of hydroxylated phenylarsenic chemicals.
Addition to chemicals discussed previously, five unknown
degradation products were detected. Based on measured masses
of protonated molecules and retention times of detected
chemicals, it was assumable that hydroxylation reactions have
occurred on aromatic ring. Proposed structures for hydroxylated
Proposed novel structure and
elemental composition
Measured
mass
Rt
[min]
[ppm]
HO OH
As
OH
+
+
C12H13AsNO2
291.99521 0.93012 1.17
290.01562 0.18097 1.32
N
H
phenylarsenic
chemicals,
corresponding
elemental
DM-OH
HO CH3
As
compositions, measures masses, mass differences compared to
theoretical values, and retention times are presented in Table 3.
OH
N
H
C13H13AsNO2
10-M-5H-
PAO-OH
Table 3. Proposed structures for hydroxylated phenylarsenic
chemicals, corresponding elemental composition, measures
masses, mass differences compared to theoretical values, and
retention times
HO OH
As
1.57;
278.99968 0.03547
1.73
OH
+
C12H12AsO3
DPA-OH
HO CH3
As
1.50;
277.02040 0.09030
1.64
OH
C13H14AsO+
MDPAO-OH
OH
As
2.39;
339.03594 0.40047
2.52
+
C18H16AsO2
HO
TPAO-OH
For example, DPA, an abiotic degradation of Clark I/II and
MDPAO identified in this study (see Figure 6) are seen in mass
spectra at m/z 263.00046 and 261.02562, respectively. Two
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Figure 7. UHPLC–HESI/HRMS EICs for hydroxylated
degradation products of Clark (A) and HRMS spectra for DPA-OH
(B) and MDPAO-OH (C) in sediment sample
Clark-type chemicals were detected with mass difference of 16
amu compared to protonated molecules of DPA and MDPAO,
suggesting that addition of hydroxyl group have been occurred
to aromatic ring. These protonated chemicals were detected at
m/z 278.99968 and 277.02040. Retention times of these
chemicals are decreased compared to DPA and MDPAO
suggesting that these unknows are more hydrophilic. Based on
measured masses, obtained elemental compositions and
retention times, these chemicals are hydroxydiphenylarsinic
acid (DPA-OH) and hydroxymethyldiphenylarsine oxide
(MDPAO-OH). Extracted ion chromatograms (EICs) for DPA,
DPA-OH, MDPAO, MDPAO-OH and HMRS spectra of DPA-
OH and MDPAO-OH are presented in Figure 7. It is also
noticed that both chemicals formed two isomers where
hydroxylation have occurred on different position on the
aromatic rings. This is seen in EICs (Figure 7) where two peaks
are detected at 1.57 and 1.73 min for m/z 278.99968 and 1.50
and 1.64 min for m/z 277.02040, respectively. Same
phenomenon was observed with hydroxytriphenylarsine oxide
(TPAO-OH), but hydroxylated forms of Adamsite-related
chemicals formed only one isomer.
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8
CONCLUSIONS
High mass accuracy provided by OT-HRMS decreases matrix
background effects allowing reliable identification and exact
molecular formula assignment for unknowns. When comparing
to TOF-HRMS utilized in previously published study on
identification of degradation products of CWA-related
chemicals in soil samples, OT-HRMS enables more exact
structure elucidation by fragmentation of protonated molecules
using HCD providing detection of fragment ions at high
resolution and mass accuracy.
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Detected novel phenylarsenic chemicals discussed in this paper
are originated from PDCA, DA, DM, and TPA, which are
widely dumped at the sea bed in the Baltic Sea and Skagerrak
areas. In the framework of this study, we weren’t able to
determine exact concentration of these identified CWA-related
chemicals discussed in this paper. Comparing peak areas of
identified phenylarsenic chemicals to peak area of target
chemicals in the same sediment sample, we can assume that the
concentration levels of methylated and sulfur-containing
chemicals are at the same level or even higher. Due to lack of
information, it’s not possible to say for sure how these novel
chemicals are formed. Methylated degradation products
identified in this study are the same as have been previously
detected from CWA contaminated soil which strongly indicates
that formation is due to microbiological activities. To prove
bacterial transformations of these phenylarsenic CWAs into
detected chemicals identified in this study, elaborate research
needs to carry out. If these transformations are resulting from
bacterial activities in the sediment, some, or maybe even most
of the intact phenylarsenic CWAs in the marine sediment will
be transformed into methylated and sulfur-containing
phenylarsenic chemicals over time and they can be further
degrade in some yet unknown species.
The more detailed structure elucidation was done by
MS/HRMS for hydroxylated products of Clark- and TPA-
related chemicals. HRMS spectra with identified fragment are
presented in Supporting Information (Figures S11-S13).
Monitoring the sea floor quality is crucial for environmental
risk assessment and furthermore maritime spatial planning.
Increasing pressure for building wind power stations,
underwater pipelines and cables require a survey of the
condition of the seabed. These previously unknown chemicals
identified in this study have significant role in the future when
analysing concentrations of CWA-related phenylarsenic
chemicals in the marine sediment. Targeted analytical methods
for these novel chemicals are needed to assess the total CWA
burden in marine sediments. Especially methylated and sulfur
containing degradation products of phenylarsenic CWAs
should be taken into account when measuring CWA
contamination levels in marine sediments
These novel chemicals discussed in this paper, might also have
a hazardous impact to ecosystem. There are no toxicity data
available for these methylated and sulfur-containing
phenylarsenic chemicals and non-existent knowledge on how
they behave in aqueous environment. It has already proven that
abiotic degradation product of Clark I and/or II is accumulating
in fish tissues. These novel chemicals identified in this study are
most like more lipophilic than known abiotic degradation
products suggesting that these chemicals are more prone to
accumulate in fish tissues.
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Analytical Chemistry
Karjalainen, M.; Niemikoski, H.; Vanninen, P.; Broeg, K.;
Lehtonen, K.; Berglind, R. Toxic Effects of Chemical Warfare
Agent Mixtures on the Mussel Mytilus Trossulus in the Baltic Sea:
A Laboratory Exposure Study. Mar. Environ. Res. 2019, 145
ASSOCIATED CONTENT
1
2
3
4
5
6
7
8
Supporting Information
The Supporting Information is available free of charge on the ACS
Publications website.
(February),
112–122.
https://doi.org/10.1016/j.marenvres.2019.02.001.
Methods and result and discussion: Table S-1 List of current target
phenylarsenic CWAs in sediment analysis. Table S-2
Concentrations of current target chemicals detected in sediment
samples quantitated in CHEMSEA, MODUM and DAIMON
projects. Figure S-1 Total ion chromatogram for sediment sample
#1. Figure S-2 Extracted ion chromatograms for sediment sample
#6 containing methylated phenylarsenicals and target chemicals.
Figure S-3 Total ion chromatogram and spectrum for
diphenylarthiorsinic acid.
(6)
(7)
Missiaen, T.; Söderström, M.; Popescu, I.; Vanninen, P.
Evaluation of a Chemical Munition Dumpsite in the Baltic Sea
Based on Geophysical and Chemical Investigations. Sci. Total
Environ.
2010,
408
(17),
3536–3553.
https://doi.org/10.1016/j.scitotenv.2010.04.056.
Bełdowski, J.; Klusek, Z.; Szubska, M.; Turja, R.; Bulczak, A. I.;
Rak, D.; Brenner, M.; Lang, T.; Kotwicki, L.; Grzelak, K.;
Jakacki, J.; Fricke, N.; Östin, A.; Olsson, U.; Fabisiak, J.;
Garnaga, G.; Nyholm Rattfelt, J.; Broeg, K.; Södesrtröm, M.;
Vanninen, P.; Popiel, S.; Nawala, J.; Lehtonen, K.; Berling, R.;
Schmidt, B. Chemical Munitions Search & Assessment—An
Evaluation of the Dumped Munitions Problem in the Baltic Sea.
Deep Sea Res. Part II Top. Stud. Oceanogr. 2016, 128, 85–95.
https://doi.org/https://doi.org/10.1016/j.dsr2.2015.01.017.
9
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49
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59
60
Figure S-4 Total ion chromatogram and spectrum for
methyldiphenylarsine sulfide. Figure S-5 Total ion chromatogram
and spectrum for 10-methyl-5H-phenarsazinine-10-sulfide. Figure
S-6
Total
ion
chromatogram
and
spectrum
for
(8)
(9)
Tørnes, J. A.; Opstad, A. M.; Johnsen, B. A. Determination of
Organoarsenic Warfare Agents in Sediment Samples from
Skagerrak by Gas Chromatography-Mass Spectrometry. Sci.
dimethylphenylarsine sulfide. Figure S-7 Total ion chromatogram
and spectrum for triphenylarsine sulfide. Table S-3 Detected
fragments and their relative abundance for all detected sulfur
containing chemicals. Figure S-8 Extracted ion chromatogram for
sediment sample #8 containing sulfur-containing phenylarsenic
chemicals and target chemicals.
Figure S-9 Extracted ion chromatogram for sediment sample #8
containing sulfur-containing phenylarsenic chemicals and target
chemicals. Figure S-10 Spectrum for hydroxy-phenarsazinic acid.
Figure S-11 Extracted ion chromatogram and spectra for two
isomers of hydroxy-diphenylarsinic. Figure S-12 Extracted ion
chromatogram and spectra for two isomers of hydroxy-
triphenylarsine oxide (pdf).
Total
Environ.
2006,
356
(1–3),
235–246.
https://doi.org/10.1016/j.scitotenv.2005.03.031.
Haas, R.; Schmidt, T. C.; Steinbach, K.; Von Löw, E.
Chromatographic Determination of Phenylarsenic Compounds.
Fresenius. J. Anal. Chem. 1998, 361 (3), 313–318.
https://doi.org/10.1007/s002160050892.
Lignell, H.; Karjalainen, M.; Aalto, S.; Taure, T.; Tuomala, N.;
Vanninen, P. DAIMON Report on Chemical Analysis of Sea-
Dumped Chemical Warfare Agents in Sediment Samples; 2019.
Ishii, K.; Tamaoka, A.; Otsuka, F.; Iwasaki, N.; Shin, K.; Matsui,
A.; Endo, G.; Kumagai, Y.; Ishii, T.; Shoji, S. Diphenylarsinic
Acid Poisoning from Chemical Weapons in Kamisu, Japan. Ann.
Neurol. Off. J. Am. Neurol. Assoc. Child Neurol. Soc. 2004, 56
(5), 741–745.
Ishizaki, M.; Yanaoka, T.; Nakamura, M.; Hakuta, T.; Ueno, S.;
Komuro, M.; Shibata, M.; Kitamura, T.; Honda, A.; Doy, M.;
Ishii, K.; Tamaoka, A.; Shimojo, N.; Ogata, T.; Nagasawa, E.;
Hanaoka, S. Detection of Bis(Diphenylarsine)Oxide,
Diphenylarsinic Acid and Phenylarsonic Acid, Compounds
Probably Derived from Chemical Warfare Agents, in Drinking
Well Water. J. Heal. Sci. 2005, 51 (2), 130–137.
Baba, K.; Arao, T.; Maejima, Y.; Watanabe, E.; Eun, H.;
Ishizaka, M. Arsenic Speciation in Rice and Soil Containing
Related Compounds of Chemical Warfare Agents. Anal. Chem.
(10)
(11)
(12)
AUTHOR INFORMATION
Corresponding Author
* E-mail: hanna.niemikoski@helsinki.fi
Notes
The authors declare no competing financial interest.
(13)
(14)
ACKNOWLEDGMENT
This study was performed within the frame work of the EU BSR
Project DAIMON (www.daimonproject.com), and was partially
financed from European Regional Development fund #R013. The
content of this publication is the sole responsibility of its Authors
and can in no way be taken to reflect the views of the European
Union.
2008,
80
(15),
5768–5775.
https://doi.org/Doi
10.1021/Ac8002984.
Arao, T.; Maejima, Y.; Baba, K. Uptake of Aromatic Arsenicals
from Soil Contaminated with Diphenylarsinic Acid by Rice.
Environ. Sci. Technol. 2009, 43 (4), 1097–1101.
https://doi.org/10.1021/es8023397.
(15)
(16)
Maejima, Y.; Arao, T.; Baba, K. Transformation of
Diphenylarsinic Acid in Agricultural Soils. J. Environ. Qual.
2011, 40 (1), 76. https://doi.org/10.2134/jeq2009.0496.
Guan, L.; Hisatomi, S.; Fujii, K.; Nonaka, M.; Harada, N.
Enhanced Transformation of Diphenylarsinic Acid in Soil under
Sulfate-Reducing Conditions. J. Hazard. Mater. 2012, 241–242,
355–362. https://doi.org/10.1016/j.jhazmat.2012.09.054.
Hisatomi, S.; Guan, L.; Nakajima, M.; Fujii, K.; Nonaka, M.;
Harada, N. Formation of Diphenylthioarsinic Acid from
Diphenylarsinic Acid under Anaerobic Sulfate-Reducing Soil
Conditions. J. Hazard. Mater. 2013, 262, 25–30.
https://doi.org/10.1016/J.JHAZMAT.2013.08.020.
Söderström, M.; Östin, A. Analysis of Sediment Samples for Sea-
Dumped Chemical Weapons. In Recommended operating
procedures for analysis in the verification of chemical
disarmament; 2017; pp 631–649.
Organisation for the Prohibition of Chemical Weapons, (OPCW).
Work Instruction for the Reporting of the Results of the OPCW
Biomedical Proficiency Test.; 2018.
REFERENCES
(1)
Bełdowski, J.; Been, R.; Turmus, E. K. Towards the Monitoring
of Dumped Munitions Threat (MODUM): A Study of Chemical
Munitions Dumpsites in the Baltic Sea; Springer, 2017.
Knobloch, T.; Bełdowski, J.; Böttcher, C.; Söderström, M.; Rühl,
N. P.; Sternheim, J. Chemical Munitions Dumped in the Baltic
Sea. Report of the Ad Hoc Expert Group to Update and Review
the Existing Information on Dumped Chemical Munitions in the
Baltic Sea (HELCOM MUNI). Balt. Sea Environ. proceeding no
2013, 142.
(2)
(17)
(18)
(3)
(4)
(5)
Bełdowski, J.; Fabisiak, J.; Popiel, S.; Östin, A.; Olsson, U.;
Vanninen, P.; Lastumaki, A.; Lang, T.; Fricke, N.; Brenner, M.
CHEMSEA Findings. Institute of Oceanology Polish Academy of
Sciences 2014.
Niemikoski, H.; Söderström, M.; Vanninen, P. Detection of
Chemical Warfare Agent-Related Phenylarsenic Compounds in
Marine Biota Samples by LC-HESI/MS/MS. Anal. Chem. 2017,
89 (20). https://doi.org/10.1021/acs.analchem.7b03429.
Höher, N.; Turja, R.; Brenner, M.; Nyholm, J. R.; Östin, A.;
Leffler, P.; Butrimavičienė, L.; Baršienė, J.; Halme, M.;
(19)
(20)
Meija, J.; Coplen, T. B.; Berglund, M.; Brand, W. A.; De Bièvre,
P.; Gröning, M.; Holden, N. E.; Irrgeher, J.; Loss, R. D.;
Walczyk, T. Isotopic Compositions of the Elements 2013 (IUPAC
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Technical Report). Pure Appl. Chem. 2016, 88 (3), 293–306.
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For TOC only
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Analytical Chemistry
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9
RT: 0.70
RT: 0.71
100
100
80
60
40
20
A)
B)
80
60
DMPAO
DMPAO
10
11
12
13
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40
20
RT: 1.43
RT: 1.43
100
80
100
80
60
40
20
60
40
10-M-5H-PAO
10-M-5H-PAO
20
RT: 1.81
RT: 1.82
100
80
100
80
60
40
20
60
MDPAO
MDPAO
40
20
1
2
3
4
5
1
2
3
4
5
Time (min)
Time (min)
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Page 12 of 16
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9
168.96292
C H6O
168.96291
C6H5OAs
As
6
100
80
60
40
20
0
100
80
60
40
20
0
B)
A)
10
11
12
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90.91614
90.91615
[M+H]+
199.00987
C8H12OAs
[M+H]+
199.00989
As
105.04488
100
105.04487
100
77.03878
C 6H5
152.96806
6H6 As
77.03878
C6H5
C
152.96805
C6H6As
8H12O
C
80
120
140
m/z
160
180
200
80
120
140
m/z
160
180
200
167.07298
C
167.07298
C12H9N
N
12H9
100
100
80
60
40
20
0
D)
C)
80
60
40
20
0
241.99458
As
241.99458
C12H9NAs
C
12H9N
[M+H]+
[M+H]+
274.02084
274.02084
C13H13ONAs
As
C13H13ON
80
100 120 140 160 180 200 220 240 260 280 300
m/z
80
100
120
140
160
180
m/z
200
220
240
260
280
300
154.07776
C12H10
154.07777
C12 H10
100
80
60
40
20
0
100
E)
F)
80
60
40
20
0
168.96286
168.96283
C6H6OAs
C6
H
6 OAs
[M+H]+
261.02563
C13H14OAs
[M+H]+
261.02563
91.05438
C7H7
91.05441
C7
C13
H14O
As
226.98367
H
226.98369
C12H8As
7
C12
H
8As
80
100
120
140
160
180
m/z
200
220
240
260
280
80
100
120
140
160
180
m/z
200
220
240
260
280
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Analytical Chemistry
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8
Methyldiphenylarsine sulfide
10-methyl-5H-phenarsazinine-10-sulfide
A)
B)
Chemical Formula: C7H8AsS+
Chemical Formula: C12H10As+
Exact Mass: 228.99930
Exact Mass: 198.95572
S
As CH3
9
CH3
As
Chemical Formula: C7H8As+
Exact Mass: 166.98365
As
10
11
12
13
14
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18
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As
N
H
N
H
As
Chemical Formula: C13H12AsN•+
Exact Mass: 257.01802
Chemical Formula: C12H9AsN+
Exact Mass: 241.99455
HS
As
As
HS
As
CH3
CH3
Chemical Formula: C12H8As+
Exact Mass: 226.98365
Chemical Formula: C13H14AsS+
Exact Mass: 277.00267
Chemical Formula: C13H14AsS+
Exact Mass: 277.00267
+
Chemical Formula: C7H7
Exact Mass: 91.05423
As
S
N
H
•+
Chemical Formula: C12H10
Exact Mass: 154.07770
Chemical Formula: C6H4AsS+
Exact Mass: 182.92442
Chemical Formula: C12H10N•+
Exact Mass: 168.08078
Triphenylarsine sulfide
Dimethylphenylarsine sulfide
C)
D)
As
As
Chemical Formula: C2H6AsS+
Exact Mass: 136.94007
As CH3
CH3
CH2
Chemical Formula: C7H8As+
Exact Mass: 166.98365
AsH
Chemical Formula: C11H7As•+
Exact Mass: 213.97582
S
Chemical Formula: C12H10As+
Exact Mass: 228.99930
AsH
AsH
SH
As
As
HS
As
HS
CH3
CH3
As
Chemical Formula: C6H5As•+
Exact Mass: 151.96017
Chemical Formula: C6H5As•+
Exact Mass: 151.96017
Chemical Formula: C12H8As+
Chemical Formula: C6H6AsS+
Exact Mass: 184.94007
Chemical Formula: C18H16AsS+
Exact Mass: 339.01832
Chemical Formula: C8H12AsS+
Exact Mass: 226.98365
Exact Mass: 214.98702
As
H2C CH2
As
CH3
As
+
As
S
Chemical Formula: C7H7
Exact Mass: 91.05423
CH3
Chemical Formula: C18H12As•+
Exact Mass: 303.01495
Chemical Formula: C2H4As+
Exact Mass: 102.95235
•+
Chemical Formula: C12H10
Exact Mass: 154.07770
Chemical Formula: C6H4AsS+
Exact Mass: 182.92442
Chemical Formula: C8H11As2•2+
Exact Mass: 182.00657
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Analytical Chemistry
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Relative
abundance
of
Mass
difference
[ppm]
Proposed structure and elemental
composition
Measured
mass
Rt [min]
[M+H]++2
peak (34S )*
PDCA-related chemical
9
10
11
12
13
14
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C8H12AsS+
dimetylpenylarsine
214.98701
0.02052
1.96
3.97
sulfide
Adamsite-related chemicals
C12H11AsNOS+ 291.97723
0.05111
2.57
2.92
4.44
4.16
10-hydroxy-5H-
phenarsazinine-10-
acid
C13H13AsNS+
289.99792
0.02315
10-methyl-5H-
phenarsazinine-10-
sulfide
Clark-related chemicals
C12H12AsOS+
278.98196
277.00275
0.10915
3.30
3.41
3.82
3.93
diphenylthiorsinic
acid
C13H14AsS+
0.07746
methyldiphenylarsine
sulfide
Triphenylarsine-related chemical
C18H16AsS+
339.01842
0.30191
4.53
4.24
triphenylarsine
sulfide
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Analytical Chemistry
Page 16 of 16
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Mass
differen
ce
Proposed novel structure and
elemental composition
Measured
mass
Rt
[min]
[ppm]
7
8
9
+
+
C12H13AsNO2
291.99521 0.93012 1.17
DM-OH
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
C13H13AsNO2
290.01562 0.18097 1.32
1.57;
10-M-5H-
PAO-OH
+
C12H12AsO3
278.99968
0.03547
1.73
DPA-OH
1.50;
1.64
C13H14AsO+
277.02040 0.09030
MDPAO-OH
2.39;
2.52
+
C18H16AsO2
339.03594
0.40047
TPAO-OH
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