Aerosol Science and Technology, 41:418–437, 2007
c American Association for Aerosol Research
Copyright ISSN: 0278-6826 print / 1521-7388 online
DOI: 10.1080/02786820701203215
Contribution of Selected Dicarboxylic and ω-Oxocarboxylic
Acids in Ambient Aerosol to the m/z 44 Signal
of an Aerodyne Aerosol Mass Spectrometer
N. Takegawa,1 T. Miyakawa,1 K. Kawamura,2 and Y. Kondo1
1
2
Research Center for Advanced Science and Technology, University of Tokyo, Tokyo, Japan
Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido, Japan
The Aerodyne aerosol mass spectrometer (AMS) employs flash
vaporization (600◦ C) followed by 70-eV electron impact ionization (EI) to detect organic and inorganic aerosols. The signal at
mass-to-charge ratio (m/z) 44 (mainly CO+
2 ) is considered the
most reliable marker of oxygenated organic aerosol. This study
is the first to evaluate the contribution of selected low molecular
weight dicarboxylic acids (diacids) and ω-oxocarboxylic acids (ωoxoacids) to the particle-phase m/z 44 signal of the AMS mass spectrum. Ambient measurements were conducted at a surface site in
Tokyo (35◦ 39 N, 139◦ 40 E) during August 3–8, 2003. Diacids and
ω-oxoacids were measured using a filter sampling followed by extraction, derivation, and gas chromatograph-flame ionization detector (GC-FID) analysis. The mass concentrations of diacids and
ω-oxoacids show tight correlation with the m/z 44 signal (r2 = 0.85–
0.94) during the measurement period. Laboratory experiments
were also performed to determine the fragment patterns of selected
diacids (C2 –C6 diacids and phthalic acids) and ω-oxoacid (glyoxylic
acid) in ambient aerosols. Here, we report for the first time that the
selected organic acids could account for 14 ± 5% of the observed
m/z 44 signal on average during the measurement period. Oxalic
acid (C2 ) is the largest contributor, accounting for 10 ± 4% of the
observed m/z 44 signal. These results would be useful for interpreting the m/z 44 signals obtained from ambient measurements in
various locations.
1. INTRODUCTION
Organic compounds are ubiquitous in ambient aerosols and
constitute approximately 10–70% of total dry fine particle mass
in the troposphere (Turpin et al. 2000, and references therein).
Received 19 August 2006; accepted 8 January 2007.
The authors thank M. Koike and K. Asano for their support in the
filter sampling. They also thank J. D. Allan for providing the AMS
analysis software and M. R. Alfarra, J. L. Jimenez, and D. R. Worsnop
for useful information on the fragment patterns of some organic compounds. This study was funded by the Japanese Ministry of Education,
Culture, Sports, Science and Technology (MEXT) and the Japanese
Science and Technology Agency (JST).
Address correspondence to Nobuyuki Takegawa, Research Center for Advanced Science and Technology, University of Tokyo, 4-61 Komaba, Meguro-ku, Tokyo 153-8904 Japan. E-mail: takegawa@
atmos.rcast.u-tokyo.ac.jp
418
The fraction of water-soluble organic carbon (WSOC) is important in estimating direct and indirect radiative forcing of aerosols
because they can significantly alter the hygroscopic properties
of aerosols (Saxena et al. 1995). Dicarboxylic acids (diacids),
which contain two carboxyl groups, are the major constituents of
WSOC and can be found in various locations in the troposphere
(Saxena and Hildemann 1996; Kawamura and Ikushima 1993;
Kawamura and Yasui 2005; Mochida et al. 2003). Kawamura
and Ikushima (1993) suggested that oxidation of volatile organic compounds (VOCs) is the major source of low molecular
weight (C2 –C6 ) diacids observed at an urban site in Tokyo, based
on the seasonal variation of these diacids. More recently, Ervens
et al. (2004) proposed that cloud processing could be an important source of low molecular weight diacids, although there
are still many uncertainties in the production pathway of these
compounds.
The Aerodyne aerosol mass spectrometer (AMS) can provide
size-resolved mass concentrations of submicron non-refractory
(NR-PM1 ) aerosols with a time resolution of the order of minutes (Jayne et al. 2000). The AMS employs flash vaporization
followed by electron impact (EI) at ionization energy of 70 eV.
There are three kinds of AMS, classified by the type of detector employed: quadrupole AMS (Q-AMS), compact timeof-flight AMS (C-ToF-AMS), and high-resolution ToF-AMS
(HR-ToF-AMS) (DeCarlo et al. 2006). In this study we use
a Q-AMS, which is hereafter referred to simply as the AMS.
The mass spectrum of “organics” is defined as the residual
fragments after subtracting all the identified signals originating from ambient gas molecules, inorganic compounds, and instrumental artifacts such as sodium (Na) and potassium (K)
ions from surface ionization on the vaporizer (Allan et al.
2004). For some organic compounds, the mass spectra of the
AMS have been compared to those from the standard reference database provided by the National Institute of Standards
and Technology (NIST) (http://webbook.nist.gov/chemistry/)
(Alfarra 2004). Alfarra (2004) has found that the fragmentation
patterns of the AMS are generally shifted to smaller mass-tocharge ratios (m/z) because of its higher vaporization/ionization
temperature (600◦ C) compared to those obtained by gas
419
AMS M/Z 44 VS DIACIDS
chromatograph - mass spectrometer (GC-MS) (100◦ –200◦ C). In
the AMS, decarboxylation and other thermal degradation often
occur prior to ionization.
In spite of this complexity, some m/z peaks can be used
as distinct markers of hydrocarbon-like or oxygenated organic
aerosols. The signal at m/z 44, which originates mainly from
CO+
2 , is considered the most reliable marker of oxygenated organic aerosol (Zhang et al. 2005b; and references therein). Previous studies showed that the increase in m/z 44 signal was
often associated with photochemical processing of air masses
(Takegawa et al. 2006a, 2006b; Zhang et al. 2005a), and that the
m/z 44 signal correlated well with the mass concentrations of
WSOC (Kondo et al. 2007). Diacids are considered the major
compounds that can contribute significantly to the m/z 44 signal,
as well as ω-oxocarboxylic acids (ω-oxoacids) containing carboxyl and aldehyde groups. However, the contribution of these
compounds in ambient aerosols to the m/z 44 signals has not
been evaluated. Further, there has been no published comparison between the m/z 44 signal and the mass concentrations of
organic acids determined by GC analysis.
The purpose of this paper is to evaluate the contribution of selected low molecular weight diacids and ω-oxoacids to the m/z
44 signal of AMS mass spectra. Here we use ambient measurement data obtained in Tokyo in August 2003 and laboratory experiment data obtained using authentic standards of the selected
organic acids. This study will present fundamental information
that could be applied to better interpret AMS data obtained in
various locations. This information would also be useful for the
analysis of ToF-AMS data because ToF-AMS employs the same
vaporization/ionization scheme as Q-AMS.
2. EXPERIMENTAL
2.1. Ambient Measurements
2.1.1. Observation Site
Ambient measurements were conducted at a surface site in
Tokyo from 21:00LT on August 3 to 20:00LT on August 8, 2003.
The observation was made on the top floor of a 5 story building (∼18 m above ground level) on the campus of the Research
Center for Advanced Science and Technology (RCAST), University of Tokyo (35◦ 39 N, 139◦ 40 E). RCAST is located near
the center of the city and is surrounded by a major highway
system (at ∼2 km distance from RCAST). A number of on-line
instruments including the AMS were installed in the observation room (Takegawa et al. 2006a). The AMS data were recorded
every 10 min.
The mass concentrations of diacids and ω-oxoacids were
measured using a filter sampling method followed by GC analysis. The aerosol samples were collected every 3 h during August
4–5, 2003 on a pre-combusted quartz filter using a high-volume
air sampler without any size-cut. After August 5, the aerosol
samples were collected every 12 h. The high-volume sampler
was placed on the rooftop of the observation building.
2.1.2. Quantification Procedure of the Aerodyne
AMS for Ambient Data
The AMS quantification procedure for ambient data has been
described previously (e.g., Jimenez et al. 2003, Alfarra et al.
2004). The key equations for organic aerosol are presented here
because the expression used in this paper is slightly different
from those in previous publications. Similar expressions can
be applied to the mass concentrations of inorganic compounds
(equations for inorganics are not shown here).
1 MW N O3 1012
1
Sm/z
CEorg RIEorg IENO3 QN A
OA =
Mm/z (m/z = 1−300)
Mm/z =
[1]
[2]
m/z
where CEorg and RIEorg represent the average particle collection efficiency (CE) and relative ionization efficiency (RIE) for
organic compounds, respectively. MWNO3 (62 g mol−1 ) is the
molecular weight of nitrate; IE N O3 is the ionization efficiency
for nitrate. Q (cm3 s−1 ) is the sample flow rate, and N A is Avogadro’s number. The factor of 1012 in Equation (1) is needed for
unit conversion. Sm/z (Hz) is the signal (ion count rate) at the m/z
originating from organic compounds. As mentioned in section 1,
the Sm/z is obtained by subtracting the signals from ambient gas
molecules, inorganic compounds, and instrumental artifacts. For
example, the m/z 44 signal originating from organic compounds
(S44 ) is determined by subtracting the contribution of gas-phase
CO2 (equivalent to 0.09 μg m−3 on average). Mm/z (μg m−3 ) represents the equivalent mass concentration with respect to Sm/z ,
and OA (μg m−3 ) represents the mass concentration of total organic aerosol measured by the AMS. The parameters used in
this study and their abbreviations are summarized in Table 1.
The IENO3 was routinely determined by supplying monodisperse ammonium nitrate (NH4 NO3 ) particles from a calibration unit. The uncertainty in determining IENO3 was estimated to
be 14% (Takegawa et al. 2005). The uncertainty in the RIE values
for major inorganic compounds (sulfate, nitrate, chloride, and
ammonium) is considered to be small because the mass spectra
of these compounds are well defined. The RIE values for organics can vary with functional group: ∼2 for hydrocarbons and
∼1.4 for oxygenated organic compounds (Jimenez et al. 2003).
We assume RIEorg = 1.4 based on the work of Alfarra et al.
(2004). The CE values are assumed to be 0.5 both for inorganic
and organic compounds.
For the major inorganic compounds, the combined uncertainty (accuracy) due to IENO3 , RIEinorg , and CEinorg (inorg =
sulfate, nitrate, chloride, and ammonium) has been evaluated
based on intercomparison with a Particle-Into-Liquid Sampler
combined with Ion Chromatography (PILS-IC) (Takegawa et al.
2005). The intercomparison was performed on July 23–30 of
2003 (prior to the filter sampling period). A PM1 cyclone (URG
Corp., USA) was used for the PILS-IC inlet because the sizecut of the AMS (aerodynamic lens) is similar to the commonly
used PM1 cutoff. The linear regression slope of the AMS versus
420
N. TAKEGAWA ET AL.
TABLE 1
Definition of parameters used in this study
Parameter
Unit
Definition
NA
MWNO3
Q
IENO3
CEorg
RIEorg
Sm/z
Mm/z
OA
mol−1
g mol−1
cm3 s−1
None
None
None
Hz
μg m−3
μg m−3
CEi
RIEi
u im/z
None
None
None
i
sm/z
i
Rm/z
mi
εi
fi
Hz
None
μg m−3
None
None
Avogadro’s number
Molecular weight of nitrate (NO3 )
Sample flow rate of the AMS
Ionization efficiency of the AMS for nitrate
Average particle collection efficiency (CE) of the AMS for total organic aerosol
Average relative ionization efficiency (RIE) of the AMS for total organic aerosol
Observed ion signal at an m/z peak of the AMS mass spectrum for total organic aerosol
Equivalent mass concentration with respect to Sm/z
Mass concentration
of total organic aerosol in sample air measured by the AMS
(OA = m/z Mm/z )
CE of the AMS for compound i (i = C2 , C3 , etc.)
RIE of the AMS for compound i
Relative intensity at an m/z peak of the AMS mass spectrum for compound i,
as determined by the laboratory experiments ( m/z u im/z = 1)
Estimated ion signal at an m/z peak of the AMS mass spectrum for compound i
i
i
Contribution ratio of compound i to the observed m/z signal (Rm/z
= sm/z
/Sm/z )
Mass concentration of compound i in ambient aerosol
Recovery of compound i from the filter samples
PM1 fraction of compound i
PILS-IC ranged from 0.81 to 1.26 for the major inorganic compounds. Therefore, the combined uncertainty due to IE N O3 ,
RIEinorg , and CEinorg (and also to the approximation of the AMS
size-cut to PM1 ) is estimated to be less than 26%. We assume
that this error estimate is also applicable to organic compounds:
i.e., the combined uncertainties in Mm/z and OA due to IENO3 ,
RIEorg , and CEorg are both assumed to be 26%. Although we use
a constant value for the contribution of gas-phase CO2 at m/z 44
(equivalent to 0.09 μg m−3 ), the uncertainty of M44 due to the
variability in the gas-phase CO2 is relatively minor (∼0.002 μg
m−3 ). The overall validity of the quantification of organic aerosol
by the AMS has been evaluated based on intercomparison with a
Sunset Laboratory semi-continuous elemental and organic carbon (EC/OC) analyzer (Takegawa et al. 2005). The linear regression slope of the AMS OA versus Sunset OC was found to
be 1.8, which is consistent with the expected ratio of organic
matter (OM) to OC in urban air (Turpin and Lim 2001).
2.1.3. Measurements of Dicarboxylic Acids
and ω-Oxocarboxylic Acids in Aerosol Samples
Details of the analytical method have been presented by
Kawamura and Yasui (2005), and thus only a brief description
is given here. The filter samples were extracted with pure water
and concentrated using a rotary evaporator in the laboratory.
The concentrates were reacted with 14% BF3 /n-butanol at
100◦ C to derive the carbonyl groups to butyl esters. The butyl
esters were extracted with n-hexane after adding pure water and
then determined using a gas chromatograph-flame ionization
detector (GC-FID). Peak identification was performed by com-
parison with the GC retention times of the samples with those of
authentic standards. Identification of the esters was confirmed
by GC-MS analysis. The uncertainty in the measurements is
given in Kawamura and Yasui (2005). Recoveries of authentic
standards spiked to a pre-combusted quartz filter were 71% for
oxalic (C2 ) acid and better than 80% for malonic (C3 ), succinic
(C4 ), and adipic (C6 ) acids. Procedural blank filter samples
showed small peaks of oxalic and phthalic (Ph) acids in the
GC chromatograms, although they were small (<2% for oxalic
acid and <5% for phthalic acid). The data used in this analysis
are corrected for the procedural blanks but are not corrected for
the recoveries. The analytical errors are within 15% for these
major species.
2.2. AMS Laboratory Experiments
Laboratory experiments were performed between July 2005
and April 2006 to estimate the fragment patterns of selected
diacids (C2 –C6 and Ph) and ω-oxoacid (glyoxylic acid: ωC2 )
in the AMS vaporization/ionization system. We have selected
these organic acids because these compounds were the major constituents of total diacids and ω-oxoacids during the
measurement period (see section 3.1.1). The physical parameters of the selected organic acids are given in Table 2. These
parameters were taken from the International Chemical Safety
Cards (ICSC) of the International Labour Organization (ILO)
(http://www.ilo.org/) and also from Chemical Dictionary (1994).
The selected organic acids can be vaporized and/or decomposed
at the temperature of the AMS vaporizer (600◦ C). The particle
421
AMS M/Z 44 VS DIACIDS
TABLE 2
Physical parameters of selected organic acids
Species
Melting point, ◦ C
Oxalic (C2 )a
Malonic (C3 )a
Succinic (C4 )b
Glutaric (C5 )a
Adipic (C6 )a
Phthalic (Ph)b
Dicarboxylic acids
189.5 (Decomposes) N/A
135 (Decomposes)
N/A
185
235 (Dehydrates)
98
302–304
152
338
191
210–211 (Decomposes)
ω-Oxocarboxylic acids
Glyoxylic
(ωC2 )b
98
Boiling point, ◦ C
N/A
a
The parameters were taken from the International Chemical
Safety Cards (ICSC) of the International Labour Organization (ILO)
(http://www.ilo.org/).
b
The parameters were taken from Chemical Dictionary (1994).
generation system used in this study is basically the same as
that described in Takegawa et al. (2005). The system consists
of a Collison atomizer (Model 3076, TSI, Inc., USA), two diffusion dryers, and a scanning mobility particle sizer (SMPS)
(Model 3936, TSI, Inc., USA). The organic acid particles were
generated by atomizing water solutions of authentic standards
of these compounds. Pure oxygen (O2 ) was used to atomize the
water solutions in order to detect the m/z 28 signal (mainly CO+ )
originating from the organic acids. The whole system was purged
with O2 for a few hours prior to each experiment to eliminate
the contribution of N+
2 to the m/z 28 signal. The possible dependence of the fragment patterns on carrier gas and mass loadings
is discussed in the appendix. We obtained ∼10 mass spectra for
each compound during the laboratory experiment period. The
integration time for each mass spectrum was generally ∼10 min.
The “best estimate” of the mass spectrum for each compound
is determined using the following procedure (a)–(c): (a) Each
mass spectrum is normalized so that the sum of all m/z peaks
is equal to unity. For a compound i (= C2 , C3 , etc.), the m/z
component
of each normalized mass spectrum is expressed as
u im/z ( m/z u im/z = 1). The u im/z value corresponds to the ratio
of the m/z signal to the total signal. (b) The average u im/z (ū im/z )
is calculated for each compound (from ∼10 mass spectra for
each compound). The ū im/z is referred to as the best-estimate
mass spectrum. Note that m/z ū im/z = 1 holds without additional normalization. (c) The standard deviation of u im/z is used
as a measure of the uncertainty. Note that the complete table of
the best-estimate mass spectra is available as electronic supplemental material.
3. RESULTS
3.1. Ambient Measurements
3.1.1. Mass Concentrations
Table 3 summarizes the average and median values of OA and
M44 measured by the AMS and those of selected diacids (C2 –
C6 and Ph) and ω-oxoacid (ωC2 ) measured by the GC analysis.
TABLE 3
Average mass concentrations of organic compounds on August 3–8, 2003
Speciesa
Average
Total organics (OA)
M44
9.7
0.79
C2
C3
C4
C5
C6
Ph
Selected diacidsb
Total diacidsc
259.9
98.5
78.2
16.7
11.0
41.5
505.8
579.6
ωC2
Total ω- oxoacidsc
37.3
41.2
1σ
Median
AMS organics, μg m−3
5.7
9.0
0.58
0.68
Dicarboxylic acids, ng m−3
244.3
174.0
89.0
51.3
67.4
52.3
16.8
10.2
10.0
7.1
30.5
33.9
446.6
308.8
509.1
357.7
ω-Oxocarboxylic acids, ng m−3
38.3
24.2
41.3
26.2
Minimum
Maximum
2.3
0.08
23.8
2.29
21.4
7.9
5.7
1.4
1.1
5.9
47.3
54.5
937.7
335.7
238.1
62.8
38.4
119.1
1731.8
1971.2
2.6
3.0
155.7
168.2
a
Total organics and M44 were measured by AMS. Dicarboxylic acids (diacids) and ω-oxocarboxylic acids (ω-oxoacids) were measured using
a filter sampling followed by GC-FID analysis. The AMS data were averaged over the integration time of the filter sampling.
b
Selected diacids represent the sum of the selected diacids listed in this table.
c
Total diacids and ω-oxoacids represent the sum of all diacids (C2 –C12 ) and ω-oxoacids (C2 –C9 ), respectively, identified by the GC analysis.
These are listed by Kawamura and Yasui (2005).
422
N. TAKEGAWA ET AL.
TABLE 4
Linear regression parameters for selected diacids and
ω-oxoacids versus M44
Species
Slope
Intercept, μg m−3
r2
Dicarboxylic acids
0.40 ± 0.06
−(0.05 ± 0.06)
0.89
0.15 ± 0.02
−(0.02 ± 0.02)
0.94
0.11 ± 0.02
−(0.01 ± 0.02)
0.91
0.027 ± 0.004 −(0.005 ± 0.004) 0.92
0.016 ± 0.003 −(0.002 ± 0.003) 0.89
0.048 ± 0.009
0.003 ± 0.009
0.85
0.85 ± 0.09
−(0.10 ± 0.09)
0.94
ω-Oxocarboxylic acids
ωC2
0.063 ± 0.009
−(0.01 ± 0.01)
0.91
Total ω-oxoacids 0.068 ± 0.009
–(0.01 ± 0.01)
0.91
Selected acids (C2 -C6 , Ph, and ωC2 )
Selected acids
0.81 ± 0.09
–(0.10 ± 0.09)
0.94
Total acids (Dicarboxylic acids +ω-Oxocarboxylic acids)
Total acids
0.92 ± 0.10
–(0.11 ± 0.10)
0.94
C2
C3
C4
C5
C6
Ph
Total diacids
The number of data points is 23. The uncertainties are 95% confidence intervals.
The AMS data were averaged according to the integration time
of the filter samples before calculating the average and median
values. The total diacids (or ω-oxoacids) represent the sum of
all diacids (or ω-oxoacids) identified by the laboratory analysis.
The full list of the identified diacids and ω-oxoacids are given
in Kawamura and Yasui (2005). As described in section 2.2,
only major diacids and ω-oxoacid were selected for the present
analysis. On average, the sum of the selected diacids (C2 –C6
and Ph) accounts for ∼87% of the total diacids (C2 –C12 ), and
glyoxylic acid accounts for ∼91% of the total ω-oxoacids (C2 –
C9 ). Oxalic acid is found as a dominant diacids species. This
feature has been observed in various locations in previous studies
(Kawamura and Ikushima 1993; Kawamura and Yasui 2005;
Mochida et al. 2003). Figure 1 shows the time series of OA and
M44 observed by the AMS and the mass concentrations of oxalic
acid (C2 ), total diacids, and total ω-oxoacids measured by the
filter sampling technique. Both M44 and di-/ω-oxo- acids show a
distinct peak at around noon. Figure 2 shows the correlation plots
of oxalic acid, total diacids, and total ω-oxoacids versus M44 .
The linear regression parameters (slope, intercept, and r 2 ) for
the selected diacids and ω-oxoacids versus M44 are summarized
in Table 4. The high correlation coefficients (r 2 = 0.85–0.94)
indicate a strong relationship between M44 and di-/ω-oxo-acids.
The ozone (O3 ) mixing ratios measured at the same location also exhibited a distinct peak at around noon during the
measurement period (Takegawa et al. 2006a). Specifically, high
concentrations of O3 exceeding 100 parts per billion by volume were observed at around noon on August 4–6, 2003. The
mass concentrations of M44 , oxalic acid, total diacids, and total ω-oxoacids showed positive correlations with O3 during the
daytime (06:00–18:00LT), although the r 2 values were not very
high (0.66, 0.51, 0.59, and 0.62, respectively) (correlation plots
are not shown here). The positive correlation with O3 suggests
that photochemical production could be an important source of
these organic acids during the measurement period. This is consistent with the findings by Kawamura and Ikushima (1993).
3.1.2. AMS Mass Spectrum
Figure 3 represents the average mass spectrum of organics obtained at 12:00–15:00LT on August 5, 2003. Based on
FIG. 1. Time series of (a) the mass concentrations of total organics and M44 observed by the AMS and (b) those of oxalic acid (C2 : solid), total dicarboxylic acids
(total diacids (C2 -C12 ): open), and total ω-oxocarboxylic acids (total ω-oxoacids (C2 -C9 ): shaded) measured by filter sampling followed by laboratory analysis.
AMS M/Z 44 VS DIACIDS
FIG. 2. Correlation plots of oxalic acid (solid), total diacids (open), and total
ω-oxoacids (shaded) versus M44 . The lines represent the linear regression results.
laboratory experiments that have previously been performed,
the standard AMS analysis procedure assumes that the m/z 18
signal (H2 O+ ) from organics is equal to the m/z 44 signal (Allan
et al. 2004). This is because the high background level at m/z 18
generally makes it difficult to estimate the m/z 18 signal originating from ambient particles and also because H2 O molecules
produced from thermal decomposition of organics are not distinguishable from those originating from particle-phase H2 O.
On the other hand, the AMS standard analysis procedure does
not include the m/z 28 signal originating from organics (mainly
CO+ ) because the observed m/z 28 signal is dominated by nitrogen (N+
2 ) in air. In this analysis, we assume that the m/z 28
signal from organics is also equal to the m/z 44 signal during the
measurement period. The basis for this assumption is described
below.
Zhang et al. (2005b) first evaluated the m/z 28 signal from
organics using particle-time-of-flight (PToF) data. They used
an exponential fit that has the same function form as the onedimensional Boltzmann velocity distribution functional in order
423
to represent the N+
2 signal in the PToF mode. They have found
that the m/z 28 signal from organics could be ∼30% larger than
m/z 44 during the Pittsburgh Air Quality Study. Here we use a
simpler method to estimate the contribution of organics to the
m/z 28 signal. Figure 4a shows the plots of signal at m/z 28 versus PToF observed during the daytime (high SOA) and nighttime
(low SOA). The broad peak at PToF = 0–2 ms corresponds to
N+
2 in ambient air. The small difference between the daytime
and nighttime at the tail of the N+
2 signal (PToF = 2–8 ms) corresponds to the organic fragment. The N+
2 peak height of the
high SOA data agreed with that of the low SOA data to within
0.3%. Figure 4b represents the size distributions of S28 and
S44 , where denotes the difference between the daytime and
nighttime data. The conversion of PToF to vacuum aerodynamic
diameter (dva ) is based on polystyrene latex (PSL) calibrations.
Although S28 is very noisy because of the large contribution of
N+
2 to the baseline, it exhibits a very similar size distribution to
S44 . The signals were integrated over the size range of dva =
30–2000 nm. The ratio of the integrated S28 to the integrated
S44 is found to be 1.0, suggesting the importance of m/z 28
for the analysis of organics. Based on this result, we assume that
the m/z 28 signal from ambient organic aerosol is equal to m/z
44 during the measurement period.
3.2. AMS Laboratory Experiments
3.2.1. Mass Spectra of Oxalic Acid and Its Salts
The best-estimate mass spectrum of oxalic acid obtained in
the laboratory is shown in Figure 5. The major peaks of the selected organic acids are summarized in Table 5. The mass spectrum from the NIST standard reference database is also shown
for comparison. In the AMS mass spectrum, m/z 18 (H2 O+ ), 28
(CO+ ), and 44 (CO+
2 ) are the three major peaks. The m/z 44 peak
is the largest, accounting for ∼34% of the sum of all m/z peaks.
The signals at m/z 16 (O+ ) and 17 (OH+ ) originating from oxalic acid were estimated from the m/z 18 signal, based on the
fragment pattern of H2 O in the AMS ionizer (Allan et al. 2004).
In the NIST mass spectrum, m/z 45 (COOH+ ) and 46 (CH2 O+
2)
are the two major peaks. The similarity between the AMS and
FIG. 3. Average mass spectrum of organics obtained at 12:00–15:00LT on August 5, 2003.
424
N. TAKEGAWA ET AL.
TABLE 5
Major mass fragment ions derived from various organic acids
m/z
Composition
Parent molecules
14
18
26
28
29
42
44
45
50
76
104
CH+
2
H 2 O+
C 2 H+
2
CO+
CHO+
CH2 CO+ , C3 H+
6
CO+
2
COOH+
C 4 H+
2
C6 H+
4
C6 H4 CO+
C3
C2 , C4 , C5 , *C6
C4
C2 , *C4 , C5 , C6 , *Ph, *ωC2
ωC2
C3 , *C5
*C2 , *C3 , Ph
C2
Ph
Ph
Ph
Major fragments are defined as those contributing more than 10% of
the sum of all fragments.
∗
Base peak.
NIST mass spectra is the positions of the significant peaks such
as m/z 18, 28, 44, 45, and 46, while the major difference is
the relative intensities of those peaks: the contributions of the
m/z 18, 28, and 44 peaks in the AMS mass spectrum are much
larger than those in the NIST spectrum. Thermal decomposition
of oxalic acid could result in the formation of H2 O (dehydration), CO, CO2 (decarboxylation), and formic acid (HCOOH)
(Chemical Dictionary 1994). It is suggested that dehydration
and decarboxylation of oxalic acid could be more significant in
AMS spectra than those of NIST due to the higher vaporizer
temperature of the AMS (600◦ C compared to 100◦ –200◦ C).
It should be noted that the standard AMS analysis procedure
does not assign organic fragments for m/z 46 (only nitrate fragment) (Allan et al. 2004). Considering the fragment patterns and
RIE of nitrate and organics, the m/z 46 signal from oxalic acid
could be comparable to that from nitrate if the mass concentration of oxalic acid is 6–7 times greater than nitrate. Note that the
interference of the m/z 46 signal may not be a problem for the
newly developed HR-ToF-AMS (DeCarlo et al. 2006) because
+
it can distinguish NO+
2 from CH2 O2 .
Figure 6 shows the mass spectra of sodium oxalate
((COONa)2 ) and ammonium oxalate ((COONH4 )2 ) obtained in
the laboratory, illustrating the possible dependence of the fragment pattern of oxalate on its counter ions. The NIST mass
spectrum is not available for these compounds. The m/z 45 and
46 peaks do not show up in the mass spectrum of (COONa)2 ,
which is expected from its elemental composition. This result
indicates that the mass spectrum of (COONa)2 could be significantly different from (COOH)2 . On the other hand, the major
peaks in the mass spectrum of (COONH4 )2 are similar to those
of (COOH)2 . Figure 7a shows the comparison of the individual
m/z signals between (COONH4 )2 and (COOH)2 . Each m/z signal has been normalized by the m/z 44 signal (base peak). The
relative intensities of the m/z 18, 28, 44, 45, and 46 signals for
FIG. 4. (a) Plots of the m/z 28 signal (S28 ) versus particle-time-of-flight
(PToF) observed during the daytime (black) and nighttime (grey). (b) Size distributions of S28 (black) and S44 (grey), where represents the difference
between the daytime and nighttime data.
(COONH4 )2 agree well with those for (COOH)2 . However, the
mass spectrum of (COONH4 )2 cannot be explained by the sum
of (COOH)2 and NH3 : i.e., the observed m/z 16 (NH+
2 ) and 17
(NH+
)
peaks,
which
are
the
major
fragments
of
NH
, appears
3
3
smaller by a factor of ∼3 than those expected from the RIE N H 3
value for ammonium sulfate/nitrate (RIENH3 = 3.5). There are
two possible explanations for this feature. The first possibility is
that (COONH4 )2 is mainly decomposed to (COOH)2 and NH3
but the RIENH3 value for (COONH4 )2 is significantly smaller
than that for ammonium sulfate/nitrate. The second possibility is that (COONH4 )2 is not simply decomposed to (COOH)2
and NH3 . In fact, (COONH4 )2 could be converted to oxalic diamide, (CONH2 )2 by a dehydration process at high temperatures
(Chemical Dictionary 1994). In order to test the second possibility, we examined the mass spectrum of (CONH2 )2 in the laboratory. Figure 7b shows the comparison of the individual m/z
signals between (COONH4 )2 and (CONH2 )2 . Again, each m/z
signal has been normalized by the m/z 44 signal. The relative intensities of the m/z 18, 28, 44, 45, and 46 signals for (COONH4 )2
AMS M/Z 44 VS DIACIDS
425
FIG. 5. Mass spectrum of oxalic acid obtained in the laboratory (solid bars). Mass spectrum from the NIST standard reference database is also shown as shaded
bars. Each mass spectrum has been normalized so that the sum of all m/z peaks is equal to unity.
FIG. 6.
Mass spectra of sodium oxalate ((COONa)2 ) and ammonium oxalate ((COONH4 )2 ) obtained in the laboratory.
FIG. 7. (a) Comparison of the individual m/z signals between (COONH4 )2 and (COOH)2 and (b) between (COONH4 )2 and (CONH2 )2 . Each m/z signal has
been normalized by the m/z 44 signal (base peak). The m/z numbers are shown beside the data points.
426
N. TAKEGAWA ET AL.
FIG. 8.
Same as Figure 5 but for the other selected diacids (C3 –C6 and Ph) and ω-oxoacid (ωC2 ).
are significantly different from those for (CONH2 )2 , indicating
that the second possibility is unlikely. It is interesting to note that
the base peak of (CONH2 )2 is m/z 44 (CONH+
2 ), which implies
that amide compounds could be an important source of m/z 44
signal in some cases.
The filter sampling/GC analysis detects both (COONH4 )2
and (COONa)2 as (COOH)2 . In the case of this study, the contribution of (COONa)2 in the AMS mass spectrum is likely negligible because of the low concentration of Na+ in the PM1
mode during the measurement period (Takegawa et al. 2005).
The contribution of (COONH4 )2 may not be negligible because
there was enough NH3 to fully neutralize sulfate, nitrate, and
chloride during this period (Morino et al. 2006). However, we
can use the mass spectrum of (COOH)2 for the present analysis
assuming that (COONH4 )2 is mainly decomposed to (COOH)2
and NH3 on the AMS vaporizer. Same assumption is applied to
the other selected organic acids. Note that the RIE N H 3 issue remains uncertain and requires additional laboratory experiments
in future studies.
3.2.2. Mass Spectra of Other Selected Organic Acids
Mass spectra of the other selected diacids (C3 –C6 and Ph)
and ω-oxoacid (ωC2 ) obtained in the laboratory are shown in
Figure 8. The positions of the significant peaks are similar to the
NIST database, although the major fragments of the AMS mass
spectrum are shifted to smaller m/z numbers as compared to
NIST. The difference can be attributed to the higher vaporization
temperature of the AMS than used in the NIST experiments, as
mentioned earlier. These similarities and differences between
the NIST and AMS mass spectra have been noted in Alfarra
(2004), although m/z 28 is not included in the mass spectra of
organic compounds given in Alfarra (2004).
It should be noted that the m/z 39 signal (mainly C3 H+
3 ) is
present in the mass spectra of relatively higher molecular weight
diacids (C4 –C6 and Ph). The m/z 39 signal is also detected in the
NIST mass spectra. The AMS standard analysis procedure does
not include the m/z 39 signal originating from organics because
there is an artifact of K+ produced by surface ionization on the
vaporizer. The artifact of K+ , which varies with each instrument,
427
AMS M/Z 44 VS DIACIDS
TABLE 6
Fraction of m/z 44 signal and relationship between m/z 44 and other m/z signals for selected organic acids
Species
i
Molecular formula
Expected mass
fraction of COa2
C2
C3
C4
C5
C6
Ph
HOOC-COOH
HOOC-CH2 -COOH
HOOC-(CH2 )2 -COOH
HOOC-(CH2 )3 -COOH
HOOC-(CH2 )4 -COOH
C6 H4 (COOH)2
0.49
0.42
0.37
0.33
0.30
0.27
ωC2
OHC-COOH
0.60
Best estimateb
ū i44
u i18 /u i44
Dicarboxylic acids
0.34 (8%) 0.45 (39%)
0.21 (13%) 0.41 (72%)
0.069 (27%) 1.8 (35%)
0.049 (22%) 2.4 (32%)
0.071 (3%) 1.6 (18%)
0.082 (32%) 0.79 (80%)
ω-Oxocarboxylic acids
0.15 (34%) 0.89 (31%)
u i46 /u i44
Number
of data
0.67 (8%)
N/A
0.35 (10%)
N/A
4.9 (45%) 0.023 (80%)
2.5 (15%) 1.1 (21%)
2.3 (8%)
0.69 (6%)
2.3 (27%) 0.20 (13%)
0.12 (40%)
0.007 (14%)
0.057 (54%)
0.026 (19%)
0.017 (10%)
0.008 (20%)
12
8
12
9
7
9
1.4 (22%)
0.16 (67%)
14
u i28 /u i44
u i39 /u i44
N/A
a
Assuming that one of the carboxyl groups is detected as the m/z 44 signal.
Values in parenthesis are the relative uncertainties (i.e., ratio of the standard deviation to the average). N/A means that the m/z 39 signal is
not assigned as a fragment of the compound.
b
depends on the condition of the vaporizer and perhaps on the
loadings of ambient aerosol, which generally makes it difficult
to extract the m/z 39 signal originating from organiccompounds.
Figure 9 shows the correlation plots of S39 versus Sm/z for C2
and C5 diacids. No significant S39 was observed for C2 diacid,
which is expected from its elemental composition.
On the other
hand, S39 shows tight correlation with
Sm/z for C5 diacid
(∼6% of the total), indicating that m/z 39 is one of the significant
peaks for this compound. The m/z 39 signal was also found in the
2
mass spectra for
C4 , C6 , and Ph diacids (Figure 8). The r values
Sm/z were 0.88, 0.99, and 0.99 for C4 , C6 , and
of S39 versus
Ph diacids, respectively. The m/z 39 signals from the selected
organic acids are negligibly small as compared to the signals
from total organics during the measurement period, given the
low ambient concentrations of C4 –C6 and Ph. However, there
may be some other cases where the m/z 39 signal from organics
could become important. Again, this may not be a problem for
+
the HR-ToF-AMS because it can distinguish C3 H+
3 from K .
Table 6 gives the summary of the m/z 44 fraction and the
relationship between m/z 44 and the other m/z signals (m/z 18,
28, 39, and 46) for the selected organic acids. In ambient data, the
m/z 18, 28, 39, and 46 signals originating from organic aerosol
are generally difficult to extract from the observed mass spectra.
This information provides the basis for estimating those signals
using the observed m/z 44 signal.
laboratory. The signal at an m/z peak originating from a comi
, is estimated
pound i (= C2 , C3 , etc.) in ambient aerosol, sm/z
as follows (reverse of Equation [1]):
i
sm/z
= 10−12 QN A
IENO3
fi
RIEi CEi m i ū im/z
MWNO3
εi
[3]
where CEi and RIEi represent the CE and RIE values for compound i, respectively. m i (μg m−3 ) is the mass concentration
of compound i in ambient aerosol, εi (≤1) is the recovery of
compound i from the filter samples based on the GC analysis,
and f i (≤1) is the PM1 fraction of compound i.
4. DISCUSSION
4.1. Estimate of m/z 44 Signals from Selected Organic
Acids in Ambient Aerosol
Here we estimate the mass spectra of the selected diacids and
ω-oxoacid in ambient aerosol in a bottom-up manner. The estimate is based on the ambient mass concentrations obtained from
the filter sampling and the fragment patterns characterized in the
FIG. 9. Correlation plots of the m/z 39 signal (S39 ) versus the sum of all m/z
signals ( Sm/z ) for C2 and C5 diacids. The line represents the linear regression
for the C5 diacid data.
428
N. TAKEGAWA ET AL.
FIG. 10. Mass spectra of total organics (grey), oxalic acid (C2 : orange), and the sum of the other selected acids (C3 –C6 , Ph, and ωC2 : blue) in ambient aerosol
at 12:00–15:00LT on August 5, 2003. Note that the blue bars are stuck on the orange bars.
From Equations (1) and (3), the contribution ratio of comi
, is estimated as follows:
pound i to the observed m/z signal, Rm/z
i
Rm/z
=
i
sm/z
Sm/z
=
i
CEi RIEi f i m i ū m/z
CEorg R I E org εi Mm/z
[4]
Although we assume CEi /CEorg = 1, RIEi /RIEorg = 1, and
f i /εi = 1 in the following discussion, these factors are explicitly
included in Equation (4) to evaluate the possible uncertainties
(see next section).
Figure 10 shows the estimated mass spectra of oxalic acid
(C2 ) and the sum of the other selected acids (C3 –C6 , Ph, and
ωC2 ) in ambient aerosol at 12:00–15:00LT on August 5, 2003,
together with the observed mass spectrum of total organics. It
can be seen that m/z 28 and m/z 44 are the largest two peaks
from the selected acids and have significant contributions to the
mass spectrum of total organics. Figure 11 shows the time series
C2
selected
of R44
, R44
, and M44 , illustrating the contribution ratios of
oxalic acid and the selected acids to the m/z 44 signal during
the measurement period. The 10-min average of M44 is also
C2
selected
shown for comparison. Both R44
and R44
tend to be higher
during the daytime, suggesting that these ratios were largely
controlled by photochemical activity. It should be noted that
selected
R44
reaches as high as 24% during the midnight of August 7
(8/6/2006 20:00 - 8/7/2006 8:00). The 10-min M44 data indicates
that there was a significant enhancement of M44 during this time
period. Possible explanations for the nighttime peak of SOA (i.e.,
formation of SOA by O3 and NO3 and/or shift in gas/particle
partitioning of SOA) were discussed in Takegawa et al. (2006a).
Note that the last two data points obtained on August 8 are not
C2
selected
used for calculating the R44
and R44
values because the
FIG. 11. Time series of M44 (3-12-h average: thick shaded line; 10-min average: thin shaded line) and the contribution ratios of oxalic acid (solid circles) and
the sum of the selected acids (open circles) to S44 .
AMS M/Z 44 VS DIACIDS
relative errors of these data points may be large considering the
low concentrations of M44 and possible artifacts in the diacid
measurements at low concentrations (Ray and McDow 2005).
On average, the selected acids account for 14 ± 5% of
S44 . The difference in the integration time of the filter samples
(3–12 h) is not taken into account in calculating the average.
The error represents the standard deviation and does not include the uncertainties in the ambient measurements and laboratory experiments. These uncertainties will be discussed in
the next section. Oxalic acid is the largest contributor, accounting for 10 ± 4% of S44 on average. It should be noted that
seven low molecular weight compounds alone could explain a
substantial fraction (∼14%) of M44 observed during the measurement period. The rest of M44 may have originated from
mono-/poly- carboxylic acids and perhaps from peroxides because these compounds could produce CO+
2 in the vaporization and ionization processes of the AMS. In fact, significant
amounts of mono-/poly- carboxylic acids have been found in urban aerosol (e.g., Alves et al. 2002; Fuzzi et al. 2001; Rogge et al.
1993).
4.2. Possible Uncertainties
Possible uncertainties in estimating the contributions of oxalic acid to the m/z 44 signal are now evaluated using Equation (4). The uncertainty in u C2
44 is estimated to be 8% based
on Table 6. The uncertainty in m C2 is estimated to be 15%, as
described earlier. The uncertainty in M44 is assumed to be 26%,
as described in section 2.1.2. The uncertainties in RIEC2 /RIEorg
and CEC2 /C E org depend on how the RIE and CE values of oxalic acid are similar to or different from those of total organic
aerosol. Because the assumed R I E org (= 1.4) is close to the
RIE values for oxygenated organic compounds, the uncertainty
in RIEC2 /RIEorg would be small. Alfarra (2004) showed that CE
values of pure C4 diacid particles generated in the laboratory
were smaller than 0.5. However, it has been demonstrated that
solid compounds generated in the laboratory (e.g., (NH4 )2 SO4 )
generally show lower CE values than those in ambient air. Assuming that oxalic acid in ambient aerosol is internally mixed
with most of the organic compounds in ambient air, the uncertainty in CEC2 /CEorg would also be small. The uncertainty in
f C2 /εC2 is estimated as follows. The recoveries are estimated to
be ∼0.7 for oxalic acid, as described earlier. During the summer of 2004, we conducted measurements of diacids using a
high-volume sampler and also using a PM1 low-volume sampler at the RCAST observatory. The analysis and evaluation of
the filter measurements are now being performed (Kawamura
et al., manuscript in preparation). The preliminary results show
that the PM1 diacids account for 40–80% of the high-volume
diacids. Based on these results, the f i /εi values are estimated to
be 0.6–1.1 for oxalic acid. Therefore, the uncertainty in f C2 /εC2
is estimated to be <40%. In summary, the overall uncertainty in
C2
R44
is estimated to be ∼50%.
429
5. CONCLUSIONS
The relationship between low molecular weight diacids and
ω-oxoacids in ambient aerosol and the AMS m/z signal has, for
the first time, been investigated based on ambient measurements
and laboratory experiments. Oxalic acid was found to be the
most abundant compounds of total diacids identified in the filter
samples. The mass concentrations of oxalic acid, total diacids,
and total ω-oxoacids correlated well with the m/z 44 signal (r 2 =
0.85–0.94), indicating a strong link between m/z 44 and these
compounds.
Detailed analysis of ambient mass spectra and particle timeof-flight data suggests that m/z 28 from organics could be comparable to m/z 44 during the measurement period, although the
AMS standard analysis procedure does not include m/z 28 for the
mass spectrum of organics. Mass spectra of selected diacids (C2 –
C6 , and Ph) and ω-oxoacid (ωC2 ) were investigated in the laboratory. For the selected compounds, m/z 28 and 44 were found
to be the major fragments. Both ambient and laboratory data
suggest the importance of m/z 28 for the analysis of organics.
Mass spectra of the selected diacids and ω-oxoacid in ambient aerosol were estimated based on the mass concentrations
of these compounds obtained from the filter sampling and the
fragment patterns of these compounds characterized in the laboratory. On average, the selected compounds accounted for 14 ±
5% of the observed m/z 44 signal during the measurement period. Oxalic acid was the largest contributor, accounting for 10 ±
4% of the observed m/z 44 signal. These results could be useful for the interpretation of m/z 44 data obtained from ambient
measurements.
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APPENDIX. DEPENDENCE OF FRAGMENT PATTERNS
ON CARRIER GAS AND MASS LOADINGS
In our laboratory experiments, pure O2 was used as the carrier gas (i.e., compressed gas to atomize the water solutions of
the selected organic acids) in order to detect the m/z 28 signal
originating from the organic acids. Synthetic air (N2 + O2 ) and
argon (Ar) were also used for oxalic acid to examine possible
effects of the carrier gas on the mass spectra. In addition, the
mass concentrations of oxalic acid were varied by adjusting a
dilution flow of O2 , in order to examine possible dependence of
the fragment patterns on the mass loadings.
Figure A1 shows the correlation of S44 versus
Sm/z for
oxalic acid particles generated with O2 , synthetic air, and Ar.
Note that the S28 signal for synthetic air was estimated based
on the PToF data (see section 3.1.2). Only data obtained
with
O2 were used for the linear regression analysis. The S44 / Sm/z
ratios forthe synthetic air and Ar data agreed with the average S44 / Sm/z ratio calculated from the O2 data to within
9%, suggesting that the dependence of the fragment pattern
on the carrier gas is small. The dynamic range of
Sm/z
FIG.
A1 Correlation of the m/z 44 signal (S44 ) versus the sum of all m/z signals
( Sm/z ) for oxalic acid. The solid, open, and shaded circles represent the data
obtained using O2 , synthetic air, and Ar, respectively, as the carrier gas of the
particle generation system. The line represents the linear regression for the O2
data.
431
AMS M/Z 44 VS DIACIDS
corresponds to mass concentrations of 3-300 μg m−3 if we
assume CEorg = 0.5 and
RIEorg = 1.4 in equation [1]. The
Sm/z exhibits very good linearity
correlation of S44 versus
(r 2 = 0.99) over the whole mass concentration range consid-
2
ered here. Similar
results were obtained for m/z 28 (r = 0.99
for S28 versus
Sm/z ). This result suggests that the dependence of the fragment pattern on the mass concentration is also
small.
TABLE S1 ELECTRONIC SUPPLEMENTAL MATERIAL
Best-estimate mass spectra (std: standard deviation)
m/z
1
2
3
4
5
6
7
8
9
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
C2
C2 std
C3
C3 std
C4
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0304
0.0007
0.0044
0.0109
0.0060
0.0375
0.1498
0.0002
0.0003
0.0000
0.0000
0.0000
0.0001
0.0000
0.0006
0.0014
0.2279
0.0272
0.0018
0.0005
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0013
0.0017
0.0013
0.0013
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0038
0.0001
0.0018
0.0051
0.0021
0.0131
0.0526
0.0001
0.0001
0.0000
0.0000
0.0000
0.0001
0.0001
0.0003
0.0005
0.0310
0.0066
0.0011
0.0005
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0007
0.0014
0.0002
0.0007
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0356
0.0261
0.1663
0.0335
0.0033
0.0205
0.0821
0.0001
0.0002
0.0000
0.0000
0.0000
0.0056
0.0085
0.0038
0.0011
0.0751
0.0227
0.0028
0.0076
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0088
0.0339
0.1423
0.0248
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0046
0.0038
0.0152
0.0045
0.0020
0.0125
0.0501
0.0001
0.0001
0.0000
0.0000
0.0000
0.0007
0.0009
0.0007
0.0008
0.0089
0.0025
0.0008
0.0013
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0014
0.0049
0.0171
0.0034
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0148
0.0078
0.0188
0.0053
0.0046
0.0288
0.1151
0.0001
0.0002
0.0000
0.0000
0.0000
0.0044
0.0171
0.0933
0.0800
0.3025
0.0313
0.0041
0.0031
0.0000
0.0000
0.0000
0.0000
0.0011
0.0025
0.0017
0.0014
0.0016
0.0043
0.0129
0.0040
C4 std
C5
C5 std
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0026
0.0140
0.0026
0.0005
0.0095
0.0014
0.0016
0.0525
0.0083
0.0009
0.0178
0.0015
0.0016
0.0044
0.0009
0.0100
0.0272
0.0054
0.0401
0.1089
0.0214
0.0000
0.0001
0.0000
0.0001
0.0002
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0006
0.0035
0.0002
0.0017
0.0098
0.0008
0.0074
0.0390
0.0028
0.0084
0.0584
0.0045
0.0234
0.1191
0.0066
0.0051
0.0198
0.0012
0.0006
0.0020
0.0005
0.0005
0.0051
0.0005
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0019
0.0002
0.0002
0.0088
0.0005
0.0002
0.0127
0.0008
0.0007
0.0522
0.0020
0.0003
0.0149
0.0015
0.0004
0.0416
0.0034
0.0023
0.1405
0.0093
0.0009
0.0173
0.0008
(Continued on next page)
432
N. TAKEGAWA ET AL.
Best-estimate mass spectra (std: standard deviation) (Continued)
m/z
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
C2
C2 std
C3
C3 std
C4
C4 std
C5
C5 std
0.3419
0.0957
0.0401
0.0010
0.0001
0.0000
0.0002
0.0001
0.0000
0.0002
0.0003
0.0013
0.0034
0.0007
0.0005
0.0001
0.0001
0.0000
0.0001
0.0001
0.0002
0.0003
0.0003
0.0003
0.0002
0.0003
0.0002
0.0002
0.0001
0.0010
0.0003
0.0001
0.0000
0.0001
0.0001
0.0001
0.0001
0.0002
0.0001
0.0002
0.0000
0.0001
0.0001
0.0000
0.0000
0.0000
0.0002
0.0001
0.0000
0.0267
0.0307
0.0132
0.0006
0.0002
0.0001
0.0002
0.0001
0.0001
0.0002
0.0002
0.0006
0.0017
0.0005
0.0007
0.0003
0.0001
0.0000
0.0001
0.0001
0.0003
0.0005
0.0007
0.0004
0.0002
0.0004
0.0003
0.0002
0.0002
0.0004
0.0004
0.0001
0.0002
0.0002
0.0001
0.0002
0.0001
0.0002
0.0002
0.0002
0.0002
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0003
0.0001
0.2133
0.0372
0.0015
0.0001
0.0001
0.0000
0.0001
0.0000
0.0002
0.0002
0.0000
0.0005
0.0003
0.0002
0.0001
0.0003
0.0281
0.0006
0.0001
0.0000
0.0002
0.0001
0.0002
0.0001
0.0022
0.0024
0.0003
0.0000
0.0000
0.0007
0.0001
0.0000
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0011
0.0023
0.0001
0.0000
0.0000
0.0001
0.0000
0.0269
0.0066
0.0002
0.0001
0.0002
0.0000
0.0002
0.0001
0.0001
0.0002
0.0001
0.0005
0.0003
0.0002
0.0001
0.0002
0.0085
0.0003
0.0001
0.0001
0.0002
0.0002
0.0002
0.0001
0.0009
0.0009
0.0002
0.0000
0.0001
0.0003
0.0001
0.0000
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0000
0.0000
0.0001
0.0006
0.0009
0.0000
0.0000
0.0000
0.0001
0.0000
0.0691
0.0367
0.0034
0.0011
0.0001
0.0001
0.0002
0.0002
0.0012
0.0052
0.0071
0.0280
0.0418
0.0020
0.0002
0.0001
0.0002
0.0000
0.0000
0.0003
0.0001
0.0000
0.0001
0.0001
0.0002
0.0005
0.0006
0.0006
0.0037
0.0125
0.0116
0.0005
0.0001
0.0001
0.0000
0.0001
0.0000
0.0001
0.0004
0.0002
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0000
0.0185
0.0066
0.0005
0.0002
0.0001
0.0000
0.0001
0.0001
0.0001
0.0005
0.0013
0.0041
0.0111
0.0005
0.0001
0.0000
0.0001
0.0000
0.0000
0.0000
0.0001
0.0000
0.0001
0.0001
0.0001
0.0002
0.0002
0.0001
0.0004
0.0022
0.0018
0.0001
0.0001
0.0001
0.0000
0.0001
0.0000
0.0000
0.0001
0.0001
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0000
0.0490
0.0355
0.0012
0.0003
0.0003
0.0015
0.0029
0.0024
0.0029
0.0031
0.0031
0.0277
0.0032
0.0018
0.0077
0.0005
0.0176
0.0004
0.0001
0.0001
0.0001
0.0002
0.0005
0.0002
0.0094
0.0018
0.0063
0.0010
0.0005
0.0062
0.0003
0.0000
0.0000
0.0001
0.0002
0.0000
0.0001
0.0001
0.0002
0.0001
0.0001
0.0009
0.0203
0.0026
0.0004
0.0001
0.0000
0.0001
0.0000
0.0106
0.0012
0.0001
0.0001
0.0000
0.0001
0.0001
0.0001
0.0002
0.0003
0.0001
0.0010
0.0012
0.0001
0.0008
0.0001
0.0024
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0000
0.0015
0.0002
0.0020
0.0001
0.0001
0.0013
0.0001
0.0000
0.0000
0.0001
0.0001
0.0000
0.0001
0.0001
0.0001
0.0001
0.0001
0.0003
0.0047
0.0006
0.0002
0.0000
0.0000
0.0001
0.0000
433
AMS M/Z 44 VS DIACIDS
Best-estimate mass spectra (std: standard deviation) (Continued)
m/z
C2
C2 std
C3
C3 std
C4
C4 std
C5
C5 std
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0000
0.0000
0.0000
0.0001
0.0001
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0002
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0002
0.0002
0.0002
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0001
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0002
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0002
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0002
0.0001
0.0060
0.0022
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0000
0.0014
0.0005
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0001
0.0005
0.0002
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0025
0.0010
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0001
0.0002
0.0000
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0002
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0009
0.0004
0.0001
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
End of Table S1
434
N. TAKEGAWA ET AL.
TABLE S2
Best-estimate mass spectra (std: standard deviation)
m/z
1
2
3
4
5
6
7
8
9
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
C6
C6 std
Ph
Ph std
ωC2
ωC2 std
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.011904
0.002729
0.008574
0.005621
0.004471
0.027946
0.111783
0.000133
0.000224
0.000000
0.000000
0.000000
0.001463
0.005971
0.039705
0.072800
0.163620
0.023896
0.001403
0.004654
0.000000
0.000000
0.000000
0.000000
0.000975
0.006070
0.008829
0.048527
0.008466
0.036503
0.025149
0.018472
0.070780
0.027316
0.001184
0.000393
0.000537
0.003297
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000384
0.000061
0.000455
0.000560
0.000851
0.005316
0.021268
0.000026
0.000043
0.000000
0.000000
0.000000
0.000054
0.000175
0.001281
0.005255
0.009560
0.001753
0.000058
0.000081
0.000000
0.000000
0.000000
0.000000
0.000062
0.000197
0.000164
0.001980
0.000258
0.000881
0.000788
0.001295
0.001948
0.001881
0.000092
0.000038
0.000045
0.000071
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.016532
0.000908
0.002146
0.001127
0.002019
0.012619
0.050476
0.000056
0.000095
0.000000
0.000000
0.000000
0.000664
0.002530
0.009332
0.005242
0.176104
0.005619
0.000475
0.001309
0.000000
0.000000
0.000000
0.000000
0.002134
0.020434
0.024591
0.015939
0.001388
0.001680
0.000711
0.001541
0.082092
0.007668
0.000644
0.000541
0.001543
0.012402
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.003330
0.000288
0.001843
0.000608
0.001514
0.009461
0.037846
0.000051
0.000085
0.000000
0.000000
0.000000
0.000188
0.000587
0.002580
0.002039
0.009228
0.003019
0.000436
0.000930
0.000000
0.000000
0.000000
0.000000
0.000420
0.004553
0.005105
0.002962
0.000628
0.001236
0.000526
0.000881
0.026012
0.001608
0.000198
0.000069
0.000615
0.001859
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.019254
0.007829
0.010883
0.010848
0.004977
0.031108
0.124431
0.000148
0.000249
0.000000
0.000000
0.000000
0.000984
0.001512
0.005838
0.019387
0.202722
0.171030
0.049330
0.006487
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.003820
0.009788
0.008297
0.004420
0.152102
0.063991
0.019810
0.023732
0.000685
0.000112
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.004946
0.000967
0.001903
0.002320
0.001275
0.007965
0.031860
0.000038
0.000063
0.000000
0.000000
0.000000
0.000117
0.000291
0.002779
0.012772
0.032941
0.050751
0.015346
0.014783
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.001178
0.001582
0.001676
0.001763
0.052177
0.022654
0.006837
0.006929
0.000852
0.000092
435
AMS M/Z 44 VS DIACIDS
Best-estimate mass spectra (std: standard deviation) (Continued)
m/z
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
C6
C6 std
Ph
Ph std
ωC2
ωC2 std
0.011355
0.011018
0.008112
0.018646
0.020536
0.054086
0.013177
0.003026
0.003002
0.001820
0.013679
0.001418
0.001200
0.001894
0.000809
0.003184
0.004197
0.002490
0.005186
0.008104
0.000693
0.000494
0.000613
0.007990
0.001148
0.000163
0.000128
0.000309
0.000302
0.000411
0.003465
0.003529
0.011635
0.002420
0.004239
0.000869
0.000623
0.005333
0.000269
0.000074
0.000022
0.000102
0.000668
0.000077
0.000173
0.000060
0.000111
0.000116
0.000320
0.000354
0.000536
0.000791
0.001479
0.004527
0.000292
0.000159
0.000113
0.000214
0.001399
0.000228
0.000153
0.000201
0.000113
0.000364
0.000409
0.000406
0.000780
0.000964
0.000026
0.000078
0.000036
0.001408
0.000153
0.000023
0.000057
0.000021
0.000052
0.000137
0.000346
0.000418
0.001474
0.000269
0.000519
0.000118
0.000087
0.001009
0.000044
0.000011
0.000011
0.000040
0.000166
0.000034
0.000042
0.000014
0.000020
0.000027
0.094249
0.015456
0.006395
0.005605
0.000437
0.000963
0.000315
0.000470
0.000073
0.000028
0.001057
0.003965
0.002981
0.004828
0.003072
0.012834
0.002307
0.000225
0.000145
0.000154
0.000016
0.000089
0.000656
0.009741
0.031551
0.017086
0.110239
0.023940
0.004087
0.000310
0.000123
0.000121
0.000124
0.000087
0.000087
0.000290
0.000202
0.000089
−0.000041
0.000086
0.000043
0.000246
0.002739
0.004310
0.001627
0.000177
0.000033
−0.000036
0.013614
0.001875
0.000617
0.000851
0.000241
0.000546
0.000184
0.000282
0.000067
0.000055
0.000239
0.000308
0.000349
0.000682
0.000831
0.001892
0.000391
0.000339
0.000096
0.000399
0.000124
0.000288
0.000107
0.000754
0.002538
0.000582
0.006922
0.000716
0.000360
0.000258
0.000094
0.000109
0.000100
0.000089
0.000185
0.000127
0.000115
0.000053
0.000101
0.000079
0.000092
0.000397
0.000224
0.000598
0.000347
0.000308
0.000138
0.000165
0.000313
0.000518
0.000394
0.000642
0.000962
0.002599
0.007997
0.001763
0.002987
0.000410
0.000468
0.000063
0.000083
0.000127
0.000393
0.000250
0.000263
0.000778
0.001081
0.001346
0.000764
0.000377
0.000127
0.002547
0.001079
0.001763
0.000449
0.000307
0.000068
0.000371
0.000225
0.000433
0.000335
0.000499
0.000316
0.000600
0.000380
0.000266
0.000118
0.000135
0.000057
0.000259
0.000155
0.000207
0.000144
0.000231
0.000230
0.000254
0.000273
0.000115
0.000112
0.000265
0.000257
0.000853
0.003708
0.000754
0.001957
0.000181
0.000241
0.000135
0.000150
0.000156
0.000655
0.000178
0.000213
0.000357
0.000600
0.000374
0.000244
0.000244
0.000203
0.000926
0.000387
0.000698
0.000389
0.000240
0.000215
0.000310
0.000099
0.000340
0.000272
0.000333
0.000170
0.000355
0.000222
0.000177
0.000140
0.000205
0.000085
0.000284
0.000162
0.000202
0.000182
0.000220
0.000141
0.000159
(Continued on next page)
436
N. TAKEGAWA ET AL.
Best-estimate mass spectra (std: standard deviation) (Continued)
m/z
C6
C6 std
Ph
Ph std
ωC2
ωC2 std
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
0.000079
0.000397
0.016573
0.001414
0.000273
0.000039
0.000026
0.000035
0.000020
0.000079
0.000126
0.000094
0.002081
0.000488
0.000057
0.000045
0.000039
0.000149
0.000050
0.000037
0.000024
0.000027
0.000012
0.000016
0.000020
0.000008
0.000007
0.000009
0.000021
0.000055
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000002
0.000012
0.000005
0.000014
0.000012
0.000009
0.000013
0.000010
0.000008
0.000027
0.000074
0.003489
0.000513
0.000037
0.000018
0.000016
0.000015
0.000009
0.000016
0.000033
0.000039
0.000389
0.000110
0.000031
0.000009
0.000015
0.000057
0.000013
0.000010
0.000009
0.000013
0.000008
0.000008
0.000005
0.000008
0.000005
0.000007
0.000010
0.000007
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000003
0.000003
0.000005
0.000014
0.000014
0.000005
0.000009
0.000005
0.000007
0.000029
0.000020
0.000003
0.000189
0.000032
0.000241
0.086466
0.042414
0.005683
0.000379
−0.000032
−0.000012
−0.000003
0.000072
−0.000055
0.000016
0.000021
0.000070
−0.000024
−0.000033
0.000025
0.000187
0.000286
0.001667
0.021228
0.005418
0.000380
0.000056
0.000029
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
−0.000032
0.000043
0.000007
−0.000039
−0.000029
−0.000007
−0.000021
−0.000006
0.000006
0.000055
0.000142
0.000088
0.000055
0.000093
0.000151
0.011601
0.005802
0.002908
0.000292
0.000125
0.000154
0.000068
0.000078
0.000097
0.000199
0.000066
0.000072
0.000092
0.000157
0.000015
0.000104
0.000121
0.000279
0.004180
0.003269
0.000325
0.000044
0.000043
0.000072
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000089
0.000097
0.000072
0.000079
0.000063
0.000057
0.000046
0.000070
0.000022
0.000266
0.000179
0.000169
0.000244
0.000182
0.000129
0.000248
0.000088
0.000066
0.000099
0.000058
0.000144
0.000134
0.000098
0.000098
0.000378
0.000171
0.000196
0.000125
0.000122
0.000098
0.000128
0.000083
0.000092
0.000061
0.000082
0.000061
0.000044
0.000064
0.000076
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000073
0.000092
0.000037
0.000059
0.000076
0.000056
0.000040
0.000036
0.000114
0.000230
0.000221
0.000229
0.000300
0.000122
0.000143
0.000199
0.000375
0.000112
0.000150
0.000126
0.000130
0.000113
0.000093
0.000231
0.000205
0.000187
0.000189
0.000142
0.000133
0.000112
0.000140
0.000137
0.000135
0.000165
0.000088
0.000091
0.000109
0.000065
0.000101
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000000
0.000123
0.000115
0.000061
0.000098
0.000073
0.000111
0.000100
0.000177
0.000212
437
AMS M/Z 44 VS DIACIDS
Best-estimate mass spectra (std: standard deviation) (Continued)
m/z
C6
C6 std
Ph
Ph std
ωC2
ωC2 std
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
0.000193
0.000058
0.000000
0.000041
0.000009
0.000012
0.000010
0.000013
0.000009
0.000008
0.000010
0.000008
0.000008
0.000003
0.000004
0.000003
0.000006
0.000005
0.000023
0.000009
0.000014
0.000024
0.000012
0.000005
0.000039
0.000030
0.000000
0.000053
0.000012
0.000005
0.000003
0.000008
0.000007
0.000007
0.000005
0.000012
0.000005
0.000003
0.000004
0.000003
0.000005
0.000004
0.000035
0.000006
0.000010
0.000027
0.000009
0.000005
0.000235
0.003720
0.004044
0.001435
0.000231
0.000195
0.000090
0.000076
0.000033
−0.000023
−0.000003
−0.000014
−0.000027
−0.000036
−0.000014
−0.000007
−0.000016
−0.000011
0.000005
0.000647
0.000360
0.000152
0.000076
−0.000008
0.000146
0.001924
0.002606
0.001161
0.000174
0.000103
0.000115
0.000094
0.000055
0.000074
0.000066
0.000068
0.000056
0.000075
0.000061
0.000042
0.000085
0.000067
0.000073
0.000347
0.000319
0.000131
0.000092
0.000056
0.000613
0.000520
0.000000
0.000083
−0.000003
0.000033
0.000038
0.000054
0.000042
0.000052
0.000059
0.000047
0.000025
0.000050
0.000105
0.000263
0.000309
0.000067
0.000076
0.000050
0.000068
0.000019
0.000042
0.000070
0.000425
0.000514
0.000000
0.000204
0.000131
0.000068
0.000065
0.000059
0.000103
0.000093
0.000136
0.000125
0.000139
0.000085
0.000119
0.000342
0.000410
0.000178
0.000070
0.000089
0.000112
0.000119
0.000074
0.000075