IfrERA
u.. ued states
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
P.O. Box 93478
Las Vegas NV 89193-3478
EPA 600/4-91/032
May 1992
Research and Development
Measurement of Polycyclic
Aromatic Hydrocarbons in
Soils and Sediments by
Particle-Beam/High-
Performance Liquid
Chromatography/Mass
Spectrometry
5292GR92QAD
-------
MEASUREMENT OF POLYCYCLIC AROMATIC HYDROCARBONS
IN SOILS AND SEDIMENTS BY PARTICLE-BEAM/HIGH-
PERFORMANCE LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY
by
C. M. Pace
D. A. Miller
M. R. Roby
Environmental Programs
Lockheed Engineering & Sciences Company
Las Vegas, Nevada 89114
EPA Contract No. 68-CO-0049
Technical Monitor
L. D. Betowski
Quality Assurance and Methods Development Division
Environmental Monitoring Systems Laboratory
Las Vegas, Nevada 89114
ENVIRONMENTAL MONITORING SYSTEMS LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
-------
NOTICE
The information in this document has been funded wholly by the U.S. Environmental Protection Agency
under contract number 68-CO-0049 to Lockheed Engineering & Sciences Company. It has been subject
to the Agency's peer and administrative review, and it has been approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
-------
ABSTRACT
A tentative analytical method was developed for the measurement of certain polycyclic
aromatic hydrocarbons (PAHs) in soils and sediments by particle beam/liquid chromatography/mass
spectrometry. The method applies to PAHs with a molecular weight greater than 220. Samples are
prepared by SW-846 Method 3540 with optional cleanup using SW-846 Method 3630. The sample
extracts are then analyzed for PAHs using a particle/beam liquid chromatography/mass spectrometry
system. Method detection limits are within the range of 0.01 to 0.10 ng/g depending on the sample
size. Mean method accuracy was greater than 75% for most of the target analytes with relative
standard deviation values between 10% and 20%. An analysis of a standard reference material using
this method agreed with certified values and with an analysis performed using high performance liquid
chromatography (HPLC) with fluorescence detection (SW-846 Method 8310). The method shows
potential as a means to measure high molecular weight PAHs not measurable by current EPA
methods.
111
-------
IV
-------
CONTENTS
Abstract iii
Figures vi
Tables vii
Acronyms and Abbreviations viii
Section 1: Introduction 1
Section 2: Conclusions and Recommendations 2
Section 3: Experimental 3
Section 4: Results and Discussion 5
References 18
Appendixes
A. Particle Beam El Mass Spectra of Polycyclic Aromatic Hydrocarbons A-l
B. Preliminary Draft Method: Particle Beam/Liquid Chromatography/
Mass Spectrometry Analyses of Polycyclic Aromatic Hydrocarbons B-l
-------
FIGURES
Number Page
1 Comparative Chromatograms of 16 PAHs by HPLC/UV and PB LC/MS 6
2 Comparative Particle Beam El Mass Spectra 10
3 Particle Beam TIC of a PAH Contaminated Soil 11
4 Selected Ion Chromatograms of a PAH Contaminated Soil 11
5 Particle Beam TIC of a PAH/Standard Reference Material 17
A-l Particle Beam El Mass Spectrum of Benzo(a)anthracene A-2
A-2 Particle Beam El Mass Spectrum of Chrysene A-3
A-3 Particle Beam El Mass Spectrum of Benzo(b)fluoranthene A-4
A-4 Particle Beam El Mass Spectrum of Benzo(k)fluoranthene A-5
A-5 Particle Beam El Mass Spectrum of Benzo(a)pyrene A-6
A-6 Particle Beam El Mass Spectrum of Dibenzo(a,l)pyrene A-7
A-7 Particle Beam El Mass Spectrum of Dibenzo(a,h)anthracene A-8
A-8 Particle Beam El Mass Spectrum of Benzo(g,h,i)perylene A-9
A-9 Particle Beam El Mass Spectrum of Indeno(l,2,3-c,d)pyrene A-10
A-10 Particle Beam El Mass Spectrum of Dibenzo(a,e)pyrene . A-11
A-ll Particle Beam El Mass Spectrum of Dibenzo(a,i)pyrene A-12
A-12 Particle Beam El Mass Spectrum of Dibenzo(a,h)pyrene A-13
B-l Particle Beam Liquid Chromatography/Mass Spectrometry
of Polynuclear Aromatic Hydrocarbons B-9
VI
-------
TABLES
Number . Page
1 Liquid Chromatographic Mobile Phase Program 4
2 Detection Limits and Precision of the PB LC/MS for the Analysis of PAHs 5
3 Six-Point Calibration Curve 7
4 Retention-Time Stability of the PB LC/MS Analysis of PAHs 9
5 Comparison of PB LC/MS Quantification Method vs. Fluorescence for
PAH Target Analytes '12
6 Tentatively Identified, Selected Nontarget Compounds in Soil Sample 13
7 PAH Spike Recoveries (Percent) 14
8 Method Detection Limits, Precision, and Accuracy 15
9 Results of SRM Analysis 16
B-l Characteristic Ions for Particle Beam/Liquid Chromatography/
Mass Spectrometry of Polycyclic Aromatic Hydrocarbons B-l
B-2 PAH Spike Recoveries B-10
B-3 Method Detection Limits, Precision, and Accuracy B-10
B-4 Results of SRM Analysis B-ll
vn
-------
ACRONYMS AND ABBREVIATIONS
GC/MS gas chromatograph/mass spectrometer
HP Hewlett Packard
LC liquid chromatograph
LC/MS liquid chromatograph/mass spectrometer
MS mass spectrometer
MW molecular weight
PAHs polycyclic aromatic hydrocarbons
PB particle beam
PFTBA perfluorotributylamine
RSD relative standard deviation
SRM standard reference material
THF tetrahydrofuran
TIC total ion chromatogram
UV ultraviolet
El electron ionization
HPLC high performance liquid chromatography
Vlll
-------
SECTION 1
INTRODUCTION
Polycyclic aromatic hydrocarbons (PAHs) comprise a class of potentially hazardous compounds of
environmental concern. The PAHs were selected for this study as part of a continuing effort to
evaluate applications of particle beam (PB) liquid chromatography/mass spectrpmetry (LC/MS) to the
measurement of pollutants in environmental samples. Initial studies determined instrument response
characteristics to the EPA Method 610 target analytes. These analytes comprise 16 PAHs ranging in
molecular weight from naphthalene (MW 128) to dibenzo(a,h)anthracene (MW 278).
The PB LC/MS was unsuitable for the analysis of the lower molecular weight PAHs (MW<220).
Consequently, the lower molecular weight PAHs were dropped from further study, and four higher
molecular weight PAHs were added as potential target analytes. The additional analytes included
three MW 302 PAHs from Appendix IX: dibenzo(a,e)pyrene, dibenzo(a,h)pyrene, and
dibenzo(a,i)pyrene (1). The fourth add-on analyte was another MW 302 PAH isomer,
dibenzo(a,l)pyrene.
The instrument performance characteristics of the PB LC/MS system were investigated with respect to
the target PAHs. Specific parameters considered were chromatography, detection limits and precision,
response range, spectral quality, and the ability to analyze for PAHs in "real world" samples.
Following examination of instrument performance characteristics, a method was developed for the
analysis of the target PAHs in soils and sediments. The method utilized Soxhlet extraction and silica
gel column clean-up for sample preparation and the PB LC/MS for measurement. The overall
method performance was evaluated on spiked soil samples and on a standard reference material
(SRM). A preliminary draft method is presented in Appendix B.
-------
SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
Low molecular weight PAHs (MW<220) cannot be measured accurately with the PB instrument
However, PAHs with MW>220 can be measured with good accuracy and precision. The PB
instrument sensitivity to these PAHs was on the order of 1 to 10 ng in the full-scan mode. Such
sensitivity allows method detection limits comparable to or better than those of current GC/MS-based
EPA methods.
Instrument response to PAH standard solutions covering a 50-fold concentration range (20 to
1000 ng) was nonlinear for most target PAHs (response factor RSDs > 20%). Response factors
tended to increase with increasing concentration. On one occasion, however, a six point calibration
(20 to 1000 ng) exhibited essentially linear response for most target PAHs. This occurrence was the
exception and could not be reproduced. Responses over a smaller concentration range were also
nonlinear but gave response factor RSDs closer to 20%. Nonlinear response did not appear to
present particular difficulties, however, provided the response was correctly modeled (i.e., point-to-
point calibration or polynomial curve fits). The nonlinear response was reproducible over the course
of an analytical run (24 h), and calibration check samples gave values within 20% of initial calibration.
Further, the nonlinear PB calibration gave results in agreement with HPLC/UV and
HPLC/fluorescence analysis of "real world" samples. For best results over a wide concentration range,
polynomial curve fits should be used.
The El mass spectra obtained from each of the target analytes were consistent with structure and
comparable to reference spectra. In general, the spectra obtained from "real" samples were of
sufficient quality to allow tentative identification of nontarget PAHs. However, some spectral
variation was observed that did not correspond to differences in tuning and mass calibration. These
variations take the form of enhanced relative abundance of the doubly charged molecular ion.
One of the potential applications of PB LC/MS emerging from these studies is the measurement of
high-mass PAHs (MW>300). Current EPA methods do not measure for PAHs above mass 300.
Analysis of the Canadian SRM and the PAH-contaminated soil (from The Dalles, OR) by PB LC/MS
revealed the presence of eight mass 302 PAHs and five mass 326 PAHs. Evidence for PAHs above
mass 326 was also obtained. These high-mass PAHs were only present at low concentrations.
However, the low amount observed was probably due, in part, to poor extraction efficiency with the
solvents employed (methylene chloride or acetonitrile).
We recommend that work on the application of PB LC/MS for the measurement of high-mass PAHs
be pursued. This work would entail characterizing a PAH-contaminated sample for high-mass PAHs.
The work would involve investigation of suitable extraction solvents, chromatographic separation of
the high-mass fraction, and the identification and quantitative estimation of high-mass PAHs by PB
LC/MS in combination with stop-flow fluorescence spectroscopy.
-------
SECTION 3
EXPERIMENTAL
Chromatographic separations employed a Hewlett-Packard (HP) 1090L liquid chromatograph (LC)
with a 250-mm x 4.6-mm I.D. 5-jim CIS column (Vydac 201TP54). An ultraviolet (UV) filter
photometric detector was used to monitor the column effluent in some cases. The column was at
room temperature and a flow rate of 0.4 mL/min was used. The mobile phase programs used to
separate the analytes are described later in this section. The LC was controlled by a local user
interface.
The LC system was coupled to an HP 5988A mass spectrometer (MS) by an HP 59980A PB interface.
The interface was operated with a desolvation chamber temperature of 45° C. The PB probe was kept
at a distance of 0.5 mm from the ion source of the MS. The PB interface was tuned by setting the
nebulizer capillary position and helium flow to maximize the response of the m/z 302 ion of 10 ng
dibenzo(a,h)pyrene. This was done by using single-ion monitoring under flow-injection conditions at
the mobile phase composition corresponding to the retention time of dibenzo(a,h)pyrene.
The HP 5988A MS used in this study had a modified ion source. First, a stainless steel plug was
inserted into the GC inlet of the source. Second, the instrument manufacturer enlarged the diameter
of the PB inlet to the source. Source temperature was either 280° C or 300° C for the analysis done
here. A typical MS operating pressure of 1.2 x 10'5 torr was measured by a Bayard-Alpert ion gauge
tube. The MS was run in electron ionization mode with an electron energy of 70 eV and an emission
current of 300uA. The electron multiplier was a Galileo channeltron. The ion source was tuned with
perfluorotributylamine (PFTBA) by maximizing the m/z 219 ion with solvent at 0.4 mL/min
(methanol/THF, 95:5). PFTBA was introduced through a reservoir on the PB transfer tube. An HP
59970 MS Chemstation data system controlled the instrument.
Two separate sample preparation schemes, were used. One procedure called for a soil (or sediment) to
be sonicated in acetonitrile. A portion of the sonication extract was then passed through a C-18 solid
phase cartridge and was concentrated. The second procedure was more detailed. It consisted of using
Method 3540 of the SW-846 followed by solvent exchange into cyclohexane. The cyclohexane extract
was then cleaned up using Method 3630 followed by solvent exchange into acetonitrile.
Two objectives were considered for the liquid chromatographic separation method used on the target
PAHs. First, a mobile phase and column were selected to effect separation of most target analytes in
30 to 40 minutes. Second, the separation had to be compatible with the PB and MS systems. For
these reasons, a ternary solvent program was employed. Acetonitrile was selected because it gave the
best selectivity for the later-eluting target analytes. Methanol was selected because it gave the best PB
response to the target analytes. Tetrahydrofuran (THF) was selected because it reduced retention
times on the last two eluting analytes and reduced the overall chromatographic run time by 15
minutes. The mobile phase program is listed in Table 1.
-------
TABLE 1. LIQUID CHROMATOGRAPHIC MOBILE PHASE PROGRAM
Time (min) % Methanol % Acetonitrile % Tetrahydrofuran
0 95 05
2 95 0 5
10 45 45 10
15 45 25 30
-------
SECTION 4
RESULTS AND DISCUSSION
The PB LC/MS was unsuitable for the analysis of the lower molecular weight PAHs (MW < 220).
Presumably, these PAHs are too volatile to pass the PB interface. Figure 1 illustrates the poor PB
response to lower molecular weight PAHs by comparison with the UV response from a photometric
detector connected in series with the PB interface. Accordingly, only the higher molecular weight
PAHs were studied.
INSTRUMENT PERFORMANCE
Detection Limits and Precision
The estimated instrument detection limits and precision of the PB LC/MS system for those PAHs
investigated in this study are shown in Table 2. The detection limits were determined from full-scan
extracted ion chromatograms at the 25-ng level. These values are 3 times the standard deviation of
seven replicates. The precision values were calculated from the same set of seven injections of 25 ng.
Considerably better detection limits can be achieved with single-ion monitoring.
TABLE 2. DETECTION LIMITS AND PRECISION OF THE
PB LC/MS FOR THE ANALYSIS OF PAHs
Compound
benzo(a)anthracene
chrysene
benzo(b)fluoranthene
benzo(k)fluoranthene
benzo(a)pyrene
dibenzo(a,l)pyrene
dibenzo(a,h)anthracene
benzo(g,h,i)perylene
indeno( l,2,3-c,d)pyrene
dibenzo(a,e)pyrene
dibenzo(a,i)pyrene
dibenzo(a,h)pyrene
Quantitation
Ion
228
228
252
252
252
302
278
276
276
302 .
302
302
Detection
Limit (ng)
1.8
3.0
1.6
1.0
2.2
6.1
2.4
2.4
1.5
2.5
3.0
4.8
Precision
RSD(%)
2.4
4.1
2.1
1.4
2.9
8.1
3.1
3.2
2.0
3.4
4.0
6.3
-------
XM£OM T.WATER
1OO og each
7S
7S
1OO
ZS
25
O
AA_A
UV CHROMATOGRAM OF EPA METHOD 610 PAHs (2S4nm)
PARTICLE OEAM TIC OF EPA M6THOO 6 IO PAHs
Figure 1. Comparative Chromatograms of 16 PAHs by HPLC/UV and PB LC/MS.
-------
Response Characteristic and Calibration
Instrument response to PAH standard solutions covering a 50-fold concentration range (20 to 1000
ng) was nonlinear for most target PAHs (response factor RSDs > 20 percent). Response factors
tended to increase with increasing concentration. This observation is consistent with the notion that
at low analyte concentrations smaller particles are produced in the interface and that smaller particles
are not transported through the interface as efficiently as larger particles. On one occasion, however,
a six point calibration (20 to 1000 ng) exhibited essentially linear response for most target PAHs.
This occurrence was the exception and could not be reproduced. Responses over a smaller
concentration range were also nonlinear but gave response factor RSDs closer to 20 percent. Table 3
lists response factors from a typical calibration curve.
TABLE 3. SIX-POINT CALIBRATION CURVE
Compound
25 ng
RESPONSE FACTORS x 103
50 ng iOOng 250 ng 500 ng
1,000 ng %RSD
benzo(a)anthracene
chrysene
benzo(b)fluoranthene
benzo(k)fluoranthene
benzo(a)pyrene
dibenzo (a,l) pyrene
dibenzo(a,h)anthracene
benzo(g,h,i)perylene
indeno(l,2,3-c,d)pyrene
dibenzo(a,e)pyrene
dibenzo(a,i)pyrene
dibenzo(a,h)pyrene
6.64
4.09
8.68
6.39
7.93
4.32
2.13
3.88
5.41
3.74
3.88
4.35
6.80
3.65
11.1
6.74
8.92
5.59
2.43
4.01
6.34
4.98
3.86
4.15
6.36
3.52
13.1
6.42
9.49
6.98
2.38
4.29
5.64
5.47
3.60
3.55
7.00
3.33
16.4
6.71
11.4
8.45
2.73
5.24
6.07
4.27
3.59.
3.18
7.71
4.00
19.3
8.00
13.6
10.4
3.55
6.90
8.21
5.52
3.87
3.49
10.9
4.89
.24.7
11.9
20.3
12.6
5.43
10.6
12.9
9.11
6.49
4.34
22.4
14.3
37.7
27.8
38.2
38.3
39.9
44.6
38.4
34.3
26.6
13.0
The enhancement of analyte signal in PB LC/MS systems by mobile additives (e.g., ammonium
acetate) or coelution of the analyte with other compounds has been reported (2). The coelution effect
is potentially detrimental to quantitative analysis because the extent of signal enhancement is
dependent on a number of variables. Some of the factors reported to contribute to signal
enhancement include the relative concentrations of the target analytes and the coeluting substance,
molecular structure of the coeluting substance, and desolvation chamber temperature (2,3). Other
factors not explicitly reported may be operating.
We investigated the use of perylene-d!2 as an internal standard. Perylene-dl2 coelutes with
benzo(b)fluoranthene under the chromatographic conditions employed. A standard solution
containing both benzo(b)fluoranthene and perylene-d!2 exhibited no signal enhancement for .
-------
benzo(b)fluoranthene when compared with a standard solution that did not contain perylene-d!2. A
mitigating factor in this observation was the fact that benzo(b)fluoranthene and perylene-d!2 were
present in the standard solution at the same concentration, 100 ng/uL, well above detection limits. It
has been reported that coelution effects can be negligible when the coeluters are present in similar
amounts at levels well above detection limits (3).
Analysis of a PAH contaminated soil showed little practical difference in quantitative results between
external and internal standard calibration (see Table 5). The relative percent difference between
internal standardization results and external standardization results were within expected measurement
precision (see Table 8) for most of the target PAHs detected. That these results were in good
agreement was somewhat unexpected because of the potential for coelution effects.
Also unexpected was good agreement between results obtained by fluorescence detection and those
obtained by PB LC/MS using external standardization (Table 5). The analyzed samples were complex
with all target PAHs coeluting with one or more matrix components (e.g., non-target PAHs or other
coextracted substances). PB LC/MS analyte signal from the samples would be expected to be subject
to coelution effects whereas the external standard solutions would not. Even so, external
standardization gave reasonably accurate results as compared with fluorescence detection. From this
limited data set, it appears that coelution effects do not present a significant problem for quantitative
analysis. However, because of the limited number of samples examined, we cannot conclude that
coelution effects are not a potential source of error.
Retention Times
The stability of the retention times of the target PAHs eluting from the LC column was investigated.
We observed that the retention times were susceptible to small changes in column temperatures under
the conditions used. Upon elevating the LC oven compartment to 37.5° C (lowest stable temperature
capable by the system) drastic losses in chromatographic resolution were observed. Therefore, the
analyses were carried out at ambient temperature. Table 4 displays the range of the retention times
observed over a 4.5 hour period during which six standards were analyzed. During the analysis of the
standards, the room temperature gradually increased, shortening the analysis times.
Spectral Quality
The PB LC/MS mass spectra of the 12 target analytes are displayed in Appendix A. One of these,
dibenzo(a,e)pyrene, is also shown in Figure 2. This figure displays spectral features common to all of
the PAHs studied. One, the molecular ion, is the base peak and appears with several (M-nH)+ ions
where n can be as many as six. Another prominent feature is the presence of doubly charged ions
that appear at a mass to charge of one half as large as the molecular ion and (M-nH)+ ions. Spectra
A and B of Figure 2 display some of the spectral variations we have observed with the PAHs on this
system. The spectra were obtained under similar conditions but at different times. It can be seen that
in spectra B, the doubly charged ions have a greater relative abundance than in spectra A. The reason
for this anomaly is not known at this time but may be related to local ion source pressure.
Examination of mass spectra for dibenzo(a,e)pyrene over the width of the eluting peak shows the
doubly charged ions to be more abundant by as much as 40% on the peak upslope compared with the
doubly charged ion abundance at the peak apex. Doubly charged ion abundance on the peak
downslope was unchanged from apex values. This phenomenon appears in all the spectra of the
PAHs examined but is more pronounced in the heavier ones.
-------
TABLE 4. RETENTION-TIME STABILITY OF THE
PB LC/MS ANALYSIS OF PAHs
Compound
benzo(a)anthracene
chrysene
benzo(b)fluoranthene
benzo(k)fluoranthene
benzo(a)pyrene
dibenzo(a,l)pyrene
dibenzo(a,h)anthracene
benzo(g,h,i)perylene
indeno( l,2,3-c,d)pyrene
dibenzo(a,e)pyrene
dibenzo(a,i)pyrene
dibenzo(a,h)pyrene
Retention Time
Change (min)
11.04 to 10.89
11.85 to 11.63
13.56 to 13.28
14.93 to 14.49
15.% to 15.45
16.10 to 15.73
. 17.% to 17.43
19.11 to 18.56
20.25 to 19.62
21.04 to 20.51
26.79 to 26.18
28.55 to 27.72
Difference
(min)
0.15
0.22
0.28
0.44
0.51
0.37
0.53
0.55
0.63
0.53
0.61
0.83
Relative
% Difference
1.4
1.9
2.1
3.0
3.3
2.3
3.0
2.9
3.2
2.6
2.3
3.0
Performance on Soil Extracts
Figure 3 is a total ion chromatogram (TIC) of a PAH contaminated soil from The Dalles, OR. The
soil was extracted by using the acetonitrile sonication as described in the experimental section. A
stack plot of four selected ions is illustrated in Figure 4. Note the presence of several peaks at mass
326. Examination of spectra from these peaks indicate them to be PAHs. Table 5 lists the quantities
of each target compound found by internal (d!2-perylene) and external standard calibration
techniques. Also listed for comparison are the quantities of target compounds found on a separate
LC system with fluorescence detection. Examination of Table 5 reveals agreement between PB
quantitative results and results obtained by fluorescence detection. Table 6 lists some selected
nontarget compounds tentatively identified in this soil sample. Compounds listed in Table 6 illustrate
PB capabilities for the identification of unknowns.
-------
100-
90-
80:
0) 7®-
c 60-i
-S 50-
c
3 40-
E 30-
20-:
10:
0'
1
100-
90:
80-:
u 70:
o :
c fa 0-
-S 50-i
C :
3 40-
CC 30^
20-:
"
10-i
0j
1
!\ 124 i
..,...,?>... .T.rr.,.i,^rJ
100 120 140
1
112 124
"\ / || 1
. .-^J.L. r^i...U| .... ,|lll. -.L..I!
• ' "• I1 | T T r | f TT " T 1
100 120 140
d i benzo ( a, e )pyrene c
MW 302
50
/
i 158 198 222 224 248 ^^
160 180 200 220 240 260 280 30
Mass/Charge
Z
50
'
ICQ 248 276
/ 188 . 237 / / ll
I • / / / . ...1,1. Jll
160 • 180 200 220 240 260 280 301
Mass/Charge
\ R
02
2
\ B
02
I
7j
Figure 2. Comparative Particle Beam El Mass Spectra.
-------
column: Sum Vyd.c 28ITP 4.6mmx25cm
flow: 0.4mlXnln
mob I Ie phase:
t(mln) MEOH(X) CH3OUX) THF(X)
95
95
<0
0
0
0
55
70
5
5
5
30
0.0E+0
30
Figure 3. Particle Beam TIC of a PAH Contaminated Soil,
o
u
c
a
•a
c •
3
cc
o
u
c
-o
c
3
SI
"•
0
u
c
0
flbund
o
c
a
T3
C
3
(T
40000J " . j!
30000-j M/Z 252 ll
!
20000-j
,0000j _ |!\/v/v
5 10 15 20 25 30
T ( me ( m I n . )
,
4000-
2000-
M/Z 279
•
^-, ys/Vy^_/^ — /V^y^vx -l\. /^ f^ l\. 1 V_
5 10 15 20 25 30
T 1 me ( m 1 n . )
2769-1 . |
0-
M/Z 302 0
A A II
. ,1\AIU.,
5 10 15 20 25 30
T 1 me ( m 1 r» . )
400-
300-
200-
100-i
.
M^Z 326 « i ft 1
1 A ll A i
1 \ J (I A
iWtf k'AJi
5 10 15 20 25 30
T 1 me ( m 1 n . )
Figure 4. Selected Ion Chromatograms of a PAH Contaminated Soil.
11
-------
TABLE 5. COMPARISON OF PB LC/MS QUANTIFICATION METHOD VS.
FLUORESCENCE FOR PAH TARGET ANALYTES
Soil Extract (ug/g)
RT (min)
10.94
11.75
13.43
14.69
15.75
—
17.67
18.84
19.%
20.77
—
—
m/z
228
228
252
252
252
302
278
276
276
302
302
302
Compound
benzo(a)anthracene
chrysene
benzo(b)fluoranthene
benzo(k)fluoranthene
benzo(a)pyrene
dibenzo(a,l)pyrene
dibenzo(a,h)anthracene
benzo(g,h,i)perylene
indeno(l,2,3-c,d)pyrene
dibenzo(a,e)pyrene
dibenzo(a,i) pyrene
dibenzo(a,h)pyrene
IS*
6.5
26
19
5.9
6.2
~
0.8
3.7
5.6
0.9
—
—
FLb
6.4
21
16
6.8
8.8
•
—
6.4
5.2
-
—
-
EXC
5.4
19
18
7.0
6.8
-
"•1.1
4.8
4.5
1.0
—
-
a quantitated by d!2-perylene internal standard
b quantitated by fluorescence detection
c quantitated by external standards
12
-------
TABLE 6. TENTATIVELY IDENTIFIED, SELECTED NONTARGET
COMPOUNDS IN SOIL SAMPLE
RT (min)
7.91
9.78
9.90
10.76
12.23
12.95
15.05
16.69
19.30
19.38
21.22
21.40
22.35
23.00
23.03
24.30
27.45
Base m/z
217
254
228
253
234
252
266
268
268
302
302
278
284
278
302
300
326
Tentative Identification
benzo(a)carbazole
binaphthalene
triphenylene
(chrysene/etc.)nitrile
benzonaphthothiophene isomer
benzopyrene/fluoranthene isomer
methyl-substituted 252 isomer
methyl cholanthrene isomer
methyl cholanthrene isomer
dibenzopyrene/fluoranthene isomer
* dibenzopyrene/fluoranthene isomer
278 PAH isomer
dinaphthothiophene isomer
picene
dibenzopyrene/fluoranthene isomer
coronene
dibenzoperylene isomer
METHOD PERFORMANCE
The existing SW-846 Soxhlet extraction procedure (Method 3540) was incorporated into a sample
preparation scheme for the PB analysis of PAHs in soils and sediments. Because of difficulties
encountered during the initial PB analysis of an acetonitrile extract of a Canadian SRM, a clean-up
method was sought. Initial analysis of the SRM suggested interference from hydrocarbons. For this
reason, the SW-846 silica gel clean-up (Method 3630) was employed. To evaluate overall method
performance, several spiked blank soils and the Canadian SRM were analyzed.
A sandy loam soil was spiked in triplicate at two different levels, 0.5 jig/g and 2.5 ug/g. The samples
were prepared as just described and the extracts were analyzed with the PB instrument. Recoveries
were calculated by using integrated quantitation ion abundances and a six point external calibration.
Table 7 lists the target analyte recoveries as percentages of the spiked amount and the standard
deviations in percent recovery. Results from one of the low-level spikes (0.5 ng/g) were discarded.
13
-------
Preparation of this particular spike resulted in a two-phase extract. The two-phase extract was
probably the result of incomplete solvent exchange.
The data from all three high-level spikes (2.5 ug/g) were used to determine mean recovery and
standard deviation although two of the higher level spikes gave significantly lower recoveries.
HPLC/UV examination of the pentane wash from the silica gel clean-up from one of the low recovery
samples revealed 5% to 15% of the spiked amount for most of the target analytes had washed off the
column prior to elution of the analytical fraction. This loss may have resulted from improper
preparation of the silica column or from nonuniform activation of the silica gel. These results indicate
the silica gel clean-up is an area of concern and the potential source of problems for overall method
performance. However, losses to the column wash do not account for the low recoveries observed for
dibenzo(a,h)pyrene, as this target analyte was not found in the pentane wash. This PAH was
probably not extracted efficiently with the solvent system employed.
TABLE 7. PAH SPIKE RECOVERIES (PERCENT)
Compound
benzo(a)anthracene
chrysene
benzo(b)fluoranthene
benzo(k)fluoranthene
benzo(a)pyrene
dibenzo(a,l)pyrene
dibenzo(a,h)anthracene
benzo (g,h,i) perylene
indeno( 1 ,2,3-c,d)pyrene
dibenzo(a,e)pyrene
dibenzo (a,i) pyrene
dibenzo(a,h)pyrene
0.5 ue/c
Mean
Recovery
108
131
88
112
63
41
122
96
96
74
84
31
fn=2)
Relative %
Difference
2.5
12
1.5
1.0
11
1.0
8.0
5.0
4.5
8.5
ND
ND
2.5 ue/e
Mean
Recovery
76
100
71
83
59
42
86
70
72
79
80
50
(n=3)
Standard
Deviation
12
18
14
15
13
13
19
15
15
14
19
16
The recovery data were pooled and treated as a single data set to generate overall method precision
and accuracy values. These values are listed in Table 8 along with estimated method detection limits.
Method detection limits were estimated from observed instrument detection limits (Table 2). Values
were adjusted for concentration/dilution factors imposed by the sample preparation scheme (SW-846
Method 3540 and Method 3630): A 20-(iL injection, a 1-mL final extract volume, and a 10-g sample
size. Final values were corrected with the observed recoveries, multiplied by a factor of two, and
rounded to two decimal places. The method detection limits are estimates and have not been
experimentally verified.
14
-------
TABLE 8. METHOD DETECTION LIMITS, PRECISION, AND
ACCURACY
Mean Method
MDL Accuracy (n=5) Standard
Compound
benzo(a)anthracene
chrysene
benzo(b)fluoranthene
benzo(k)fluoranthene
benzo(a)pyrene
dibenzo(a,l)pyrene
dibenzo(a,h)anthracene
benzo(g,h,i)perylene
indeno(l,2,3-c,d)pyrene
dibenzo(a,e)pyrene
dibenzo(a,i)pyrene
dibenzo(a,h)pyrene
(ng/g)
0.02
0.03
0.02
0.01
0.04
0.14
0.02
0.03
0.02
0.03
0.04
0.11
(% of true value)
89
112
77
95
61
42
100
80
82
77
81
45
Deviation (%)
20
23
14
19
12
9
25
18
18
12
15
16
Analysis of a Standard Reference Material
An SRM was analyzed using the procedures described in this report to evaluate method performance
on "real world" samples. The SRM was a marine sediment obtained from the National Research
Council of Canada and designated as HS-3. The material was prepared in triplicate (5 g each) and
taken through the silica gel clean-up procedure. Target analyte amounts were obtained by integrated
quantitation'ion areas and a six point external calibration. In addition, the extracts were analyzed by
HPLC with UV diode array detection for comparative purposes. The results are listed in Table 9
along with the certified SRM values and the initial PB results on an acetonitrile extract without clean-
up.
The PB results with extract clean-up failed to meet acceptance criteria (p±2s) for only one analyte,
benzo(k)fluoranthene. Values for p and s were taken from the experimentally determined method
performance parameters listed in Table 8. The HPLC/UV analysis failed acceptance criteria for two
of the target analytes. The PB results on the acetonitrile extract without clean-up failed acceptance
criteria for all target analytes. In this particular instance, extract clean-up appears to be essential for
accurate analysis. In general, results obtained from PB analysis with extract clean-up and HPLC/UV
were in agreement and agreed with certified values. A PB total ion chromatogram of one of the SRM
extracts is shown in Figure 5.
15
-------
TABLE 9. RESULTS OF SRM ANALYSIS
Compound
benzo(a)anthracene
chrysene
benzo(b)fluoranthene
benzo(k)fluoranthene
benzo(a)pyrene
dibenzo(a,l)pyrene
dibenzo(a,h)anthracene
benzo(g,h,i)perylene
indeno( l,2,3-c,d)pyrene
dibenzo (a,e) pyrene
dibenzo(a,i)pyrene
dibenzo(a,h)pyrene
Certified
Value (jig/g)
14.6±2.0
14.1 ±2.0
7.7 ±1.2
2.8±2.0
7.4±3.6
NA
1.3±0.5
5.0±2.0
5.4±1.3
NA
NA
NA
HPLC/UV
Og/g)
15.2±1.5
7.0±0.6
4.8±0.6
4.8±0.5
4.3 ±0.5
NF
0.8 ±0.2
4.1 ±0.6
3.6±0.6
1.2±0.2
2.0 ±0.4
NF
PB with
Clean-up
(ng/g)
12.1*1.1
19.4±2.6
4.4±0.5
5.1 ±0.4
3.9±0.4
NF
1.7±0.4
3.7±0.4
3.6±0.4
0.7±0.1
0.3 ±0.03
0.2±0.06
PBw/o
Qean-up
Og/g)
5.1
3.7'
2.5
1.2
1.4
NF
NF
0.8
0.8
NF
NF
NF
w/o = without
NA = certification not available
NF = not found
PB = particle beam
16
-------
o
0
-Q
c
3
J3
tr
7.0E+5-
6.0E+5-
5.0E+5-
4.0E+5-
3.0E+5-
2.0E+5-
1.0E+5-
0.0E+0
column: Sum Vydac 201TP 4.6mmx25cm
flou rate: 0.4ml/min
mobile phase:
t(min) '/. MEOH '/, RON '/. THF
0
2
10
15
95
95
45
45
0
0
45
25
5
5
10
30
16
i-
18 20
T1 ma (m1n. )
22
24
26
28
30
Figure 5. Particle Beam TIC of a PAH/Standard Reference Material. ,
-------
REFERENCES
1. 51 Federal Register 5561, February 1986.
2. Bellar, T. A., T. D. Behymer, and W. L. Budde; J. Am. Soc. Mass Spectrom. I, 92-98 (1990).
3. Bajic, S., D.R. Doerge, and C.J. Miles; An Investigation of Ion Abundance Enhancements for the
Particle Beam LC/MS Analysis of Ethylenethiourea (ETU) in Food Samples; Proceedings of the
39th ASMS Conference on Mass Spectrometry and Allied Topics, Nashville, TN, May 19-24, 1991.
18
-------
APPENDIX A
Particle Beam El Mass Spectra
of
. Polycyclic Aromatic Hydrocarbons
-------
100-
90-
80-
70-
60-
0
c
a
•o 50-
c ^
.a
1 40^
30-
20-
10-
^
c
benzoC a) anthracene
MN 228
113
101
/ 122 ,07 150 174 200
ll / / X \ 187 / 213
/ / \ / ,i /
.*..•, . 1 1 II ..|ii_ jl . ....u. , ( ,....,. .1 |n . . . ... lit. „ .. l|l In .(III. -i . , ll
28
.
1
100 120 '140 160 180 200 220
Mass/Charge
Fig. A-l. Particle Beam El Mass Spectrum of Benzo(a)anthrancene.
-------
• 100^
90-
80-
70-
60-
139 / \ 1/87 [I 213
. .1.. . .1 1 1 1 1 ., . .. ,. ..t 1 . - -..1 L_r 1 .. ....... r... i. . ...Ill . . . . 1. » .. ... 1 1 1.. ... . Ill . .Ill 1 II ... i 'till
100 120 '140 160 180 200 220
Mass/Charge
\
28
Fig. A-2. Particle Beam El Mass Spectrum of Chrysene.
-------
1001
90-
80-
benzo(b)fluoranthene
MN 252
52
70-
0)
0
c
ft)
•o
c
3
ja
CE
60-
50-
40-
30-
20-
10-
99
100
126
112
.||>'|'H
120
150
174
187
/
200
/
..Mlfi..
140' 160 180
Mass/Ch arge
200
220
240
260
Fig. A-3. Particle Beam El Mass Spectrum of Benzo(b)fluoranthene.
-------
100n
90-
80-
70-
benzo(k)f1uoranthene
MN 252
52
>
0)
0
c
a
T3
c
D
CE
60-
50-
40-
30-
20-
10-
126
112
I00
224
149
174
187
200
100
120 140
*i' •' i*-' i—"i «'r'—| 1-
160 180
Mass/Ch arge
• n|«i .|i • ^
200 220 240 260
Fig. A-4. Particle Beam El Mass Spectrum of Benzo(k)fluoranthene.
-------
1001
90-
80-
70-
benzo(a)pyrene
MN 252
52
>
o\
a)
0
c
a
-o
c
3
CE
60-
50-
40-
30-
20-
10-
1 13
101
—,"—
100
120
126
.-(u-
150
/
•-'->± r-
140
160 180
Mass/Ch arge
226
200
220
240
260
Fig. A-5. Particle Beam El Mass Spectrum of Benzo(a)pyrene.
-------
ID
u
c
a
•D
c
3
J3
CE
100-1
90-
80-
70-
60-
50-
40-
30-
20-
10-
d i benzo(a,1)pyrene
MH 302
150
/
1 12
125
/
0J
100 120 140
169
/
, ._,._i__
198
263
274
/
160 180 200 220
Mass/Ch arge
240 260 280 300
Fig. A-6. Particle Beam El Mass Spectrum of Dibenzo(a,l)pyrene.
-------
>
QO
0)
o
c
a
"O
c
3
SI
en
1001
90-
80-
70-
60-
50-
40-
30-
20-
10-
125
99
^^.^jjlJit^^
dibenzo(a,h)anthracene
MN 278
139
150 187
200
/
237 /
./.. Jil..
78
100 120 140 160 180 200 220 240 260 280
Mass/Ch ar ge
Fig. A-7. Particle Beam El Mass Spectrum of Dibenzo(a,h)anthracene. ,
-------
1001
90-
80-
76
benzo(g,h,i)perylene
MN 276
70-
0)
u
c
-------
1001
90-
80-
76
i n'deno ( 1,2,3-c,d)pyrene
MN 276
70-
a)
u
c
10
T3
C
3
J3
CE
60-
50-
40-
. 30-
20-
10-
0-
92
100
138
/
124
/
150 187
I- ,"••!-
198
/
224 246
248
-I" . •>••"•!-
120 140
160 .180 200 220 240
Mass/Ch arge
260 280
Fig. A-9. Particle Beam El Mass Spectrum of Indeno(l,2,3-c,d)pyrene.
-------
u
o
c
a
-a
c
D
.a
CE
1001
90-
80-
70-
60-
50-
40-
30-
20-
10-
1 1 1
124
dibenzo(a,e)pyrene
MW 302
150
/
158 198 222 224
100 120 140
"tlj> f •*-*! "'I' •**! " I*' I
160 180
^ • 'i •
200
\
02
248
274
/
11-. |tli
220 240 , 260 280 300
Mass/Charge
Fig. A-10. Particle Beam El Mass Spectrum of Dibenzo(a,e)pyrene.
-------
Q)
O
C
ID
T>
C
3
JQ
(E
100-1
90-
80-
70-
60-
50-
40-
30-
20-
10-
\
; 02
dibenzoCa, i)pyrene
MN 302
15 1
158 197 202 224
248
274
/
100 120 140
160 180 200 220
M as s /"Ch a r g e
240 260 280 300
Fig. A-ll. Particle Beam El Mass Spectrum of Dibenzo(a,i)pyrene.
-------
O
c
ft)
73
C
3
JJ
o:
1001
90-
80-
70-
60-
50-
30-
20-
10-
ra J
d i benzo(a,h)pyrene
MN 302
15 1
124
157
202 223
185
/
248
274
/
•t"
Jlljl.
02
100 120 140
160 180 200 220
Mass/Ch arge
240 260 280 300
Fig. A-12. Particle Beam El Mass Spectrum of Dibenzo(a,h)pyrene.
-------
APPENDIX B
PRELIMINARY DRAFT METHOD
PARTICLE BEAM/LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY
ANALYSES OF POLYCYCLIC AROMATIC HYDROCARBONS
1.0 SCOPE AND APPLICATION
1.1 This method is used to determine the concentration of certain polycyclic aromatic
hydrocarbons (PAHs) in extracts prepared from soils and sediments. Table B-l lists the
nominal retention times of the target PAHs along with their quantitation ion and secondary
ion.
TABLE B-l. CHARACTERISTIC IONS FOR PARTICLE BEAM/
LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY
OF POLYCYCLIC AROMATIC HYDROCARBONS
Compound
benzo(a)anthracene
chrysene
benzo(b)fluoranthene
benzo(a)pyrene
dibenzo(a,l)pyrene
dibenzo(a,h)anthracene
benzo(g,h,i)perylene
indeno( l,2,3-c,d)pyrene
dibenzo(a,e)pyrene
dibenzo(a,i)pyrene
dibenzo(a,h)pyrene
Retention
Time (min)
10.95
11.67
13.20
15.20
15.45
16.27
17.66
18.56
19.31
24.36
26.13
Quantitation
Ion
228
228
252
252 .
302
278
276
276
302
302
302
Secondary
Ion
113
113
126
126
150
139
138
138
150
151
151
a) see 6.2 for liquid chromatographic conditions
B-l
-------
2.0 SUMMARY OF METHOD
2.1 This method provides particle beam (PB) liquid chromatography/mass spectrometry (LC/MS)
conditions for detecting certain PAHs. Prior to using this method, appropriate sample
extraction techniques must be used. A 20-uI aliquot of the extract is injected into a liquid
chromatograph (LC), and compounds in the effluent are passed through a PB interface and
subsequently analyzed by a quadrupole mass spectrometer (MS) operated in the electron
ionization (El) mode.
B-2
-------
3.0 INTERFERENCES
3.1 Raw LC/MS data from all blanks, samples, and spikes must be evaluated for interferences.
Determine if the source of interference originates in the preparation or clean-up of the
samples and correct the problem.
3.2 Contamination by carryover can occur whenever high-level and low-level samples are
sequentially analyzed. To reduce carryover, a solvent blank should be analyzed following an
unusually concentrated sample.
3.3 The chromatographic conditions described allow for a unique resolution of the specified PAH
compounds covered by this method. Other PAH compounds, in addition to matrix artifacts,
may interfere.
B-3
-------
4.0 APPARATUS AND MATERIALS
4.1 Particle beam/liquid chromatograph/mass spectrometer system.
4.1.1 Liquid chromatograph: An analytical system complete with a ternary gradient pumping
system and all necessary accessories.
4.1.2 Reverse-phase column: C-18, 5-jim particle-size diameter, in a 250-mm x 4.6-mm I.D.
stainless steel column (Vydac No. 201TP54 or equivalent).
4.1.3 Particle beam interface: Any PB type interface that meets all analysis criteria may be used
(HP 59980A or equivalent).
4.1.4 Mass Spectrometer: Capable of producing full-scan El type mass spectra when interfaced to
an LC system.
4.1.5 Data system: A computer system must be interfaced to the MS. The system must allow the
continuous acquisition and storage of all mass spectra obtained during the chromatographic
program on machine-readable media. The computer must also have the ability to integrate
extracted ion profiles for quantitation purposes and the ability to match acquired spectra
against a spectral library for compound identification. Provisions for fitting response data to
second or third order curves may also be necessary.
B-4
-------
5.0 REAGENTS
5.1 Methanol: HPLC quality
5.2 Acetonitrile: HPLC quality
5.3 Tetrahydrofuran: HPLC quality
5.4 Stock standard solution:
5.4.1 Prepare individual 1.0-mg/mL solutions of dibenzo(a,e)pyrene and dibenzo(a,i)pyrene in
benzene or toluene. Next, prepare a 0.5-mg/mL solution of dibenzo(a,h)pyrene in benzene or
toluene. Finally, prepare 1.0-mg/mL solutions in acetonitrile for the remainder of target
compounds listed in Table 1. Mix 1.0 mL dibenzo(a,h)pyrene standard along with 0.5 mL of
each of the other target compound solutions prepared above. Bring this solution up to 10.0
mL with acetonitrile giving a final concentration of 50 ng/mL of each compound.
Commercially prepared stock standards can be used at any concentration if they are certified
by the manufacturer or by an independent source.
5.4.2 Transfer the stock standard solution into a Teflon-sealed screw-cap bottle. Store at 4° C and
protect from light. The stock standard should be checked frequently for signs of degradation
or evaporation, especially just prior to using it to prepare calibration standards.
5.4.3 The stock standard solution must be replaced after one year, or sooner if comparison with
check standards indicates a problem.
5.5 Calibration standards: Calibration standards at a minimum of five concentration levels should
be prepared through dilution of the stock standard with acetonitrile. One of the concentration
levels should be at a concentration near, but above, the method detection limit. The remaining
concentration levels should correspond to the expected range of concentrations found in real
samples or should define the working range of the PB LC/MS system. Calibration standards
must be replaced after six months, or sooner if comparison with check standards indicates a
problem.
5.6 PB LC/MS tuning compound: Perfluortributylamine should be introduced through the PB
interface into the MS with solvent flow on. The MS should be tuned to maximize mass 219.
5.7 Internal standards: The use of internal standards is optional. To use this approach, the
analyst must select one or more internal standards that are similar in analytical behavior to the
compounds of interest.. The analyst must further demonstrate that the measurement of the
internal standard is not affected by method or matrix interferences. Coelution effects on the
use of internal standards have not been clearly established.
5.7.1 Prepare calibration standards at a minimum of five concentration levels for each analyte as
described in Paragraph 5.5.
5.7.2 To each calibration standard, add a known constant amount of one or more internal
standards, and dilute to volume with acetonitrile.
5.7.3 Analyze each calibration standard according to Section 6.0.
B-5
-------
6.0 PROCEDURE
6.1 Extraction and Cleanup: See SW-846 Methods 3540 and 3630. Method 3540 is followed by a
solvent exchange into cyclohexane and Method 3630 is followed by a solvent exchange into
acetonitrile.
6.2 LC conditions: Using the column described in Paragraph 4.1.2, follow the conditions
recommended below.
Time(min) % ACN % MEOH % THF
0
2
10
15
0
0
45
25
95
95
45
45
5
5
10
30
Mobile phase flow rate = 0.4 mL/min
Column temperature = ambient
6.3 PB conditions: A desolvation chamber temperature of 45° C is recommended. The
nebulizer and helium flow should be set to maximize the response of the m/z ion of 10 ng
dibenzo(a,h)pyrene with 25% acetonitrile, 45% methanol, and 30% tetrahydrofuran as the
mobile phase.
6.4 Recommended MS conditions:
scan range: 100-500
scan time: 0.5 to 1.0 scans/sec
source temperature: 280° C to 300° C
electron energy: 70eV
emission current: 300 uA
tuning: maximize m/z 219 of perfluorotributylamine
6.5 Calibration:
6.5.1 Refer to Method 8000 of the SW-846 for proper calibration procedures. Use the areas from
each for the proper quantitation ions listed in Table 1 to quantify each of the PAHs. The
procedure for internal or external standard calibration may be used. Use Table 3 for guidance
in selecting the lowest point on the calibration curve.
6.5.2 Assemble the necessary PB LC/MS apparatus and establish operating parameters equivalent to
those indicated in Section 6.2 through 6.4. By injecting 20 ul of the calibration standards,
establish the sensitivity limit of the MS and the linear range of the analytical systems for each
compound. In case of a nonlinear response over the concentration range required for
analysis, the analyst may apply a more appropriate model (i.e., point-to-point calibration or
B-6
-------
polynomial curvefits). A curve will be considered nonlinear when the relative standard
deviation in response factors is 20 or greater.
6.5.3 Before using any cleanup procedure, the analyst should process a series of calibration
standards through the procedure to confirm elution patterns and the absence of interferences
from the reagents.
6.6 Daily calibration: A calibration standard at mid-level concentration containing all target
analytes must be performed every 20 samples during analysis. Compare the response factor
data from the standards every 20 samples with the average response factors from the initial
calibration if it is considered linear. If another calibration model is used, then the response
factor from the mid-point chosen for the daily calibration should be compared with the
response factor from the initial calibration of that same concentration. In either case, the
daily calibration can have no more than 20% relative difference for any of the compounds or
a new calibration curve must be constructed.
6.7 PB LC/MS analysis:
6.7.1 Table B-l summarizes the estimated retention times of the PAHs determined by this method.
Figure B-l is an example of the separation achievable using the conditions given in Paragraph
6.2.
6.7.2 If internal standard calibration is to be performed, add the internal standard to the sample
prior to injection. Inject 20 \iL of the sample extract into the LC. Re-equilibrate the LC
column at the initial gradient conditions for at least 10 minutes between injections.
6.7.3 Using either the internal or external calibration procedure (Method 8000), determine the
quantity of each component peak, in the sample chromatogram, that corresponds to the
compounds used for calibration purposes. See Section 7.8 of Method 8000 for calculation
equations.
6.7.4 Using either a self-created mass spectral library or a computer library, confirm the identity of
each component in the sample.
6.7.5 If the peak area exceeds the linear range of the system, dilute the extract and reanalyze.
6.7.6 If interferences prevent measurement of the peak area, further cleanup is required.
B-7
-------
7.0 METHOD PERFORMANCE
7.1 This method was tested using a sandy loam soil spiked at levels of 0.5 jig/g and 2.5 ug/g in
triplicate. The recovery results for the analysis of the extracts are displayed in Table B-2. One
of the low-level extracts was a two-phase mixture and was not used to calculate the percent
recovery. Two of the higher level spikes gave significantly lower recoveries. HPLC/UV
examination of the pentane wash from the silica gel clean-up from one of these samples
revealed 5% to 15% of the spiked amount for most of the target analytes had washed off the
column prior to elution of the analytical fraction.
7.2 Table B-3 presents the detection limits, precision, and accuracy for this method. Method
detection limits were estimated from observed instrument detection limits. Values were
adjusted for concentration/dilution factors imposed by the sample preparation scheme,
assuming use of a 20-|iL injection and a 10-g sample size. Final values were corrected with
the observed recoveries. The method detection limits are estimates and have not been
experimentally verified. The recovery data are pooled and treated as a single data set to
generate overall method precision and accuracy values.
7.3 Method performance was also tested by analyzing an SRM obtained from the National
Research Council of Canada and designated as HS-3. In addition, the extracts were analyzed
by HPLC with UV diode array detection for comparative purposes. The SRM (marine
sediment) was extracted and cleaned-up using the silica gel procedure in triplicate. Table B-4
lists the results of the SRM analysis. The PB results failed to meet acceptance criteria (p ±
2s) for only one analyte, benzo(k)fluoranthene. The HPLC/UV analysis failed acceptance
criteria for two of the target analytes. In general, results obtained from PB analysis and
HPLC/UV were in agreement and agreed with certified values.
B-8
-------
60000-
50000-
40000-
Cd
.a
cr
30000-
20000-^
10000-
10
12
14
16
18 20
T t me (m1n . )
22
26
28
Figure B-l. Particle Beam Liquid Chromatography/Mass Spectrometry
of Polynuclear Aromatic Hydrocarbons.
-------
TABLE B-2. PAH SPIKE RECOVERIES
0.5 ue/2 (n=2) 2.5 ue/e
Compound
benzo(a)anthracene
chrysene
benzo(b)fluoranthene
benzo(k)fluoranthene
benzo(a)pyrene
dibenzo(a,l)pyrene
dibenzo(a,h)anthracene
benzo(g,h,i)perylene
indeno(l,2,3-c,d)pyrene
dibenzo(a,e)pyrene
dibenzo(a,i)pyrene
dibenzo(a,h)pyrene
Mean
Recovery (%)
108
131
88
112
63
41
122
96
96
74
84
31
TABLE B-3. METHOD DETECTION
Compound
benzo(a)anthracene
chrysene
benzo(b)fluoranthene
benzo(k)fluoranthene
benzo(a)pyrene
dibenzo(a,l)pyrene
dibenzo(a,h)anthracene
benzo(g,h,i)perylene
indeno(l,2,3-c,d)pyrene
dibenzo(a,e)pyrene
dibenzo(a,i)pyrene
dibenzo(a,h)pyrene
MDL
(ng/g)
0.02
0.03
0.02
0.01
0.04
0.14
0.02
0.03
0.02
0.03
0.04
0.11
Standard Mean
Deviation Recovery (%)
2.5 76
12 100
1.5 71
1.0 83
11 . 59
1.0 42
8.0 86
5.0 70
4.5 72
8.5 79
ND 80
ND 50
fn=3)
Standard
Deviation
12
18
14
15
13
13
19
15
15
14
19
16
LIMITS, PRECISION, AND ACCURACY
Mean Method
Accuracy (n=5)
(% of true value)
89
112
77
95
61
42
100
80
82
77
81
45
Standard
Deviation (%)
20
23
14
19
12
9
25
18
18
12
15
16
B-10
------- |