£EPA
United States Office of EPA-560/5-84-001
Environmental Protection Toxic Substances February, 1984
Agency Washington DC 20460
Toxic Substances
METHODS OF ANALYSIS
FOR POLYCHLORINATED
DIBENZO-p-DIOXINS (PCDDs)
AND POLYCHLORINATED
DIBENZOFURANS (PCDFs)
IN BIOLOGICAL MATRICES -
LITERATURE REVIEW AND
PRELIMINARY RECOMMENDATIONS
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METHODS OF ANALYSIS FOR POLYCHLORINATED DIBENZO-£-DIOXINS (PCDDs) AND
POLYCHLORINATED DIBENZOFURANS (PCDFs) IN BIOLOGICAL MATRICES -
LITERATURE REVIEW AND PRELIMINARY RECOMMENDATIONS
by
John S. Stanley
TASK 6
FINAL REPORT
February 16, 1984
EPA Prime Contract No. 68-01-5915
MRI Project No. 4901-A(6)
U.S. EPA
OPPTS Chemical Library
401 M St. SW, MC7407
Washington, D.C. 20460
(202) 260-394/
For
U.S. Environmental Protection Agency
Office of Toxic Substances
Field Studies Branch, TS-798
Washington, DC 20460
Attn: Dr. Frederick W. Kutz, Project Officer
Mr. David P. Redford, Task Manager
Mr. Daniel Heggem, Task Manager
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DISCLAIMER
This document has been reviewed and approved for publication by the
Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S.
Environmental Protection Agency. Approval does not signify that the contents
necessarily reflect the views and policies of the Environmental Protection
Agency, nor does the mention of trade names or commercial products constitute
endorsement or recommendation for use.
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PREFACE
This report presents a literature review of the analytical methods used
for the measurement of polychlorinated dibenzo-£-dioxins (PCDDs) and poly-
chlorinated dibenzofurans (PCDFs) in human adipose tissue. Also included in
this report are recommendations from a meeting of scientists recognized for
their efforts in PCDD and PCDF analyses held April 27th and 28th at MRI.
This work was accomplished on MRI Project No. 4901-A, Task 6, "Planning Survey
and Analysis Projects," for the U.S. Environmental Protection Agency (EPA Prime
Contract No. 68-01-5915). The review was conducted and the document prepared
by Dr. John S. Stanley, with assistance from Jerry Hurt, Barbara Mitchell,
Kathy Funk, Lanora Moore, Cindy Melenson, Carol Shaw, Gloria Sultanik,
Judy Daniels and Mary Walker. MRI would also like to thank the people listed
in Appendix A for their cooperation, as well as David Redford, Madeline
O'Neill-Dean and Daniel Heggem of FSB/OTS, EPA.
MIDWEST RESEARCH INSTITUTE
>y
'At
?ohn E. Going
Program Manager
Approved:
James L. Spigarelli, Director
Analytical Chemistry Department
11
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CONTENTS
Preface ii
Figures iv
Tables vi
List of Terms, Abbreviations, and Symbols viii
1. Summary 1
2. Introduction 2
3. Literature Acquisition and Review Procedure . 5
Sources of information 5
Review procedure 5
4. Analytical Methods - A Review 8
Extraction 8
Cleanup 12
Instrumental analysis 25
5. Applicable Techniques - Recommendations 72
Discussion meeting summary 72
Discussion meeting recommendations 77
Appendices
A. Invited participants 82
B. Discussion meeting schedule of events 89
C. Bibliography 92
111
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FIGURES
Number
1 RP-HPLC fractionation chromatograras of (a) calibration
standard and (b) European refuse incineration fly ash
demonstrating the application for collection of PCDDs
by homolog 15
2 Schematic of EPA sample preparation procedures for prepara-
tion procedures for preparation of biological matrices for
TCDD analyses 17
3 Schematic presentation of the sample presentation used by
FDA and laboratories and the New York State Department of
Health in collaborative study of fish sample preparation
and analysis 18
4 Flow diagram for enrichment and fractionation of PCDDs and
PCDFs from tissue samples (FWS procedure) 19
5 Schematic for sample preparation for PCDD analysis by the
Dow analytical approach 20
6 Glass chromatography columns for sample cleanups:
A = silica, B = 22% sulfuric acid on silica, C = 44% sul-
furic acid on silica, D = 33% 1 M sodium hydroxide on
silica, E = 10% AgNOg on silica, and F = basic alumina . . 21
7 GC/ECD chromatograms of extracts from unfortified catfish
(1/20 of the sample extract) 23
8 Range of application of some analytical techniques for
dioxins 26
9 PGC/MS chromatogram of PCDD homologs extracted from incin-
erator fly ash sample 27
10 Comparative 2,3,7,8-TCDD PGC/MS mass chromatograms for
electrostatic fly ash (a) after RP-HPLC, and (b) subse-
quent silica-HPLC 29
11 Separation of PCDD-isomers by GC/MS using a high resolution
capillary column 30
IV
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FIGURES (continued)
Number
12 Mass chromatograms (m/e 320) of a composite pyrolyzate sam-
ple showing elution of all 22 TCDD isomers on HRGC
columns 31
13 HRGC chromatogram of a mixture of the 22 TCDD isomers on
glass and fused silica capillary columns (60 m) coated
with SP-2330 and SP-2340, respectively, indicating isomer
specified separation for 2,3,7,8-TCDD 32
14 Electron capture chromatograms of (a) entire nonphenolic
fraction, (b) first microcolumn fraction containing
chlorodiphenyl ethers (c) second basic alumina micro-
column fraction containing chlorodibenzo-£-dioxin and
chlorodibenzofurans 40
15 HRGC/MS-SIM chromatogram of TCDD analysis 43
16 Method detection limit versus final extract volume and ini-
tial sample size assuming a GC/MS instrumental detection
limit of 5 pg/Ml on-column 52
17 Statistical treatment of validation data for 2,3,7,8-TCDD
and OCDD in human milk samples 62
18 Statistical treatment of reported concentrations versus
concentrations of TCDD actually added to standard solu-
tions and beef adipose 63
19 Schematic of proposed analytical method using high resolu-
tion mass spectrometry (HRMS) 75
20 Schematic of proposed analytical method using low resolu-
tion mass spectrometry (LRMS) 76
21 Example of possible interlaboratory organization 81
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TABLES
Number
1 Molecular Formula, Molecular Weight, and Number of Isomers
of PCDD 3
2 Sample Types Analyzed for TCDD 3
3 Criteria for Rating Published PCDD Analytical Methods. ... 6
4 Relative Efficiency of Various Methods Used at Each Stage
of Analysis 7
5 Estimated Half-Lives (tj) of Several Dioxins in Refluxing
KOH Solutions. . . . ? 9
6 Effect of Potassium Hydroxide Concentration, Time, and
Temperatures on Polychlorodibenzo-£-dioxin Stability ... 10
7 A Listing of Some Cleanup Procedures 13
8 Resources Required to Extract and Clean Up Fish Samples. . . 22
9 Summary of GC/MS-SIM Results of Study of TCDD Extraction-
Cleanup 24
10 Response From Possible Environmental Contaminants 34
11 EPA Phase I Dioxin Implementation Plan Beef Fat Samples
Analyzed for TCDD 36
12 Some Compounds that may Interfere with the Determination of
TCDD at m/z Values of 319.8966 and 321.8936 37
13 Interferences of Selected Chemical Families in MS Determina-
tion of PCDFs and PCDDs 41
14 Partial Scan Confirmation for TCDD 44
15 Range of Reported Percent Relative Abundances for Most
Intense Ion in Isotope Clusters From Electron Impact Mass
Spectra of the Chlorinated Dibenzo-£-dioxins 45
16 Are'a Response Factors of PCDDs Relative to 1,2,3,4-TCDD at
m/z 322 47
vi
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TABLES (continued)
Number
17 Comparison of Relative Peak Ratios of PCDDs Through a Glass
Jet and Silicone Membrane Separator 47
18 Exact Masses and Relative Isotope Abundances of Major
Molecular Cluster Ions for PCDDs 50
19 Feasibility Study for the Quantitative Determination of TCDD
in QA Tissue Samples 53
20 Detection Limits for TCDD in Various Samples 54
21 Percent Recovery of Internal Standard and Percent Accounta-
bility for Native Dioxins Spiked into Control Milk
Homogenate 57
22 Summary of Some Published Method Validation Data for
2,3,7,8-TCDD Recovered From Fortified Biological Matrices. 59
23 Results of Recovery Tests Performed on the Analytical
Procedure, or Its Single Parts 60
24 Interlaboratory Studies and Method Validations for the
Analysis of Tetrachlorodibenzo-p_-dioxins (TCDD) 64
25 Results of Analysis of TCDD in Human Adipose Tissue 66
26 Results of Interlaboratory Validation Studies 68
27 Concentration of 2,3,7,8-TCDD in Fish Samples From Inter-
laboratory Study 69
28 Percent Recoveries of Internal Standard TCDD in the Inter-
laboratory Study 70
Vll
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LIST OF TERMS, ABBREVIATIONS, AND SYMBOLS
Accuracy
AOAC
Congener
DDE
DDT
2,4-D
BCD
El
EIMS
FID
GC
GC/MS
HCDD
HpCDD
Homolog
HPLC
HRGC
silica.
Closeness of analytical result to "true"
value.
Association of Official Analytical Chemists.
One of 75 PCDDs or 135 PCDFs, not necessarily
the same homolog.
1,1,-Dichloro-2,2-bis(£-chlorophenyl)-
ethylene.
1,1, l-Trichloro-2,2, -bis (js-chlorophenyl) -
ethane.
2,4-Dichlorophenoxyacetic acid.
Electron capture detector.
Electron impact ionization (mass spectrometry).
Electron impact mass spectrometry.
Flame ionization detector.
Gas liquid chromatography (column type
unspecified).
Gas liquid chromatography/mass spectrometry
(ionization mode unspecified).
Hexachlorodibenzo-£-dioxin.
Heptachlorodibenzo-£-dioxin.
One of the eight degrees of chlorination
of PCDDs and PCDFs.
High performance liquid chromatography.
High resolution gas chromatography, glass or fused
vxii
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HRMS
Internal standard
Isomer
KOH
LOD
LOQ
LRMS
MDL
Mean
MS
m/z
NRCC
OCDD
PCB
PCDD
PCDF
PGC
ppb
ppm
High resolution electron impact mass
spectrometry.
Standards used expressly for quantitation
added to sample extract immediately prior
to the analytical determination. Internal
standards are used for PCDD and PCDF analy-
ses to accurately measure recoveries of
spiked surrogate compounds.
One of up to 22 PCDDs or 38 PCDFs possessing the
same degree of chlorination (1,2,3,4-TCDD and 2,3,7,8-
TCDD are different isomers).
Potassium hydroxide.
Lower limit of detection (see also MDL). Lowest
concentration at which an analyte can be identified
as present in a sample at a stated statistical con-
fidence level.
Lower limit of quantitation. Lowest concentration
to which a value can be assigned at a stated statis-
tical confidence level.
Low resolution mass spectrometry.
Method detection limit.
Arithmetic mean.
Mass spectrometry.
Mass-to-charge ratio.
National Research Council of Canada.
Octachlorodibenzo-£-dioxin.
Polychlorinated biphenyl.
Polychlorinated dibenzo-£-dioxin (including
monochlorodibenzo-£-dioxins).
Polychlorinated dibenzofuran (including
monochlorodibenzofuran).
Packed column gas liquid chromatography.
Parts per billion (1 x 10 9 g/g, ng/g).
Parts per million (1 x 10 6 g/g, Mg/g).
IX
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ppt
Precision
QA
QC
RP-HPLC
RSD
SD
Sensitivity
SIM
Surrogate
TCDD
13C12-TCDD
37C14-TCDD
2,4,5-T
Parts per trillion (1 x 10 12 g/g, pg/g).
Reproducibility of an analysis, measured
by standard deviation (SD) of replicates.
Quality assurance. An organization's pro-
gram for assuring the integrity of data it
produces or uses.
Quality control. The specific activities
and procedures designed and implemented to measure
and control the quality of data being produced.
Reverse phase high performance liquid
chromatography.
Percent relative standard deviation
(SD/mean x 100).
Standard deviation.
The slope of instrument response with respect to
the amount of analyte. Also used colloquially to
refer to lowest detectable amount of analyte.
Selected ion monitoring (also mid or mass
fragmentography).
Standard compounds added to the sample prior to any
analytical manipulations for the express purpose of
measuring recovery through extraction, cleanup, etc.,
and to provide true internal standard quantitation.
Tetrachlorodibenzo-£-dioxin.
Carbon-13 stable isotope labeled TCDD.
Chlorine-37 stable isotope labeled TCDD.
2,4,5-Trichlorophenoxyacetic acid.
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SECTION 1
SUMMARY
The published literature on polychlorinated dibenzo-£-dioxins (PCDDs)
analyses for biological matrices is reviewed. The analytical methods are dis-
cussed for sample extraction, cleanup, and instrumental analysis.
This report also presents a synopsis of a discussion meeting concerning
the analysis of polychlorinated dibenzo-£-dioxins (PCDDs) and polychlorinated
dibenzofurans (PCDFs) held at Midwest Research Institute (MRI) on April 27
and 28, 1983. The primary objective of this meeting was to define the needs
of an analytical method for the analysis of PCDDs and PCDFs in human adipose
tissue. This method will be used in the future for population studies.
Several major programs were identified as necessary to achieve these goals,
These included (a) the need for establishing a repository of PCDD/PCDF stan-
dards of known quality; (b) the organization and implementation of a strong
quality assurance program; (c) the acquisition of sufficient human adipose
tissue to generate a homogeneous sample matrix for the QA program; (d) inde-
pendent studies of extraction procedures using bioincurred radiolabeled PCDDs;
(e) intralaboratory ruggedness testing of a proposed analytical method; and
(f) interlaboratory evaluation of the proposed method. Simultaneous activity
in several of these areas is necessary in the coming months.
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SECTION 2
INTRODUCTION
Polychlorinated dibenzodioxins (PCDDs) are a series of compounds with
varying chlorine atom substitution on the dibenzo-£-dioxin parent compound.
Table 1 presents the 75 possible positional isomers distributed from monochloro-
to octachlorodibenzo-£-dioxin. The dioxin considered to be most toxic is the
2,3,7,8-tetrachlorodibenzo-D-dioxin (TCDD) .
The potential long-term consequences of exposure to PCDDs, particularly
2,3,7,8-TCDD, are an issue of increasing public concern. Highly intense an-
alytical and toxicological investigations have been conducted in recent years
as a result of the presence of TCDD as an unexpected contaminant in the de-
foliant, Agent Orange, which ,is a formulation of 2,4,5-trichlorophenoxyacetic
acid (2,4,5-T), 2,4-dichlorophenoxyacetic acid (2,4-D), and related ester her-
bicides. Also, the accidental release of TCDD from a factory near Seveso,
Italy, the discovery of TCDD contaminated soil in Missouri, and the indica-
tion that PCDDs are emitted from numerous combustion sources have generated a
demand for highly sensitive and specific analytical measurements for these
contaminants in a wide spectrum of matrices. Table 2 presents some of the
highly diverse sample matrices that have been analyzed for PCDDs, particularly
for 2,3,7,8-TCDD.
The need to determine PCDDs in these diverse matrices has resulted in
the development of a number of well-documented approaches to analysis. Al-
though the exact approaches vary between laboratories, the basic requirements
of all methods include quantitative extraction, efficient cleanup and separa-
tion from the bulk of the sample matrix and chlorinated compounds that might
act as interferences, and sensitive and specific methods of instrumental analy-
sis. The early work of Baughman and Meselson (1973) has been refined and ex-
panded to accommodate complex matrices and to achieve detection at parts per
trillion levels in numerous samples.
The overall objective of this review and preliminary method recommenda-
tion is to assist the EPA's Office of Toxic Substances (OTS) in proposing an
analytical method for PCDDs in human adipose tissue in conjunction with the
Veterans Administration's (VA) Agent Orange study. The Field Studies Branch
of EPA/OTS has for many years been directly involved with the EPA's National
Human Monitoring Network. The Network has adipose specimens archived which
may provide evidence of exposure to Agent Orange. Part of the overall plan
is (a) the identification of specimens for which exposure can be documented,
and (b) the analysis of those specimens for evidence of exposure. The second
part of the study is addressed in this document.
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TABLE 1. MOLECULAR FORMULA, MOLECULAR WEIGHT, AND NUMBER
OF ISOMERS OF PCDD
Chlorinated
dibenzo-£-dioxin
Molecular formula
Total number
of isomers
Monochloro (MCDD)
Dichloro (DCDD)
Trichloro (T3CDD)
Tetrachloro (TCDD)
Pentachloro (P5CDD)
Hexachloro (HCDD)
Heptachloro (HpCDD)
Octachloro (OCDD)
C 12^7^102
£12^5^1302
2
10
14
22
14
10
2
1
TABLE 2. SAMPLE TYPES ANALYZED FOR TCDD
Human milk
Human adipose tissue'
Beef liver
Beef adipose tissue
Beef blood
Wildlife samples - deer,
elk, shrew, etc.
Fisha
Water, soil and sediment
Workplace air samples
Fly ash samples
Gasoline and diesel automobile
exhaust
o
Chemical products
Chemical process streams
o
Municipal incinerator
Source: Harless, R. L., and R. G. Lewis, "Quantitative Determin-
ation of 2,3,7,8-Tetrachlorodibenzo-£-dioxin Residues by
Gas Chromatography/Mass Spectrometry," in Chlorinated
Dioxins and Related Compounds. Impact on the Environment,
0. Hutzinger, R. W. Frei, E. Merian, and F. Pocchiari (Eds.),
Pergamon Press, 1982, pp. 25-36.
a 2,3,7,8-TCDD residues were confirmed and quantified. Presence
of other TCDD isomers confirmed in various samples.
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This report reviews methods used for analysis of PCDDs in biological ma-
trices. Section 3 describes the literature review procedures. Analytical
methods are reviewed in Section 4 in terms of sample preparation, extraction,
instrumental analysis, quantitation, and quality assurance. The advantages
of specific methodologies, the purpose of specific steps, and the limitations
of the particular technology are discussed. Section 5 presents a synopsis of
a meeting held at MRI to discuss analytical approaches to the analysis of human
adipose for PCDDs and PCDFs. Section 5 also provides recommendations for iden-
tifying an analytical method and organization of major program areas for method
validation and sample analyses. Appendix A provides a list of persons who
provided peer reviews and were invited to attend the meeting held at MRI.
Appendix B provides the schedule of discussion topics for that meeting.
Appendix C is a bibliography of references compiled and reviewed for this
literature review.
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SECTION 3
LITERATURE ACQUISITION AND REVIEW PROCEDURE
This section describes how the published literature on analytical tech-
niques for PCDDs in biological matrices was reviewed and presents in tabular
form some suggested criteria for rating published methods.
SOURCES OF INFORMATION
Computerized and manual searches and relevant references in recent arti-
cles were used. Also, many documents not available in the open literature
were obtained from the working files of MRI scientists professionally involved
in PCDD research. Recent issues of several key journals (Analytical Chemistry,
Journal of Chromatography, Journal of the Association of Official Analytical
Chemists, Environmental Science and Technology) were searched manually to pick
up any recent references not yet in the computer data bases. In addition,
several leading scientists (Appendix A) were called to discuss analytical ap-
proaches. In these discussions, they were asked to send copies or give
references to any recent publications or preprints.
The computer searches were done using DIALOG. Chemical Abstracts (CA)
files were searched back to 1978, printing all references containing "poly-
chlorinated dibenzo-p-dioxin," "PCDD," "TCDD," CAS registry numbers, and syn-
onyms and keywords beginning with the following notations: "anal," "detn,"
"quant," "measure," "tissue," "milk," "adipose" and "biol." A similar search
was performed on the National Technical Information Service data base (in-
cluding Smithsonian Science Information Exchange) and the Toxline data base.
Once the primary search data had been reviewed, it became apparent that
several authors were of primary interest and all of their recent (1980 to
1983) publications were retrieved by a CA name search. These authors in-
cluded H. Buser, W. Crummet, A. Dupuy, M. Gross, R. Harless, L. Lamparski,
T. Nestrick, C. Rappe, D. Stalling, T. Tiernan, H. Tosine, and A. Young.
References contained in primary literature and review articles were also
checked to assure that no important articles had been missed by the computer
search. Several articles were added to the files by these searches.
REVIEW PROCEDURE
All articles cited in the bibliography of this document were surveyed
for relevant analytical details. The salient features of each article were
noted and any key subject areas were listed. Each citation was cross filed
in applicable key subject areas such as extraction, cleanup, HRGC/MS, method
validation, interlaboratory study, etc.
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The analytical methodologies for the analysis of PCDDs have previously
been reviewed by several authors (Harless, 1977; Firestone, 1978; McKinney,
1978; Hass and Friesen, 1979; Buser, 1980; Cairns et al., 1980; Esposito et al.,
1980; Baker, 1981; NRCC, 1981; Fishbein, 1982; Karasek, 1982; Mahle and Shadoff,
1982; Tiernan, 1983). Although these reviews were directed principally toward
the final measurements with mass spectrometry, they contained a wealth of in-
formation in terms of consolidated analytical results and method performance
data.
The National Research Council of Canada (NRCC, 1981) and Mahle and Shadoff
(1982) have directed attention to complete analytical methods. The NRCC rated
analytical methods current to 1981 by the criteria listed in Table 3. None
of the techniques reviewed by NRCC received the highest point rating since no
method had been fully evaluated through collaborative testing. Mahle and
Shadoff (1982), on the other hand, rated methods from low to high with respect
to the technical aspects of extraction and cleanup, separation of isomers,
and detection and quantitation. Table 4 is an example of the rating scheme
reported by Mahle and Shadoff (1982).
TABLE 3. CRITERIA FOR RATING PUBLISHED PCDD ANALYTICAL METHODS
Point rating
Essential elements
1 (highest) Complete quality assurance as described by ACS (1980). An
ideally developed, evaluated method including collaborative
studies.
2 Isomer specific, extensive recovery studies, interferences
removed and separation achieved through extensive chemical
workup; lacks collaborative evaluation and assumes confirma-
tion.
3 Incompletely isomer specific, some recovery studies, inter-
ferences partially removed and partial separation achieved
through chemical workup; lacks collaborative evaluation and
assumes confirmation.
5
6
Essentially a screening method for most homologs, inter-
ferences partially removed and partial separation through
limited chemical workup; lacks collaborative evaluation
and assumes confirmation.
Same as 4, except inadequately documented for recovery,
cleanup, etc.
Insufficient for the present state of the art.
Source: National Research Council of Canada, "Polychlorinated Dibenzo-£-
dioxins: Limitations to the Current Analytical Techniques,"
NRCC No. 18576, ISSN 0316-0114 (1981).
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TABLE 4. RELATIVE EFFICIENCY OF VARIOUS METHODS USED
AT EACH STAGE OF ANALYSIS :
Method
Description
Stage I: sample preparation
L Chemical treatment and/or extraction without chromatography
M L + column chromatography
H M + HPLC
Stage II: sample introduction
L No gas chromatography (direct probe)
M Packed column GC
H Capillary column GC
Stage III: mass spectrometry
L Low resolution (300-2000)
M Medium resolution (> 2000-9000)
H High resolution (> 9000)
Source: Mahle, N. H., and L. A. Shadoff, "The Mass Spectrometry of
Chlorinated Dibenzo-p_-dioxins," Biomedical Mass Spectrometry,
9:45-60 (1982).
a L = Low, M = medium, H = high.
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SECTION 4
ANALYTICAL METHODS - A REVIEW
The analytical methods applicable to the measurement of PCDDs in biolog-
ical matrices are discussed in this section. The quality and limitations of
the applicable methods are frequently documented by referral to data published
in the literature. Most of the methods reviewed in this section allow the
simultaneous analysis of polychlorinated dibenzofurans (PCDFs) and PCDDs in
biological matrices.
EXTRACTION
Reliable PCDD analyses begin with the quantitative extraction of the
analytes from the sample matrix. In general, the extraction method is depen-
dent on the sample type and the complexity of the matrix. Extraction methods
used in preparing biological samples have included neutral extractions, alco-
holic potassium hydroxide saponifications, and acidic digestions followed by
transfer of the PCDDs into an organic solvent such as hexane, methylene
chloride, or petroleum ether.
Neutral extraction of fatty tissues, liver, and milk have been reported
in several studies. The procedures begin with homogenization of the tissues
with anhydrous sodium sulfate (Na2S04) in ratios of 1 part tissue to 4-10
parts Na2S04- The resulting dry mixture can then be Soxhlet extracted, packed
into a chromatography column and eluted, or it can be blended directly with
an organic solvent. Ryan et ai. (1980), Albro and Corbett (1977), and Hass
et al. (1978) have blended liver samples directly with chloroform and meth-
anol, then subsequent back extracted with aqueous solutions. O'Keefe et al.
(1978) have used an approach that consists of rendering the fatty sample and
dissolving it in hexane. Shadoff (1980) has reported the used of a cellulose
gauze to absorb the fat content of human milk samples as the first step in
analyzing human milk samples for 2,3,7,8-TCDD. The cellulose gauze with the
adsorbed milk sample was extracted with hexane under refluxing conditions.
An additional neutral extraction procedure has been described by DeRoos et al.
(1982). High pressure liquid carbon dioxide extraction of fish samples
proved to be quantitative for samples (5 g) spiked at 20 to 200 parts per
trillion of 2,3,7,8-TCDD.
The saponification of fatty tissues with alcoholic KOH preceding the ex-
traction of PCDDs from the matrix with an organic solvent evolved from the
early work of Baughman and Meselson (1973). Modifications of this procedure
have been used for preparation of most samples for analysis for 2,3,7,8-TCDD
under the Dioxin Monitoring Program (DMP). The digestion carried out under
the reflux conditions as presented by Baughman and Meselson (1973), however,
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may lead to the destruction of the higher chlorinated homologs of the PCDDs.
Table 5 presents the estimated half-lives (tj) of several PCDD compounds in-
cluding the hexa-, hepta-, and octachloro-hoiflologs, with no sample matrix in
refluxing KOH solution. As indicated on Table 5, the concentrations of the
octa- and heptachlorinated homologs are significantly reduced during the
recommended 1.5- to 2-hr reflux step.
TABLE 5. ESTIMATED HALF-LIVES (t, ) OF SEVERAL DIOXINS IN
REFLUXING KOH SOLUTION3
Dioxin
1,2,3,6,7,8- and 1,2,3,7,8,9-HCDD
1,2,4,6,7,9- and 1,2,3,4,7,8-HCDD
1,2,3,4,6,7,8-HpCDD
1,2,3,4,6,7,9-HpCDD
1,2,3,4,6,7,8,9-OCDD
S
7 hr
2 hr
23 min
16 min
4.5 min
Source: Firestone, D., JAOAC, 60:354-356, 1977.
Report on Oils and Fats
a Ten to 40 ng dioxin refluxed gently with 50 ml 32%
aqueous KOH solution and 20 ml ethanol.
b HCDD = hexachlorodibenzo-£-dioxin; HpCDD = heptachloro-
dibenzo-£-dioxin; OCDD = octachlorodibenzo-£-dioxin.
Lamparski et al. (1978) have studied this effect in somewhat greater de-
tail. Table 6 presents data for the decomposition of hexa- (HCDD) and octa-
chlorodibenzo-£-dioxin (OCDD) based on the effects of KOH concentration, time,
and digestion temperature. These data were generated during a study of the
determination of pentachlorophenol, hexa- and octachlorodibenzo-£-dioxin in
bovine milk. As can be seen from these data, lengthy periods of digestion at
elevated temperatures will drastically reduce HCDD and OCDD concentrations.
To avoid this problem, a less alkaline digestion matrix or shaking at room
temperature rather than refluxing has been used to prepare samples for ex-
traction.
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TABLE 6. EFFECT OF POTASSIUM HYDROXIDE CONCENTRATION, TIME, AND TEMPERATURES
ON POLYCHLORODIBENZO-E-DIOXIN STABILITY
HCDD
Temperature
digestion, °C
22
35
60
80
22
22
Digestion
time , h
24
24
24
24
1
2
Percent KOH
concentration
20
20
20
20
4
4
Initial
concentration,
ppb
1
1
1
1
o.ia
0.1
Percent
decomposition
14
54
72
> 95
10a
10b
OCDD
Initial
concentration ,
ppb
1
1
1
1
o.ia
0.1
Percent
decomposition
44
72
> 95
> 95
10b
10b
Source: Lamparski, L. L., N. H. Mahle, and L. A. Shadoff, "Determination of Pentachlorophenol,
Hexachlorodibenzo-£-dioxin, and Octachlorodibenzo-£-dioxin in Bovine Milk,"
J. Agric. Food Chem.. 26:1113-1116 (1978).
a Lower detection limits are possible because no sample matrix is present.
b These values are reported to one significant figure.
-------
Tiernan and Taylor (1983, personal communication) have provided additional
data reflecting that saponification at elevated temperatures also provided
degradation of OCDD in beef adipose tissue. Aklaline conditions at room tem-
perature (22°C) with shaking (12 hr) provided complete digestion of liver tis-
sue with quantitative recovery of a chlorine-37 labeled OCDD internal standard.
These researchers, however, point out that heating was necessary for complete
digestion of the beef adipose tissue.
Langhorst and Shadoff (1980) and Tosine et al. (1982, 1983) have provided
the only published reports on the use of acid digestion of a biological sample
matrix prior to the determination of PCDDs. Langhorst and Shadoff (1980) re-
ported that 30-g samples of human milk were digested with 200 ml of concen-
trated HC1 prior to solvent extraction. The advantage of the extraction pro-
cedure is that it eliminates the caustic digestion that affects the stability
of the higher chlorinated dioxins. The reported recoveries of stable isotope-
labeled PCDDs from spiked milk homogenates ranged from an average of 36% for
the tetra- to 78% for the hexachlorodibenzo-£-dioxin. Validation data for
reagent blanks were also presented and recoveries varied from an average of
34% for the tetra-, to 85% for the hexa-, to 31% for the octachlorodibenzo-£-
dioxin. However, it is not clear from the data presented what effect the con-
centrated HC1 digestion had on the recovery of these components.
Regardless of the exact extraction procedure employed, the reliability
of the data in most of the studies has been supplemented by the repeated re-
covery of surrogate compounts spiked into the sample prior to extraction.
Typically, carbon-13 or chlorine-37 stable labeled PCDDs were added at con-
centration levels 10 to 100 times higher than the analytical method limit of
detection.
In summary, three methods for the extraction of PCDDs from biological
matrices have been reported, although there has been no study intended to
address the advantages of one procedure over another. Brumley et al. (1981)
have reported on six different extraction and cleanup procedures with one
common instrument analysis approach for final analysis. However, this study
lacks the specificity to identify differences arising from the various extrac-
tion techniques since all sample preparations were completed with different
cleanup steps. Thus, the need remains to evaluate the three extraction pro-
cedures with a common sample source followed by a consistent cleanup procedure
and final analysis.
One possibility for determining the true extraction efficiency of PCDDs
and PCDFs in adipose tissue with any of the three procedures will require the
use of bioincurred radiolabeled compounds. Radiolabeled PCDD and PCDF com-
pounds are used to provide a measurement independent from GC/MS techniques.
This approach to study the extraction mechanism was proposed recently at MRI
during a meeting to discuss approaches to the analysis of human adipose dif-
ferences for PCDDs and PCDFs.
11
-------
CLEANUP
The effective separation of PCDDs from materials coextracted from the
sample matrix has required a combination of efficient cleanup techniques.
The cleanup methods used for isolating PCDDs have been developed by several
analysts. Table 7 is a summary of cleanup procedures used for biological
matrices. The cleanup procedures reviewed include acid and base washes,
liquid-liquid partition, column chromatography with alumina, florisil, silica
gel, chemically modified silica, and carbon impregnated foam. Reverse phase
(RP) and normal high performance liquid chromatography (HPLC) have been used
to remove interferences that are chemically similar to the PCDDs and to im-
prove isomer specificity with the final instrument determination.
A large percentage of the lipid materials in tissue extracts are pre-
sumably sulfonated or saponified with the concentrated sulfuric acid or
strong base washes. These procedures promote the degradation and hydrolysis
of complex molecules including some pesticide residues. Many of the proce-
dures listed in Table 7 used a concentrated sulfuric acid wash. Several of
the methods followed the acid wash with a saponification step using a basic
solution, typically IN KOH. As can be seen from the data presented in Table 6,
there should be little or no adverse effect of the base at this concentration
on the stability of the hexa- through octachlorinated PCDD homologs. Some
samples however have a tendency to form emulsions with a wash procedure.
The decision to use a chemically modified acid or base silica column is
based on the analyst's experience. The advantages of using the impregnated
column materials include less manipulation of samples, reduced exposure to
active glass surface, and greater rate of sample turnover. The emulsion prob-
lem is not encountered with treated columns. However, the eluent flow from
concentrated acid columns may become restricted due to impaction from precipi-
tated or charred coextractives in samples with high concentrations of lipid
and other oxidizable compounds. Langhorst and Shadoff (1980) have overcome
this problem in human milk analyses by using a precolumn with a lower acid
(22%) loading prior to the more concentrated acid (44%) column. The 22% acid
column is a less effective reagent than the 44% acid column but is also less
prone to plugging or reduced flow. The combination of these reagents was re-
ported as quite successful.
Column chromatography following the acid/base extract treatment is used
to separate PCDDs from chlorinated residues such as the organochlorine pesti-
cides and polychlorinated biphenyls (PCBs). Alumina is the most widely used
adsorbent material, as indicated in Table 7. Florisil and silica have been
used in a few specific procedures as a means of separating bulk interferences
preceding final separation with alumina columns. The final column chromatog-
raphy step in many instances was accomplished using micro-columns of alumina
(1.0 g) in disposable Pasteur pipettes. Harless et al. (1980) have used two
such columns in sequence as the final cleanup step.
A 10% silver nitrate impregnated silica column has been used by Lamparski
et al. (1979) preceding the final column for the analysis of fish. The sil-
ver nitrate column is effective for the removal of DDE, chlorinated aliphatic
hydrocarbons, and sulfides. The basic alumina column in this sequence is used
primarily to separate PCBs from the PCDD-containing fraction.
12
-------
TABLE 7. A LISTING OF SOME CLEANUP PROCEDURES
Column chromatography
W3sh
Acid Base
Silica
Acid Base Alumina Florisil gel
Foam RP
charcoal HPLC HPLC
Reference
AgN03
Harless et al. (1980)
Harless et al. (1980)
Mitchum et al. (1980)
Lamparski et al. (1978)
Lamparski et al. (1979)
O'Keefe et al. (1978)
Firestone et al. (1979)
Mahle et al. (1977)
Baughman and Meselson
(1973)
Pbillipson and Puma
(1980)
AgN03
AgNOg
Fanelli et al. (1980)
+ Langhorst and Shadoff
(1980)
Tosine (1981)
Norstrom et al. (1981)
Hummel (1977)
Chess and Gross (19.80)
Buser (1978)
Baughman and Meselson
(1971)
Hummel (1977)
Ryan and Pilon (1980)
Haas et al. (1978)
Haas et al. (1978)
Tiernan et al. (1980)
DiDomenico et al. (1979)
DiDomenico et al. (1979)
TLC
Levin and Nilsson (1977)
Albro and Corbett (1977)
Source:National Research Council of Canada (NRCC), "Polychlorinated Dibenzo-g-dioxins:Limitations
to the Current Analytical Techniques," NRCC No. 18576, 1981, 172 pp.
a + indicates used only as one step of the procedure.
b ++ indicates two separate columns were used.
13
-------
'The separation of PCDDs into fractions containing combinations of the
various isomers prior to final instrumental analyses has been accomplished
using reverse phase (RP) and/or normal HPLC technique. Lamparski et al.
(1979) and Langhorst and Shadoff (1980) have used RP-HPLC cleanup to provide
additional removal of contaminants (e.g., PCBs, DDE, phthalates) and to re-
move components that are very similar to dioxins, such as chlorinated benzyl-
phenyl ethers. Specific fractions of the eluent from the RP-HPLC are collected
for analysis of PCDDs by homolog. This approach is especially significant
for studies that require data on low parts per trillion concentration levels
for tetra- to octa-PCDD homologs. Typically, the low parts per trillion mea-
surements require final concentration of sample extracts to 10-20 (Jl. Instru-
mental analysis for a specific PCDD homolog may consume a major portion of
the extract, presenting difficulties if the need exists to include other PCDD
homologs. The RP-HPLC separation of the sample extract as shown in Figure 1
allows collection of PCDDs by homolog, enabling the measurement of all PCDDs
at low parts per trillion levels. This approach has been demonstrated by
Langhorst and Shadoff (1980) for the analysis of tetra-, hexa-, hepta-, and
octachlorodibenzo-£-dioxins in human milk. Langhorst and Shadoff (1980) have
also used RP and normal silica HPLC for separation and identification of
2,3,7,8-TCDD from the other TCDD isomers in extracts from human milk.
Regardless of the specific cleanup procedure, the analyst must take pre-
cautions to ensure that adsorbents are fully activated and method blanks do
not yield extracts with high backgrounds. Huckins et al. (1976) have reported
on some contaminants and limitations of silica gel for the chromatographic
separation of polychlorinated aromatics and pesticides. The data presented
in this paper implicated the presence of sulfuric acid in silica gel as re-
sponsible for producing contaminants that interfered with the analysis. It
is our experience that sulfuric acid modified silica gels and batch extrac-
tions with concentrated sulfuric acid generate contaminants that appear to
be oxygenated compounds with aliphatic moieties. These artifacts can be re-
moved by base modified silica gel, batch extraction with a base and/or the
use of fully activated basic alumina.
As mentioned earlier, the approach to the determination of PCDDs in bi-
ological matrices is dependent on the experience of the analyst and the as-
sociated laboratory. The actual extraction and cleanup procedures practiced
may differ markedly from one laboratory to another. In view of the variety
of methods in use, a comparison of six different extraction and cleanup pro-
cedures was conducted by Brumley et al. (1981) with respect to the analysis
of 2,3,7,8-TCDD in fish. The relative efficiency of the different methods
was determined based on two criteria: (1) the relative number and amounts of
undesired components present in the final extracts, and (2) the extent to
which these components interfered with TCDD analysis. The objective of the
study was to compare the overall efficiency of the six available analytical
cleanup procedures using a common GC/MS (low resolution) analysis approach.
Six fish samples were submitted to six participating laboratories including
the Bureau of Foods, Food and Drug Administration (BF/FDA), Detroit District/
FDA, Dow Chemical Company, the Environmental Protection Agency (EPA), Fish and
Wildlife Service (FWS), and the New York State (NYS) Department of Health.
The samples were prepared for TCDD analysis according to the procedure routinely
14
-------
?
in
CM
o
o
s
o
i
o
8-
2
u
£
>
CHCI3
Solvent
\
RP-HPLC Collection Zone Calibration Standard
TCDDs
1
2378 l!
~\\
L A
>0
OCDD
= 2
AA
l H7DDs
1 , .
.
HCDDs
I
J^_
1 |
_/v
i
i — • — i
_/v_
,
• i i i ii
CM
O
8
o
Q_
Q
>
24 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44
(Minutes)
RP-HPLC European Fly Ash (Municipal Refuse Incinerator)
OCDD
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44
(Minutes)
Source: Lamparski, L. L., and T. J. Nestrick, "Determination of Tetra-, Hexa-, Hepta-, and Octachloro-
dibenzo-£-dioxin Isomers in Particulate Samples at Parts per Trillion Levels," Anal. Chem.,
_52_, 20A5-205A (1980).
Figure 1. RP-HPLC fractionation chromatograms of (a) calibration standard and (b) European refuse
incineration fly ash demonstrating the application for collection of PCDDs by homolog.
-------
used by each laboratory. All extracts were then analyzed by one laboratory
using gas chromatography/mass spectrometry by selected ion monitoring (GC/MS-SIM),
scanning GC/MS, and GC/ECD (electron capture detector).
This study did not evaluate the overall analytical method used by any of
the participating laboratories. The results of the evaluation of the cleanup
efficiency did not necessarily reflect upon the validity of TCDD analyses per-
formed by the participating laboratories using these combined cleanup and MS
procedures. Figures 2 to 6 are schematic representations of the extraction
and cleanup procedures used by the different participating laboratories.
As part of this study, each laboratory was asked to specify the time and
personnel requirements necessary for sample preparations. Table 8 is a sum-
mary of the resources required to extract and clean up fish samples. As in-
dicated on Table 8, the EPA-neutral procedure and FWS carbon/dual column pro-
cedure provided the most rapid turnaround time. The methods that require the
use of HPLC equipment were more labor intensive.
Figure 7 presents data from representative sample extracts prepared by
the six laboratories, as determined by GC/ECD at the BF/FDA laboratory. The
results indicate that the BF/FDA, Detroit District/FDA, Dow, and FWS sample
preparations provide extracts that are significantly less complex than the
other approaches. Further analysis by BF/FDA of the sample extracts using
low resolution GC/MS-SIM yielded the data presented in Table 9. Twelve ions
were monitored, including eight ions representative of the molecular ion
cluster and the loss of COC1, two ions representative of the internal stan-
dard [13C12] TCDD, and two ions representative of possible interferences
arising from tetrachloromethoxybiphenyl. Analysis of all 12 ion chromatograms
for all six of the participating laboratories indicated that only the NYS,
Dow, and FWS cleanup procedures provided sample extracts with no interference
at the retention time of TCDD. The summary of results (Table 9) obtained by
GC/MS-SIM indicate whether TCDD was confirmed in the sample and quantitation
of observed responses for the appropriate ions.
Based on their findings, Brumley et al. (1981) placed the six extraction-
cleanup procedures into four categories. The Dow and FWS procedures were in
the first category because TCDD was confirmed and quantitated and the ion cur-
rents for the 12 ions monitored indicated that the extracts were free of inter-
ferences. The NYS procedure was placed in a second category since the overall
levels of coextractants appeared to be significant. The FDA and EPA procedures
comprised the third and fourth categories, respectively, because of excessive
amounts of coextractive, greater than 100% recovery of the surrogates, and
interferences appearing for the monitored ions.
16
-------
Ac id/Base Procedure
Neutral Procedure
Alcoholic Potassium
Hydroxide Saponificafion
Hexane Extraction
Acid/Base Washes
Alumina Microcolumn
Fractionation
®CCI4
(2)CH2CI2
Discard
Alumina Microcolumn
Fractionation
®CCI4
©CH2CI2
f
i
Discard
Homogenize with Dry Ice
1
Acetonitrile Extraction
I
Partition with Acetonitrile
Saturated Hexane
I
Florisil Column
CO 10%CH,
(2)25% CH2CI2/Hexane
Discard
1
Alumina Microcolumn
Fractionation
©cc,4
(2)CH2CI2
Discard
Figure 2. Schematic of EPA sample preparation procedures for preparation of
biological matrices for TCDD analyses.
-------
FDA Acid-Base Cleanup
New York State Department of Health
Neutral Cleanup
Alcoholic Potassium
Hydroxide Saponification
i
Hexane Extraction
1
Acid/ Base Washes
t (T) Eth
Neutral Alumina Column 1
Discard
0 20 %CCI4 Hexane (f)CH2CI2
* t
LHScard ..,*.,
Florist 1 Column
(T) 10% CH2CI2/Hexane (5) CH2CI2
* I
Discard HPLC
Zorbax-ODS
*
HRGC/MS
Neutral Extraction
Blend Sample/CH2CI2/No2SO4
*
Filter and Solvent
Exchange to Hexane
1
Magnesia -Celine 545 Column
*
Neutral Alumina
©CCI4 (D
1 ,_
Discard
m
^— *
r
Discard
Florisil Column
(T) Hexane
©CH2CI2
Figure 3. Schematic presentation of the sample preparation schemes used by FDA and laboratories and
the New York State Department of Health in collaborative study of fish sample preparation and
analysis.
-------
PART I EXTRACTION ond ADSORPTION on CARBON
-Solvent
(C6H12/CH2Cl2 1:1 v/v)
(500g 1 :4w/w)
-Potassium Silicate (30g)
-Silica Gel (30g)
-Cesium Silicate (lOg)
-Silica Gel (6g)
Remove acidics and other polar
biogenic compounds that interfere
" with adsorption of PCDDs and
PCDFs on carbon
-Carbon (50mg)
Glass Fibers Mixture
• Selective adsorption of PCDDs
and PCDFs and similar residues
PART II FRACTIONATION of AROMATIC RESIDUES
Cesium Silicate (0.54g) |
I Removal of residual biogenic
[substances
H2SO4/Silica Gel (0.47g)
'Alumina (3.65g) •
•Fractionation of xenobiotic residues
Fraction
Solvent
Compounds
Source:
0-23 ml 0-2%CH2CI2/C0H14 PCBs, PCNs
23-55 mL 5-8% CH2CI2/C6HU PCDDs, PCDFs
Stalling, D. L., J. D. Petty, L. M. Smith, C. Rappe, and H. R.
Buser, "Isolation and analysis or Polychlorinated Furans in
Aquatic Samples," in Chlorinated Dioxins and Related Compounds;
Impact on the Environment, 0. Hutzinger, R. W. Frei, E. Merian,
F. Peschari, Eds., Pergamon Press, 1982.
Figure 4. Flow diagram for enrichment and fractionation of PCDDs and
PCDFs from tissue samples (FWS procedure).
19
-------
Benzene Soxhlet Extraction
Chemically Modified Classical
Adsorbent Chromotogrophy
Classical Adsorbent Chromatography
(TCDD Fractions)
RP-HPLC Fractionation
—(Higher Chlorinated CDDs)
RP-ISO*! TCDDs
10 HCDD Isomers
2 H7CDD Isomers
RP-ISO*2 TCDDs
Silico-HPLC Refractionation
RP-ISO'2/SIL'l
RP-2378/SIL-2378
2378-TCDD
RP-ISO»1/SIL'1
RP-2378/SIL*!
1237-TCDD
1238-TCDD
1247-TCDD
1248-TCDD
RP-ISO'2/SIL*2
RP-ISO')/SI 1*2
RP-2378/SIL*2
1278-TCDD
RP-2378/SIL*3
1246-TCDD
(1249-TCDD)
1236-TCDD
1239-TCDD
RP-2378/SIL*4
(1246-TCDD)
1249-TCDD
Source: Lamparski, L. L., and T. J. Nestrick, "Determination of Tetra-,
Hexa-, Hepta-, and Octachlorodibenzo-£-dioxin Isomers in Par-
ticulate Samples at Parts per Trillion Levels," Anal. Chem.,
52, 2045-2054 (1980).
Figure 5. Schematic for sample preparation for PCDD analysis by the
Dow analytical approach.
20
-------
20mm
20mm
22cm
T
Ocm
9cm
-A
-B
10 mm
9cm
6mm
36cm
-C
•A
•D
•A
Source: Lamparski, L. L., and T. J. Nestrick, "Determination of Tetra-,
Hexa-, Hepta-, and Octachlorodibenzo-p_-dioxin Isomers in Par-
ticulate Samples at Parts per Trillion Levels," Anal. Chem.,
_52, 2045-2054 (1980).
Figure 6. Glass chromatopraphy columns for sample cleanups: A = sil.ica,
B = 22% sulfuric acid on silica, C = 44% sulfuric acid on silica, D =
33% 1 M sodium hydroxide on silica, E = 10% AgN03 on silica, and F =
basic alumina.
21
-------
TABLE 8. RESOURCES REQUIRED TO EXTRACT AND CLEAN UP FISH SAMPLES
Analyst1 s
Cleanup method per set
FDA acid/base HPLC
Dow dual-column/HPLC
EPA-A/B
EPA-Neutral
FWS carbon/dual column
NYS multicolumn
1
2
2
1
1
1
Number Extraction-cleanup
of samples Extraction-cleanup time, h, per sample
per set time, h, per set per analyst
6
4
4
4
6
2
24
16
8
8
20
16
4
8
4
2
3.3
8
Source: Brumley, W. C., J. A. Roach, J. A. Sphon, P. A. Dreifuss, D. Andrzejewski, R. A.
and D. Firestone, "Low-Resolution Multiple Ion Detection Gas Chromatographic-Mass
Spectrometric Comparison of Six Extraction-Cleanup Methods for Determining 2,3,7,
chlorodibenzo-p-dioxin in Fish," J. Agric. Food Chem. , 29:1040-1096 (1981).
Niemann,
8-Tetra-
a Time required for one or two analysts (see second column) to extract and clean up a set of
samples.
-------
16X
12
16 20
Minutes
24 28 32 36
8 12
16 20
Minutes
24 28 32 36
12
16 20
Minutes
24 28 32 36
12
16 20
Minutes
24 28 32
36
12
16 20
Minutes
24 28 32 36
\J
12
16 20
Mi nutes
24 28 32 36
Source:
Brumley, W. CL., J. A. Roach, J. A. Sphon, P. S. Dreifuss,
D. Andrzejewski, R. A. Niemann, and D. Firestone, "Low-
Resolution Multiple Ion Detection Gas Chromatographi-Mass
Spectrometric Comparison of Six Extraction-Cleanup Methods
for Determining 2,3,7,8-Tetrachlorodibenzo-p-dioxin in
Fish," J. Agric. Food Chem., 29, 1040-1046 (1981).
Figure 7. GC/ECD chromatograms of extracts from unfortified catfish
(1/20 of the sample extract). (A) BF/FDA; (B) Det/FDA; (C) Dow;
(D) EPA-A/B; (E) EPA-Neut; (F) FWS; (G) NYS. The arrows indicate
the retention time of 2,3,7,8-TCDD, as determined by GC of a 2,3,7,8-
TCDD standard solution.
23
-------
TABLE 9. SUMMARY OF GC/MS-SIM RESULTS OF STUDY OF TCDD EXTRACTION-CLEANUP
Sample
no.
1
2
3 .
4
5
6
Source:
BF/FDA
conf. quant.
no 5
no 67
no 34
no 188
e e
no 178
DET/FDA
conf. quant.
no 6
no 89
no 42
no 99
no 53
no 199
NYS
conf.
no
yes
yes
yes
yes
yes
quant,
c
77
57
128
38
107
EPA-A/B
conf. quant.
no c
no c
no c
d d
d d
d d
EPA-neut
conf. quant.
no
no
no
no
d
d
c
c
c
c
d
d
Dowb
conf.
no
yes
yes
yes
yes
yes
quant .
c
67
25
113
45
100
FWS
conf.
no
yes
yes
yes
yes
yes
quant.
9
47
22
117
56
96
Brumley, W. C., J. A. Roach, J. A. Sphon, P. A. Dreifuss, D. Andrzejewski, R. A. Niemann, and
D. Firestone, "Low-Resolution Multiple Ion Detection Gas Chromatographic-Mass Spectrometric
Comparison of Six Extraction-Cleanup Methods for Determining 2,3,7 ,8-Tetrachlorodibenzo-p_-
dioxin in Fish," J. Agric. Food Chem. , 29:1040-1046 (1981).
a Confirmation of the identity of TCDD was obtained if the responses of the 12 monitored ions for the sample extract
were consistent with the responses of the 12 monitored ions of the TCDD standard. Quantitation was based on the
observed responses at m/z 322 and -334. Quantitation in nanograms per kilogram.
b Quantitation by the external standard because of the [13C]TCDD carrier.
c No entry in original data presentation.
d Samples were not analyzed due to large amounts of coextractives.
e Some or all of the sample was lost.
-------
INSTRUMENTAL ANALYSIS
The selection of the analytical methodology must take into account a wide
concentration range of PCDDs and the possible interferences in different sam-
ple matrices. Figure 8 illustrates the detection ranges of analytical tech-
niques that have been used for measurement of PCDDs. This figure presents
techniques used in industrial quality control for relatively simple samples
at the higher concentration range. Environmental and biological matrices re-
quire instrumental methods that have lower limits of detection to achieve
parts per billion (nanograms/gram) and parts per trillion (picograms/gram)
measurements. Although gas chromatography with electron capture detection
(GC/ECD) is capable of low level measurements, the technique lacks the neces-
sary specificity to positively identify PCDDs in a sample extract that con-
tains other halogenated hydrocarbons, pesticides, PCBs, phthalates, etc.
Radioimmunoassay (Luster et al., 1980, 1981) and GC/MS-SIM are comparable
with respect to achievable limits of detection. However, radioimmunoassay does
not yield the identification of individual dioxins and has been used primarily
for the screening of a large number of samples for the presence or absence of
PCDDs. Two alternate screening techniques for the presence of PCDDs based on
biological or biochemical properties are the hydrocarbon hydroxylase induction
assay (Bradlaw and Casterline, 1979) and the cytosol receptor assay (Hutzinger
et al., 1981). Since the bioanalytical methods do not provide the specificity
necessary forjidentification of PCDDs, these techniques are not discussed in
detail below. '• For a thorough discussion, see National Research Council of
Canada (1981).!
I
The analytical detection method most frequently reported for the mea-
surement of PCDDs by homolog or by specific isomer in all sample types is gas
chromatography combined with mass spectrometry (GC/MS).
i
Gas Chromatography
i
The final separation of PCDDs from interferences in the sample extract
requires gas chromatography with either packed or capillary columns (HRGC).
The NRCC (1981.) has compiled a listing of column lengths and liquid phases
used for specific and general PCDD analyses.
i
i
Packed Column Gas Chromatography--
Packed column gas chromatography (PGC) has been used primarily for screen-
ing applications to determine the presence of PCDDs and the range of occurring
homologs. Figure 9 is an example of packed column gas chromatographic sepa-
ration of PCDD homologs in an extract from an incinerator fly ash sample
(Liberti et al., 1982). The packed column was a2mxl.5mmID glass column
packed with Supelcoport (100/120 mesh) coated with 1.5% SP-2250 and 1.95%
SP-2401. The PCDDs in the sample extract were identified by high resolution
mass spectrometry. The packed column chromatogram shown in Figure 9 indicates
that tetra- through octachlorodibenzo-£-dioxins were identified in the sample.
25
-------
,
GC/MS
' GC/FID, LC/UV Detection
GC/ECD
GC/MS-SIM (Selected Ion Monitoring)
Radio! mmunoassay
10 pg/mL 100 pg/mL 1 ng/mL 10 ng/mL 100 ng/mL 1 /Ag/mL 15/ig/mL
MO'14 MO'13 MO'12 MO-11 ID'10 10'9 1.5-10'8
Source: Karasek, F. W. , and I. Onuska, "Trace Analysis of the.
Dioxins," Anal. Chem. , _54, 309A-324A (1982).
Figure 8. Range of application of some analytical techniques for dioxins.
The selection- ion monitoring (SIM) mode of GC/MS is the most applicable.
26
-------
2 m Packed Column
1.5% SP-2250/1.95% SP-2401
Supelcoport 100/120 Mesh
Number of Chlorine Atoms
8-
I
20
\
30
\
40
Time (Minutes)
I
50
Source: Liberti, A., P. Ciccioli, E. Brancaleoni, and A. Cecinato, "Determination of Polychlorodibenzo-£-dioxins
and Polychlorodibenzofurans in Environmental Samples by Gas Chromatography-Mass Spectrometry," J. Chrom.,
242, 111-118 (1982).
Figure 9. PGC/MS chromatogram of PCDD homologs extracted from an incinerator fly ash sample.
-------
Packed column gas chromatography columns lack the necessary resolution
for isomer specific separation of PCDDs other than the hepta- and octachloro-
compounds, as indicated in Figure 9. However, Nestrick et al. (1979) have
demonstrated the isomer specific determination of 2,3,7,8-TCDD using a packed
column following the fractionation of a mixture of the 22 possible TCDD iso-
mers by RP-HPLC and normal HPLC, as discussed in the section on cleanup pro-
cedures. The packed GC column used for the specific analysis was a 210 cm x
2 mm ID glass column packed with a 0.6% OV-17/0.4% Poly S-179 on a specially
deactivated Chromosorb W-AW (80/100) support. Lamparski et al. (1979),
Langhorst and Shadoff (1980), and Lamparski and Nestrick (1980) have used this
procedure for the determination of 2,3,7,8-TCDD at spike levels equivalent to
10 ppt in fish, 1 ppt in human milk, and 10 ppt in particulates (fly ash, in-
dustrial dust, urban dust, etc.).
Figure 10 presents packed column gas chromatograms of fractions collected
from the RP-HPLC and silica HPLC procedures allowing the isomer specific mea-
surement of 2,3,7,8-TCDD by low resolution mass spectrometry (Nestrick and
Lamparski, 1980). Quantitation of the peak corresponding to the RP-HPLC frac-
tion for 2,3,7,8-TCDD yielded a value that was approximately four times the
concentration found after the extract had been fractionated further with the
silica HPLC system. The value obtained before the silica HPLC fractionation
was qualified as being the concentration of 2,3,7,8-TCDD plus possibly four
unseparated isomers. This demonstrates that PGC can be used for isomer speci-
fic PCDD analysis if extended efforts are made to isolate the desired component
prior to gas chromatographic separation.
High Resolution Capillary Chromatography--
The current approach in many analyses for PCDDs by homolog or for spe-
cific isomers is the application of high resolution capillary gas chromatog-
raphy (HRGC) (either glass or fused silica columns). High resolution glass
capillary columns were first used by Buser (1975) for the analysis of PCDDs
and PCDFs in chlorinated phenols. Since that time numerous studies have re-
ported qualitative identification and quantitation of PCDDs using HRGC columns
for separation. Liquid phases for the HRGC columns have ranged from low (SE-30,
OV-17, OV-101) to high polarity phases (Silar IOC, SP-2330, SP-2340), and col-
umn lengths have ranged from 18 m for general analysis of PCDD to 60 m for
isomer specific measurements. Figure 11 is a chromatogram depicting the elu-
tion of tetra- to octa- PCDDs on a HRGC column.
Isomer specific measurements have been of prime importance in most stud-
ies (both environmental and biological), particularly for 2,3,7,8-TCDD. Fig-
ures 12 and 13 present chromatograms of the mixture of the 22 possible TCDD
isomers yielding the isomer specific separation for 2,3,7,8-TCDD. Buser (1980)
used the three liquid phases (Figure 12) Silar IOC, OV-17, and OV-101 to deter-
mine specific assignments for the 22 isomers. Figure 13 presents the separation
of TCDDs on a glass column coated with SP-2330 and a fused silica column coated
with SP-2340 that is currently recommended for 2,3,7,8-TCDD specific analyses
(EPA, 1982, 1983). In addition to these columns, Harless (1980) has reported
isomer specific determination with a 30-m SE-30 column, and the current EPA
method for the determination of 2,3,7,8-TCDD in soils and sediments implies
that 30-m Durabond DB-5 fused silica columns provide sufficient separation
for specific 2,3,7,8-TCDD measurements.
28
-------
(a)
13C-2378-TCDD
(b)
c
o
m/e 332
native TCDDs
m/e 324
m,
i/e 322
m/e 320
(Minutes) 3
c
jl)
1:
c
o
(Minutes) 3
13C-2378-TCDD
m/e 332
native 2378-TCDD
m/e 324
m/e 322
m.
i/e 320
I
5
•
6
Source: Lamparski, L. L., and T. J. Nestrick, "Determination of Tetra-,
Hexa-, Hepta-, and Octachlorodibenzo-p_-dioxin Isomers in Par-
ticulate Samples at Parts per Trillion Levels," Anal. Chem.,
52., 2045-2054 (1980).
Figure 10. Comparative 2,3,7,8-TCDD PGC/MS mass chromatograms for
electrostatic fly ash (a) after RP-HPLC and (b) subsequent silica-
HPLC.
29
-------
Peok No. PCDD Congener
CO
O
1
2
3
ML
1 ,3,6.8-leiro-CDD 15 .2.4,6.7,9- (or 1 .2.4.6,7,9- )hexo-CDD
2 ,3.7,9- 16 .2,3.4.6.8-
3 ,3.7.8- 17 ,2,3,6.8.9- (or 1,2.3.6.7.9-)
4 .3,6.7- 18 .2.3,4,7,8-
5 ,3.7.8- 19 .2.3,6,7.8-
6 .3.8.9- 20 .2.3.7,8.9-
7 ,2,7.8- 21 .2.3.4.6,7-
8 ,2.4.6.8- (or 1.2. 4,7.9- )pento-CDD 22 .2.3.4,6.7-rieplo-CDD
9 .2.3.6.8- 23 .2,3,4,6,7,8-
10 .2,4.7.8- 24 ocio-CDD
II .2,3.7.9-
12 ,2.3.7.8-
13 ,2.3.6,7-
14 ,2,3.8.9-
8
9
10 "
|12
JljAXlX
15 + 16
u
17
22
1 23
1
\\ \ 1 1
J V-Jv-Aili^^ \_JV_I __Jv-
tetra-
pento-
- CDDs
T
—T~
200
~~T~
210
~T~
220
230
—r~
240
Source: Lustenhower, T. W. A., K. Olie, and 0. Hutzinger, "Chlorinated Dibenzo-p-dioxins and
Related Compounds in Incinerated Effluents," Chemosphere, J9, 501-522 (1980).
Figure 11. Separation of PCDD-isomers by GC/MS using a high resolution capillary column. .
-------
55M SIIAR I0c
50M OV-i;
50M OV-IOI
1237/1238 I 1246/1249
220 °C
2IO°C
Source: Buser, H. R. , and C. Rappe, "High Resolution Chromatography of the 22 Tetrachlorodibenzo-_p_-dioxin
Isomers," Anal. Chem., 52, 2257-2262 (1980).
Figure 12. Mass chromatograms (m/e 320) of a composite pyrolyzate sample showing elution of all 22
TCDD isomers on HRGC columns.
-------
SP-2330 Gloss Column
u
VJ
11
12
13
14
Mi nutes
15
16
17
SP-2340 Fused Silica Column
12
13
14 15
Minutes
16
17
18
Source: "Rapid Separation of 2,3,7,8-TCDD from Other TCDD Isomers,"
The Supelco Reporter,.1(4), 1 (1982).
Figure 13. HRGC chromatogram of a mixture of the 22 TCDD isomers on
glass and fused silica capillary columns (60 m) coated with SP-2330
and SP-2340, respectively, indicating isomer specific separation
for 2,3,7,8-TCDD. 32
-------
The advantages of using HRGC columns over PGC columns include increased
isomer specificity, resolution of interferences from analytes of interest,
and increased sensitivity due to less band spreading. Fused silica HRGC
columns allow the direct routing of the column into the ion source of the
mass spectrometer, a procedure which leads to fewer problems resulting from
dead volumes and to greater sensitivity. The major disadvantage of HRGC col-
umns is the ease of overloading by coextractives. This problem has been
overcome in most cases, however, by using effective and efficient cleanup pro-
cedures prior to HRGC separation of the sample extract.
Gaps in PGC and HRGC Information--
A major deficiency in the area of PGC and HRGC separation is the lack of
information regarding the retention times of common interferences with respect
to the PCDDs. This information would indicate whether polychlorinated bi-
phenyls (PCBs), the common pesticides (e.g., DDE and DDT), polychloromethoxy-
biphenyls, or polychlorobenzylphenyl ethers actually elute within the reten-
tion windows required for the measurement of the PCDDs. This problem has
been partially addressed by Hummel (1977), who considered possible interfer-
ences from pesticides and PCBs for the analysis of TCDD. Table 10 provides
some of the information for relative retention times and responses for the
ions characteristic of 2,3,7,8-TCDD.
Mass Spectrometry
The application of mass spectrometry for the analysis of PCDDs in bio-
logical matrices, commercial products, and environmental samples has been re-
viewed by Hass and Friesen (1979), Cairns et al. (1980), the National Research
Council of Canada (1981), Mahle and Shadoff (1982), and Tiernan (1983). Mass
spectrometry measurements have been reported for quadrupole (low resolution)
and magnetic sector ,(high resolution) instruments. Electron impact is the
most common method of ionization but chemical ionization mass spectrometry
techniques have also been reported as a means of confirmation of the identity
of PCDDs.
As indicated in Figure 8, MS-SIM techniques are required to obtain the
necessary sensitivity for measurement of PCDDs at the parts per trillion con-
centration range required for biological matrices. The sensitivity of the
SIM method is enhanced as a result of making multiple measurements of a few
selected ions characteristic of the PCDDs rather than scanning an entire
molecular range in the same time frame.
Most of the analytical studies reported in the literature have focused
on the measurement of TCDDs. Langhorst and Shadoff (1980) have reported an-
alytical methods for the analysis of tetra-, hexa-, hepta-, and octachlorodi-
benzo-j>-dioxins in human milk based on the RP-HPLC fractionation scheme com-
bined with PGC/MS. The alternative to this approach is computer-sequenced
analysis of each PCDD homolog in a single analysis. Tiernan (1983) and
Liberti et al. (1982) have emphasized the application of this procedure to
provide data at the parts per trillion level for a wide range of PCDD homologs.
33
-------
TABLE 10. RESPONSE FROM POSSIBLE ENVIRONMENTAL CONTAMINANTS
Compound
Chlordane
£,£' -DDE
p,p* -DDD
£,£'-DDT
Dieldrin
Endrin
Endosulfan
Mi rex
PCBs
Aroclor 1242
Aroclor 1254
Aroclor 1260
Toxaphene
Retention time
difference
from 2,3,7,8-TCDD (sec)
-251, -194, -184
-158
-83
-16
-155
-120
-96
+257
-35
+15
+85
+187
-85
-38
+9
+57
2,3,7,8-TCDD ^
equivalent peak
3 m/e 320
NDd
1
0.07
0.01
0.005
0.060
0.0002
0.00028
ND
ND
0.001
0.001
ND
0.0005
0.000002
0.00001
0.00005
0.000005
height
m/e 322
ND
0.2
0.03
0.003
0.003
0.024
0.0009
0.00022
ND
ND
0.020
0.015
0.032
0.008
0.000002
0.00001
0.000005
ND
Source: R. A. Hummel, "Cleanup Techniques
Trillion
Residue Levels of 2,3,7,
for the Determination of Parts per
8-TCDD," J. Agric. Food
Chem . ,
25:1049-1053 (1977).
a 2,3,7,8-TCDD retention time 390 sec. Peak width at half-height = 30 sec.
b The ratio of response of the compound at its retention time to the response
of an equal weight of 2,3,7,8-TCDD measured at 390 sec.
c Only those peaks near 2,3,7,8-TCDD are listed.
d ND = not detected; no peaks were detected at m/e 320 or 322.
34
-------
Low Resolution versus High Resolution Mass Spectrometry—
One of the major points of contention in the analyses of low level (ppt)
PCDDs is the necessity of low resolution (M/AM = unit) versus high resolution
(M/AM = 10,000) mass spectrometry measurements. Many of the methods rely on
efficient cleanup steps prior to low resolution mass spectrometry to provide
low level backgrounds. Other methods, however, utilize the mass resolving
power of single or double focusing mass spectrometers to identify and quanti-
tate low level PCDDs in the presence of other chlorinated compounds (Harless
et al., 1980). The need for high resolution mass spectrometry for various
extraction and cleanup procedures has been demonstrated by Bruinley et al.
(1981) via the interference noted for electron capture detector and low reso-
lution mass spectrometry measurements for extracts prepared by six different
laboratories.
Hummel and Shadoff (1980) have directed attention to the need for high
resolution confirmation of TCDDs in sample extracts, especially when the con-
centration approaches values of 20 ppt or less as measured by low resolution
mass spectrometry. Table 11 provides data presented by Hummel and Shadoff
(1980) for the levels of TCDD in beef fat samples analyzed for Phase I of the
EPA Dioxin Implementation Plan. The data presented in this table indicate
that of 93 total samples analyzed by low resolution mass spectrometry 37 were
determined to contain TCDD. Further analyses of these positives by high reso-
lution mass spectrometry yielded that only 20 of the 37 samples contained TCDD.
The two control samples identified as positive by high resolution mass spec-
trometry present the additional problem of false positives for measurements
near the detection limit. Additional studies of the extracts after a second
cleanup also presented the possibility of false negatives by high resolution
mass spectrometry when sample extracts are dirty. Shadoff and Hummel (1980)
concluded that analysis by low resolution mass spectrometry is acceptable if
suitable control samples demonstrate the absence of interferences. Otherwise,
high resolution mass spectrometry should be used for confirming positive re-
sults.
Interferences—
Some of the compounds identified as interferences in the analysis of
TCDDs by mass spectrometry are presented in Table 12. The alternate methods
of resolution are the approaches that have been specifically addressed in the
literature. The separation of PCBs, polychlorodiphenyl ethers and poly-
chlorobenzyl phenyl ethers has been reported by Mieure et al. (1977) and
Lamparski et al. (1979).
35
-------
TABLE 11. EPA PHASE I DIOXIN IMPLEMENTATION PLAN
BEEF FAT SAMPLES ANALYZED FOR TCDD
Sample
Grazed on treated land
Control
Fortified extracts and
solutions
No. of samples
analyzed by
PGC/LRMS
64
20
9
No. of apparent
positive results by
PGC/LRMS
19
9
9
PGC/HRMSa
9
2
9
Source: R. A. Hummel and L. A. Shadoff, "Specificity of Low Resolution
Gas Chromatography-Low Resolution Mass Spectrometry for the
Detection of Tetrachlorodibenzo-p_-dioxin in Environmental Samples,"
Anal. Chem., 52:191-192 (1980).
a In this part of the study, only those extracts showing an apparent
positive result or a limit of detection greater than 20 ppt were
analyzed by PGC/HRMS.
b The fortification level was 20 to 100 ppt TCDD in the beef fat.
36
-------
TABLE 12. SOME COMPOUNDS THAT MAY INTERFERE WITH THE DETERMINATION OF TCDD
AT tn/2 VALUES OF 319.8966 AND 321.8936
LO
Compound
Heptachloro-
biphenyl
Nonachloro-
biphenyl
Tetrachloro-
methoxy
biphenyl
Tetrachloro-
benzylphenyl
ether
Pentachloro-
benzylphenyl
ether
DDT
DDE
Elemental
composition Ion
C12H3
C12H
C12H
cl3Hs
C13H8
aa
35C17 M+
35C19 M*
35C18 37C1 M
35C140 M*
35C13 37C10 M
35CL40 M*
35C13 37C10 M
C13H7 35C14 37C10 M*
C13H7 35C13 M
37C120
C14H9
C14H9
C14H8
35pi 37p-i M+
Ll3 L12 "j_
35C12 37C13 M
35C12 37C12 M*
35C1 37C13 M
Mass lost m/z
-235C1
-435C1
-335C1
37C1
-H35C1
-H35C1
-H35C1
-H35C1
321
319
321
319
321
319
321
319
321
319
321
319
321
.8678
.8521
.8491
.9329
.9299
.9329
.9300
.9143
.91138
.9321
.92917
.9321
.92916
AM
TCDD
0
0
0
0
0
0
0
0
0
0
0
0
0
.0258
.0445
.0445
.0363
.0364
.0363
.0364
.01773
.01778
.03552
.03557
.03550
.03556
Mass
resolution
for
separation Alternate means
M/AM of resolution
12476
7189
7233
8805
8848
8813
8843
18043
18104
9006
9050
9011
9052
Alumina micro
column, HPLC, HRGC
Alumina micro
column, HPLC, HRGC
AgN03 (10%)
impregnated silica,
alumina, HPLC
Alumina micro
column, HPLC, HRGC
Alumina micro
column, HPLC, HRGC
Alcoholic saponi-
fication converts
DDT to DDE
AgN03 (10%)
impregnated silica
(continued)
-------
TABLE 12 (continued)
oo
Compound
Hydroxy-
tetrachloro-
dibenzofuran
Tetrachloro-
phenylbenzo-
quinone
Tetrachloro-
xanthene
Elemental
composition Ion
C12H4C1402 M+
C12H4C1402 M+
C13H60 35C13 37C1 M*
C13H60 35C12 M
§7C12
Mass lost m/z
319.8966
321.8936
319.8966
321.8936
319.9143
321.9114
AM
TCDD
0.00
0.00
0.00
0.00
0.01773
0.01778
Mass
resolution
for
separation Alternate means
M/AM of resolution
a NRb
a
a NR
a
18043 NR
18104
Source: Adapted from National Research Council of Canada, "Polychlorinated Dibenzo-j>-dioxins:
Limitations to the Current Analytical Techniques," NRCC Report No. 18576, ISSN 0316-0114,
1981.
a Cannot be resolved by MS.
b NR = not reported specifically in the literature.
-------
Mieure et al. (1977) specifically reported that PCBs and polychlorobenzyl-
phenyl ethers are separated from PCDDs on a microalumina column (basic, super
grade 1). Figure 14 is an example of separation of chlorinated interferences
using the microalumina column. The first chromatogram is representative of
the total nonphenolic fraction from technical grade pentachlorophenol obtained
after removing the phenolic components with a macroalumina column (Fisher A-540,
5% deactivated). The second chromatogram is the first fraction from the micro-
alumina column and contains the polychlorodiphenyl ethers (hexa- to decachloro),
chlorobenzenes, and PCBs. The third chromatogram represents the second fraction
collected from the microalumina column that contains PCDDs and PCDFs (hexa-
to octachloro). It is concluded from these chromatograms that the octachloro-
dibenzo-£-dioxin and octachlorodibenzofuran can be measured without possible
interferences from the other chlorinated compounds. However, the micro column
cleanup is necessary to isolate the lower chlorinated homologs of the PCDDs
and PCDFs for specific analysis.
Chlorinated methoxybiphenyls were reported as interferences in the analysis
of PCDDs in fish extracts by Phillipson and Puma (1980). These compounds eluted
in the retention window for tri- to pentachlorodioxins by PGC/ low resolution
mass spectrometry and produced intense molecular ions having the same nominal
masses and chlorine isotopic abundances as those observed for the PCDDs. These
authors suggested the need for monitoring fragment ions in addition to ions
representative of the molecular ion cluster for low resolution mass spectrometry.
Alternately, high resolution mass spectrometry may be used as presented in
Table 12 to differentiate the PCDDs from interfering chlorinated methoxybi-
phenyls. This interference might also be removed by the cleanup procedures
as described by Nestrick et al. (1980).
Smith and Johnson (in press) have presented detailed information on the
potential of interferences to arise from selected congeners of seven families
of polychlorinated aromatic compounds with the analytical method for part-per-
trillion determinations of PCDFs and PCDDs used by the Fish and Wildlife Ser-
vice (Stalling et al. 1982). The polychlorinated aromatic compounds evaluated
as potential interferences included polychlorinated-biphenyls (PCBs),
-naphthalenes (PCNs), -diphenyl ethers (DPEs), methoxy-PCBs (MeO-PCB),
-hydroxy-PCBs (HO-PCB), -methoxy-diphenyl ethers (MeO-DPE), -hydroxy-diphenyl
ethers (HO-DPE), -benzylphenyl ethers (BzPE) and -biphenylenes. The potential
interferences from these compounds arise from the large number of congeners
of each chemical family exhibiting chromatographic retention times that are
similar to PCDDs and PCDFs and from mass spectral patterns that overlap to
varying degrees with PCDDs and PCDFs. In addition, some of these potential
interferences have the same nimonal masses and the same number of chlorine
substituents as those of PCDDs and PCDFs, making the molecular ions indis-
tinguishable by low resolution mass spectrometry. Also, at least five of the
chemical families include compounds that under thermal conversions and/or con-
version following ionization produce PCDDs and PCDFs. Table 13 presents
the potentially interfereing chemical according to the degree of potential
interference that can be encountered.
Smith and Johnson (in press) concluded that the specific polychlorinated
aromatic compounds used in this study did not produce a significant number of
false positives with the particular analytical procedure. However, these
authors do note that only a few of the large number of potential compounds
were available for this study.
39
-------
a ) Total Non-Phenolic
Fraction
o
o
&
£
3
a.
o
U
b) Diphenyl Ether
Fraction
c) PCDD/PCDF
Fraction
Time (Minutes)
Source: Mieure, J. P., 0. Hicks, R. G. Kaley, and P. R. Michael,
"Determination of Trace Amounts of Chlorodibenzo-p_-dioxins
and Chlorodibenzofurans in Technical Grade Pentachlorophenol,"
J. Chrom. Sci., _15, 275-277 (1977).
Figure 14. Electron capture chromatograms of (a) entire nonphenolic
fraction, (b) first microcolumn fraction containing chlorodiphenyl
ethers, (c) second basic alumina microcolumn fraction containing
chlorodibenzo-p_-dioxins and Chlorodibenzofurans.
40
-------
TABLE 13. INTERFERENCES OF SELECTED CHEMICAL FAMILIES IN
MS DETERMINATIONS OF PCDFs AND PCDDs
Level of interference
Family of
polychlorinated
compounds
Overlap of
fragmentation
patterns
Indistinguishable
by LRMS
Indistinguishable
by HRMS
PCDDs
PCDFs
PCDDs
PCDFs
PCDDs
PCDFs
PCBs ++/+++
PCNs +
DPEs ++/+++
MeO-PCBs +++ +++
HO-PCBs +++
MeO-DPEs +++ ++
HO-DPEs +++
BzPEs +++
Biphenylenes ++
X X
XX X
X X
X X
X X
X
Source: L. M. Smith and J. L. Johnson,
"Evaluation of Interferences from
Seven Series of Polychlorinated Aromatic Compounds in an Analytical
Method for Polychlorinated Dibenzofurans and Dioxins in Environmen-
tal Samples," in Chlorinated Dioxins and Dibenzofurans in the Total
Environment, L. H. Keith, G. Choudry, and C. Rappe (Eds.), Pergamon
Press, in press.
NOTE: In the first two columns "+" indicates minor overlap, "++" indicates
major overlpa, and "+++" indicates complete overlap.
In the last four columns, an "X" indicates that a particular type of
interference is observed.
The abbreviations used for polychlorinated compounds are:
PCBs-biphenyls; DPE-diphenyl ethers; PCNs-naththalenes/ BzPEs-benzylphenyl
ethers. The prefixes Meo- designate methoxy and HO- hydroxy.
41
-------
In summary, a number of chlorinated compounds have been noted to inter-
fere with the mass spectrometry analysis of PCDDs, particularly 2,3,7,8-TCDD.
The problems arising from these interferences have been overcome in part by
using efficient cleanup procedures or high resolution mass spectrometry, or a
combination of the two.
Criteria for Positive Identification of PCDDs—
Positive identification of PCDDs as a particular homolog or specific
isomer requires the analyst to ensure that the instrumental response meets
specific criteria. Most analysts to date have used the coincident response
of a minimum of three different ions from the molecular ion cluster (M ,
[M-2] , [M+2] ) and from fragment ions (e.g., [M-COC1] ). The retention time
of the selected ions must fall within a designated or established retention
window. In addition the selected ions must have the correct response ratios.
Figure 15 is an example of a KRGC/MS-SIM analysis for 2,3,7,8-TCDD demonstrat-
ing these criteria. The ion at m/z 257 is representative of the fragment ion
[M-COC1] , while m/z 320 and 322 are indicative of the molecular ion cluster
for TCDD. Isomer specific measurement of the 2,3,7,8-TCDD was accomplished
with the SP-2330 glass column discussed earlier. Documentation of the 2,3,7,8-
TCDD retention time is represented by m/z 332 for the carbon-13 labeled 2,3,7,8-
TCDD.
Harless et al. (1980) have specifically designated the following criteria
as essential to the final analysis for TCDD by HRGC/HRMS.
1. Correct HRGC-HRMS retention time for 2,3,7,8-TCDD.
2. Correct HRGC-HRMS multiple ion response for 37C1-TCDD and TCDD
masses (simultaneous response for elemental composition of m/z
320, m/z 322, m/z 328).
3. Correct chlorine isotope ratio for the molecular ions (ra/z 320
and m/z 322).
4. Correct responses for the co-injection of sample fortified with
37C1-TCDD and TCDD standard.
5. Response of the m/z 320 and m/z 322 must be greater than 2.5 times
the noise level.
Supplemental criteria that Harless et al. (1980) suggested may be ap-
plied to highly contaminated sample extracts are:
(A) COC1 loss indicative of TCDD structure, and
(B) HRGC-HRMS peak matching analysis of m/z 320 and m/z 322 in real
time to confirm the TCDD elemental composition.
Other supplemental information for confirmation of TCDD in particular
can be obtained from the partial scan of the TCDD peak (Table 14) when present
at parts per billion concentrations (EPA, 1983). Table 15 provides a range
of reported relative abundances for the most intense ion in the isotopes
clusters.
42
-------
SCANS 758 TO 875
320 _
160.8-1
322 _
TCDD
754 765
38.6-1 '
332 _
17i44
780
18:12
800
18i40
824 831 836842 849 854 860 - 869
108288
257.07"
± 0.501
248576
320.031
± 0.50)
297472
322.091
* 0.501
822 832 837
847
863. 872
820
19:68
840
19i36
114816
332.09:
* 0.50)
SCAN
TIME
Source: MRI RC-693-A, "Analytical Chemistry Application of Isotopically Labeled Compounds, 1982.
Figure 15. HRGC/MS-SIM chromatogram of TCDD analysis. Mass charge (m/z) ratios 257, 320, and 322
are representative of natural abundance TCDD isomers, while m/z 322 represents the level of 13C-
labeled 2,3,7,8-TCDD internal standard. This chromatogram was obtained on a 60-m SP-2330 glass
capillary column. Fifty picograms of the 13C-TCDD were injected.
-------
TABLE 14. PARTIAL SCAN CONFIRMATION FOR TCDD3
m/z Ratios Response ratios
320/324 1.58 ± 0.16
257/259 1.03 ± 0.10
194/196 1.54 ± 0.15
Source: "Determination of 2,3,7,8-TCDD in Soil and
Sediment," U.S. Environmental Protection Agency,
Region VII, Kansas City, Kansas, February 1983.
a All ions including 160 and 161 must be presented with
at least 5% relative abundance to the ion at 322.
44
-------
TABLE 15. RANGE OF REPORTED PERCENT RELATIVE ABUNDANCES FOR MOST INTENSE ION IN
ISOTOPE CLUSTERS FROM ELECTRON IMPACT MASS SPECTRA OF THE CHLORINATED
DIBENZO-E-DIOXINS
Ion
[M] +
[M-C1]+
[M-COC1]+
[M-2C1]+
[M-C202C1]+
[M-C202C12]+
1
100
2
14
0
9
0
2
100
5-7
20-24
0-3
0-3
13-18
3
100
5
24-36
1
2
10-23
Number of
4
100
0-10
21-60
0-5
0
13-55
chlorines
5
100
20
40
15
5
35
6
100
7-10
31-34
4-6
0
17-21
7
100
5-15
28-35
0-4
0-3
3-25
8
100
3-10
11-35
2-5
1-5
10-25
Source: Mahle, N. H. , and L. A. Shadoff, "The Mass Spectrometry of Chlorinated Dibenzo-j)-dioxins,"
Biomedical Mass Spectrometry, 9:45-60 (1982).
-------
Quantitation
Several variables have been reported for quantitation of PCDDs by mass
spectrometry methods. These variables include electron impact versus chem-
ical ionization mass spectrometry, selection and availability of standard com-
pounds, and internal versus external standard calibration.
Electron Impact Versus Chemical Ionization Mass Spectrometry--
Although chemical ionization mass spectrometry, especially the negative
chemical ionization mode, has the potential to enhance specificity and sensi-
tivity for individual isomers (Hass et al., 1978; Mitchum et al., 1981; Rappe
et al.), electron impact ionization has been used most often for quantitative
analysis of PCDDs. The inconsistencies of response factors across a homolog
of PCDDs noted with negative chemical ionization (NCI) mass spectrometry (Kuehl
and Dougherty, 1980) and the scarcity of all the specific standard PCDDs are
disadvantages to its use for routine analysis of PCDDs. Kuehl and Dougherty
(1980) have reported that the relative sensitivity for 2,3,7,8-TCDD is roughly
a factor of 50 less than that for other TCDD isomers or higher chlorinated
dioxins. However, specific analysis for 2,3,7,8-TCDD has been reported for
NCI methods (Hass et al., 1978). Hass et al. (1981) have also suggested that
both negative chemical ionization and electron impact ionization are necessary
to provide reliable measurements for PCDDs and PCDFs in the presence of PCBs
and polychlorinated diphenyl ethers.
Selection of Calibration Standards—
There is concern regarding the need for standard compounds representing
each homolog to provide appropriate assessment of the possible effects aris-
ing from trace levels of PCDDs in biological samples. Nestrick et al. (1982)
addressed this problem as a systematic error that affects accuracy and relia-
bility in the analysis of environmental samples for PCDDs. The source of er-
ror originated by assuming that the response factors for penta- through octa-
chloro PCDDs were consistent with the response factor for TCDD.
Table 16 provides response factors of several PCDDs relative to 1,2,3,4-
TCDD at the molecular ion (m/z) 322. These data illustrate the possible mar-
gin of quantitative error that could be introduced by the assumption of a con-
stant response factor for all PCDD homologs. The data from Table 16 indicate
differences of approximately 3 to 1 when comparing the response of 1,2,3,4-TCDD
to the response for octachlorodibenzo-p_-dioxin (OCDD).
Nestrick et al. (1982) also demonstrated the differences in response fac-
tors that arise when working with PGC/MS systems that rely on silicone membrane
separators and jet separators for introduction of the PCDDs to the ion source
of the mass spectrometer. Table 17 summarizes the data and indicates a sig-
nificant difference for the response factors of hepta- and octa-PCDDs measured
with a quadrupole mass spectrometer equipped with silicone membrane or jet
separators.
46
-------
TABLE 16. AREA RESPONSE FACTORS OF PCDDs RELATIVE
TO 1,2,3,4-TCDD AT m/z 322a
Component
1,2,3,4-TCDD
2,3,7,8-TCDD
1,2,3,7,8-PCDD
HCDD mixture
1,2,3,4,6,7,8-HpCDD
OCDD
m/z
322
322
356
390
426
460
Rel response
(± rel std dev)
1.00 ± 0.03
0.89 ± 0.03
0.52 ± 0.02
0.44 ± 0.02
0.46 ± 0.01
0.32 ± 0.01
No. of
replicates
5
5
2
4
3
3
Source: Nestrick, T. J., L. L. Lamparski, W. B. Crummett, and L. A.
Shadoff, "Comments on Variations in Concentrations of Organic
Compounds Including Polychlorinatd Dibenzo-£-dioxins and
Polynuclear Aromatic Hydrocarbons in Fly Ash from a Municipal
Incinerator," Anal. Chem., 54:824-825 (1982).
a One hundred picograms of each component injected.
TABLE 17. COMPARISON OF RELATIVE PEAK RATIOS OF PCDDs THROUGH A
GLASS JET AND SILICONE MEMBRANE SEPARATOR3
Component
1,2,3,6,7,8-HCDD membrane
jet
1,2,3,4,6,7,8-HpCDD membrane
jet
OCDD membrane
jet
Rel response
(± rel std dev)
1.00
1.00
0.34 ± 0.04
0.63 ± 0.10
0.21 ± 0.05
0.38 ± 0.04
No. of
replicates
7
4
7
4
7
4
Source: Nestrick, T. J., L. L. Lamparski, W. B. Crummett, and L. A.
Shadoff, "Comments on Variations in Concentrations of Organic
Compounds Including Polychlorinatd Dibenzo-p_-dioxins and
Polynuclear Aromatic Hydrocarbons in Fly Ash From a Municipal
Incinerator," Anal. Chem., 54:824-825 (1982).
a All values normalized to HCDD response.
47
-------
Data summarizing the response factors for PCDDs by homolog or by isomer
by electron impact ionization versus chemical ionization mass spectrometry do
not appear in the primary literature. There is a need to determine the vari-
ability of the response factors for isomers within a homolog in order to eval-
uate the maximum systematic error that might be encountered in using a response
factor for a single isomer within a homolog.
Rappe et al. (in press) have recently reported some response factor data
for PCDFs using electron impact and negative chemical ionization mass spectrom-
etry. The data presented indicated the relative response factors for 13 TCDFs
varied considerably less with electron impact than with negative chemical ioni-
zation. The range of response factors however, was not markedly different
for higher chlorinated PCDFs when comparing the two ionization techniques,
although the negative chemical ionization absolute response is considerably
greater.
Internal Versus External Standard Quantitation--
Quantitation for PCDDs requires calibration of the instrument with stan-
dards bracketing the expected concentration range of any sample extracts.
The internal standard quantitation method has been used by most analysts for
measurement of the levels of PCDDs in biological and environmental matrices.
This method requires response factors be determined for the internal standard
versus an authentic analyte. Typically, the stable isotope labeled compounds,
such as carbon-13 or chlorine-37 analogs of native PCDDs, are incorporated in
calibration solutions and samples as internal standards. The level of the
labeled internal standard is usually held constant and the native PCDD is
varied for calibration purposes. If response factors are determined to re-
main constant over the expected concentration range, the true internal stan-
dard quantiation method is applicable for calculation of the PCDD concentra-
tion.
On the other hand, if the response factor is not consistent across the
calibration range, it becomes necessary to use external standards and cali-
bration curves routinely for measurements of PCDD contamination. The EPA
methods for analysis of 2,3,7,8-TCDD in water and wastewater (EPA, 1982) and
soil and sediment (EPA, 1983) require measurement of the response factors over
a designated concentration range at the initiation of any sample analysis event
and the daily check of the response factor value. If the response factor does
not agree within ± 10% of the value generated for the concentration range, a
recalibration is necessary.
True internal standard quantitation provides a correction of the reported
value without a true measure of the recovery for each analysis. Recovery can
be estimated by comparing the response of the labeled compound in a sample
extract versus an external standard. More accurate measurements of method
recovery are achieved by using a second internal standard added to the sample
extract immediately before GC/MS analyses. For instance, carbon-13 (13Cj2)
labeled 2,3,7,8-TCDD can be added as a surrogate prior to sample preparation
to provide true internal standard quantitation for native TCDD and chlorine-37
(37C14) labeled 2,3,7,8-TCDD can be added to the sample extract prior to GC/MS
analyses to provide accurate recovery measurement of the carbon-13 TCDD.
48
-------
The true internal standard quantitation is accomplished using the fol
lowing equation:
C = (As) (I )/(AT_)(RF)(W)
A 5 AD
where C = concentration of the PCDD in the original sample
As = peak area response for the PCDD quantitation ion
A,,, = peak area response for the internal standard quantitation ion
I_ = amount of internal standard added to the sample
b
W = weight or volume of the sample
RF = response factor
The response factor (RF) is calculated according to the equation
where A , = peak area response for the standard PCDD quantitation ion
S UQ
ATO = peak area response for the internal standard quantitation ion
la
C . , = concentration of the standard PCDD
std
C = concentration of the internal standard
Stable isotope labeled compounds are commercially available for internal
standard quantitation of tetra-, hepta-, and octachloro-PCDDs , KOR Isotopes,
Division of ICN Pharmaceuticals, and Lamparski and Nestrick (1982) have pre-
sented details for the laboratory preparation of carbon-13 (13Cj2) labeled
penta- through octachloro-PCDDs from the commercially available carbon-13
(13C12) 2,3,7,8-TCDD. Bell (in press) has recently reported on the synthesis
of carbon-13 labeled PCDFs.
Regardless of the quantitation technique, the quantitation ion monitored
for each PCDD isomer or homolog is selected from the molecular ion cluster.
Table 18 provides the exact masses, relative isotope abundances, and the
chlorine pattern for the major molecular cluster ions for the mono-through
octachlorinated dibenzo-j>-dioxins .
Limit of Detection —
The limit of detection is the lowest concentration of an analyte that
the analytical method can reliably detect. The limit of detection in most
PCDD studies is the concentration of the analyte that gives rise to a response
signal that is at least 2.5 times the background noise for the sample matrix.
49
-------
TABLE 18. EXACT MASSES AND RELATIVE ISOTOPE ABUNDANCES
OF MAJOR MOLECULAR CLUSTER IONS FOR PCDDs
No. of
chlorines Exact mass
0 184.0524
1 218.0135
220.0105
2 251.9746
253.9716
255.9686
3 285.9356
287.9326
289.9296
291.9266
4 319.8967
321.8937
323.8907
325.8877
327.8847
5 353.8578
355.8546
357.8518
359.8488
361.8458
6 387.8188
389.8158
391.8128
393.8909
395.8068
7 421.7799
423.7769
425.7739
427.7709
429.7679
8 455.7410
457.7380
459.7350
461.7320
463.7290
Relative
abundance
-
100.00
33.82
100.00
66.45
11.43
100.0
99.07
33.10
3.86
75.93
100.00
49.68
11.13
0.99
60.86
100.00
65.96
21.91
3.70
50.78
100.00
82.25
36.23
9.05
43.56
100.00
98.55
54.10
17.90
33.21
87.08
100.00
65.76
27.10
Source: Radolovich, G., Midwest Research Institute (personal communication)
(1983).
50
-------
The limit of detection has been found to vary with each sample (Crummett, 1979).
The differences in reported limits of detection are dependent on initial sample
size, final extract volume, volume of final extract analyzed, residual inter-
ferences from the sample matrix, extraction and cleanup procedures, chromatog-
raphy and instrumental performances, purity of reagents used for preparation
of samples, and absolute sensitivity obtainable with any particular mass spec-
trometer. Figure 16 presents the direct relationships of method limit of de-
tection with respect to initial sample size and final extract volumes. The
data generated for Figure 16 were calculated assuming a conservative GC/MS
instrumental detection limit of 5 pg per 1.0 pi on-column injection. Based
on these data, the instrumental detection limit required for measurement of 1
ppt levels of a PCDD in a 1-g sample concentrated to 10 |Jl would be 0.1 pg/pl
assuming 100% recovery. The only study approaching this level of effort has
been presented in part by Harless (1980). Table 19 provides the data presented
for the feasibility study regarding the analysis of TCDD at the parts per
trillion level in 250-mg samples of human adipose tissue (equivalent to a
needle biopsy). These data suggest than an extremely clean and sensitive mass
spectrometer was used to measure these levels of TCDD.
Limits of detection have been presented in many of the studies dealing
with the analysis of PCDDs in biological matrices. Table 20 is a summary of
data presented in a review of TCDD analysis by Shadoff and Hummel (1978).
The data presented in Table 20 generated by gas chromatography low resolution
mass spectrometry show that the original biological sample matrix has little
effect on the average detection limit that is obtainable. The lowest parts per
trillion limits of detection were obtained for samples sizes of 10 to 20 g.
Final extract volumes were taken to 10 to 20 pi, providing concentration (or
enrichment) factors of 1,000 for the larger sample sizes. In comparison, the
evidently higher LOD reported for a 1-g blood sample is in part due to the dif-
ference in achievable enrichment (100) of TCDD in the final extract. Thus,
actual limits of detection vary with the sample extract and instrumental con-
dition. If significant interferences prevent measurement of the desired LOD
value with low resolution mass spectrometry, the alternative approach is to
use high resolution mass spectrometry.
51
-------
100 g
S3
Method Detection Limit Versus Final Extract Volume
40 50 60
Detection Limit (pg/g)
Figure 16. Method detection limit versus final extract volume and initial sample size assuming a GC/MS
instrumental detection limit of 5 pg/yl on-column.
-------
TABLE 19. FEASIBILITY STUDY FOR THE QUANTITATIVE DETERMINATION
OF TCDD IN QA TISSUE SAMPLES
TCDD detection
limit (ppt)
3
5
1
1
1
TCDD detected
(ppt)3
8
16
2
3
6
TCDD
(pg)
1
0
0.5
2
16
fortification
level
(ppt) .
4
0
. 2C
8
6C
Source: Harless, R. L., "Analytical Methodology for 2,3,7,8-Tetrachloro-
dibenzo-£-dioxin and Its Application by the United States
Environmental Protection Agency to Human and Environmental
Monitoring," presented at the Assistant Administrators Program
Review, U.S. EPA, Washington, D.C., April 1980.
a 37C1-TCDD mean percent recovery - 75%. Values are not corrected for
percent recovery losses.
b Each 0.250 g sample was fortified with 0.5 ng 37C1-TCDD.
c Standard solutions.
53
-------
TABLE 20. DETECTION LIMITS FOR TCDD IN VARIOUS SAMPLES
Arkansas and Texas
Catfish
Viscera
Bass, walleyed pike
Sunfish, etc.
Flesh
Viscera
Liver
Skin
Eel
Flesh
Viscera
Skin
Shark liver
Sea cucumber
Flesh
Viscera
Crayfish
Whole
Muscle
Viscera
Tadpole
Toad
Rabbit
Liver
Pelt
Beaver liver
Opossum
Liver
Fat
Deer
Liver
Fat
Insects
Insect larvae
Diving beetles
Snails
Mice
Liver
Skin
Whole
Rat liver
Shrimp
No. of
determinations
57
2
52
11
6
2
5
1
1
1
1
1
1
1
1
1
1
1
1
1
11
1
1
3
1
1
1
1
1
1
3
10
1
4
Limit
Range
2-22
1-14
2-3
2-8
5-15
2-10
3-17
4-5
10-40
3-8
1
of detection (ppt)
Average
8
10
7
3
4
10
7
7
5
4
11
1
1
4
4
7
20
3
8
2
9
10
10
4
4
3
8
30
2
8
20
5
20
1
(continued)
54
-------
TABLE 20 (continued)
No. of Limit of detection (ppt)
determinations Range Average
Beef
Fat
Liver
Sheep
Fat
Liver
Kidney
Muscle
Bovine
Milk (40 g)
Cream
Human milk
Rice
Rat feed
Sheep feed
Cattle feed
Grass
Seed (grass)
Sorghum
Leaves
Roots
Soil
Water
Blood (1 g)
60
7
7
15
12
5
28
4
6
21
5
1
1
2
5
2
1
2
100
4
2
3-10
2-7
5-15
3-10
3-6
2-6
0.5-1
3-5
1-6
2-7
4-6
12-14
2-12
2-3
4-6
3-10
0.1-0.2
40
6
4
9
7
5
5
1
4
3
4
5
3
6
13
7
3
4
5
6
0.2
40
Source: Shadoff, L. A., and R. A. Hummel, "The Determination of 2,3,7,8-
Tetrachlorodibenzo-£-dioxin in Biological Extracts by Gas Chroma-
tography Mass Spectrornetry," Biomed. Mass Spectrom., 5:7-13 (1978)
55
-------
Quality Assurance
All studies concerning the analysis of biological samples for PCDDs have
included some form of a quality assurance (QA) program. The routine use of
stable isotope labeled PCDDs as surrogates for internal standard quantitation
and method recovery is practiced most frequently as a QA procedure. Studies
undertaken by the Dioxin Monitoring Program (Harless et al., 1980) included
the use of stable labeled surrogates, submission of blind samples, duplicates,
and blanks to the analyst, establishing of criteria for the positive identifi-
cation of PCDDs, and interlaboratory studies to bolster the significance and
validity of TCDD data generated. The methods adopted by EPA for the analysis
of TCDD in water, wastewater (EPA, 1982), soil and sediment (EPA, 1983) re-
quire a specified number of samples to be analyzed in duplicates or as spiked
samples at levels near the detection limit. In addition, these methods spe-
cify routine performance evaluations with respect to isomer specificity by
KRGC, consistency of response factors, evaluation of method blanks, qualita-
tive criteria, and analysis of blind spiked samples. Other analysts (Gross
et al., 1981; Langhorst and Shadoff, 1980; Kocher et al., 1978; Stalling et
al., 1982; Tosine, 1981; O'Keefe et al., 1978; Mahle, 1977; Mitchum et al.,
in press) have also completed method validations as QA procedures with respect
to the analysis of PCDDs.
Stable Isotope Labeled Compounds—
Chlorine-37 or carbon-13 labeled 2,3,7,8-TCDD were available for use as
surrogate compounds for the analysis of 2,3,7,8-TCDD in most studies. The
advantage of using these compounds is that they behave exactly as native TCDDs
throughout extraction, cleanup, and gas chromatography separation. The mass
spectra of the native and stable isotope labeled compounds vary enough to al-
low differentiation during the analysis. The surrogate compound added to the
sample is used as a true internal standard for quantitation. The concentra-
tion calculated by the internal standard method provides a recovery correction.
The method recovery can be determined by comparing area response of the quanti-
tation ion for the internal standard in the sample extract versus the area
response in an external standard. A more accurate measurement of method re-
covery can be achieved by adding a second internal standard to the sample ex-
tract prior to instrumental analysis. For example, TCDD can be measured in a
sample by internal standard quantitation with accurate method recovery deter-
mination by combining the use of the carbon-13 and chlorine-37 labeled TCDD
compounds. Stable isotope labeled compounds are also commercially available
for the hepta- and octa-PCDDs. Nestrick and Lamparski (1982) have described
techniques for synthesizing carbon-13 labeled penta- to octa-PCDDs from per-
chlorination of microgram amounts of carbon-13 labeled 2,3,7,8-TCDD.
Langhorst and Shadoff (1980) have reported the analysis of tetra-, hexa-
and octa-PCDDs in human milk samples and have provided recovery data for each
homolog determined by comparing external standards to the surrogate compounds.
Table 21 is an example of the end use of surrogate recovery and internal stan-
dard quantitation as presented by Langhorst and Shadoff (1980). These data
were generated while validating an analysis method for human milk. The val-
ues for percent recovery are the recoveries of the isotopically labeled sur-
rogates. The percent accountability refers to the amount of observed native
dioxin corrected for recovery of internal standard compared to the actual
56
-------
TABLE 21.
PERCENT RECOVERY OF INTERNAL STANDARD AND PERCENT ACCOUNTABILITY
FOR NATIVE DIOXINS SPIKED INTO CONTROL MILK HOMOGENATE
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
avg
Concn,
Added
1.0
1.0
1.3
1.3
1.3
2.0
2.0
2.6
2.6
2.6
2.6
2.6
2.6
2.6
2.6
3.9
3.9
12
12
2,3,
ppt
Found
0.2
0.2
0.7
0.8
0.8
1.6
2.2
2.0
2.4
2.2
1.9
1.9
2.5
1.9
1.4
2.3
3.3
10
12
std dev
7, 8-TCDD
%
Recovery
42
65
56
33
49
38
96
25
25
32
26
21
11
23
34
34
25
33
33
37
±19
Account-
abili ty
20
20
54
62
62
80
110
77
92
85
73
73
96
73
54
59
85
84
97
77
±16
Precision data
Comp
2,3,7,
HCDD
OCDD
Source
ound
8-TCDD
: Langhorst
, M. L.
Cone
, and L. A
added, ppt
2.6
13
53
Concn, ppt
Added Found
5.3 4.5
5.3 3.7
6.6 7.0
6.6 7.2
6.6 7.2
9.9 5.7
9.9 8.0
13 9.0
13 9.9
13 8.9
13 8.1
13 13
13 13
13 13
13 10
20 17
20 11
60 42
60 42
HCDD
% Account
Recovery ability
70
67
64
57
57
70
86
76
68
85
74
47
38
53
52
59
61
81
85
67
±11
for eight replicates samples
Shadoff, "Determination of
and Octachlorodibenzo-£-dioxins in Human Milk Samples
% Recovery
25 ± 7
65 ± 13
45 ± 8
84
70
106
109
109
58
81
68
74
67
61
98
98
98
75
86
56
70
70
81
±17
(no.
OCDD
Concn, ppt %
Added
21
21
27
27
27
41
41
53
53
53
53
53
53
53
53
80
80
240
240
8-15)
Found
21
38
23
40
37
49
41
41
33
42
38
38
40
45
57
51
98
360
270
Recovery
52
39
53
31
45
33
110
53
49
55
48
43
32
43
35
50
31
45
58
48
±17
Account-
ability
100
180
85
150
140
120
101
77
62
79
71
71
75
84
108
64
120
150
110
94
±43
% Accountability
Parts per Trillion
," Anal. Chem. ,
78 ± 13
80 ± 16
78 ± 14
Concentrations of Tetra-, Hexa-
52:2037-2044
(1980).
, Hepta-,
a Corrected for internal standard recovery.
-------
amount of the native PCDD that was added. The precision of the analysis was
also demonstrated by the results of eight replicates (Table 21). These data
show the usefulness and applicability of isotopically labeled compounds for
producing analytical results of known quality. The data demonstrate the im-
provement of precision at concentrations much higher than the detection limit
and also enlighten the analyst on the difficulties of measurements near the
detection limits.
Intralaboratory Validation of Method—
Methods development for the analysis of any particular compound or com-
pounds requires validation of the partial steps (extraction, cleanup, etc.)
as well as the entire method. Table 22 is a summary of some of the published
method vaidation data for PCDDs reported in the literature. Many of the
methods reported were validated using replicate measurements of samples forti-
fied with native PCDDs and/or the available isotopically labeled PCDDs. The
mean percent recovery of the native compounds and the isotopic surrogates vary
with respect to the validation experiments near the detection limit. The val-
ues summarized in Table 22 are indications of the total method performance.
Intralaboratory validation requires a closer study of the individual
method steps or procedures. This subject has already been demonstrated in
this review with respect to extraction, cleanup and quantitation procedures
in general. Table 23 is a specific example of intralaboratory validation of
specific steps for a single method. The data in Table 23 were generated by
diDomenico et al. (1979) while developing analytical methods for 2,3,7,8-TCDD
in environmental samples near Seveso, Italy. The sample extracts were cleaned
using a combination of the four procedures alluded to in Table 23 as cleanup
steps A to D. Step A was a wash with concentrated sulfuric acid that did not
introduce any appreciable losses. Procedure B involved a chromatographic
cleanup with sulfuric acid treated Celite 545. Acetonitrile partitioning
(Step C) of the extract from Step B proved to be an alternate to Step A but
was also found to be more time consuming. Final cleanup (Step D) was ac-
complished using a micro alumina chromatography column. The data presented
in Table 23 are representative of replicate analyses of spike recovery ex-
periments for the individual steps and combination of procedures without the
influence of a sample matrix. The recovery values for the extraction and
cleanup of soil, grass, and cotton swabs are also compiled in Table 23 and
are indicative of the entire method performance for samples spiked with 5 to
550 |jg of 2;3,7,8-TCDD.
Two other studies reported in the literature provided statistical evalu-
ation of the method validation data. Langhorst and Shadoff (1980) and Gross
et al. (1981) evaluated data for human milk and bovine fat samples, respec-
tively. The methods of sample preparation and mass spectrometry analysis
differed significantly between these two studies.
58
-------
TABLt 22. SUMMARY OK SOUK PUBLISHED METHOD VALIDATION DATA FOR 2,3,7,8-TCDD
RECOVERED FROM FORTIFIED BIOLOGICAL MATRICES
TCDD Level of fortification
Reference
Langhorst and Shadoff
(1980)
Tosine (1981)
Gross et al. (1983)
Harless et al. (1980)
O'Keefe et al. (1978)
Mahle et al. (1977)
O'Keefe et al. (1978)
Baugbman ar.i Meselson
(1973)
Kocher et al. (1978)
Native
Bovine milk ng-kg 1
Human milk 2.6
Fish 20
Human adipose 0
6
16
38
Fish, liver 0-125
Human milk 0-5
Bovine milk
0.7
13
65
Bovine milk 2
-
Bovine fat
13
25
100
200
Liver 20
Bovine fat 10
Isotope
ng-kg l, "C, ("'CD
166
(37C1)
1000
250
_
66
66
66
.
625a
.
390
+c
+c
+c
1000
Number of
replicates
8
6
1
1
1
1
17
17
4
4
4
4
3
U
4
4
4
4
4
9
7
Mean % recovery
with s.d.
Native
25 ± 7
-
ND
150
125
no
V.
- 15b
i 38b
ND
86 + 17
100 i 8
85 + 9
83.3
-
NT)
100 ± 15
80 + 5
85 + 7
88 ± 18
34 + 7
76 + 10
Isotopes
37 + 19
92 + 4
40
40
45
40
86 + 15
68
ND
71 + 12
71 + 12
87 + 21
.
64
NT)
77 + 18
77 + 18
77 i 18
105 ± 9
27 + 5
Source: Adapted from National Research Council of Canada, "Polychlorinated Dibenzo-g-dioxins: Limitations
to Current Analytical Techniques," NRCC No. 18576, ISSN 0316-0114, 1981.
a Indicates publishing author's recovery data were converted from ng to ppt or from ppt to % by the Panel.
b These data indicate the mean % accuracy for TCDD obtained with quality assurance samples.
c Plus indicates fortified with isotope but amount not specified clearly.
59
-------
TABLE 23. RESULTS OF RECOVERY TESTS PERFORMED ON THE ANALYTICAL
PROCEDURE, OR ITS SINGLE PARTS3
Operation and number of tests
Cleanup step B, 12
Cleanup step C, 15
Cleanup step D, 14
Cleanup steps B-D, 18
Cleanup steps B-C-D, 8
Soil, 28C
Grass, 12°
Cotton swabs, 46°
Minimum
80
73
95
80
58
74
72
68
TCDD % Recovery
Maximum
124
114
120
115
93
101
98
112
Average
101 ± 12b
91 ± 13
102 ± 7
96 ± 12
76 ± 11
86 ± 7
85 ± 7
86 ± 10
Source: diDoraenico, A., et al., "Analytical Techniques for 2,3,7,8-Tetra-
chlorodibenzo-£-dioxin Detection in Environmental Samples After
the Industrial Accident at Seveso," Anal. Chem., 51:735-740 (1979).
a Cleanup step A did not introduce any appreciable 2,3,7,8-TCDD loss provided
the operation was performed with the utmost care. This conclusion was
reached after a number of recovery tests had been carried out by
applying a sequence of cleanup steps including A. 2,3,7,8-TCDD quantity
used: 0.1 and 0.01 |Jg/test in 1 ml solvent.
b Standard deviation.
c Values reported take into account 2,3,7,8-TCDD losses due to cleanup steps.
60
-------
The data generated by Langhorst and Shadoff (1980) for the analysis of
tetra-, hexa- and octa-PCDDs for seven controls, seven replicate samples and
spiked samples were presented in Table 21. The actual limitations of the
method were defined by the dioxin level in the control sample and by statisti-
cal treatment of the data. Figure 17 is an example of the statistical data
treatment for 2,3,7,8-TCDD and OCDD analysis. The heavy solid line is the
actual level of native dioxin spiked. The dashed line represents the least
squares fitted line for the dioxin concentration observed. The shaded area
represents the total uncertainty of the determination including the error as-
sociated with the least squares fitted line and the error associated with the
final recovery of dioxin for GC/MS analysis.
The statistical validation of the method practiced by Gross et al. (1981)
was generated from analytical results for 26 bovine fat samples and 26 stan-
dard solutions spiked at levels ranging from 0 to 81 ppt. The samples and
standards were prepared and submitted simultaneously for TCDD analysis by PGC/
HRMS with blind sample codes. The sample identifications were decoded when
all the analytical results (52 samples) were submitted for statistical analysis,
The statistical analysis results for the standard solutions and beef fat sam-
ples are illustrated in Figure 18. The theoretical line y = x representing
perfect extraction and quantitation was included for comparative purposes.
Two sets of upper and lower 95% confidence limits were included for least
squares regression of reported values (y) on spiking levels (x). The boundary
lines closest to the regression lines represent the upper and lower 95% confi-
dence limits for an infinite number of analyses under the same conditions.
The outer boundary lines are indicators of the 95% confidence limits for a
single analysis. Based on the results of the statistical analysis of the data,
Gross et al. (1981) determined the lower limit of quantitation to fall between
5 and 9 ppt.
Interlaboratory Studies—
The review of analytical methods for PCDDs presented by the NRCC (1981)
included an evaluation of the techniques with respect to applicability to ma-
trix, specificity, method validation, and interlaboratory studies. None of
the methods reviewed at the time was given the highest rating because evalua-
tion through a collaborative study was not included. Since that time several
interlaboratory studies have1been completed or are still in progress. These
studies are summarized in Table 24. The only study conducted for biological
matrices with directions to follow a specific analytical method is with the
pork adipose matrix (EMSL/LV). The participants were instructed to follow
the procedures published by Harless et al. (1980) for parts per trillion mea-
surements of 2,3,7,8-TCDD in pork adipose tissues. Samples that were analyzed
in other studies were prepared according to Harless et al. (1980), while GC/MS
measurements of 2,3,7,8-TCDD were conducted according to the practices of the
individual laboratory.
61
-------
14
12
10
2,3,7,8-Tetrachlorodibenzo-p-Dioxin
§ 6
I I I I
45678
Amount Added (ppt)
10 11 12
350
300
250
"3.
a
^200
o
LL.
| 150
100
50
Octachlorodibenzo-p-Dioxin
50
200
250
100 150
Amount Added (ppt)
Source: Langhorst, M. L., and L. A. Shadoff, "Determinations or Parts
per Trillion Concentrations of Tetra-, Hexa-, Hepta-, and
Octachlorodibenzo-p-dioxins in Human Milk Samples," Anal.
Chem., 52, 2037-2044 (1980).
Figure 17. Statistical treatment of validation data for 2,3,7,8-TCDD
and OCDD in human milk samples.
62
-------
90
80
70
D-
1 50
o
I" 40
Q
5 30
20
10
Theoretical Line, Y = X
Regression Line,
Y= 0.98X - 1.30
95% Conf. Limits for
Regression Line
95% Conf. Limits for
Individual Analyses
90
80
70
§. 60
| 50
o
a
40
30
20
10
0
10 20 30 40 50 60
TCDD Added (ppt)
Theoretical Line, Y = X
Regression Line
Y=0.89X +
95% Conf. Limits:
Regression Limits
Individual
70 80
10 20 30 ' 40 50 60
TCDD Added (ppt )
70 80
Source: Gross, M. L., T. Sun, P. A. Lyon, S. F. Wojinski, D. R. Hilker,
A. E. Dupuy, Jr., and R. G. Heath, "Method Validation for the
Determination of Tetrachlorodibenzodioxin at the Low Parts per
Trillion Level," Anal. Chem., 53, 1902-1906 (1981).
Figure 18. Statistical treatment of reported concentrations versus
concentrations of TCDD actually added to standard solutions and
beef adipose.
63
-------
TABLE 2A. INTERLABORATORY STUDIES AND METHOD VALIDATIONS FOR THE ANALYSIS
OF TETRACHLORODIBENZO-p-DIOXINS (TCDD)
Matrix
Water
Wastewater
Soil
Sediment
Pork adipose
Human adipose
Beef adipose
Fish
Fish
Fish
Beef adipose
Soil
Sediment
Pottery clay
Number of
participating
Method(s) laboratories
EPA Method 613 13
EPA Region VII protocol a
for soil and sediment
Harless et al. (1980)c
Harless et al. (1980)d 3
Harless et al. (1980)d 4
e 6
e 13
f 8
Harless et al. (1980)d 2
EPA Region VII protocol
for soil and sediment
EPA Region VII protocol
for soil and sediment a
TCDD concentration
range
20 - 200 ppt
1 - 100 ppb
1 - 100 ppt
1 - 100 ppt
1 - 100 ppt
105 - 121 ppt
1 - 100 ppt
1 - 200 ppt
1 - 100 ppt
1-100 ppt
1 - 10 ppb
Reference
McMillin et al. (1982)
EMSL/LVb
EMSL/LVb
Dioxin Monitoring Program
Gross et al. (1981)
Dioxin Monitoring Program
Gross et al. (1981)
Brumley et al. (1981)
Ryan et al. (1983)
O'Keefe et al. (1983)
Dioxin Monitoring Program
Gross et al. (1980)
EMSL/LVb
EMSL/LVb
a These samples are used as performance evaluation samples for laboratories involved with
analysis of 2,3,7,8-TCDD in soils and sediments.
b Personal communicaton J. Donnelley (1983).
c Participating laboratories were instructed to follow procedure as described by Harless et al. (1980).
Some modifications to the method were reported.
d Samples prepared by method described by Harless et al. (1980), but GC/MS conditions varied.
e Each Participting laboratory used current in-house analytical method.
f Sample extracts divided at specific steps of one protocol and submitted to participating laboratories
for further analysis.
64
-------
Some examples of the data generated in these interlaboratory studies are
presented in Tables 25 to 28. Table 25 illustrates the results of the analy-
sis of human adipose samples for 2,3,7,8-TCDD. These samples were analyzed
initially by PGC/HRMS. A subset of these samples were reextracted and/or re-
analyzed at other laboratories to provide interlaboratory validation of re-
ported detections at these low levels. The validation of the analyses was
accomplished in two ways. Remaining extracts from PGC/HRMS were reanalyzed
using HRGC/HRMS, and portions of the tissues were submitted for reextractibn
and cleanup followed by HRGC/HRMS. All samples were coded and their identi-
ties were not known to the analysts. Based on the interlaboratory validation
study, it was confirmed that two of the three samples designated as having
heavy exposures contained 2,3,7,8-TCDD at higher levels than those observed
for other participants. In addition, 2,3,7,8-TCDD was detected in tissue from
other exposed and nonexposed persons designated as controls that were also
examined by the interlaboratory studies.
Table 26 provides a comparison of the results obtained by the different
methods, PGC/HRMS versus HRGC/HRMS. Gross et al. (1981) have discussed the
differences in concentration as reflecting the relatively large uncertainties
in quantitation techniques in the parts per trillion range. Some of the varia-
tions between sample extracts analyzed by PGC/HRMS and HRGC/HRMS may be due in
part to differences in resolution of the 2,3,7,8-TCDD from the other 21 possible
isomers. In addition, the results may indicatetsample inhomogeneities since dif-
ferent portions of unhomogenized tissue were used in each experiment.
The interlaboratory study reported by Ryan et al. (1983) involved 13
laboratories having experience in determination of low levels (parts per
trillion) of 2,3,7,8-TCDD in biological samples. Each laboratory agreed to
analyze four fish samples for 2,3,7,8-TCDD using their routine extraction,
cleanup and detection procedures. Table 27 presents the data reported by 8
of the 13 laboratories. The relative standard deviation for samples A, C and
D is surprisingly low (14.0, 18.4, and 25.3%, respectively) considering the
picograms per gram levels in the original sample. This variation is signifi-
cantly less than that predicted by Horowitz et al. (1980) for low level quan-
titation. -
The recoveries of the internal standard (either carbon-13 or chlorine-37)
2,3,7,8-TCDD are presented in Table 28 for six of the laboratories that used
internal standard quantitation. The average recovery of the individual labo-
ratories ranged from 57 to 82% with a relative standard deviation of approxi-
mately 25%. The range of all the individual measurements yielded 29 to 109%
recovery of the internal standard. This difference in method performance in-
dicated the needs and usefulness of the internal standard quantitation approach.
The results indicated fish samples C and D (Table 27) contained similar
levels of 2,3,7,8-TCDD. These data were statistically evaluated according to
the methods of Youden to determine variations between laboratories (systematic
error) and within laboratories (random error). The results indicated that
the difference between laboratories (reproducibility) was somewhat greater
than the variance within laboratories (repeatability), although the differences
reported were not significant at the 95% confidence level.
65
-------
TABLE 25. RESULTS OF ANALYSIS OF TCDD IN HUMAN ADIPOSE TISSUE'
Concentration
VA code number (ppt)
"Heavily Exposed Veterans"
10
10
19
26
26
"Lightly Exposed Veterans"
1
13
28
28
34
"Possibly Exposed Veterans"
6
8
9
11
12
14
16
24
24
25
25
27
29
30
"Controls"
5
7
17
18
20
21
23
23
31
32
33
23
35
ND°
99
63
ND
ND
7
8
5
5
5
NDa
3
9
4
ND
5
5
12
10
ND
13
ND
4
3
4,3
ND
5
6
8
6
7
4
14
Detection
limit Percent
(ppt) recovery
4
9
3
10
6
5
2
4
6
3
3
3
3
2
3
3
4
3
4
4
3
6
5
3
4
2
3
4
4
3
2
3
4
4
7
(continued)
65
100+
20
90
45
50
80
50
40
100
65
50
40
55
60
65
60
80
45
45
100+
100
60
95
65
60
75
30
50
35
100
55
50
60
100
Ratio0
.85
.75
•
.77
-
_
-
.88
.78
.85
.90
.90
.77
.88
.74
-
.71
-
-
.78
-
.88
-
1.02
.92
.84
'-
.86
1.07
.78
-
.98
.74
.94
66
-------
TABLE 25 (continued)
VA code number
"USAF Scientists"
2
3
4
Concentration
(ppt)B
5
4
6
Detection
limit
(ppt)
2
1
2
Percent
recovery
50
85
50
RatioC
.77
.94
.76
Source: Gross, M. L., J. 0. Lay, P. A. Lyon, D. Lippstred, N. Kangas,
R. L. Harless, S. E. Taylor, and A. E. Dupuy, "2,3,7,8-
Tetrachlorodibenzo-£-dioxin Levels in Adipose Tissue of
Vietnam Veterans" (personal communication).
a Sample sizes ranged from 2.2 to 11.6 g for each extraction.
Internal standard amounts used varied from 2.0 - 2.6 ng/extraction.
b ND = not detected.
c Ratio of intensities of m/z 320 and m/z 322. Acceptable values
are 0.78 ± 0.10.
67
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TABLE 26. RESULTS OF INTERLABORATORY VALIDATION STUDIES
VA Code UN-L/UN-L3
"Heavily Exposed
VA-26
VA-10
VA-19
USAF Researchers
VA-3
VA-2
Veterans"
63,99
23,35
ND(3)e
48
5
UNL/RTPb
_
36
3
-
TAC/RTPC
173
_
-
10
-
TAC/RTPd
_
86
20
—
24
UN-L/UN-L6
_
-
ND(29)
_
-
Other Vietnam Veterans
VA-13
VA-8
VA-9
VA-15
VA-34
Controls
VA-17
VA-18
VA-21
VA-31
VA-20
ND(2)
5
ND(3)
7
5
4,3 f
ND(4r
69
ND(4)
5
ND(0.2)
3
3
_
-
5
3
-
~
ND(7)
5
'
_
-
20
8
12
ND(3)
~
_
-
ND(7)
18
ND(5)£
14
-
-
-
19
_
-
-
-
-
-
9
-
20
Source: Gross, M. L., J. 0. Lay, P. A. Lyon, D. Lippstred, N. Kangas,
R. L. Harless, S. E. Taylor, A. E. Dupuy, "2,3,7,8-Tetra-
chlorodibenzo-£-dioxin Levels in Adipose Tissue of Vietnam
Veterans" (personal communication).
a Extracted at UN-L/analyzed at UN-L (University of Nebraska, Lincoln).
The values given in parentheses are the detection limits.
b Portion of the extract from UN-L/analyzed at RTP (Research Triangle
Park).
c Extracted at TAG (Toxicant Analysis Center)/analyzed at RTP.
d Another portion of tissue shipped from UN-L, extracted at TAC/analyzed
at RTP.
e Extracted at UN-L/analyzed at UN-L. Results obtained with knowledge
of the code.
f Poor recovery of internal standard (< 40%).
g Isotope ratio for m/z 320 and n/z 322 not correct.
68
-------
TABLE 27. CONCENTRATION OF 2,3,7,8-TCDD IN FISH SAMPLES FROM
INTERLABORATORY STUDY
Values are single determinations expressed in pg/g (ppt).
Fish sample
Lab No.
la
3
4d
5e
6
7
9
12
Av.h
SD
cv, %
n
A
104b
58
49
58
ND(5)f
72
70
60
61.2
8.5
14.0
6
B
NDC(10)
ND(1.3)
ND(2)
ND(1)
ND(5)
ND(2.3)
ND(5)
378
3.6
0
-
6
C
35
37
23
34
51f
25
33
26
30.4
5.6
18.4
7
D
45
33
19
38
55
32
27
32
32.3
8.2
25.3
7
Source: Ryan, J. J., J. C. Pilon, H. B. S. Conacher, and D. Firestone,
"Interlaboratory Study for the Analysis of Fish for 2,3,7,8-
Tetrachlorodibenzo-£-dioxin," in press, 1983.
a Also reported GC/ECD values of 103, ND(10), 39, 37 pg/g, respectively.
b Value given judged to be an outlier by Dixon's test; recovery of this
sample was judged by the analyst to be high (74%), so an average
recovery (51%) was used to calculate value given.
c Not detected followed by bracketed detection limits in pg/g.
d Also reported higher values of 58, ND(2), 37, 38 pg/g for acid-base method;
these values are closer to average than neutral method preferred by the
analyst.
e Confirmed by atmosphere pressure-negative chemical ionization GC/MS on same
extract with values of 54, ND(2.3), 32, and 31 ppt, respectively, for
samples A, B, C, D.
f Value given judged to be outlier.
g Value given judged to be outlier; subsequent analysis showed a value of
ND(10) pg/g.
h Does not include any outliers or values from laboratory 6.
69
-------
TABLE 28. PERCENT RECOVERIES OF INTERNAL STANDARD
TCDD IN THE INTERLABORATORY STUDY
Lab No.
lb
3C
4d
5C
7d
9C
12C
Range
Av.a
57.0
69.0
80.0
83.1
35.3
74.6
81.8
67.7
29-109
SD
11.6
16.6
12.3
18.7
5.2
18.4
14.5
cv, %
20.4
24.1
15.4
22.5
14.7
24.7
17.7
Source: Ryan, J. J., J. C. Pilon, H. B. S. Conacher,
and D. Firestone, "Interlaboratory Study
for the Analysis of Fish for 2,3,7,8-Tetra-
chlorodibenzo-£-dioxin," in press, 1983.
a Each value represents the average of 4 reported
values.
b Fortified duplicate with native 2,3,7,8-TCDD.
c 13C-2,3,7,8-TCDD.
d 37Cl-2,3,7,8-TCDD.
70
-------
The analytical results for samples C and D, although somewhat limited,
were further evaluated to see if there were significant differences for the
different analytical methodologies. No differences were determined with this
treatment for methods that used digestion or extraction; high or low resolu-
tion mass spectrometry; and specific or nonspecific isomer separaton.
Needs for Future Validation Studies--
Although several interlaboratory studies have been conducted, there is
need for further validation of specific procedures. The results from such
studies presented by Ryan et al. (1983), Brumley et al. (1981), Gross et al.
(1980), and O'Keefe et al. (1983) demonstrate that the available methodologies
are comparable in performance and provide reasonably valid measurements with
respect to other approaches. Critical assessments of specific steps of the
methodologies have not been attempted. There is need for a single laboratory
to compare the best approach, for example, for initial extraction of PCDDs
from the sample matrix (acid digestion, alcoholic saponification, or neutral
extraction). Likewise, cleanup procedures should be compared and evaluated
to generate information on recovery of analytes and separation from specific
contaminants such as PCBs, chlorodiphenylethers, chloromethoxybiphenyls, etc.
In order to accomplish this evaluation of methodology, it is important to vary
only one parameter at a time. Additional validation of the methods is re-
quired if it is necessary to measure other homologs of PCDDs other than TCDD.
Another important aspect that must be evaluated when considering interlabora-
tory validation of a single method is the ease of individual analytical steps.
In order to demonstrate and fully evaluate the validity of a method all par-
ticipating laboratories should be able to manipulate all procedural steps
with good precision and accuracy.
71
-------
SECTION 5
APPLICABLE TECHNIQUES - RECOMMENDATIONS
Following the first submission of the literature review (Sections 1-4,
this report), MRI was requested to organize a meeting to discuss analytical
approaches for the analysis of PCDDs and PCDFs. This Section presents a synop-
sis of a discussion meeting held at Midwest Research Institute, Kansas City,
Missouri, on April 27 and 28, 1983. The specific purpose of this meeting was
to discuss analytical methods that are applicable to the analysis of polychlor-
inated dibenzo-p_-dioxins (PCDDs) and dibenzofurans (PCDFs) in human adipose
tissues. The discussion meeting was attended by scientists (Appendix A) recog-
nized as experts in the field of PCDD and PCDF analysis. The meeting served
as an additional source of information pertaining to specific considerations
for low parts-per-trillion measurements of PCDDs and PCDFs in human adipose
tissue. The meeting followed the first draft of the written literature re-
view with preliminary method recommendations for analysis of PCDDs in adipose
tissue and a peer review (Stanley, 1982) of the initial document.
DISCUSSION MEETING SUMMARY
The meeting was organized to promote open and detailed discussion on the
criteria that must be considered for an effective analytical method and study
of PCDD levels in human adipose tissue. Scientists recognized as experts in
the field of PCDD and PCDF analysis were invited to participate (Appendix A).
Most of the participants had previously provided peer review comments to the
literature review and preliminary recommendations.
Representatives from EPA/OTS and the VA presented overviews on the de-
sign of a general population study to determine PCDD exposure using existing
adipose sample repositories and an update of the VA involvement with Agent
Orange studies.
A summary of the primary issues identified from the peer reviews of the
literature review and preliminary recommendations was presented. These is-
sues included (a) the need for stating the primary objectives of the program,
(b) the use of high resolution mass spectrometry (HRMS) versus low resolution
mass spectrometry (LRMS), (c) the practical limitations of the proposed ex-
tract cleanup procedures, and (d) additional measures for the quality assur-
ance program.
The discussion of methods of analysis were held to four major subject
headings. They were: primary objectives of the method, instrumental analy-
sis, sample preparation, and method validation (Appendix B).
72
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Primary Objectives
The primary objective of the method was defined as the need to accurately
determine the level of 2,3,7,8-TCDD in human adipose tissue. However, higher
chlorinated PCDDs and PCDFs including tetrachlorodibenzofurans are also of
interest in the overall program. It was recognized that it may be difficult
to achieve this additional data if sufficient sample sizes are not available.
It was emphasized that if possible, a method should provide data on PCDDs and
PCDFs with chlorine substitution in the 2,3,7,8-positions. The objectives of
a method as expressed in the discussion were (a) isomer specific measurement
of 2,3,7,8-TCDD, (b) determination of PCDDs and PCDFs with chlorine substitu-
tion in the 2,3,7,8-positions, and (c) measurement of total PCDDs and PCDFs
by homolog.
Instrumental Analyses
It was a consensus that mass spectrometry is necessary for the identi-
fication and quantitation of PCDDs and PCDFs. The criteria for qualitative
identification of PCDDs and PCDFs are similar regardless of whether low reso-
lution or high resolution mass spectrometry is used for analysis. These cri-
teria include (1) coincident response of at least two ions characteristic of
the molecular ion cluster of a specific homolog, (2) the proper ion response
ratio, and (3) the correct retention times. In addition, response of a frag-
ment ion characteristic of the loss of COC1 is necessary to confirm the pres-
ence of a PCDD congener.
Electron impact ionization mass spectrometry was presented as the most
useful for analysis of PCDDs and PCDFs. It was pointed out, however, that
other mass spectrometry methods, negative ion chemical ionization in particu-
lar, are applicable to the analysis of specific PCDD or PCDF congeners. These
alternate mass spectrometry methods also provide additional sensitive confirm-
atory information.
Method detection limits for analysis of 2,3,7,8-TCDD were estimated at 1
to 5 parts per trillion (ppt), providing that the original sample size is at
least 1 to 3 g. It was recognized by the meeting participants that this small
sample size may not be sufficient to allow analysis for other PCDDs and PCDFs.
The only means of extending a small sample for the analysis of all PCDDs and
PCDFs is to isolate the different chlorinated homologs using liquid chromatog-
raphy techniques. Estimates for method detection limits of octachlorodibenzo-
g-dioxins and octachlorodibenzofurans ranged from 20 to 100 ppt.
It was generally recognized that the use of high resolution rather than
low resolution is based on the extent that potential interferences are removed
from the sample extract. If sufficient extract cleanup is achieved, low reso-
lution mass spectrometry is acceptable for the analysis of PCDDs and PCDFs at
low parts per trillion.
Compounds that are known to interfere with the analysis of 2,3,7,8-TCDD
were presented in the literature review. A set of compounds that was not
considered in the review was chlorinated benzoquinones. The need to study
73
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the potential interferences of these types of compounds was addressed and dis-
cussed. The potential interferences to the analysis of higher chlorinated
PCDDs and PCDFs have not been identified. It was speculated that compounds
similar to the interferences for 2,3,7,8-TCDD analysis, but with greater chlo-
rine substitution, may interfere with the analysis of other PCDDs and PCDFs.
These compounds include the polychlorinated biphenyls, benzoquinones, benzyl-
phenyl ethers, and diphenyl ethers.
Sample Preparation
The procedures for sample preparation were discussed with respect to
quantitative extractions of PCDDs and PCDFs from sample matrices and the de-
gree of cleanup necessary for instrumental analysis. Several of the partici-
pants were asked to describe their analytical preparation schemes and to pro-
vide comments as to the advantages or purpose of the particular method steps.
The cleanup procedures discussed were designed with final instrumental
technique in mind. The procedure presented in the preliminary recommendation
required less stringent cleanup and high resolution gas chromatography/high
resolution mass spectrometry. Other procedures require mass extensive clean-
up, fractionation of the sample extract with high performance liquid chroma-
tography and analysis by packed column gas chromatography/low resolution mass
spectrometry.
Figures 19 and 20 are schematics of the two analytical schemes presented
at the meeting following the discussion of sample preparation. These schemes
represent routes to final analysis by HRGC/HRMS and HRGC/LRMS. A macro alu-
mina column is recommended to provide additional separation of PCDDs and PCDFs
from interferences. If it is necessary to separate PCDDs and PCDFs by homo-
log, an HPLC step may be necessary. Several of the meeting attendees com-
mented on the advantages of activated charcoal for separating PCDDs and PCDFs
from interferences. This step has been proposed as part of the overall scheme
for low resolution mass spectrometry.
Considerable discussion centered around the equivalency of extraction
procedures. There have been some indirect comparisons of the recovery effi-
ciencies of acidic digestions, basic saponifications, and neutral extractions
with fish samples in previous interlaboratory studies. There is a need for a
direct comparison of these procedures followed using a common rigorous cleanup
procedure to fully evaluate the extraction efficiencies. A more definitive
study could be performed by using adipose containing a bioincurred radio-
labeled PCDD. Recovery of the radiolabeled PCDD versus recovery of a spiked
stable isotope PCDD would provide detailed information on the actual recovery
from adipose tissue for each specific technique.
74
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Initial Sample Preparation
Spike with Stable Isotope
Labeled PCDDs
I
Extraction
Neutral Extraction or
Basic Saponification
I
Bulk Matrix
Cleanup
Macro- Column
Acid/Base
Modified
Silica Gel
Removal of Chemical
Interferences
Alumina Macro-Column
I
HRGC/HRMS
• 37CI-2,3,7,8-TCDD
• 13C-2,3,7,8-TCDD
• Other 13c- Labeled PCDDs/PCDFs
Provides Cleanup of Oxidizable Compounds
with Rapid Sample Turnaround, Improved
Cleanup Efficiency and Recovery
Provide Separation of PCBs and Other
Potential Interferences from PCDDs
Simultaneous Detection, Quantitation
and Confirmation
Figure 19. Schematic of proposed analytical method using
high resolution mass spectrometry (HRMS).
75
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Initial Sample Preparation
Spike with Stable Isotopes
Labeled PCDDs
I
Extraction
Neutral Extraction or
Basic Saponification
Bulk Matrix
Cleanup
Macro-Column
Acid/Base
Modified
Silica Gel
I
Carbon/Glass Fiber
or
Carbon/Celite
Adsorption Column
Removal of Chemical
Interferences
Alumina
Macro-Column
I
HRGC/LRMS
•37CI-2,3,7,8-TCDD
• 13C-2,3,7,8-TCDD
•Other 13C- Labeled PCDDs/PCDFs
Provides Cleanup of Oxidizable Compounds
with Rapid Sample Turnaround, Improved
Cleanup Efficiency and Recovery
Provides Selective Adsorption of PCDDs/PCDFs
and Similar Residues
Provide Separation of PCBs and Other Potential
Interferences from PCDDs/PCDFs
Simultaneous Detection, Quantitation
and Confirmation
Figure 20. Schematic of proposed analytical method using
low resolution mass spectrometry (LRMS).
76
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Method Validation
Validation of a primary analytical method will require participation of
at least eight laboratories with a minimum of four samples prepared as Youden
pairs at mid-level and lower concentration ranges. A few of the meeting par-
ticipants felt that a comprehensive evaluation requires the analysis of mul-
tiple samples (7-10) at several spiked concentration levels to measure preci-
sion of the analytical procedures and to define the actual method detection
limit. In addition, an interest was expressed to analyze the same set of sam-
ples used for the method validation by alternate analytical methods to indepen-
dently verify the analysis.
Other points that were presented regarding preparation for a full-scale
method validation are presented below. Some samples prepared for the method
validation should be spiked with potential interferences to define limitations
of the analytical methods. Also, samples of known spiked PCDD concentrations
should be provided to a small group of laboratories as a means of identifying
potential problems with the written analytical method.
One of the more significant contributions was the suggestion to include
actual adipose samples with spiked quality control (QC) samples in the inter-
laboratory study. Actual adipose samples of sufficient mass would be selected
from the repository. These samples would be split and supplied to different
laboratories along with the QC samples. The resulting data from the paired
laboratories should provide some preliminary information on general population
exposure as well as method performance.
Ideally, the method validation study should encompass analyses for tetra-
to octachloro-PCDDs and PCDFs. Realistically, this may not be possible be-
cause of the significant cost and time required to complete a validation of
this magnitude in a single study. It must be kept in mind that the most impor-
tant issue is analysis for 2,3,7,8-TCDD.
DISCUSSION MEETING RECOMMENDATIONS
The discussion meeting was beneficial in identifying several major pro-
grams necessary for the success of the primary analytical method validation
and the proposed population studies. These programs include (a) the need for
establishing a repository of PCDD/PCDF standards of known quality, (b) the
organization and implementation of a strong quality assurance program, (c)
the acquisition of sufficient human adipose to generate a homogeneous sample
matrix for the QA program, (d) independent studies of extraction procedures
using adipose with bioincurred radiolabeled PCDDs, (e) intralaboratory rugged-
ness testing of a proposed analytical method, and (f) interlaboratory evalua-
tion of the proposed method. Simultaneous activity in several of these areas
is necessary in the coming months. The participation of scientists experienced
in analysis of PCDDs and PCDFs is needed in many of these programs to aid in
designing solid approaches for a successful program. The major action items
are discussed in more detail below.
77
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Intralaboratory Testing
A draft of a method will be prepared. The individual steps of the method
will be characterized using clean samples or spiked blanks. The total method
will be evaluated using adipose tissue spiked with PCDDs .and. PCDFs. Carbon-14
radiolabeled PCDDs and PCDFs will be used if available to help define critical
variables in a more rapid fashion than can be achieved with HRGC/MS. Rugged-
ness testing of the method will require varying sample sizes, quantities of
adsorbent, volumes of solvent, etc., to help define the critical variables
and limitations of the method.
The total method including HRGC/MS will be challenged with potential in-
terferences spiked in the sample matrix. A formal method will be written and
will undergo peer review to identify uncertainties in the written instructions.
Tissue Program
A large pool of homogeneous adipose tissue is needed to prepare quality
control (QC) samples for the overall QA program and interlaboratory validation
studies. It is estimated that 40 to 50 kg of adipose tissue are needed to
prepare a sufficient number of control samples at known spiked concentration
levels with and without the addition of potential interferences. The adipose
tissues will be collected through the National Human Monitoring Program net-
work. A repository of the samples will be established. When sufficient sam-
ples are collected (40 to 50 kg total), the samples will be pooled and ren-
dered to provide a homogeneous matrix that will be subdivided for spiking pro-
cedures. The timing of tissue collection is important since these activities
will overlap with the design of the Quality Assurance Program, the Standards
Program and needs of the intralaboratory testing and interlaboratory studies.
The following parameters will be considered for collection of the pool
of adipose tissues. The adipose tissues will be collected from male trauma
victims within 24 hr after death. The specimens will be collected from males
born between 1937 and 1952, which is coincident with birtfidates for veterans
serving in the Vietnam area. All adipose tissues will be frozen until com-
posited for homogenization with other specimen.
A background analysis of the homogenized tissue is necessary to provide
information on the levels of PCDDs, PCDFs, and potential interferences. It
is recognized that the assistance of laboratories (EPA/RTP; University of
Nebraska; Wright State University; Health Protection Branch, Food Division,
Canada; Fish and Wildlife Services) with experience in the analysis of PCDDs
and PCDFs in adipose tissues will be of benefit in obtaining this information
in the most expedient manner. These background analyses must be completed
before proceeding with subdividing the homogeneous tissue for spiking purposes
as designed under the QA program.
78
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Quality Assurance Program
The Quality Assurance Program will influence the success of the overall
program with respect to method validation and performance evaluations for the
routine analysis of tissue samples for population studies. The quality assur-
ance program plan will provide details for preparation of fortified tissue
samples containing PCDDs and potential interferences. The tissue samples
should be spiked with at least one isomer from each PCDD and PCDF homolog.
A subset of QA tissue samples should be spiked with compounds known to
interfere with the analysis of PCDDs and PCDFs. This type of performance
evaluation sample will provide information on the potential for false positive
results.
The QA program will specify the procedures for sample handling, sample
coding, frequency of the spiked QC samples, distribution of samples, data han-
dling, and decoding. The design of the QA program must be initiated immedi-
ately to provide support to the intra- and interlaboratory method validations.
Standards Program
Procurement of a sufficient quantity of PCDD and PCDF congeners of known
quality is essential to provide consistent results from interlaboratory stud-
ies, method validations, and actual analysis programs. There is a critical
need to establish a repository of the PCDD and PCDF compounds. Currently,
participants from the discussion meeting are being surveyed for inventories
of PCDDs and PCDFs in specific laboratories. The information gathered from
this survey will be useful in identifying needs for procurement or synthesis
of specific congeners for the overall program.
Labeled PCDDs are commercially available as carbon-13, chlorine-37, and
carbon-14 labeled TCDDs, and carbon-13 labeled octachlorodibenzo-£-dioxin.
These compounds will be used as surrogates or internal standards for sample
analyses. Stable isotope labeled compounds are not currently available for
penta-, hexa-, and heptachloro-PCDDs or any of the PCDFs. If the overall ob-
jective of the analysis program is to include tetra- through octachloro-PCDDs
and PCDFs, there is a need to study the most cost-effective means to acquire
these compounds.
The standards program will also cover collection of potential interfer-
ences. Polychlorinated biphenyls and DDE are readily available for addition
to samples as interferences. However, compounds such as the chlorinated di-
phenyl ethers, chlorinated benzylphenyl ethers, and chlorinated benzoquinones
may be more difficult to obtain.
Purity of the standard compounds, stable isotope labeled standards, and
potential interferences must be known before these compounds can be used for
spiking the homogenized tissues for the QA program. Once the purity of the
compounds is documented and the repository established, distribution of the
compounds to collaborators may occur. Distribution of the standards will be
most effective by supplying solutions of accurately determined concentrations.
79
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Bioincurred Program
The need to investigate the extraction efficiency of PCDDs and PCDFs from
adipose tissue was discussed at the meeting. A feasible approach to study
the extraction efficiency is through use of tissue with bioincurred compounds.
The use of carbon-14 radiolabeled 2,3,7,8-TCDD in feeding studies will provide
the necessary bioincurred matrix. The recovery of bioincurred carbon-14 la-
beled compound compared to recovery of spiked stable isotope labeled or native
compounds will indicate the adequacy of sample spiking procedures and provide
an absolute extraction efficiency.
The bioincurred program will necessarily require several months for com-
pletion of the study. Again, there is need for the overlap of this study with
other aspects of the total program.
Interlaboratory Studies
Interlaboratory studies are necessary for primary analytical method vali-
dation and background analyses of homogenized tissues. The interlaboratory
studies required for method validation include a preliminary study of three
to four laboratories followed by a full-scale collaborative study with 10 to
12 participants. The preliminary method evaluation will be conducted with
samples of known concentration. The purpose of the preliminary study is to
familiarize the participants with the method and identify potential difficul-
ties of the method. The analytical method will be refined if necessary based
on the preliminary study.
The full-scale method validation will require a significantly larger
number of participants. The samples will include the samples prepared under
the QA program and will be submitted to the participants under blind codes.
The design of the interlaboratory studies should include adipose samples that
are (a) spiked near the method limit of detection, (b) spiked with potential
interferences, and (c) Youden pairs to determine accuracy and precision.
Actual samples may possibly be included in the interlaboratory validation.
These samples would be selected from the pool of samples identified by EPA/OTS
and the VA as representative of the general population and Vietnam veterans.
Figure 21 is an example of such a study. The TAG sample numbers are included
only for illustration purposes. Each actual sample would be split between
two laboratories to provide additional data on the accuracy and precision of
interlaboratory measurements.
Organization of the interlaboratory studies must begin several months
before the actual study. The efforts for organization of the interlaboratory
study will overlap with the quality assurance program, standard program, tis-
sue collection, and intralaboratory studies.
80
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Laboratory
Sample Method Validation
Fat
Fat
Fat + Interf.
Fat + Interf.
Fat + PCDD
Fat + PCDD
Fat + PCDD + Interf.
Fat + PCDD + Interf.
TAG
352
353
354
355
356
357
358
359
A
X
X
X
X
X
X
X
X
1
x ,
.
X
B
X
X
X
X
X
X
X
X
X
X
c
X
X
X
X
X
X
X
X
X
X
D
X
X
X
X
X
X
X
X
X
X
E
X
X
X
X
X
X
X
X
X
X
F
X
X
X
X
X
X
X
X
X
X
G
X
X
X
X
X
X
X
X
X
X
H
X
X
X
X
X
X
X
X
X
X
Figure 21. Example of possible interlaboratory organization.
81
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APPENDIX A
INVITED PARTICIPANTS
82
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"METHODS OF ANALYSIS FOR POLYCHLORINATED DIBENZO-p_-DIOXINS (PCDDs)
IN BIOLOGICAL MATRICES"
EPA/VA/MRI Meeting
April 27-28, 1983
Invited Participants:
Dr. Donald Barnes*
Environmental Protection Agency
401 M Street, S.W.
Mail Drop TS-788
Washington, DC 20460
FTS 382-2897
Dr. David Bayse
Center for Environmental Health
Center of Disease Control
Atlanta, GA 30333
FTS 236-4111
Dr. Warren Bontoyan
Environmental Protection Agency
Building 402
ARC East
Beltsville, MD 20705
FTS 344-2187
Dr. Mike Dellarco
Environmental Protection Agency
Office of Exploratory Research
RD 680
401 M Street, S.W.
Washington, DC 20460
FTS 382-5730
Dr. Fred DeRoos*
Battelle Institute
Columbus Laboratories
505 King Avenue
Columbus, OH 43201
(614) 424-4247
Attendees.
83
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Dr. Joseph Donnelly*
LEMSCO
USEPA/Lockheed
P.O. Box 15027
Las Vegas, NV 89114
FTS 545-2299
Dr. Ralph C. Dougherty*
Department of Chemistry
Florida State University
Tallahassee, FL 32306
(904) 644-5725
Dr. Aubry Dupuy*
USEPA
Toxicant Analysis Center
Building 1105, NSTL
NSTL Station, MS 39529
FTS 494-3212
Dr. David Firestone*
Food and Drug Administration
HFF426
200 C Street S.W.
Washington, DC 20204
FTS 245-1381
Dr. Michelle Flicker*
Vetrans Administration
Kansas City, MO
(816) 861-4700
Dr. Jean Futrell*
University of Utah
Department of Chemistry
Salt Lake City, UT 84112
(801) 581-7307
Dr. Michael Gross
University of Nebraska
Department of Chemistry
Lincoln, NE 68586
(402) 472-2794
* Attendees.
84
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Mr. Robert Harless*
Environmental Monitoring
Systems Laboratory
Environmental Protection Agency
Research Triangle Park, NC 27711
FTS 629-2248
(919) 541-2248
Dr. Harry Hertz
A113, Chemistry
National Bureau of Standards
Washington, DC 20234
Dr. Fred Hileman*
Monsanto Research Center
1515 Nicholas Road
P.O. Box 8, Station B
Dayton, OH 45407
(513) 258-3411
Dr. Mike Hoffman*
USDA, FSIS
Building 318
ARC-East
Beltsville, MD 20705
(301) 344-1846
Dr. Verne Houk
Center for Environmental Health
Center for Disease Control
Atlanta, GA 30333
FTS 236-4111
Dr. Philip C. Kearney
USDA
Building 050
BARC-West
Beltsville, MD 20705
FTS 344-3076
Dr. Lawrence H. Keith*
Radian Corporation
P.O. Box 9948
8501 MoPac Blvd.
Austin, TX 78766
(512) 454-4797
* Attendees.
85
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Dr. Robert Kleopfer*
Environmental Protection Agency
Region VII
25 Fuston Road
Kansas City, KS 66115
(913) 374-4285
Dr. Frederick W. Kutz
Environmental Protection Agency
Office of Toxic Substances, TS-798
401 M Street, S.W.
Washington, DC 20460
FTS 382-3583
Dr. Lester L. Lamparski
Analytical Laboratories
Dow Chemical Company
Building 574
Midland, MI 48640
(517) 636-6207
Dr. W. Ligon*
General Electric
Corporate Research and Development
P.O. Box 8
Building K-l
Schenectady, NY 12301
Dr. Willie May*
A113, Chemistry
National Bureau of Standards
Washington, DC 20234
Dr. James D. McKinney*
National Institute of Environmental
Health Sciences
P.O. Box 12233
Research Triangle Park, NC 27709
Dr. Larry Needham*
Center for Environmental Health
Center of Disease Control
Atlanta, GA 30333
FTS 236-4111
* Attendees.
86
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Dr. Ross J. Norstrom*
Department of the Environment
National Wildlife Research Center
100 Game1in Boulevard
Building 9
Hull, Quebec
Canada
(819) 997-1410
Dr. Patrick O'Keefe*
Center for Laboratories and Research
New York State Department of Health
Empire State Plaza
Albany, NY 12201
(518) 473-3378
Dr. Jim Petty*
Columbia National Fisheries
Research Laboratory
U.S. Fish and Wildlife Service
Department of the Interior
Route 1
Columbia, MO 65201
FTS 276-5399; (314) 875-5399
Mr. David P. Redford*
Environmental Protection Agency
Office of Toxic Substances, TS-798
401 M Street S.W.
Washington, DC 20460
FTS 382-3583
Dr. John J. Ryan*
Health Protection Branch
Food Division
Tunney's Pasture
Ottawa K1A OL2
Canada
(613) 593-4482
Dr. Lewis Shadoff*
Analytical Laboratories
Dow Chemical Company
Building 574
Midland, MI 48640
(517) 636-5584
Attendees.
87
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Dr. David Stalling*
Colmnbia National Fisheries
Research Laboratory
U.S. Fish and Wildlife Service
Department of the Interior
Route 1
Columbia, MO 65201
FTS 276-5399; (314) 875-5399
Dr. Michael Taylor*
Wright State University
Department of Chemistry
Brehm Laboratory
Dayton, OH 45435
(513) 873-3119
Dr. Paul Taylor*
California Analytical Laboratories
5895 Power Inn Rd.
Sacramento, CA 95824
(716) 381-5105
Dr. Anthony Wong*
California Analytical Laboratories
5895 Power Inn Rd.
Sacramento, CA 95824
(716) 381-5105
Major Alvin Young*
Veterans Administration
810 Vermont Avenue, N.W.
Washington, DC 20420
FTS 389-5534
MRI Participants:
Dr. Mitch Erickson
Dr. John E. Going
Dr. Clarence Haile
Mr. Gil Radolovich
Dr. Jim Spigarelli
Dr. John Stanley
(816) 753-7600
FTS 758-6781
* Attendees.
88
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APPENDIX B
DISCUSSION MEETING SCHEDULE OF EVENTS
89
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DISSCUSSION OF
"Methods of Analysis for Polychlorinated Dibenzo-p-Dioxins (PCDD) in
Biological Matrices"
at
Midwest Research Institute
Kansas City, Missouri
April 27-28, 1983
SCHEDULE OF EVENTS
8:30 - 9:00 - Registration of Participants - Arthur Mag Conference Center
9:00 - 9:10 - J. S. Stanley (MRI) Opening Remarks and Introductions
9:10 - 9:25 - David P. Redford (EPA/OTS) Primary Objectives of EPA/OTS in
Assisting the VA with the Sampling and Analysis Program
9:20 - 9:35 - Dr. M. Flicker (VA) Overview of Veterans Administration Agent
Orange Programs
9:35 - 9:55 - J. S. Stanley (MRI) Recommendations for Analytical Method -
Identifying the Primary Issues from Peer Reviews
9:55 - 12:00 - Instrumental Analysis - Discussion
- Low Resolution vs. high resolution mass spectrometry
- Definition of high resolution mass spectrometry
- Compromises between low resolution and high resolution
mass spectrometry
- Quantitation practices
- Criteria for qualitative identification
Low resolution mass spectrometry
High resolution mass spectrometry
Gas chromatography
- Criteria for quantitation
Limits of detection
Limits of quantitation
- Isomer specificity
- What degree of confidence necessary with any method
- Possible interferences
- Quality assurance/quality control procedures
- Role of screening techniques
90
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12:00 - 1:15 - Lunch
1:15 - 2:30 - Instrumental Analysis -Discussion (Concluded)
2:30 - 3:15 - Sample Preparation - Discussion
- Surrogate spiking
- Approaches to preparing spiked samples with native PCDDs
- Extraction procedures—neutral, acid or base
- Cleanup of extract
Advantages and disadvantages of the proposed cleanup pro-
cedures
- Quality assurance/quality control procedures
- Other cleanup procedures
3:15 - 3:25 - Break
3:25 - 5:00 - Sample preparation - Discussion (Concluded)
5:30 - 7:30 - Social Hour (Hilton Plaza Hotel)
April 28, 1983
8:30 - 8:35 - J. S. Stanley - Opening Remarks
,8:35 - 9:00 - A. L. Young - VA Need for Primary Analytical Method
9:00 - 11:00 - Method Validation Studies— ~
- Intralaboratory validation of extraction procedure
- Ruggedness testing of method—intralaboratory approach
- Preliminary inter!aboratory studies
- Full-scale collaborative study
. Number of participating laboratories
. Number of total samples
. Preparation of spiked tissue samples
. Availability of native and isotopically labeled
standards
. Needs for spiking samples with potential interferences
10:15 - 10:25 - Break
10:25 - 12:00 - Summary of Discussions and Recommendations
91
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APPENDIX C
BIBLIOGRAPHY
92
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APPENDIX C
BIBLIOGRAPHY
Adamoli, P., E. Angeli, G. Bandi, A. Bertolotti, E. Bianchi, L. Boniforti, I.
Camoni, F. Cattabeni, G. Colli, M. Colombo, C. Corradi, L. De Angelis, G. De
Felice, A. Di Domenico, A. Di Muccio, G. Elli, R. Fanelli, M. Fittipaldi, A.
Frigero, G. Galli, P. Grassi, R. Gualdi, G. Invernizzi, A. Jemma, L. Luciano,
L. Manaro, A. Marinella, F. Merli, S. Nicosia, F. Rizzello, C. Rossi, G. Rossi,
G. Salvatore, A. Sampolo, G. P. Schmidt, F. Taggi, G. Tebaldi, E. Zaino, and
G. Zapponi, "Analysis of 2,3,7,8-Tetrachlorodibenzo-para-dioxin in the Seveso
Area," in C. Ramel (Ed.), Chlorinated Phenoxy Acids and Their Dioxins, Ecol.
Bull. (Stockholm), 27:31-38 (1978).
Albro, P. W., and B. J. Corbett, "Extraction and Clean-Up of Animal Tissues
for Subsequent Determination of Mixtures of Chlorinated Dibenzo-£-dioxins and
Dibenzofurans," Chemosphere, 7:381-385 (1977).
Albro, P. W., M. L. Luster, K. Chae, S. K. Chaudhary, G. Clark, L. D. Lawsori,
J.T. Corbett, and J. D. McKinney, "Radioimmunoassay for Chlorinated Dibenzo-
£-dioxins," Toxicol. Appl. Pharmacol., 50:137-146 (1979).
Albro, P. W., and C. E. Parker, "General Approach to the Fractionation and
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107
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50272-iOl
REPORT DOCUMENTATION
PAGE
I 1. REPORT NO.
EPA-560/5-84-001
3. Recipient's Accession No.
4. Title and Subtitle
Methods of Analysis for Polychlorinated Dibenzo-£-Dioxins (PCDDs)
and Polychlorinated Dibenzofurans (PCDFs) in Biological Matrices
- Literature Review and Preliminary Recommendations
7. Author(s)
J. S. Stanley
5. Report Date
February 16, 1984
8. Performing Organization Rept. No.
Final Report
9. Performing Organization Name and Address
Midwest Research: Institute
425 Volker Boulevard
Kansas City, MO 64110
10. Project/Task/Work Unit No.
4901-A(6)
11. Contract(C) or Grant(G) No.
(o 68-01-5915 Task 6
(G)
12. Sponsoring Organization Name and Address
Office of Toxic Substances
Field Studies Branch, TS-798
Environmental Protection Agency
Washington, DC 20460
13. Type of Report & Period Covered
Final
10/82 - 8/83
14.
IS. Supplementary Notes
Frederick W. Kutz, Project-Officer
David P. Redford, Task Manager
Daniel T. Heggem, Task Manager
16. Abstract (Limit: 200 words) , . „.. . , , • . t.i 1 j_ • x.
The overall objective of this review and preliminary method recommendation was to
assist the EPA's Office of Toxic Substances (OTS) in proposing an analytical method for
PCDDs in human adipose tissue in conjunction with the Veterans Administration's (VA)
Agent Orange study.
The published literature on polychlorinated dibenzo-p_-dioxins (PCDDs) analyses for
biological matrices was reviewed. The analytical methods are discussed for sample ex-
traction, cleanup, and instrumental analysis.
This report also presents a synopsis of a discussion meeting organized at the re-
quest of EPA/OTS concerning the analysis of polychlorinated dibenzo-g-dioxins (PCDDs)
and polychlorinated dibenzofurans (PCDFs) held at Midwest Research Institute (MRI) on
April 27 and 28, 1983. The primary objective of this meeting was to define the needs
of an analytical method for the analysis of PCDDs and PCDFs in human adipose tissue.
Several major programs were identified as necessary to achieve these goals. These
included (a) the need for establishing a repository of PCDD/PCDF standards of known qual-
ity; (b) the organization and implementation of a strong quality assurance program; (c)
the acquisition of sufficient human adipose tissue to generate a homogeneous sample ma-
trix for the QA program; (d) independent studies of extraction procedures using bioin-
curred radiolabeled PCDDs; (e) intralaboratory ruggedness testing of a proposed analyti-
cal method; and (f) interlaboratory evaluation of the proposed method.
17. Document Analysis a. Descriptors
2,3,7,8-Tetrachlorodibenzo-p_-dioxin
2,3,7,8-TCDD
Polychlorinated dibenzo-p_-dioxins
PCDD
b. Identifiers/Opert-Ended Terms
Chromatography
Mass spectrometry
Cleanup
Extraction
c. COSATI Field/Group
Polychlorinated dibenzofurans
PCDF
Human adipose tissues
Analysis
Literature review
Analytical methods
Recommendations
IS. Availabil^y Etatom-nt
Release unlimited
21. No. of Pages
19. Security Class (This Report)
J Unclassified , 11.2
j 20. Security Class (This Pjxe) j 22. Price
i Unclassified !
df. ANSI-Z39.1S)
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