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thesis entitled

EXPLOSIVES DECONTAMINATION OF
LABORATORY WORKBENCH SURFACES

presented by

Stephanie Jo Eckerman

has been accepted towards fulfillment
of the requirements for

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EXPLOSIVES DECONTAMINATION OF
LABORATORY WORKBENCH SURFACES

By

Stephanie Jo Eckerman

A THESIS
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
School of Criminal Justice

1999

ABSTRACT

EXPLOSIVES DECONTAMINATION OF
LABORATORY WORKBENCH SURFACES

By

Swphanie J o Eckerrnan

Instrumental sensitivity mandate that precautions be taken to ensure integrity of
explosives evidence after submission to the laboratory for examination. The risk of
invalidating potentially compelling explosives evidence by neglecting the possibility of
contamination is a concern of the forensic science community, and attention to cross-
contamination of cases is of the utmost importance. The laboratory bench
decontamination project examines the effectiveness of 4090 spray cleaner as a simple
decontamination procedure for removal of explosives residues on two types of common
laboratory bench surfaces. Bench swab samples were analyzed via gas chromatography /
thermal energy analysis (GC/TEA) for both qualitative and quantitative analyses.
Samples 1 microliter in size were used in the analysis. Acetone served as a blank and an
acetone solution containing 700ng/mL FNT, 750ng/mL NG, TNT, PETN, and RDX, and
75ng/mL EGDN was used as a standard. Results indicate that the use of the spray
cleaner alone is not sufficient in the decontamination of benches, and should be coupled

with a solvent wipe-down to provide an adequate level of decontamination.

ACKNOWLEDGEMENTS

I would like to acknowledge the Bureau of Alcohol, Tobacco and Firearms (ATF)
National Forensic Science Laboratory in Rockville, Maryland for the opportunity to
perform research at their facilities. I would especially like to thank ATF scientists Greg
Czarnopys and Tyra McConnell for their assistance throughout the project, as well as the

rest of the ATP laboratory staff.

.0.

TABLE OF CONTENTS

ADDITIONAL WORKSCONSULTED............

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LIST OF TABLES

TABLE 1: Amount of explosives in nanograms deposrted and recovered

from benches...

...10

INTRODUCTION

In order for the criminal justice system to function as it is designed to do so, every
aspect of the process must be performed as thoroughly and accurately as possible.
Ensuring quality in the analysis of forensic evidence is no exception, and an area of
serious concern for forensic scientists is in evidence cross-contamination between case
materials. The risk of invalidating potentially compelling trace evidence by neglecting
the possibility of contamination is a concern of evidence analysts and criminal justice
personnel alike.

In light of the recent negative publicity gained by various forensic laboratory
agencies, attention to contamination issues is of the utmost importance. However, a
literature review indicates that there has not been a considerable amount of written work
concerning contamination in forensic work, and very little discussion addressing
contamination concerning explosive materials.

Moore, Jackson and F irthl carried out a controlled study concerning
contamination in a trace laboratory by examining the movement of several types of
fibers. While transfer of some types of fibers fi'om one area of a laboratory to another
area within the same room was recorded, they concluded that the quality assurances
procedures practiced by the laboratory provided a sufficient safety margin to preclude
any threat of habitual contamination issues.

Kennedy and Stevens2 have addressed the issue of contamination as it pertains to
a medical context. The use of tracer materials and fluorescent dyes included in simulated

patient blood samples revealed widespread contamination throughout the laboratory and

failure of basic hygiene practices. An issue such as this is especially alarming when
samples containing the hepatitis B virus or HIV are handled The study concluded that
the use of tracers in a clinical setting is helpful when assessing the quality of hygiene
practices and in determining patterns of contamination.

Cool? addresses the issue of contamination in a forensic setting from a variety of
evidential sources such as fibers, paint, glass, firearms, body fluids in dried stains,
including a brief reference to explosive residues. A list of precautions includes cleaning
of workbenches, using disposable paper on work surfaces, changing laboratory coats or
attire between examinations, and physical separation of space of examinations.

One reference was found that addresses the issue of contamination as it pertains to
a trace explosive laboratory. Todd‘ conducts forensic investigations involving the
criminal misuse of explosives on the UK Mainland at the Forensic Explosives Laboratory
based at Fort Halstead in England His paper addresses some issues of cross-
contamination that have arisen in trials. In particular, contamination does occasionally
occur in the trace examinations area of the laboratory; however, the explosives found
were of a level less than 10ng, a background level below which no casework results were
regarded as significant. In this laboratory, contamination prevention includes dedicating
a suite of rooms in which only trace explosives contamination is carried out Samples
come in contact with only disposable surfaces (gloves, disposable glassware and plastic
tools), all bench surfaces are first cleaned, then covered with a protective paper barrier
before examinations, and monitor samples are analyzed from the laboratory benches,

floors and walls on a weekly basis.

While all of these papers and studies address the issue of contamination in a
forensic setting of one type or another, none present a set of guidelines that have been
tested in order to prevent or control contamination of a workspace in an explosives
laboratory setting. This research project will look specifically at the areas of explosives
evidence and the potential for and preventative measures against cross-contamination in
the form of effective decontamination procedures to be followed between case
examinations.

The purpose of the decontamination project is twofold First is to investigate the
ability of a workbench surface to retain high explosives residues. Explosives residues are
commonly encountered in a laboratory setting when a solvent extract of a piece of
explosives evidence is prepared, when an explosives standard solution is prepared for use
in analysis comparisons, or when explosives evidence arrives at the laboratory in the
form of a solution. Both a black epoxy resin surface and a white Formica surface were
analyzed The second purpose of the project is to investigate the effectiveness of an
ordinary, household spray cleaner (409‘) to eliminate traces of explosives residues from
the workbench surfaces.

The project was conducted at the Bureau of Alcohol, Tobacco and Firearms
(ATP) Forensic Science Laboratory in Rockville, Maryland outside of Washington, DC
through an internship opportunity in conjunction with the ATP and Michigan State
University. The internship and project were necessary for the completion of the Master
of Science in Criminal Justice with Specialization in Forensic Science degree and was
carried out over the months of May, June, July and August of 1999. The project was
organized into several steps. The first step consisted of a background check of the

fourteen workbenches used in the examination of explosives evidence in the explosives
section of the ATF laboratory. The second step involved creating calibration solutions
and a calibration program to use in the instrumental analysis of data fiom the project.
The third and fourth steps of the project concerned the deposition and recovery of
explosives residue samples on the two types of workbench surfaces in question. The
final step addressed the instrumental analysis of the samples and the interpretation of the
results. The methods used in the above steps will be explained in detail in the following

section.

METHODS

A background check of the workbenches used in the explosives section of the
ATF laboratory was performed before the actual decontamination project was initiated.
The background check, although not crucial to the project itself, gave an indication as to
whether or not low-level contamination of the workbenches was a concern for the
laboratory. The background check was performed by swabbing each of the fourteen
benches in question with first a dry, sterile cotton gauze pad, followed by a swabbing of a
different area of the bench with a sterile cotton gauze pad wetted with lmL of acetone.
The area swabbed on each bench was approximately four inches square. The bench
surfaces swabbed were a combination of the two surfaces previously mentioned. The
swabs (28 total) were placed in sterile vials containing 3mL of an internal standard
acetone solution. The internal standard, also referred to as ISTD, was FNT
(fluoronitrotoluene) at a concentration of 700ng/mL. The FNT in acetone internal

standard solution was used as an extraction solution throughout the project to monitor the

4

sensitivity of the instrumental analysis to ensure the instrument was working properly.
FNT, a compound not explosive in nature, was chosen as the internal standard since it is
easily detected by the instrument used in the analysis, and will not interfere with the
explosives’ signals. Instrumental analysis was performed with a gas chromatograph/
thermal energy analyzer (GC/I'EA).

Combining a TEA detector with a gas chromatograph is a useful and popular
method of instrumental analysis for nitrogen-containing compounds. As effluent from
the chromatograph enters a pyrolyzer, N02 is released from organic nitrosyl compounds
and converted into NO by a catalytic surface. Pyrolysis products and solvent vapors are
removed by a cold trap, and the remaining N0 gas reacts with ozone in a reaction
chamber. A characteristic infrared chemiluminescent reaction occurs, and its intensity is
monitored by an infrared-sensitive photomultiplier tube. The GC/I'EA method of
analysis for explosive compounds is both sensitive at the picogam (10 "2) level and
highly selective. The use of a TEA detector coupled with a gas chromatograph in the
analysis of explosive compounds has been documented in many instances as being a
selective and efficient method Fine, Yu and Goff5 found that the TEA analyzer
interfaced to a GC was a useful tool for the analysis of explosive residues in a wide
variety of forensic as well as environmental applications. The authors found the method
of analysis to be simple, rapid, needing little sample preparation or clean-up due to its
selectivity, and capable of detecting explosives at low picogram levels from cotton swabs
and “real world” samples of post-explosion residues. Douse'5 and LaFleur and
Morriseau7 had similar findings to Fine, et al. using a TEA detector coupled with a gas

chromatograph and a high-performance liquid chromatograph, respectively. I-Iiley8 states

that GC/TEA analysis of explosives is the principal analytical tool used at the Defence
Research Agency, UK

After the bwkground swabs had been in the extraction vials for four hours, the
FNT in acetone solution was extracted from the vials, filtered using a Gelman mini-filter
attached to a disposable sterile syringe, and placed in a small, sterile sample vial. The
desired extraction time of four hours was determined by creating test samples and leaving
them in vials for two, four, and six hours. The two-hour time length did not allow
enough of the swabbed materials to be extracted into the solvent, and the six-hour time
period gave the same results as the four-hour period. Therefore, the four-hour period was
chosen for efficiency. One microliter of each sample was then analyzed via GC/TEA and
the results were processed using ChromQuest® software. The FNT in acetone solution
was used as a blank throughout the project and was run between each sample and
standard. A standard explosives solution was used as the standard throughout the project
as well. The standard solution consisted of 750ng/mL of the explosives NG
(nitroglycerine), TNT (2,4,6-trinitrotoluene), PETN @entaerythritol tetranitrate), and
RDX (cyclotetramethylene trinitramine), 750nymL of the ISTD (internal standard)
solution, FNT in acetone, and 75ng/mL of the explosive EGDN (ethylene glycol

dinitrate). Parameters for the instrumental analysis are as follows:

GC: 5890 Hewlett Packard Gas Chromatograph
Column: Supelco SPB-5 (5% diphenyl, 95% dimethylsiloxane)
Length: 15 m
ID: 0.32 mm
Film thickness: 0.25 um
Guard column: 36 inches Supelco SPB-5
Temperature program: Initial temperature 35°C
Ramp 5°C/minute to 200°C
Column head pressure: lOpsi, Helium
TEA: Thermo Electron Corporation, TEA Model 510 Nitrogen Analyzer
Oxygen Flow to Ozonator: ZOcc/min
Pyrolyzer Temperature: GC = 800°C
GC Interface Temperature: 175°C

Upon completion of the background laboratory workbench check, a series of
calibration solutions were made and a calibration program was created to aid in the
analysis of the project data The calibration solution series consisted of four solutions
containing the explosives and ISTD mentioned above (NG, TNT, PETN, TNT, RDX,
FTN and EGDN) with the explosives and ISTD having a concentration of 200ng/mL,
300ng/mL, 500ng/mL and 750ng/mL. The exception was in the case of the explosive
EGDN whose concentration was 20ng/mL, 30ng/mL, 50ng/mL and 75ng/mL in each of
the four solutions, respectively. The four calibration solutions were each analyzed five
times using GC/I'EA. These concentrations represent a broad scale of the types of
solutions that could be encountered in an analytical laboratory setting. The concentration
of the calibration solutions were also chosen based upon the initial concentration of the
standards supplied by the company from which they were purchased Throughout the
project, the explosive EGDN had a concentration one factor lower than that of the other

explosives. This, too, was due to the initial concentration of the supplied standard.

Deposition and recovery of the deposited materials were performed on a white,
Formica bench surface and a black epoxy resin surface. These two bench surfaces are
representative of the types of surfaces found throughout the explosives laboratory. The
two particular benches used in the deposition step of the project were chosen arbitrarily.
Before deposition, the test surfaces were thoroughly cleaned with soap and water,
followed by a cleaning with 409°”. The deposition on the benches was performed by first
creating test tiles by taping off 20 squares approximately four inches square on each
bench (40 tiles total). The area of four inches square was decided upon by the area of the
bench available to dedicate to the project, and by the number of trials that were deemed
necessary to give the desired amount of data with which to work To purposely
contaminate the surfaces, lmL of an explosives solution containing 1000ng/mL of NG,
TNT, PETN, and RDX, and lOOng/mL of EGDN was applied to each tile. This
concentration is on the high end of the scale of solution concentrations that would be
encountered in the laboratory. It was determined that the deposition solution should be
made more concentrated than what would be typically encountered in the lab to truly
determine if the resulting decontamination measures are adequate for the spills or
contamination situations that are commonly encountered.

The explosives from ten tiles from each surface (20 tiles from the total 40) were
then recovered immediately upon drying of the deposited sample. The recovery was
performed in the same manner as the background swabbing of the laboratory benches in
that a sterile, cotton gauze pad was wetted with lmL acetone and each tile was swabbed

The swab was then placed in a sample vial containing 3mL of the ISTD solution, FNT in

acetone. After four hours, the solvent was extracted, filtered, and placed in a new sample
vial. One microliter of the extract was then used in instrumental analysis.

The remaining ten tiles from each surface were allowed to dry as well, and were
then cleaned with 409°. After the application of 409’, the final ten tiles from each
surface were then swabbed as the initial tiles were, and extracted in a similar manner.
The forty samples were then armlyzed via GC/TEA under the parameters described

earlier.

RESULTS

Of the fourteen benches examined in the background laboratory workbench
check, only two benches initially showed the presence of any amount of trace explosive.
Both benches possessed a white Formica surface, and explosives were recovered from the
acetone swab only. Since the background check was qualitative in nature only, the actual
amount of explosives recovered was not known. Bench 1 of the background check gives
a positive indication for the presence of the explosive RDX. Bench ll of the background
check gives a positive indication for the presence of the explosive TNT.

The five trials from each of the four calibration solutions were averaged and a plot
of the calibration solution peak area over the internal standard peak area versus the
concentration of the calibration solution over the concentration of the internal standard
was created for each calibration solution The equation that was used to calculate the plot

was then used to later determine the amount of explosives recovered fiom the benchtops

in nanograrns.

The results obtained from the analysis of the forty explosives samples recovered
from the two test workbenches were placed into one of four groups and averaged The
four groups are best described as pre-409 black bench, post-409 black bench, pre-409

white bench, and post-409 white bench These averages appear below in Table 1.

TABLE 1: Amount of explosives in nanograms deposited and recovered from benches

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EGDN NG TNT PETN RDX
Theoretical 100 1000 1000 1000 1000
deposition
Actual 127.5 771 996 822 1000
Deposition
Black bench 0 237 106.5 220.5 220.5
recovery pre-409®
Black bench 0 143.25 55.5 73.5 147.75
recovery post-
409®
White bench 0 420 52.5 369.75 502.5
recovery pre-409®
White bench O 64.5 21 10.5 84
recovery post-
409®

 

As the table indicates, the actual amount of explosives recovered is compared to the
theoretical amount of explosives deposited as well as the actual amount of explosives
deposited The theoretical amount of explosives deposited is lOOOng for the explosives
NG, TNT, PETN, and RDX, and 100ng for EGDN. The actual amount of explosives
deposited was determined by depositing lmL of the standard explosives solution used in

the depositions directly onto a cotton swab and treating the swab in a manner similar to

10

that of the samples swabbed fiom the benches. The amount of explosives was then
calculated from the chromatograph results using ChromQuest® software.

Upon the completion of the initial swabs of the 40 tiles, each tile was swabbed
once again with an acetone swab to determine if any residual explosives could be
detected. The swabs were subject to the same treatment as the others, and the results

indicated that no explosives remained from either surface.

CONCLUSIONS

It should first be stated that while the initial background check of the fourteen
benches used in the examination of explosives evidence in the ATF laboratory did
indicate the presence of trace explosives on two of the benches, this check was performed
unbeknownst to the scientists and without warning. Many of the scientists had open
explosives cases on their benchtops, and as is the general procedure, these benchtops
were covered in a protective, wax based paper. The swabbing of the benches took place
beneath this paper, an area with which, theoretically, no evidence would ever come in
contact. The results of the background check did come as a surprise to some of the
scientists; however, no one was concerned that the explosives laboratory had or has an
on-going contamination issue.

An initial concern afier examining the results of the project itself was the
discrepancy between the amount of explosives theoretically deposited and the amount of
explosives actually deposited. The most likely explanation is human error. In an

experiment of this nature, the possibility for human nature can arise in several forms.

11

The first possibility for error is in the preparation of the standard solution, but a more
likely explanation is loss of explosives due to transfer between the swab and the gloved
hand of the scientist performing the recovery, and the extraction procedure itself. Also,
the explosives EGDN and NG may succumb to a loss in amount due to evaporation
These reasons may also help to explain why the theoretical amounts of explosives were
not recovered from the benches prior to cleaning with 409®.

Based upon the results, it can be determined that more explosives were recovered
fiomthe white bench surfacethantheblackbench surfaceinthecaseofthetrials cleaned
with 409® before recovery. The use of 409® also appears to be more effective in the
elimination of explosive residues from the white bench surface than the black bench
surface. These results can most likely be explained by the nature of each of the surfaces
themselves. The black, epoxy resin surface is a more porous, uneven surface than the
smooth, white Formica surface. This would account for a smaller amount of explosives
being recovered initially, as well as the larger amount of explosives remaining after
cleaning the surface with 409® as crevices allow for residues to be trapped and not easily
accessible for recovery by swabbing.

The elimination of all traces of explosives fiom both surfaces in each scenario
following a swabbing with an acetone swab indicates that cleaning with 409® is not
effective as a sole decontamination technique. Coupling a solvent wipe-down following
a cleaning with 409® appears to provide the level of decontamination necessary for the
quality of work expected by a forensic science laboratory.

While the ATF laboratory practices careful examination mchniques and analysts

take precautions when handling evidence, there are no written protocols mandating how

12

to prepare a work area between cases. Many common procedures are used, but this study
helped to validate or invalidate those practices, and recommend a protocol that, when
followed, will hopefully control for the possibility of cross-contamination between
explosives cases.

Finally, the two bench surfaces analyzed in this project were not only common
throughout the ATF laboratory, but throughout many laboratories universally, forensic in
nature or otherwise. This study appears to indicate that at least in the area of explosives,
the smooth, white Formica workbench surface retained the contaminant explosive
solution at a lesser rate than the porous, black epoxy resin surface. This fact may help to
promote the use of a similar Formica surface to ensure the maximum level of

decontamination possible.

FUTURE RESEARCH

Since the research was carried out in a working laboratory, casework often took
precedence over the project. The laboratory possessed only one GC/TEA instrument set-
up, and case samples would sometimes occupy the instrument for weeks at a time.
Therefore, the initial goals of the project were much more ambitious than what was
actually accomplished due to this situation. As is the case for any research endeavor, this
project has the possibility for continuation and further exploration in many areas, several
of which were included in the initial project proposal.

The first of these areas is the examination of different laboratory surfaces. While
the two bench surfaces analyzed in this project are common to many laboratories, other

surfaces may be subject to explosives residues, such as floors, instrument surfaces, door

13

surfaces, and other, less common bench surfaces. A type of bench surface may even exist
where a recovery rate close to 100% can be obtained.

Another variable to be explored is the deposition samples. This project looked at
explosives residues which can occur in the extraction of a piece of explosives evidence
and other scenarios. Another possibility, and one that was initially hoped to be explored
by this project, is the deposition of bulk explosives, which are often encountered in
explosives casework. The amount and the combination of explosives used can also be
varied.

A final variable in this project is the investigation of the effectiveness of other
decontamination methods. Possibilities include a further examination of a soap and water
method, a bleach solution, solvents other than acetone, and any combination of these
methods.

Also, throughout the course of standard explosives evidence analysis, workbench
surfaces are covered in a wax-based paper. An interesting aspect of the project that could
be explored is the porosity of this paper covering, and whether or not it is durable enough

to prevent explosive solutions from seeping through to the bench surface.

14

WORKS CITED

15

WORKS CITED

. Moore, et al. “Movement of fibres between working areas as a result of routine
examination of garments.” Journal of the Forensic Science Society 1986: 26, 433-
440.

. Kennedy and Stevens. “Tracing of laboratory contamination: quality control
approach.” Lancet 1988: 1, 471-472.

. Cook “The Problem of Contamination.” Police Surgeon 1981: 20, 65-66.

. Todd. “Contamination Issues in a Trace Laboratory Environment.” Papers from the
6"“ International Symposium on Analysis and Detection of Explosives. Prague, Czech
Republic, July 6-10, 1998.

. Fine, Yu, and Goff. “Applications of the nitro/nitroso specific detector to explosive
residue analysis.” Symposium on Analysis and Detection of Explosives, Quantico,
Virginia, 1983.

. Douse. “Trace analysis of explosives at the low picograrn level using silica capillary
column gas chromatography with thermal energy analyzer detection.” Journal of
Chromatography 1983, 234: 415-425.

. LaFleur and Morriseau. “Identification of explosives at trace levels by hi gh-
perforrnance liquid chromatography with a nitrosyl specific detector.” Analytical
Chemistry 1980, 53: 1313-1318.

. Hiley. Quality control in the detection and identification of traces of organic high

explosives in Forensic Investigation of Explosives. Defence Research Agency,
Crown Copyright. England: 1993.

ADDITIONAL WORKS CONSULTED

Beveridge. “Development in the detection and identification of explosives residues.”
Forensic Science Review June 1992: 4:1, 18-48.

Brunelle, et al. “A Quality Assurance Program for the Laboratory Examination of Arson
and Explosives Cases.” Journal of Forensic Sciences 1982, 27:4, 774-782.

Cook. “The Problem of Contamination.” Police Surgeon 1981: 20, 65-66.

16

Goff, et al. “Description of a nitro/nitroso specific detection for the trace analysis of
explosives.” Symposium on Analysis and Detection of Explosives, Quantico, Virginia,
1983.

Hiley. Quality control in the detection and identification of traces of organic high
explosives in Forensic Investigation of Explosives. Defence Research Agency, Crown
Copyright. England: 1993.

Moore, et al. “Movement of fibres between working areas as a result of routine
examination of garments.” Journal of the Forensic Science Society 1986: 26, 433-440.

Policy and Procedure Guideline, Evidence Handling, Explosives Evidence,
Contamination Prevention, Contamination Protocols 1. Bureau of Alcohol, Tobacco and
Firearms, Revision 6, January 1999.

Todd “Contamination Issues in a Trace Laboratory Environment.” Papers fiom the 6‘h
International Symposium on Analysis and Detection of Explosives. Prague, Czech
Republic, July 6-10, 1998.

Wooten. Memorandum from the Assistant Director of Firearms, Explosives and Arson,
ATF. Interim Guidelines for the Prevention of Explosives Contamination

Yinon and Zitrin. Modern Methods and Applications in Analysis of Explosives. John
Wiley and Sons, Ltd. England: 1993.

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