April 2006 - Volume 8 - Number 2

Standards and Guidelines

The National Center for Forensic Science Ignitable Liquids Reference Collection and Database

Stephen P. Allen
Technical Manager
National Center for Forensic Science
University of Central Florida
Orlando, Florida

Mary R. Williams
Chemist
National Center for Forensic Science
University of Central Florida
Orlando, Florida

Craig Bryant
Forensic Scientist
Centre of Forensic Sciences
Toronto, Ontario, Canada

Doug Byron
Forensic Chemist
Forensic and Scientific Testing, Inc.
Atlanta, Georgia

James Cerven
Director
Illinois State Police Crime Laboratory
Carbondale, Illinois

Bradley D. Cooper
Forensic Chemist
Forensic Science Laboratory
Bureau of Alcohol, Tobacco, Firearms and Explosives
San Francisco, California

Dennis C. Hilliard
Director
Rhode Island State Crime Laboratory
Kingston, Rhode Island

Judi Hoffmann
Forensic Chemist
Forensic Science Division
Montana State Crime Laboratory
Missoula, Montana

Jason Kwast
Criminalist
Contra Costa County, California, Sheriff’s Criminalistics Laboratory
Martinez, California

Sherrie A. Thomas
Forensic Chemist
Forensic Science Laboratory
Bureau of Alcohol, Tobacco, Firearms and Explosives
Atlanta, Georgia

Carrie M. Whitcomb
Director
National Center for Forensic Science
University of Central Florida
Orlando, Florida

History | Ignitable Liquids Reference Collection and DatabaseFuture Work | References | Appendix A | Appendix B |

History

A national survey of forensic science laboratories conducted in 1998 revealed that an ignitable liquid reference collection and database were the most important needs in the fire debris analysis community (Allen et al. 2000). In August 1999, members of the Technical Working Group for Fire and Explosions (TWGFEX) declared an interest in meeting this need. The database would include the total ion chromatogram and the extracted ion profiles of ignitable liquid products. Associated with this database would be a repository of ignitable liquids available to forensic science laboratories and maintained by the National Center for Forensic Science (NCFS) at the University of Central Florida in Orlando. An ad hoc committee of TWGFEX members was established to begin developing the database and repository.

In February 1999, in anticipation of forming an operational committee, TWGFEX worked to derive a Definition of Work for the project. The objectives were to establish, maintain, and provide a comprehensive, single source for ignitable liquids and a comprehensive gas chromatography-mass spectrometry (GC-MS) database for ignitable liquids. The committee sought to provide an accurate, dependable product to the forensic community in a reasonable amount of time and at an affordable cost.

The Ignitable Liquid Reference Collection Committee (ILRCC), made up of TWGFEX members, was established to give oversight to the database and repository. The committee includes 8 to 10 members from the fire debris analysis community (Appendix A). The NCFS at the University of Central Florida, the American Academy of Forensic Sciences, and a contracted laboratory were all considered logical locations for the repository, with the NCFS chosen as the designated facility. NCFS personnel are permanent members of the ILRCC to give continuity to its operations and to ensure the integrity of the repository.

The goal of the ILRCC was to have a single laboratory produce and disseminate data on the ignitable liquids that may be found in fire debris. Considerations important to the committee included:

• Establishing the database in a 12- to 18-month time frame.

• Ensuring a long-term commitment.

• Using existing capital equipment.

• Maintaining the same laboratory and technician, if possible.

• Designating an on-site supervisor.

• Guaranteeing the ability of an oversight committee to manage and ensure quality.

• Maintaining a minimum of 300 reference ignitable liquids; 500 would be preferable.

• Providing data with each ignitable liquid sample.

• Including data on extracted ion profiles.

• Using total ion chromatograms.

• Dedicating one mass spectral instrument to facilitate the project.

• Validating test results prior to making data available.

• Using a consistent approach regarding analytical procedures.

• Using analytical methods approved by the American Society for Testing and Materials (ASTM).

• Maintaining the database on the NCFS Web site.

• Determining access restrictions to the database and repository.

• Remaining alert to increased workloads, with a decrease expected after 18 to 24 months.

The committee’s function was to specify which standards should be collected and which samples were appropriate for evaporation, as well as to determine GC-MS conditions and to review all data. In the interest of obtaining samples from wide geographical areas, the committee solicited volunteers to submit liquid samples to the repository.

The Ignitable Liquids Reference Collection and Database

Ignitable liquids serve many purposes required by society and fall within a variety of commercial classifications and subclassifications. Examples of ignitable liquids included in the database are gasoline; refinery stock; camping fuels; naphthas; specialty solvents; cleaners; charcoal starters; paint thinners; kerosene; jet fuels; lamp oils; diesel fuels; fuel oils; cleaners; paint thinners; charcoal starters; aviation gasoline; and refinery specialty mixtures, such as normal alkane, isoalkane, aromatic, and dearomatized mixtures. Also included are multiple brands and grades of each product; seasonal variations in these products; non-petroleum-based products such as turpentine; oxygenated mixtures; and other ignitable liquids that do not fall into a specific category. Certain samples are also evaporated for the database.

Requested information for each sample includes documentation of provenance, source, refinery, distributor or retailer, geographic location, listed formulation, intended uses, the manufacturing process, and the manufacture or purchase date. Initially, it was considered important to have liter amounts of the ignitable liquid so that a sufficient sample would be available for distribution from the reference collection. Additional liters are necessary if the sample is evaporated. Selected products within each class are available in a variety of increasingly evaporated states, including 25, 50, 75, 90, 95, and 98 to 99 percent of the original volume. The archived amount is sufficient to last 10 to 15 years. Classification is based on the ASTM E1618 classification scheme (ASTM International 2005a). Sources of samples include refineries and manufacturers, distributors, and commercially available retail products.

Selected products, particularly commercial brands sold in chain stores, are collected from different geographical areas of production, refineries, lots, and years. Eventually, bacterially degraded liquids will be added. Samples, either adsorbed on activated carbon or as neat liquids in glass ampoules in a 2-milliliter volume, are available from the repository to qualified laboratories (government and private) upon request. Neat liquids are not available for evaporated standards because of the depleted volume remaining after the evaporation process.

A Web-based inventory list, with ordering via the Internet, is now available at http://www.ncfs.org (click on “databases”). As of November 2005, the database contained 370 reference samples with an additional 45 to be added. Most of these samples are available from the NCFS repository to laboratories that request them. An order form is available on the Web site. A total of 2,472 reference samples have been sent from the repository to laboratories throughout the United States.

The current analytical protocol used for the database is found in Appendix B.

Future Work

The ILRCC also considered the availability of a pyrolysis product reference database. Forensic scientists would find a database of matrix and pyrolysis products useful because a wide variety of these components are observed in fire debris. The committee recognized that developing such a database involves extraordinary requirements. Sample preparation and analysis will be performed on a variety of substrates: slightly burned, heavily burned, and unburned. Consistency in preparation and analysis is critical. The importance of a manufactured burn chamber is recognized, as is the design of a pyrolysis technique that is realistic to fire scenarios. Possible cooperation with a fire-testing laboratory also is appropriate. The ASTM E1412 method of sample preparation will be used for these samples (ASTM International 2005b).

The pyrolysis database will include 100 to 150 materials and substrate material combinations, including the following: wood (hardwoods and softwoods used in construction and furniture); carpets (interior, exterior, foam-backed, and padding); linoleum; other floor coverings; asphalt; fabrics (all major fiber types); upholstery and batting; plastics; adhesives; and other miscellaneous materials.

An ignitable liquid microbial degradation database has also been considered; however, it is a lower-priority project. It will be initiated after the pyrolysis database is in place.

For information regarding the database or repository, contact Ms. Mary Williams, NCFS, P.O. Box 162367, Orlando, Florida 32816, or by e-mail at natlctr@mail.ucf.edu.

References

Allen, S. P., Case, S. W., and Frederick, C. Survey of forensic science laboratories by the Technical Working Group for Fire and Explosions (TWGFEX), Forensic Science Communications [Online]. (January 2000).

ASTM International. ASTM E1618-01 Standard test method for ignitable liquid residues in extracts from fire debris samples by gas chromatography-mass spectrometry. In: Annual Book of ASTM Standards 2005. Volume 14.02, ASTM International, West Conshohoken, Pennsylvania, 2005a.

ASTM International. ASTM E1412-00 (2005) Standard practice for separation of ignitable liquid residues from fire debris samples by passive headspace concentration with activated charcoal. In: Annual Book of ASTM Standards 2005. Volume 14.02, ASTM International, West Conshohoken, Pennsylvania, 2005b.

Appendix A: Committee Membership

The current members of the Ignitable Liquid Reference Collection Committee are Ms. Sherrie A. Thomas (chair), Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), Forensic Science Laboratory, Atlanta, Georgia; Mr. James Cerven (former chair), Illinois State Police Crime Laboratory, Carbondale, Illinois; Mr. Steve Allen, National Center for Forensic Science (NCFS), Orlando, Florida; Mr. Carl Anglesea, NCFS; Mr. Craig Bryant, Centre of Forensic Sciences, Toronto, Ontario, Canada; Mr. Doug Byron, Forensic and Scientific Testing, Inc., Atlanta, Georgia; Mr. Bradley D. Cooper, ATF, Forensic Science Laboratory, San Francisco, California; Mr. Dennis C. Hilliard, Rhode Island State Crime Laboratory, Kingston, Rhode Island; Ms. Judi Hoffmann, Montana State Crime Laboratory, Missoula, Montana; Mr. Jason Kwast, Contra Costa County Sheriff Criminalistics Laboratory, Martinez, California; Mr. Matthew Saluto, Colorado Bureau of Investigation, Montrose, Colorado; Dr. Michael Sigman, NCFS; and Ms. Mary Williams, NCFS.

Membership on the ILRCC has changed over the years. The following individuals are former members of the committee who are familiar with its mission and operation: Dr. William McGee, former director, NCFS, Orlando, Florida; Mr. Carl Chasteen, former TWGFEX chair, Florida State Fire Marshal’s Fire and Arson Laboratory, Havana, Florida; Ms. Julia Dolan, ATF, Fire Research Laboratory, Ammendale, Maryland; Ms. Mary Holt, Alabama Department of Forensic Sciences, Birmingham, Alabama; Mr. Dale C. Mann, MDE Laboratory, Seattle, Washington; Mr. Wayne Moorehead, Orange County, California, Sheriff’s Department Laboratory, Santa Ana, California; and Mr. Jack Nowicki, Illinois State Police, Chicago, Illinois.

Appendix B: Ignitable Liquids Reference Collection Analytical Protocols, Revised 04/26/2004

The following protocol is used for Ignitable Liquids Reference Collection (ILRC) samples received at NCFS.

When samples are received, several tasks must be completed. The first is a flame test to determine if the liquid sample is ignitable. Once a sample is deemed ignitable, a bar code is assigned, and the sample is transferred into liter bottles. Labels are placed onto the bottles, which are placed into the refrigerator, where they are stored.

The ILRC manager maintains four logbooks. The first logbook is the Maintenance logbook, in which records of repairs, replacement parts, column change, or any other changes made to the gas chromatograph-mass spectrometer are recorded. The second logbook is the Quality Assurance logbook. Daily and weekly quality assurance data—such as pressure, retention times, autotunes, and chromatograms—are recorded and kept. The third logbook, the Sample Description logbook, includes information on each sample—such as bar code number, brand/product name, intended use, date received, date purchased, source, location, and quantity. The last logbook maintained is the Product Folder logbook. This logbook contains material safety data sheets with bar codes, along with the total ion chromatograms, a product quality report (if available), and a photograph of the original retail container.

The instruments used in the ILRC laboratory are an Agilent (Hewlett-Packard (HP), Agilent Technologies Incorporated, Palo Alto, California) 6890 gas chromatograph with a Model 5973 mass spectrometer. An Agilent ALS G2614A autosampler is used with a Merlin septumless injector. The injected sample volume for all samples is 1 µl and is analyzed with a split ratio of 1 to 50. The sample is analyzed by a 25-meter HP-1 column with an internal diameter of 0.20 mm and a film thickness of 0.5 µm. High-purity-grade helium with a flow rate of 0.8 ml per minute is used as the carrier gas. The temperature of the injection port is held constant at 250°C. Temperature programming is used in these analyses, with the initial temperature held at 50°C for 3 minutes. The temperature is then ramped at 10°C per minute until a final temperature of 280°C is attained. The temperature is then held for 4 minutes, for a total run time of 30 minutes for each sample.

Daily and weekly quality assurance procedures are performed and recorded. The daily quality assurance procedures include:

1. Checking the pressure of the carrier gas and replacing when necessary.

1. Performing an autotune and ensuring that such parameters as pressure, electron multiplier voltage, peak widths, mass, and relative abundance generated are within an optimal range set forth by the manufacturer.

1. Injecting a carbon disulfide (CS₂) blank, which ensures that the system is clean of any residue.

1. Analyzing an ASTM E1618 standard mixture and recording the retention times of octane and eicosane in the Quality Assurance logbook. The total ion chromatograms of both the ASTM mixture and the CS₂ blank are recorded in the logbook.

Weekly QA procedures include performing tune evaluations and control-charting the retention times of octane and eicosane. A C₆-C₂₀ straight-chain hydrocarbon sample can be analyzed initially after parameters are established and subsequent to any parameter changes, as needed.

Sample preparation is classified into three categories: medium-carbon-range liquid samples, high-carbon-range liquid samples, and low-carbon-range liquid samples. In all three categories, sample preparation begins with labeling vials with bar codes that correspond to the bar code recorded in the Sample Description logbook. Before samples are prepared, the CS₂ is checked for contamination. This is accomplished by preparing a fresh vial of CS₂ for the daily quality assurance protocols being performed. The resulting chromatogram is examined for contamination. Preparation for the medium-carbon-range liquid samples requires that 20 µl of the sample be pipetted into the correctly labeled vial. Next, 1 ml of CS₂ is added to the vial along with one drop of deionized water, and the vial cap is crimped closed. Ignitable liquids that fall into the high carbon range are prepared according to the ASTM E1412 extraction method by placing a drop of the sample liquid into a metal can with an activated charcoal strip. The can containing the activated charcoal is placed into an oven and gently heated for 16 to 24 hours. The carbon strip is removed from the metal can and placed into the appropriately labeled vial. One ml of CS₂ is added to the vial. After the addition of a small amount of deionized water, the vial is crimped closed. Samples having a low carbon range are prepared by transferring 0.5 to 1.0 ml of the ignitable liquid into an appropriately labeled screw-cap vial.

For medium- and high-carbon-range samples, the autosampler is used. However, for the low-carbon-range samples, manual injection is necessary using the wet-needle method. This method uses no solvent and deposits approximately 0.2 µm of the sample liquid into the injection port of the GC-MS. All samples are analyzed using ILRC methods. A CS₂ blank is analyzed between each sample to ensure no carryover from sample to sample. The run sequence is printed out and placed into the Quality Assurance logbook. To verify repeatability, fresh samples are prepared and analyzed for a second time, approximately two to three days after the first analysis.

Data analysis includes obtaining, saving, and printing the total ion chromatograms for the CS₂ blanks, the ASTM standard mixture, and all reference samples. Extracted ion profiles for the reference samples are also obtained and are transferred to a Microsoft Excel spreadsheet along with the total ion chromatograms for the sample.