FIRE DEBRIS INTERPRETATION USING QUANTITATIVE MEASURES OF CHROMATOGRAPHIC FEATURES IN MEDIUM RANGE IGNITABLE LIQUIDS AND THE USE OF GRAPHICAL DISPLAY TO DEMONSTRATE DATA SUFFICIENCY

Ignitable liquid identification is based on pattern recognition techniques using chromatographic patterns.  While the analytical processes associated with the analysis of fire debris for the presence of ignitable liquids are based on fundamental chemical properties, the interpretation process is subjective.  The degree of subjectivity is directly related to the abundance and type of interference from volatile compounds produced by the matrix (inherent, pyrolysis, and combustion products) and the concentration of any ignitable liquid residues present in the sample.  Other than for gasoline, there are no published validated methods for interpretation of these complex samples. This can lead to a lack of consistency in interpretation and reporting within the field for complex samples. This project is designed to establish quantitative measures of assessing the chromatographic features of medium range ignitable liquids and applying statistical measures to create sufficiency parameters for use in interpreting data and rendering conclusions.  A methodology for establishing and measuring variables associated with quantity, quality, and confidence will be optimized and applied to neat ignitable liquids, negative matrix samples, and real world samples composed of mixtures of matrix and medium range ignitable liquids.  The final result will be a foundational validation of the identification of medium range ignitable liquids in fire debris samples.  The end-goal of the proposed project is to generate a quantitative sufficiency graph for reliable data interpretation. Ultimately, the project will make the fire debris experts’ inferential process more standard (by establishing a fully-validated method), objective (by establishing quantitative measures) and visible (by implementing a graphical display of the total data present).