Systematic Comparison of Pre-Treatment Parameters in Forensic Hair Analysis and Investigating Hair-drug Interactions

Authors

Jennett Chenevert Aijala, Florida International UniverstyFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Chemistry

First Advisor's Name

Anthony P. DeCaprio

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Bruce McCord

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Kevin O'Shea

Third Advisor's Committee Title

Committee memeber

Fourth Advisor's Name

John Berry

Fourth Advisor's Committee Title

Committee memeber

Fifth Advisor's Name

Deodutta Roy

Fifth Advisor's Committee Title

Committee member

Keywords

forensic hair analysis, design of experiments, LC-QqQ, UV/Vis

Date of Defense

5-18-2020

Abstract

Forensic toxicological analysis for the purposes of protecting human health and supporting criminal justice activities can be achieved, in part, by means of analysis of human head hair for detection of abused substances. Hair is considered an alternative sample matrix (compared to blood and urine) because of persistent interpretive challenges caused by a lack of standardization in analytical approaches and poor understanding of the biases resulting from physicochemical interactions between major hair components (e.g., melanin) and drugs of abuse. Some of the uncertainty regarding optimal techniques for the pre-treatment of hair specimens results from the unknown nature of the interactions between drugs and hair components, in particular melanin. Thus, the second focus of this work was to study these interactions with select drugs and melanin by UV/Visible spectroscopy. Another source of uncertainty is attributed to the lack of standardization in the analytical approach to hair testing. As a complex solid sample matrix, hair requires pre-treatment measures including decontamination, homogenization, and extraction to remove drug from the hair components to allow for analysis. Optimizing these pre-treatment parameters is essential for accurate toxicological analysis of this matrix. Thus, a major focus of this work was to conduct a comprehensive comparison of the efficacy of decontamination and extraction variables by means of statistical design of experiments (DoE).

Major findings of this work were a minimum of four consecutive washes were necessary for the decontamination of hair and solvent swelling of the matrix resulted in the highest extraction of the five analytes under study. The other major conclusion of this work was the interaction between eumelanin and drugs is a result of ionic interactions and van der Waals forces. Additionally, association constants between drugs and eumelanin were determined to provide additional insight into the strength of interactions between drugs with different physicochemical properties and eumelanin.

These findings will impact the forensic science community by contributing to a body of research aimed at determining the most effective method(s) for decontaminating hair samples for forensic analysis, the subsequent isolation of drugs from hair, and by investigating the interactions between melanin and select drugs of abuse.

Identifier

FIDC008999

Recommended Citation

Aijala, Jennett Chenevert, "Systematic Comparison of Pre-Treatment Parameters in Forensic Hair Analysis and Investigating Hair-drug Interactions" (2020). FIU Electronic Theses and Dissertations. 4521.
https://digitalcommons.fiu.edu/etd/4521