Visualization and LC/MS Analysis of Colorless Pepper Sprays

• NCJ Number: 206370
• Journal: Journal of Forensic Sciences Volume: 49 Issue: 3 Dated: May 2004 Pages: 469-476
• Author(s): Valerie Cavett B.A.; Eileen M. Waninger B.S.; James J. Krutak Ph.D.; Brian A. Eckenrode Ph.D.
• Date Published: May 2004
• Length: 8 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America
• Note: Portions of this work were presented in poster format at the 50th ASMS Conference on Mass Spectrometry and Allied Topics, 2002.

Annotation

This paper describes the development of a method for ascertaining the presence or absence of colorless, ultraviolet (UV) activated fluorescent dye-free pepper sprays on textiles.

Abstract

Since pepper sprays are used in a variety of circumstances -- including criminal activity, self-defense, and law enforcement -- the presence or absence of pepper sprays on evidentiary materials is often important in determining the facts of an incident. A presumptive method has been developed for the visualization of the capsaicinoids present in pepper sprays that do not contain a colored or UV-activated fluorescent dye, along with a rapid liquid chromatography mass spectrometry (LC/MS) method for analytical confirmation. Chemical derivation of the capsaicinoids was used to create chromophores that are readily observed in the visible region of the electromagnetic spectrum. This paper describes the detailed treatment of the garments to be tested. The sprays were visualized by using a diazonium salt. The appearance of a violet stain provides the presumptive indication of the pepper spray location. This reaction is immediate and permits the visualization of the Oleoresin Capsicum (OC) spray for extraction and subsequent LC/MS analysis. Potential interferences were assessed to determine their effect on the visualization process and whether false-positives would be generated by these substances during the visualization process. The experiment found that interferences from common garment stains were negligible, except in cases where the stain was overly dark (e.g., blood), such that the violet color was overwhelmed. None of the interference tests yielded false-positives. Any false positives obtained through the visualization procedures were eliminated by the confirmatory LC/MS analysis. Because the visualization occurs almost immediately, this method can provide a presumptive identification of pepper sprays in less than an hour. Extraction and LC/MS analysis for confirmation takes slightly longer. 7 figures and 10 references