Portable Near-Infrared Spectroscopy as a Screening Test of Corrosive Solutions Concealed in Plastic Containers

Abstract

The use of corrosive substances for criminal intent has recently increased in many countries, with 619 violent assaults recorded from 2019 to 2020 only in the UK. Criminals often conceal corrosive solutions, such as common household cleaners, in inconspicuous plastic bottles and splashing the content in order to incapacitate a victim while committing a robbery or to cause physical harm. There is currently no method available to law enforcement for the safe identification of these corrosive substances without being exposed to them. In this work, the feasibility of a near infrared (NIR) handheld spectrometer for the screening of corrosive inorganic solutions through plastic bottles is investigated. First, a training set comprising samples of five different corrosives was used to build a spectral library for data analysis and chemometric model design. Four models were then tested on three hundred samples of corrosive substances, as well as harmless substances such as water and soft drinks, to evaluate their performance. The models designed identified the corrosive substances in scenarios of concentrated solutions, showcasing the potential capability of this technique for the pre-screening of corrosive substances.

Portable NIR spectroscopy: the route to green analytical chemistry

“…Morillas and Frascione evaluated corrosive and harmless substances, to test the real NIR performance. Each predictive model identified the corrosive substances, enhancing the ability of this technique to pre-screen corrosive substances ( Morillas and Frascione, 2022 ).…”