Spectroscopic trends for the determination of illicit drugs in oral fluid

The present work aims to review all of the articles published so far, focusedon the determination of drugs of abuse in oral fluid. This fluid provides a simpler,faster, and more controllable sampling in comparison with the other biological fluids,such as blood or urine. Actually, the main goal of the researchers is to lower the limitof detection (LOD) to detect quantities of drugs smaller than the cut-off limitsestablished by law for drug controls. Advances in Raman, infrared (IR), and nuclearmagnetic resonance (NMR) spectroscopy applications are discussed. SurfaceenhancedRaman spectroscopy (SERS) has been shown as the most sensitive techniquefor the detection of illicit drugs in oral fluid. The use of IR spectroscopy fordetermining drugs of abuse in oral fluid is growing, although the LODs obtained untilnow do not yet satisfy the necessities in the forensic field. Finally, NMR spectroscopyhas seldom been used to determine drugs in oral fluid. Another future trend seems tobe related with the use of portable instrumentation, which would allow us to performin-situ analysis. This last application seems to be particularly promising to performroadside drug tests and to identify overdose drugs in patients in emergency conditions

Analysis of street cocaine samples in nasal fluid by Raman spectroscopy

The principal objective of this work was to demonstrate the capability of Raman spectroscopy to detectsmall amounts of cocaine in nasal fluid, and to identify the main drug and the most widely used cuttingagents. Initially, standard samples were analysed and sampling conditions were studied by comparingdifferent swabs used for the sample collection. Once the most appropriate swab was selected, whichpermitted a relatively simple detection of the standard cocaine hydrochloride, qualitative analyses of realsamples were carried out. Three street cocaine samples were analysed, and the presence of cuttingsubstances was highlighted by the appearance of different bands not corresponding to the ones of thestandard cocaine. To identify the substances present in each sample, the spectra of the street cocainesamples were collected and compared with a digital library created on purpose with the spectra of themost common cutting agents. In this case, correlation coefficients permitted to recognize the most importantsubstances presumably present in the samples, and gave an estimation of the purity of the cocaine.However, when nasal fluid was present, its strong signal could overlap or interfere with thesmaller signal of the cutting substances, hindering their identification

Chemical classification of new psychoactive substances (NPS)

This work comprehensively reviews some fundamental concepts about drugs, especially focusing on new psychoactive substances (NPS), and their typical classifications based on either their effects (hallucinogens, stimulants or depressants), their origin (natural, synthetic, or semisynthetic), or legal situation (lawful, illicit, or unregulated). These classifications are highly useful in the medicine/legal field, but completely useless for the chemical determination of drugs. Hence, a classification of NPS based on their chemical composition is revised and discussed. This classification seeks to merge those recent and dispersed chemical groupings of NPS found in scientific literature and/or health/drugs reports from World/European/American Institutions facing the illicit use of drugs (WHO, UNODC, EMCDDA, OEDA, DEA, etc.) into a unique general classification, which might be useful for every forensic practitioner/researcher dealing with the identification of new psychoactive substances

Differentiation of blood and environmental interfering stains on substrates by Chemometrics-Assisted ATR FTIR spectroscopy

Blood is the most common and relevant bodily fluid that can be found in crime scenes. It is critical to correctly identify it, and to be able to differentiate it from other substances that may also appear at the crime scene. In this work, several stains of blood, chocolate, ketchup, and tomato sauce on five different substrates (plywood, metal, gauze, denim, and glass) were analysed by ATR FTIR spectroscopy assisted with orthogonal partial least square discriminant analysis (OPLS-DA) models. It was possible to differentiate blood from the environmental interfering substances independently of the substrate they were on, and to differentiate bloodstains according to the substrate they were deposited on. These results represent a proof-of-concept that open new horizons to differentiate bloodstains from other interfering substances on common substrates present in crime scenes

Classification of Various Marijuana Varieties by Raman Microscopy and Chemometrics

Fernando Ortega Ojeda desarrolló el procedimiento de tratamiento estadístico de datos y supervisó los cálculos multivariantes en The Unscrambler y SIMCA. The Raman analysis of marijuana is challenging because of the sample's easy photo-degradation caused by the laser intensity. In this study, optimization of collection parameters and laser focusing on marijuana trichome heads allowed collecting Raman spectra without damaging the samples. The Raman spectra of Delta9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN) standard cannabinoids were compared with Raman spectra of five different types of marijuana: four Sativa varieties (Amnesia Haze, Amnesia Hy-Pro, Original Amnesia, and Y Griega) and one Indica variety (Black Domina). The results verified the presence of several common spectral bands that are useful for marijuana characterization. Results were corroborated by the quantum chemical simulated Raman spectra of their acid-form (tetrahydrocannabinol acid (THCA), cannabidiol acid (CBDA)) and decarboxylated cannabinoids (THC, CBD, and CBN). A chemometrics-assisted method based on Raman microscopy and OPLS-DA offered good classification among the different marijuana varieties allowing identification of the most significant spectral bands.Instituto Universitario de Investigación en Ciencias Policiales (IUICP), Universidad de Alcalá (UAH)

A Practical Beginner's Guide to Raman microscopy

Raman microscopy is a highly suitable and well settled down analytical techniquefor qualitative determination of chemical substances. However, many universityundergraduate chemical degrees do not incorporate its practical training in theexperimental laboratory practises that constitute their curricula. For this reason,this work aimed at designing a practical beginner's guide to Raman microscopyuseful for undergraduate students, teachers or practitioners who need to use it forthe first time. After a brief explanation of the main concepts about Ramanmicroscopy, the methodology development and results interpretation are mainlyexplained using paracetamol (acetaminophen) drugs as example. In addition, thisguide presents an application to the identification of different components withina mixture, which shows the instrumental potential and how to use it effectively.Finally, acetaminophen, ascorbic acid, and sucrose were positively detected usingRaman microscopy on a commercial drug whose major component wasacetaminophen. In fact, the guide shows the detection and unequivocalidentification of different components in the mixtures, even for those lowconcentration components (5-10 % mass ratio). This work clearly proposesdifferent pragmatic criteria at the laboratory for identifying substances in mixturesto promote an easy implementation of the Raman microscopy technique

Source determination of human and animal oral fluid stains on porous substrates by chemometrics-assisted ATR FTIR spectroscopy: A preliminary study

Oral fluids are common evidence that can be found as stains on a variety of substrates at crime scenes. The porosity of the substrate may influence their collection and analysis. Moreover, companion animals, such as dogs, may appear in many scenarios or even be involved in a crime. Determining the source (identification and classification) of human and canine oral fluid stains on different substrates found at crime scene is important prior to DNA extraction to diminish laboratory cost and time efforts. In the present work, the potential of attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR) was explored to study how several types of porous substrates influence in the source determination of human and animal (canine) oral fluid stains. Results showed that the main bands of human or canine oral fluid stains were visible among the characteristic infrared bands of the porous substrates. This allowed the identification of human or animal (canine) oral fluid stains origin in the three types of papers and six fabrics porous substrates studied. Then, the application of Orthogonal Partial Least Square-Discriminant Analysis (OPLS-DA) models to the obtained infrared spectra, allowed the classification of human and canine oral fluid stains independently of the substrate they were deposited on. This approach could be developed for real forensic investigations to distinguish the source (identification and classification) of oral fluid stains as human or animal

Increment of spontaneous human biophoton emission caused by anger emotional states. Proof of concept

Humans spontaneously emit visible radiation from their skin, which is known as biophoton or ultra-weak photon emission (UPE). Up to date, UPE intensity changes according to different external and internal factors have been reported. However, the influence in the human UPE of negative emotional states has never been studied despite their clinic and forensic interest. In this work, an ad hoc system based on a high-sensitive CCD detector was developed to detect and image UPE from human's upper body. Then, the UPE emitted by the upper part of the body of nine volunteers was imaged in two different personal states: (i) when subjects were feeling relaxed; and (ii) when they were emotionally stimulated to feel anger. For all the volunteers, the relative measurement of UPE intensity was higher when feeling anger than when feeling relaxed. Due to the relevance of this disruptive idea and the horizon this knowledge can provide, this proof of concept must be followed by further experiments. An increase in the number of subjects will be accomplished in order to enhance these preliminary results and propose UPE as a new physiological parameter of negative emotional states.Ministerio de Ciencia e Innovación (MICINN

Ultraviolet resonance Raman spectroscopy for the detection of cocaine in oral fluid

Detecting and quantifying cocaine in oral fluid is of significant importance for practical forensics. Up to date, mainly destructive methods or biochemical tests have been used, while spectroscopic methods were only applied to pretreated samples. In this work, the possibility of using resonance Raman spectroscopy to detect cocaine in oral fluid without pretreating samples was tested. It was found that ultraviolet resonance Raman spectroscopy with 239-nm excitation allows for the detection of cocaine in oral fluid at 10 mu g/mL level. Further method development will be needed for reaching the practically useful levels of cocaine detection. (C) 2017 Elsevier B.V. All rights reserved

Electrophoretic fingerprinting of benzodiazepine tablets in spike drinks

Over the last few years, there has been an increase in the reports of drug-facilitated crimes. The list of drugs associated with these crimes is extensive and benzodiazepines constitute one of the groups of substances more commonly used. The sedative properties, which characterize benzodiazepines, are enhanced when such drugs are combined with alcohol, being more attractive for committing these types of crimes. In this work, a capillary electrophoresis method was applied to the analysis of 63 different samples of club drinks spiked with benzodiazepine tablets. The resulting electropherograms were processed and analyzed with the chemometric multivariate techniques: principal component analysis (PCA) and soft independent modeling of class analogies (SIMCA) classification. The PCA results allowed a clear differentiation of each drug class in a 3D plot. In addition, the SIMCA classification model (5% significance level) showed that eight out of nine test samples were automatically assigned by software to their proper sample class. The conflicting sample was correctly classified in the Coomans? plot (95% confidence). This novel approach based on the comparison of electrophoretic profiles of spiked drinks by chemometric tools allows determining the benzodiazepine used for drink spiking without the use of drug standards.Moreover, it provides an opportunity for the forensic laboratories to incorporate the identification capability provided by the electrophoretic fingerprinting of benzodiazepine solutions in existing or new databases