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Ultraviolet resonance Raman spectroscopy for the detection of cocaine in oral fluid
... Raman spectroscopy has been used for regular analysis in forensic toxicology because of offering rapid determination, performing nondestructive, quantification of accuracy and purity of drug without any specific reagent. So, it has become the most popular and used analytical tools to the determination of illicit drugs such as cocaine, heroines, marijuana, and other illegal drugs of abuse [29][30][31][32]. (see Figure 4) ...
... Cocaine is usually found in two forms of chemical structure: Freebase Cocaine HCl, both have a different physical appearance like as powder (Freebase and Cocaine HCl), Paste (Freebase) and crack rocks (Freebase) [29][30][31][32]. ...
... B) Freebase paste in white color C) Crack rocks D) Powder form: HCl cocaine E) powder form: Freebase cocaine. [29] the type of the drug at the time of seizure may suggest the route of traffic and the way of distribution [30,31,33]. ...
The conventional technologies used for identifying, investigating, and analyzing illegal drugs, explosives, and fibers in forensic science often involve destructive methods, preventing re-analysis of evidence. Conversely, a non-destructive approach is crucial for drug characterization, synthesis route development, and identification of counterfeit and adulterated pharmaceuticals. Raman spectroscopy, renowned for its rapid, non-destructive, and cost-effective nature, has emerged as the predominant technique in forensic and pharmaceutical applications. Its inelastic light scattering properties enable drug identification, minimize forensic toxicology and criminalistics, and ensure pharmaceutical product quality. This review explores the analysis of cocaine, RDX, HMX, PETN and TNT in forensic science, where Raman spectroscopy proves invaluable in detecting and quantifying drugs and explosives, deciphering synthesis routes, identifying manufacturing labs, and unveiling trafficking patterns and distribution networks. Additionally, it examines the analysis of acyclovir, ciprofloxacin, and active pharmaceutical ingredients (APIs) in the pharmaceutical industry, offering insights for quality control, combating counterfeit and adulterated products, and facilitating real-time process monitoring. Despite limitations, recent advances in data analysis techniques position Raman spectroscopy as a versatile and promising tool for sample analysis, investigation, and determination in both forensic science and pharmaceuticals, illuminating the path towards enhanced analytical capabilities in these fields.
... Resonance Raman spectroscopy (RRS) relies on exciting vibrational bonds at a laser wavelength close to resonance for an increased signal and has been employed in several studies incorporating Raman and saliva. [105][106][107][108] Most notable, however, is surface-enhanced Raman spectroscopy, where Raman scattering is combined with plasmonic materials, supporting electron-light excitations at a surface to considerably increase the Raman signal, often by many orders of magnitude. [12] 1.3.4. ...
... Saliva for Raman studies is frequently acquired from a commercial source. Purchased saliva sample studies include Shende (Lee Biosolutions), [141] Muro (Lee Biosolutions and Bioreclamation), [154] Muro (Biological Specialty Company, Lee Biosolutions, Bioreclamation), [155] D'Elia (Bioreclamation), [105] Eom (Lee Biosolutions), [197] and Al-Hetani (Bioreclamation). [239] Obtaining saliva from a commercial source may simplify subsequent steps in saliva storage and measurement and negate problems regarding collection and questions on optimal preprocesses e.g., centrifugation. ...
... A majority of Raman-saliva studies employ a lab-based commercial system ( Figure 3D), [12] most commonly applying an excitation laser wavelength of 514/532 nm, 633 nm or 785 nm ( Figure 3C). As an exception, D'Elia et al. [105] uses stimulated resonance Raman at 239 nm excitation, establishing a LoD of 10 lg/mL for cocaine in artificially mixed saliva-cocaine samples while pointing out that a laser excitation at 200 nm could decrease the LoD further with significant sensitivity improvement required for forensic drug detection (8 ng/mL). The movement toward shorter excitation wavelengths confers a significant benefit in terms of signal due to the 1/(wavelength) 4 dependence of the Raman scattering intensity. ...
The use of Raman spectroscopy combined with saliva is an exciting emerging spectroscopy-biofluid combination. In this review, we summarize current methods employed in such studies, in particular the collection, pretreatment, and storage of saliva, as well as measurement procedures and Raman parameters used. Given the need for sensitive detection, surface-enhanced Raman methods are also surveyed, alongside chemometric techniques. A meta-analysis of variables is compiled. We observe a wide range of approaches and conclude that standardization of methods and progress to more extensive validation Raman-saliva studies is necessary. Nevertheless, the studies show tremendous promise toward the improvement of speed, diagnostic accuracy, and portable device possibilities in applications such as healthcare, law enforcement, and forensics.
... In previous works, we studied in detail the Raman spectra of COC in water and in OF [24,25]. The assignment of the COC and OF Raman bands were based on literature reports. ...
... The assignment of the COC and OF Raman bands were based on literature reports. Considering this, none of the characteristic spectral bands obtained for the bare Au NRs interfered with the dominant bands of COC or OF [16,24,25]. Fig. 3 shows the comparison between the RS and the SERS spectra of the COC aqueous solutions, at the corresponding lowest COC concentrations detectable in our experiments. ...
... For this reason, the variation of The LOD were estimated by monitoring the gradual disappearance of the selected COC band in the different spectra until that band reached a S/N ≈ 3. This method in detecting COC in OF was successful used before in Ultraviolet Resonance Raman spectroscopy studies [25]. As is evident for RS in Fig. 5, COC was only observed at the highest concentration, 1 mg/mL (10 6 ng/mL). ...
This work shows the capability of surface-enhanced Raman spectroscopy (SERS) to detect ultratraces of cocaine (COC) in oral fluid (OF). It proposes a new solid substrate made of gold nanorods (Au NRs) to perform sensitive analyses of this complex matrix without any sample pretreatment. The Au NRs were synthetized optimizing the synthesis conditions, and then characterized and tested as SERS substrate. The presented results demonstrated that the SERS methodology was able to detect COC in OF with a limit of detection (LOD) as low as 10 ng/mL. This value was five orders of magnitude smaller than the one obtained with Raman spectroscopy (RS) and in the order of the cut-off value (8 ng/mL) established for confirmatory test of COC in OF. Besides, a multivariate analysis (OPLS-DA) applied on the samples analysed by SERS evidenced that it was possible to discriminate among various COC concentrations. These are quite positive results because even the 1 ng/mL COC concentration sample could be identified as different from the OF sample. In addition, the absence of sample pretreatment and the ease of the proposed method, allowed performing rapid and non-destructive analyses, making the method suitable for in situ forensic analyses.
... At present, high-cost reagents and time-consuming assays are often employed in the laboratory for drug identification, including for example, gas chromatography with mass spectrometry (GC/MS), high-performance liquid chromatography (HPLC), and ELISA with the more rapid and portable technique of colorimetric testing lacking specificity and being subjective. [31,81,[85][86][87][88][89][90][91][92][93][94][95] At the point of need, drug testing often requires fast, inexpensive and selective testing and Raman analysis of saliva offers a potential solution, which in contrast to urine, often contains parent compounds. [81,96] Furthermore, when an illicit compound has been ingested, this can lower analytical sensitivity requirements due to contamination of the oral cavity via direct contact with the illicit substance. ...
... D'Elia et al. opted for a different strategy instead by utilizing UV Raman to detect cocaine to a cutoff value of 10 lg/mL, noting that moving further into the UV (200 nm) could increase analytical sensitivity further. [92] Farquharson et al. used a spectral database of drugs to determine cocaine at 50 ng/mL in spiked saliva, being adjudged similar to structural analogue cocaethylene (ethylbenzoylecgonine), which exhibited a comparable "hit quality index" metric value. [98] ...
The study of salivary manifestation of various health disorders via Raman spectroscopy, as a noninvasive molecular sensing technique to analyze molecular signatures in the saliva projections of health, is an emerging field of investigation of combined spectroscopy-biofluidics for early-diagnostics and monitoring, enabling structural and chemical biomarkers to be monitored overtime to predict prognosis for translation to real-world sensing applications. Here, we review the potential uses in healthcare, illicit drug detection, forensics and dental/orthodontic uses, and expound the specific challenges related to the detection of certain classes of biomolecules or smaller compounds. We highlight the potential of extracellular vesicles, a salivary constituent and its potential as an emerging vehicle for medical applications. Furthermore, portable devices for Raman-saliva based detection are discussed with a specific attention on the associated microfluidic advances for miniaturization and integration of such technologies and multimodal systems are examined. Given the low concentrations of target analytes and thus, the high analytical sensitivity required, surface-enhanced Raman spectroscopy (SERS) methods are noted across the different application areas and for development of portable devices.
... Analysis of drugs found at the scene is one thing, but knowing whether an individual involved in a crime is under the influence of drugs is also important in criminal investigations. Therefore, D'Elia et al. performed a study utilizing ultraviolet resonance Raman spectroscopy in order to detect cocaine in oral fluid [54]. The study found that at a 239-nm excitation, oral fluid shows insignificant absorption, allowing the signature of the cocaine to be enhanced via resonance phenomenon, successfully identifying cocaine in biological samples with drug concentrations as low as 10 ng/mL. ...
Vibrational spectroscopy combined with machine learning has a great potential for forensic applications. For example, handheld Raman spectroscopic instruments are already used by law enforcement agencies for precise, confirmatory identification of drugs. Beyond drug identification, several emerging technologies based on vibrational spectroscopy are currently under development for forensic investigative purposes, including the analysis of questioned documents, gunshot residue, fabrics, soil, hair, nails, and nail polish. This article provides a comprehensive overview of the application of vibrational spectroscopy in various areas of forensic analysis, particularly focusing on forensic serology and the analysis of trace evidences. In the case of forensic serology, the methodology allows for determining complex aspects of serological casework, including the time since deposition of a stain, as well as the phenotypic profile of the stain donor—namely, sex, race, and age. Furthermore, gunshot residues can be accurately identified by grain, caliber, and manufacturer when Raman spectroscopy is paired with machine learning. This integration of advanced spectroscopic techniques with machine learning holds great promise for furthering both the accuracy and efficiency of investigations, helping to reduce the total backlog of evidence investigation currently plaguing modern forensic laboratories.
... The detection of cannabis in the field of forensic science focuses on the quantitative analysis of these three compounds. 4 THC− COOH as a biosynthetic precursor of THC and an intermediate product of the THC metabolism is another crucial detection target of cannabis in urine. 5 Among the detection techniques of cannabis, chromatography is considered to be a powerful method for determining cannabis in biological samples (blood, urine, and hair) owing to its high accuracy, precision, and good sensitivity. ...
Cannabis is the most prevalent abused substance after alcohol, and its consumption severely harms human health and thus adversely impacts society. The identification and quantification of cannabis in urine play important roles in practical forensics. Excitation–emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor (PARAFAC) analysis was developed to identify and quantify the four main ingredients of cannabis in urine samples. The main ingredients of cannabis including Δ-9-tetrahydrocannabinol (THC), cannabidiol, cannabinol, and tetrahydrocannabinolic acid (THC–COOH) exhibited diverse fluorescence characteristics, and the concentrations of these compounds depicted a positive linear relationship with the fluorescence intensity at the ng/mL level. The EEM/PARAFAC method adequately characterized and discriminated the four ingredients in calibration and prediction samples with a low root-mean-square error of prediction (RMSEP; 0.03–0.07 μg/mL) and limit of quantitation (LOQ; 0.26–0.71 μg/mL). The prediction results of the EEM/PARAFAC method well correlated with that of GC–MS with a low RMSEP range (0.01–0.05 μg/mL) and LOQ range (0.07–0.44 μg/mL) in urine samples. The EEM spectroscopic investigation coupled with the PARAFAC algorithm results in an organic, solvent-less, fast, reliable tool to perform accurate and rapid screening of cannabis abusers.
... Another application of UVC irradiation is optical spectroscopy with the emission of exciting UVC light and detection of a fluorescence signal in the UVB, near UV and visible ranges. These methods are used to identify various substances, including various hazardous bio and chemical agents, explosive substances [38][39][40], drugs [41,42], molecular assemblies, such as peptides/proteins [43], as well as the traces of water and organic molecules in astrobiology research, including the study of Mars [44,45], etc. It is especially important to ensure the development of UVC emitters operating in the range of λ = 200-250 nm, where strong fluorescence cross sections improve the detection sensitivity. ...
Powerful emitters of ultraviolet C (UVC) light in the wavelength range of 230-280 nm are necessary for the development of effective and safe optical disinfection technologies, highly sensitive optical spectroscopy and non-line-of-sight optical communication. This review considers UVC emitters with electron-beam pumping of heterostructures with quantum wells in an (Al,Ga)N material system. The important advantages of these emitters are the absence of the critical problem of p-type doping and the possibility of achieving record (up to several tens of watts for peak values) output optical power values in the UVC range. The review consistently considers about a decade of world experience in the implementation of various UV emitters with various types of thermionic, field-emission, and plasma-cathode electron guns (sources) used to excite various designs of active (light-emitting) regions in heterostructures with quantum wells of AlxGa1-xN/AlyGa1-yN (x = 0-0.5, y = 0.6-1), fabricated either by metal-organic chemical vapor deposition or by plasma-activated molecular beam epitaxy. Special attention is paid to the production of heterostructures with multiple quantum wells/two-dimensional (2D) quantum disks of GaN/AlN with a monolayer's (1 ML~0.25 nm) thickness, which ensures a high internal quantum efficiency of radiative recombination in the UVC range, low elastic stresses in heterostructures, and high-output UVC-optical powers.
... Another application of UVC irradiation is optical-spectroscopy with the emission of exciting UVC-light and detecting fluorescence signal in the UV-B, near UV and visible ranges. These methods are used to identify various substances, including various hazardous bio-and chemical agents, explosive substances [36 -38], drugs [39,40], molecular assemblies, such as peptides/proteins [41], as well as the traces of water and organic molecules in astrobiology research, including the study of Mars [42,43], etc. It is especially important to ensure the development of UVC-emitters operating in the range of λ = 200 -250 nm, where strong fluorescence cross sections improve the detection sensitivity. ...
Powerful emitters of the ultraviolet C (UVC) light in the wavelength range of 230-280nm are necessary for the development of effective and safe optical disinfection technologies, high-sensitive optical spectroscopy and non-line-of-sight optical communication. This review considers such UVC-emitters with electron-beam pumping of heterostructures with quantum wells in the (Al,Ga)N material system. The important advantages of these emitters include the absence of the critical problem of p-type doping and the possibility of achieving record (up to several tens of watts for peak values) output optical power values in the UVC range. The review consistently considers about a decade of world experience in the implementation of various UV emitters with various types of thermionic, field-emission, and plasma-cathode electron guns (sources) used to excite various designs of active (light-emitting) regions in heterostructures with quantum wells AlxGa1-xN/AlyGa1-yN (x = 0 − 0.5, y = 0.6 − 1) fabricated either by metal-organic chemical vapor deposition or by plasma-activated molecular beam epitaxy. Special attention is paid to the production of heterostructures with multiple quantum wells/two-dimensional(2D) quantum disks GaN/AlN with a monolayer (1ML ~ 0.25nm) thickness, which ensures a high internal quantum efficiency of radiative recombination in the UVC range, low elastic stresses in heterostructures, and a high output UVC-optical powers.
... The growing number of seizures has increased the use of analytical techniques geared toward combating drug trafficking [2,3]. Techniques such as high-performance liquid chromatography (HPLC) [9][10][11][12][13][14], gas chromatography (GC) [15][16][17][18], and spectroscopy have been applied more frequently in expert laboratories [19][20][21][22]. However, these techniques have drawbacks. ...
The large number of drug seizures has required the development of electrochemical sensors and new analytical techniques involving portable sensors. Here, we have studied cocaine hydrochloride oxy-reduction on the surface of carbon paste electrodes chemically modified with [VIIO(salen)], and we have evaluated these electrodes as voltammetric sensors for forensic purposes. The modified working electrode for cocaine hydrochloride analysis presented the sensitivity was 1.2 µmol.L⁻¹, and the mean limits of detection and quantification were 0.31 and 1.03 µmol.L⁻¹, respectively. As for the possible interferents, the investigated analytes exhibited similar electrochemical activity, with different sensitivities. Supervised classification of the data for the detection of analytes by the SIMCA chemometric method revealed that the voltammetric methodology predicted cocaine in real samples seized by the police more effectively than the other analytes. Thus, the developed voltammetric sensor has potential use in forensic investigations.
... The signal yield in UVRR is further aided by the fact that Raman scattering intensity increases by m 4 where m is the optical frequency of the excitation laser. UVRR spectroscopy has been implemented as a bioanalytical tool to study nucleic acids like DNA and RNA [19,20], various proteins and peptides [21][22][23] including amide band monitoring [24], protein-drug interactions [25,26], and even detection of cocaine in oral fluid [27]. It has also been applied to the field of supramolecular chemistry, in particular for label-free monitoring of molecular recognition between peptides/proteins and supramolecular/artificial ligands such as guanidiniocarbonyl pyrroles (GCPs) [28][29][30][31][32]. GCPs are a class of artificial receptors carrying a carboxylate binding site (CBS) where acidic carboxylates of peptides/proteins can be recognized. ...
We present a UVRR spectroscopy setup which is equipped with a picosecond pulsed laser excitation source continuously tunable in the 210-2600 nm wavelength range. This laser source is based on a three-stage optical parametric amplifier (OPA) pumped by a bandwidth-compressed second harmonic output of an amplified Yb:KGW laser. It provides < 15 cm⁻¹ linewidth pulses in the relevant UV tuning range which is sufficient for resolving Raman lines of samples in condensed phase studies. For demonstrating the capability of this tunable setup for UVRR spectroscopy we present its application to artificial ligand guanidiniocarbonyl pyrrole (GCP), a carboxylate binder used in peptide and protein recognition. A UVRR excitation study in the range 244 to 310 nm was performed for identifying the optimum laser excitation wavelength for UVRR spectroscopy of this ligand (λmax = 298 nm) at submillimolar concentrations (400 µM) in aqueous solution. The optimum UVRR spectrum is observed for laser excitation with λexc =266 nm. Only in the relatively narrow range of λexc = 266-275 nm UVRR spectra with a sufficiently high signal-to-noise ratio and without severe interference from autofluorescence (AF) were detectable. At longer excitation wavelengths the UVRR signal is masked by AF. At shorter excitation wavelengths the UVRR spectrum is sufficiently separated from the AF, but the resonance enhancement is not sufficient. The presented tunable UVRR setup provides the flexibility to also identify optimum conditions for other supramolecular ligands for peptide/protein recognition.
... Therefore, a method which could assess the quality of a food product and perform a multicomponent characterization at the first level test represents an important issue when dealing with the monitoring of food quality or human health. For this reason, innovative screening systems, able to rapidly process samples without requiring any pretreatment or clean up, in a non-destructive way, are becoming more and more recommended (Dunn et al., 2011;Risoluti et al., 2016Risoluti et al., , 2019aD'Elia et al., 2018). Reference analytical procedures for milk analyses usually require chromatographic techniques, such as High Performance Liquid Chromatography associated to Mass Spectrometry (HPLC-MS) (Chotyakul et al., 2014;Aiello et al., 2015;Rocchetti et al., 2020), Gas Chromatography coupled to Mass Spectrometry (GC-MS) (Marchetti et al., 2002;Materazzi and Risoluti, 2014;Teng et al., 2017), and Nuclear Magnetic Resonance (NMR) (Garcia et al., 2012;Crea et al., 2014;Santos et al., 2016;Aiello et al., 2018). ...
In this work, an innovative screening platform based on MicroNIR and chemometrics is proposed for the on-site and contactless monitoring of the quality of milk using simultaneous multicomponent analysis. The novelty of this completely automated tool consists of a miniaturized NIR spectrometer operating in a wireless mode that allows samples to be processed in a rapid and accurate way and to obtain in a single click a comprehensive characterization of the chemical composition of milk. To optimize the platform, milk specimens with different origins and compositions were considered and prediction models were developed by chemometric analysis of the NIR spectra using Partial Least Square regression algorithms. Once calibrated, the platform was used to predict samples acquired in the market and validation was performed by comparing results of the novel platform with those obtained from the chromatographic analysis. Results demonstrated the ability of the platform to differentiate milk as a function of the distribution of fatty acids, providing a rapid and non-destructive method to assess the quality of milk and to avoid food adulteration.
... Though the signal from nasal fluid made it more difficult to identify cutting agents present in the samples, the authors noted that Raman spectroscopy still serves as a valuable tool for cocaine detection in biological fluids-even if an extraction is required prior to analysis. In 2018, D'Elia et al. analyzed mixtures of cocaine and oral fluid [50]. They found that ultraviolet resonance Raman spectroscopy at 239 nm excitation could be used to detect cocaine in oral fluid at levels as low as 10 mg/mL without the need for sample pretreatment. ...
This review recounts recent developments in Raman Spectroscopy with regards to forensic science. Topics covered in this manuscript include: chemometrics, controlled substances, toxicology, counterfeit pharmaceuticals, explosives, gunshot residue, hair, fibers, paints, lipstick and nail polish, body fluids, forensic anthropology, and document examination.
... Compared to other methods such as X-ray imaging, magnetic resonance imaging (MRI) and ultrasound imaging, optical methods are safer and simpler. Recently, a large variety of non-invasive in vivo optical tissue diagnostic techniques has been developed, such as optical coherence tomography (OCT) [1,2], laser speckle contrast imaging (LSCI) [2,3], confocal microscopy (CM) or, more specifically, confocal laser scanning microscopy (CLSM) [4,5], Raman and coherent anti-Stokes Raman spectroscopy (CARS) [6,7], Raman microscopy [8][9][10][11], surface-enhanced Raman scattering (SERS) [12][13][14], fluorescence spectroscopy [15,16], multiphoton microscopy (MPM) [4,5,[17][18][19][20][21], including CARS tomography [22], fluorescence lifetime imaging [23,24], second harmonic generation (SHG) imaging [25], etc. However, the main limitations of the optical imaging techniques are due to strong light scattering in tissue layers and blood, which causes low contrast and spatial resolution, as well as a small probing depth for visible and near-infrared light [26][27][28]. ...
This paper aims to review recent progress in optical clearing of the skin and over naturally turbid biological tissues and blood using this technique in vivo and in vitro with multiphoton microscopy, confocal Raman microscopy, confocal microscopy, NIR spectroscopy, optical coherence tomography, and laser speckle contrast imaging. Basic principles of the technique, its safety, advantages and limitations are discussed. The application of optical clearing agent on a tissue allows for controlling the optical properties of tissue. Optical clearing-induced reduction of tissue scattering significantly facilitates the observation of deep-located tissue regions, at the same time improving the resolution and image contrast for a variety of optical imaging methods suitable for clinical applications, such as diagnostics and laser treatment of skin diseases, mucosal tumor imaging, laser disruption of pathological abnormalities, etc.
Here, the fluorescence properties of some plant-based drug samples are characterized using a coherent excitation source at 405 nm. The laser-induced fluorescence (LIF) spectroscopy is examined to analyze opium and hashish. In order to improve traditional fluorescence methods for better analysis of optically dense materials, we have proposed five characteristic parameters based on solvent densitometry assay as the fingerprints of drugs of interest. The signal emissions are recorded in terms of various drug concentrations, such that the best fitting over experimental data determines the fluorescence extinction (α) and self-quenching (k) coefficients according to the modified Beer-Lambert formalism. The typical α value is determined to be 0.30 and 0.15 mL/(cm∙mg) for opium and hashish, respectively. Similarly, typical k is obtained 0.390 and 1.25 mL/(cm∙mg), respectively. Furthermore, the concentration at max fluorescence intensity (Cp) is determined for opium and hashish to be 1.8 and 1.3 mg/mL, respectively. Results reveal that opium and hashish benefit their own characteristic fluorescence parameters to discriminate those illicit substances promptly using the present method.
Purpose
The use of alternative matrices in toxicological analyses has been on the rise in clinical and forensic settings. Specimens alternative to blood and urine are useful in providing additional information regarding drug exposure and analytical benefits. The goal of this paper is to present a critical review on the most recent literature regarding the application of six common alternative matrices, i.e., oral fluid, hair, sweat, meconium, breast milk and vitreous humor in forensic toxicology.
Methods
The recent literature have been searched and reviewed for the characteristics, advantages and limitations of oral fluid, hair, sweat, meconium, breast milk and vitreous humor and its applications in the analysis of traditional drugs of abuse and novel psychoactive substances (NPS).
Results
This paper outlines the properties of six biological matrices that have been used in forensic analyses, as alternatives to whole blood and urine specimens. Each of this matrix has benefits in regards to sampling, extraction, detection window, typical drug levels and other aspects. However, theses matrices have also limitations such as limited incorporation of drugs (according to physical–chemical properties), impossibility to correlate the concentrations for effects, low levels of xenobiotics and ultimately the need for more sensitive analysis. For more traditional drugs of abuse (e.g., cocaine and amphetamines), there are already data available on the detection in alternative matrices. However, data on the determination of emerging drugs such as the NPS in alternative biological matrices are more limited.
Conclusions
Alternative biological fluids are important specimens in forensic toxicology. These matrices have been increasingly reported over the years, and this dynamic will probably continue in the future, especially considering their inherent advantages and the possibility to be used when blood or urine are unavailable. However, one should be aware that these matrices have limitations and particular properties, and the findings obtained from the analysis of these specimens may vary according to the type of matrix. As a potential perspective in forensic toxicology, the topic of alternative matrices will be continuously explored, especially emphasizing NPS.
In this work, an innovative screening platform is developed and validated for the on site detection of cannabinoids in hemp seed oil, for food safety control of commercial products. The novelty of this completely automated tool consists of a miniaturized NIR spectrometer operating in a wireless mode that permits processing samples in a rapid and accurate way and to obtain in a single click the early detection of a residual amount of cannabinoids in oil, including cannabidiol (CBD), the psychoactive Δ9-tetrahydrocannabinol (THC) and the Δ9-tetrahydrocannabinolic acid (THCA). Simulated samples were realized to instruct the platform and prediction models were developed by chemometric analysis of the NIR spectra using partial least square regression algorithms. Once calibrated, the platform was used to predict samples acquired in the market and on websites. Validation of the system was achieved by comparing results with those obtained from GC-MS analyses and a good correlation was observed.
We describe a new compact diode‐pumped solid‐state frequency quadrupled quasi‐three‐level neodymium‐doped gadolinium vanadate (Nd:GdVO4) laser that generates ~50 mW of 228‐nm quasi‐continuous wave light as ns pulses at a tunable kilohertz repetition rate. We developed two generations of this laser. The first generation has a high duty cycle and a tunable repetition rate. The second generation is optimized for maximum output power. We utilize these new lasers to measure ultraviolet resonance Raman (UVRR) spectra of many important chromophores that absorb in deep ultraviolet (UV). We demonstrate the utility of this excitation by measuring the 228‐nm absolute differential Raman cross sections of explosives, peptides, aromatic amino acids, and DNA/RNA nucleotides. Deep UV excitation at 228 nm occurs within the π → π* electronic transitions of these molecules. The 228‐nm resonance excitation enhances the Raman intensities of vibrations of NOx groups, peptide bonds, aromatic amino acid side chains, and DNA/RNA nucleotides. The measured 228‐nm UVRR cross sections of these molecules are 10³–10⁴ fold greater than those excited in the visible spectral region. These new lasers should be of great interest for UVRR spectroscopy and for other applications that benefit from compact, high average power deep UV laser light sources with low peak powers.
Raman spectroscopy has proven to be a valuable tool for analyzing various types of forensic evidence such as traces of body fluids. In this work, Raman spectroscopy was employed as a nondestructive technique for the analysis of dry traces of oral fluid to differentiate between smoker and nonsmoker donors with the aid of advanced statistical tools. A total of 32 oral fluid samples were collected from donors of differing gender, age and race and were subjected to Raman spectroscopic analysis. A genetic algorithm (GA) was used to determine 8 spectral regions that contribute the most to the differentiation of smokers and nonsmokers. Thereafter, a classification model was developed based on the artificial neural network (ANN) that showed 100% accuracy after external validation. The developed approach demonstrates great potential for the differentiation of smokers and nonsmokers based on the analysis of dry traces of oral fluid. This article is protected by copyright. All rights reserved.
Background:
Δ9-Tetrahydrocannabinol (THC) is already considered one of the most addictive substances since an increasing number of consumers/abusers of THC and THC based products are observed worldwide. In this work, the capabilities of a novel miniaturized and portable MicroNIR spectrometer were investigated in order to propose a practical and intelligible test allowing the rapid and easy screening of Δ9-Tetrahydrocannabinol (THC) oral fluids without any pretreatment.
Methods:
Specimens from volunteers were collected in order to consider any sources of variability in the spectral response and spiked with increasing amount of THC in order to realize predictive models to be used in real cases. Partial Least Square-Discriminant Analysis (PLS-DA) and Partial Least Square regression (PLSr) for the simultaneously detection and quantification of THC, were applied to baseline corrected spectra pre-treated by first derivative transform.
Results:
Results demonstrated that MicroNIR/Chemometric platform is statistically able to identify THC abuse in simulated oral fluid samples containing THC from 10 to 100 ng/ml, with a precision and a sensitivity of about 1.51% and 0.1% respectively.
Conclusions:
The coupling MicroNIR/Chemometrics permits to simplify THC abuse monitoring for roadside drug testing or workplace surveillance and provides the rapid interpretation of results, as once the model is assessed, it can be used to process real samples in a "click-on" device.
We compare the electrochemical behavior of cocaine hydrochloride (in acidic medium) and its free base form (in acetonitrile) by a simple, cheap, and fast square wave voltammetry method for cocaine analysis based on carbon paste electrodes without chemical modification. The electrodes performed better than the electrodes obtained for analysis on commercial screen-printed electrodes, which we also tested here. We conducted the analyses in aqueous solution containing 0.1 mol/L NH4ClO4 as supporting electrolyte. For cocaine in acidic medium, the linear correlation coefficient, the LOD, and the LOQ were 0.996, 4.66 10^(-6) mol/L, and 1.55 10^(-5) mol/L, respectively. For cocaine in acetonitrile medium, the linear correlation coefficient, the LOD, and the LOQ were 0.994, 9.77 10^(-6) mol/L, and 3.26 10^(-5) mol/L, respectively. The specificity of the methodology is advantageous when the response of different interfering substances analyzed in this work (lidocaine, procaine, caffeine and phenacetine) is concerned.
In the field of forensic toxicology, the use of non-destructive and easy-to-use analytical techniques deserves remarkable attention, especially in those situations involving public health and security. In addition, the miniaturization and portability of one-touch devices for the detection of specific threats is required more and more.
In this study, a novel on-site MicroNIR/Chemometric platform was developed to perform a real-time prediction of cocaine and its metabolites in non pre-treated oral fluid.
Simulated oral fluids were prepared in water in order to calibrate the instrumental response and the matrix effect was consequently evaluated by processing spiked oral fluids collected from volunteers. The procedure was optimized using a proper experimental design taking into account the equilibrium between cocaine and benzoylecgonine in the range 10–100 ng-ml and validated by comparing results with the reference official method (GC-MS).
The developed method was statistically able to discriminate oral fluid samples containing cocaine from 10 to 100 ng/ml and demonstrated to be not affected by the variability of the matrix as all the blank samples of different volunteers (smokers and non smokers, assuming caffeine, sugars, chewing-gum or alcohol) as well as spiked oral fluids were correctly predicted by the model. In addition, results from six real samples confirmed the feasibility of the miniaturized platform to provide a correct identification of cocaine abuse and to propose the MicroNIR as innovative personal screening system to prevent accidents and in cases involving workplace surveillance.
A novel entirely automated MicroNIR/Chemometric platform was developed for the “Lab-on-Click” detection of illicit drugs in non-pretreated oral fluids and a novel tool for the first level test is proposed. Calibration of the method was achieved by collecting oral fluids specimens from volunteers and chemometric analysis was considered for the development of models of prediction for cocaine, amphetamine and Δ9-Tetrahydrocannabinol. In addition, a comprehensive model was optimized for the simultaneously prediction of positive/negative samples and the specific illicit drug used by abusers in single “click”. The detection ability of the method was checked for true positive and false positive outcomes and results were validated by GC-MS reference official method. The MicroNIR/Chemometric platform provided the simultaneously prediction of the three most frequently addictive drugs with the sensitivity and accuracy of the confirmatory analyses, offering the advantages of rapidity and simplicity and demonstrating to be a promising tool supporting public health surveillance.
Raman spectroscopy has emerged as a valuable instrumental tool to supplement spectroscopic approaches, such as infrared spectroscopy for analyzing forensic samples including drugs, fibers, textiles, soil components, inks, pigments, paints, and body fluids, both in the field and at crime laboratories. As a result, Raman spectroscopy has been incorporated into undergraduate forensic chemistry courses. Using a Rigaku Progeny X2 Raman spectrometer, students recorded Raman spectra of organic and inorganic materials including drugs, adulterants, explosives precursors, dyes, pigments, and coordination complexes. Students searched for matches using a chemical library and assigned peaks attributable to the chemical structures using a correlation table. They observed conditions in which Raman spectroscopy recorded bands not observed with the infrared spectrometer, reflecting the complementarity of the two techniques. An advantage of Raman spectroscopy for forensic analysis compared to infrared spectroscopy is that dangerous samples can be analyzed through containers and aqueous solutions can be analyzed without interference from water.
In this study, a new method was developed to quantify cocaine and some adulterants (lidocaine, caffeine, phenacetin, procaine and benzocaine) using the nuclear magnetic resonance spectroscopy without the use of deuterated solvents (No-D qNMR). The No-D qNMR presents as main advantages: low cost (in comparison to the use of deuterated solvents), non-destructive and speed analysis, and able to detect non-volatile compounds. For the analytical validation achievement, figures of merit such as selectivity and specificity, linearity, quantification limit, detection limit, accuracy, precision and robustness were obtained. The built models presented excellent precision (< 5%), linearity (>0.99), and LOD values which varied between 0.126 and 0.666 mg mL-1. With the purpose to verify the models’ predictive capacity, 34 crack samples seized by the Civil Police of Espírito Santo State – Brazil were analyzed, and the average cocaine content found was around 17.5 wt%, which is in line with expectations (up to approximately 30 wt%). Moreover, 50 wt% of the samples contained phenacetin, 9 wt% caffeine, 3 wt% procaine and lidocaine, while benzocaine wasn’t identified.
The principal objective of this work was to demonstrate the capability of Raman spectroscopy to detect small amounts of cocaine in nasal fluid, and to identify the main drug and the most widely used cutting agents. Initially, standard samples were analysed and sampling conditions were studied by comparing different swabs used for the sample collection. Once the most appropriate swab was selected, which permitted a relatively simple detection of the standard cocaine hydrochloride, qualitative analyses of real samples were carried out. Three street cocaine samples were analysed, and the presence of cutting substances was highlighted by the appearance of different bands not corresponding to the ones of the standard cocaine. To identify the substances present in each sample, the spectra of the street cocaine samples were collected and compared with a digital library created on purpose with the spectra of the most common cutting agents. In this case, correlation coefficients permitted to recognize the most important substances 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 the smaller signal of the cutting substances, hindering their identification.
Current forensic methods for detecting and identifying cocaine and other drugs of abuse are destructive, so evidence cannot be re-analyzed. Raman spectroscopy, based on inelastic light scattering, allows for rapid, inexpensive and nondestructive analysis in forensic science. This review presents the state-of-the-art use of Raman spectroscopy as a confirmatory method for the identification of cocaine and other drugs of abuse in seized samples, including hidden compounds in legal materials such as beverages and clothes, among others, used for trafficking. Quantitative Raman spectroscopy is used to determine the actual drug concentrations in street cocaine and crack rocks and to identify possible adulterants in these samples for forensic toxicology and criminalistics. Finally, recent developments in Raman spectrometers (portable instruments and new excitation wavelengths) and advancements in data analysis offer exciting opportunities for new applications of Raman spectroscopy in the identification and quantification of drugs of abuse, including investigations conducted immediately at the scene of a crime. Copyright
Identification of cocaine and subsequent quantification immediately after seizure are problems for the police in developing countries such as Brazil. This work proposes a comparison between the Raman and FT-IR techniques as methods to identify cocaine, the adulterants used to increase volume, and possible degradation products in samples seized by the police. Near-infrared Raman spectra (785 nm excitation, 10 sec exposure time) and FT-IR-ATR spectra were obtained from different samples of street cocaine and some substances commonly used as adulterants. Freebase powder, hydrochloride powder, and crack rock can be distinguished by both Raman and FT-IR spectroscopies, revealing differences in their chemical structure. Most of the samples showed characteristic peaks of degradation products such as benzoylecgonine and benzoic acid, and some presented evidence of adulteration with aluminum sulfate and sodium carbonate. Raman spectroscopy is better than FT-IR for identifying benzoic acid and inorganic adulterants in cocaine.
© 2014 American Academy of Forensic Sciences.
Eighty drugs of abuse and metabolites were successfully measured by surface-enhanced Raman spectroscopy (SERS) using gold- and silver-doped sol-gels immobilized in glass capillaries. A method was developed that provided consistent detection of 50 ppb cocaine in saliva in a focused study. This general method was successfully applied to the detection of a number of additional drugs in saliva, such as amphetamine, diazepam, and methadone.
Recent advances in analytical techniques have enabled the detection of drugs and drug metabolites in oral fluid specimens. Although GC-MS is still commonly used in practice, many laboratories have developed and successfully validated methods for LC-MS(-MS) that can detect a large number of compounds in the limited sample volume available. In addition, several enzyme immunoassays have been commercialized for the detection of drugs of abuse in oral fluid samples, enabling the fast screening and selection of presumably positive samples. A number of concerns are discussed, such as the variability in the volume of sample collected and its implications in terms of quantitative measurements, and the drug recoveries of the many different specimen collection systems on the market. Additional considerations that also receive attention are the importance of providing complete validation data with respect to analyte stability, matrix effect, and the choice of collection method.
Raman data collected from free amino acid and peptide chains permit assignment of the seven markers located at approximately 1616, 1606, 1210, 1178, 850, 830, and 643 cm−1 to tyrosine. The effects induced by labile hydrogen deuteration, temperature, concentration, and protonation–deprotonation on these Raman markers were analyzed. Following closely a recent multiconformational analysis on phenylalanine, we could confirm the predominance of gauche-/gauche- rotamers with respect to the side chain χ1/χ2 torsion angles in both tyrosine and tyrosinate. Calculated Raman spectra, based on the consideration of both implicit and explicit hydration models, have revealed the effect of hydrogen bonding of water molecules to the phenol ring hydroxyl group of tyrosine. A special attention has been paid to the 850/830 cm−1 tyrosine doublet, for which no intensity ratio inversion could be remarked when the phenol hydroxyl group acts as a hydrogen bond donor or acceptor. On the contrary, this intensity ratio appeared to be strongly dependent on the hydrophobic/hydrophilic balance of the interactions, in which the phenol ring is involved. Based on the present theoretical calculations, the components of the tyrosine doublet might originate from two independent fundamental modes of the phenol ring: one with an in-plane character and the other with an out-of-plane character. As a consequence, the widely spread Fermi resonance-based description of the tyrosine doublet appears to be unjustified. The latter interpretation simply results from the insufficiencies of the simple model compound used at that time for analyzing the vibrational features of a more complex molecular system such as tyrosine. Copyright © 2015 John Wiley & Sons, Ltd.
The present work aims to review all the papers published so far, focused on 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 limit of detection (LOD) to detect quantities of drugs smaller than the cut-off limits established by law for drug controls. Advances in Raman, Infrared (IR) and Nuclear Magnetic Resonance (NMR) spectroscopy applications are here discussed. Surface Enhanced Raman Spectroscopy (SERS) has been shown as the most sensitive technique for the detection of illicit drugs in oral fluid. The use of IR spectroscopy for determining drugs of abuse in oral fluid is growing although the LODs obtained until now do not yet satisfy the necessities in the forensic field. Finally, NMR spectroscopy has been seldom used to determine drugs in oral fluid. Another future trend seems to be related with the use of portable instrumentation, which would permit to perform in-situ analysis. This last application seems to be particularly promising to perform roadside drug tests and to identify overdose drugs in patients in emergency conditions.
A 244 nm excitation Raman microspectroscope has been developed and successfully used to investigate a range of narcotics and explosives, both pure and contaminated. The instrument is quick and simple to operate and effective in identifying these compounds. The wavelength was chosen to exploit the resonance Raman effect, thereby enhancing the band intensities beyond the normal v4 enhancement associated with the shorter wavelength excitation. Another advantage over visibly excited Raman spectroscopy is the complete lack of any fluorescence background, even with heavily contaminated samples. The simplification of spectra caused by resonance allowed the easy identification of species contained in complex mixtures.
We demonstrate the in situ identification of crack cocaine and cocaine·HCl by using a fiber-optic Raman probe and a portable Raman spectrograph. The Raman spectrum of freebase cocaine (crack) is obtained in just seconds without any sample preparation, and differs significantly from that of cocaine·HCl. We also show that the Raman spectra of these drugs are easily distinguishable from common cutting agents and impurities such as benzocaine and lidocaine. Another advantage of using Raman spectroscopy is that the drugs can be identified while contained in transparent containers, such as clear plastic evidence containers that are used to store drug evidence and to maintain chain of custody. We also demonstrate the in situ Raman identification of drugs separated by thin-layer chromatography. We discuss the utility of surface-enhanced Raman spectroscopy (SERS) in toxicological drug screening and present preliminary SERS data for cocaine in solution using colloidal silver. We believe this to be the first published SERS spectrum of freebase cocaine.
The dangerous effects and increased usage of illicit drugs have inspired the development of analytical methodologies. We based our review of analytical procedures for determination of cocaine (COC) and its metabolites on literature from the past two decades. Our main aim was to compare the capabilities of different analytical techniques. The diversity of matrices from which COC is determined (e.g., blood, hair, saliva, plasma, urine, inner organs and meconium) has led to differences in sample preparation. To assess drug exposure, it is essential to select the sample type and the instrumental technique applied. We discuss appropriate sampling, extraction and purification techniques.
This paper reviews scientific contributions on the identification and/or quantification of metabolites of drugs of abuse in in vitro assays or various body samples using hyphenated mass spectrometry. Gas chromatography-mass spectrometry (GC-MS) as well as liquid chromatography-mass spectrometry (LC-MS) approaches are considered and discussed if they have been reported in the last five years and are relevant to clinical and forensic toxicology or doping control. Workup and artifact formation are discussed, and typical examples of studies of the metabolism of designer drugs, doping agents, herbal drugs, and synthetic cannabinoids are provided. Procedures for quantifying metabolites in body samples for pharmacokinetic studies or in enzyme incubations for enzyme kinetic studies are also reviewed. In conclusion, the reviewed papers showed that both GC-MS and LC-MS still have important roles to play in research into the metabolism of drugs of abuse, including doping agents.
The use and abuse of illegal drugs affects all modern societies, and therefore the assessment of drug exposure is an important task that needs to be accomplished. For this reason, the reliable determination of these drugs and their metabolites in biological specimens is an issue of utmost relevance for both clinical and forensic toxicology laboratories in their fields of expertise, including in utero drug exposure, driving under the influence of drugs and drug use in workplace scenarios. Most of the confirmatory analyses for abused drugs in biological samples are performed by gas chromatographic-mass spectrometric methods, but use of the more recent and sensitive liquid chromatography-(tandem) mass spectrometry technology is increasing dramatically. This article reviews recently published articles that describe procedures for the detection of opiates in the most commonly used human biological matrices, blood and urine, and also in unconventional ones, e.g. oral fluid, hair, and meconium. Special attention will be paid to sample preparation and chromatographic analysis.
Analytical tests to measure chemicals in saliva can be employed for numerous analytes, endogenous compounds or xenobiotics. The objective was to determine which chemicals can be analysed with this matrix, which analytical methods are applicable, and what application is possible for biomonitoring. We reviewed the literature using three databases, MEDLINE, PubMed and Scopus, collecting articles on different kinds of analysis in saliva. Studies were principally about molecules of clinical interest, xenobiotics, especially drugs of abuse, and chemicals used at workplaces; some substances show no relevant correlation with exposure data while others seems to be of particular interest for systematic use for biomonitoring. Currently, saliva is used far less than other biological fluids but its use for biomonitoring of exposure to chemicals might open up new areas for research and would certainly simplify the collection of biological samples.
We have directly determined the amide band resonance Raman spectra of the "average" pure alpha-helix, beta-sheet, and unordered secondary structures by exciting within the amide pi-->pi* transitions at 206.5 nm. The Raman spectra are dominated by the amide bands of the peptide backbone. We have empirically determined the average pure alpha-helix, beta-sheet, and unordered resonance Raman spectra from the amide resonance Raman spectra of 13 proteins with well-known X-ray crystal structures. We demonstrate that we can simultaneously utilize the amide I, II, and III bands and the Calpha-H amide bending vibrations of these average secondary structure spectra to directly determine protein secondary structure. The UV Raman method appears to be complementary, and in some cases superior, to the existing methods, such as CD, VCD, and absorption spectroscopy. In addition, the spectra are immune to the light-scattering artifacts that plague CD, VCD, and IR absorption measurements. Thus, it will be possible to examine proteins in micelles and other scattering media.
This paper reviews procedures for quantification of drugs in the biosamples blood, plasma, serum, or oral fluid (saliva, etc.) using liquid chromatography coupled with single-stage or tandem mass spectrometry (LC-MS, LC-MS-MS). Such procedures are important prerequisites for competent toxicological judgment and consultation in clinical and forensic toxicology. They cover blood (plasma, serum) analysis of amphetamines and related designer drugs, anesthetics, anticonvulsants, benzodiazepines, opioids, serotonergic drugs, tricyclic antidepressants, neuroleptics, antihistamines, beta-blockers, muscle relaxants, and sulfonylurea-type antidiabetics, and oral fluid analysis of amphetamines and related designer drugs, cocaine, benzoylecgonine, codeine, morphine, enantiomers of methadone and its main metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), the nicotine metabolites cotinine and hydroxycotinine, and finally risperidone and its metabolite 9-hydroxyrisperidone. Basic information on the procedures is given in two tables and an example of quantification is illustrated in two figures. The pros and cons of such LC-MS procedures including sample work-up and ion suppression effects are critically discussed.
A new deep-UV Raman spectrometer utilizing a laser source tunable between 193 and 205 nm has been designed, built, and characterized. Only selected wavelengths from this range have previously been accessible, by Raman shifting of the second, third, and fourth harmonics of the Nd:YAG fundamental in hydrogen. The apparatus was demonstrated to be a useful tool for characterizing hen egg white lysozyme structural rearrangements at various stages of fibril formation. High-quality deep-UV resonance Raman spectra were obtained for both a protein solution and a highly-scattering gelatinous phase formed by fibrillogenic species. In addition to amide bands, strong contribution of nu(12) and ring-C phenylalanine vibrational modes was observed at excitation wavelengths below 200 nm. Remarkably, the Raman cross-section of these modes revealed dramatic change of lysozyme in response to heat denaturation and fibril formation. These results indicate that phenylalanine could serve as a new deep-UV Raman probe of protein structure.
- L Caporossi
- A Santoro
- B Papaleo
L. Caporossi, A. Santoro, B. Papaleo, Biomarkers 15 (2010) 475-487.
- M Janicka
- A Kot-Wasik
- J Namieśnik
M. Janicka, A. Kot-Wasik, J. Namieśnik, TrAC Trends Anal. Chem. 29 (2010) 209-224.
- M Barroso
- E Gallardo
- D N Vieira
- J A Queiroz
- M López-Rivadulla
M. Barroso, E. Gallardo, D.N. Vieira, J.A. Queiroz, M. López-Rivadulla, Anal. Bioanal.
Chem. 400 (2011) 1665-1690.
- M Meyer
- H Maurer
M. Meyer, H. Maurer, Anal. Bioanal. Chem. 402 (2012) 195-208.
- V Elia
- G Montalvo
- C García Ruiz
V. D'Elia, G. Montalvo, C. García Ruiz, Appl. Spectrosc. Rev. 50 (2015) 775-796.
- H Sands
- I Hayward
- T Kirkbride
- R Bennett
- R Lacey
- D Batchelder
H. Sands, I. Hayward, T. Kirkbride, R. Bennett, R. Lacey, D. Batchelder, J. Forensic Sci.
43 (1998) 509-513.
- V Elia
- M Calcerrada
- G Montalvo
- C García Ruiz
V. D'Elia, M. Calcerrada, G. Montalvo, C. García Ruiz, Electrophoresis 38 (2017)
1217-1223.
- F Inscore
- C Shende
- A Sengupta
- H Huang
- S Farquharson
F. Inscore, C. Shende, A. Sengupta, H. Huang, S. Farquharson, Appl. Spectrosc. 65
(2011) 1004-1008.
- J C Carter
- W I E B Er
- S M I Angel
J.C. Carter, W.I.E.B. Er, S.M.I. Angel, Appl. Spectrosc. 54 (2000).
- C A F Penido
- M T T Pacheco
- R A Zangaro
- L Silveira
C.A.F. de O. Penido, M.T.T. Pacheco, R.A. Zangaro, L. Silveira Jr., J. Forensic Sci. 60
(2015) 171-178.
- B Hernández
- Y M Coïc
- F Pflüger
- S G Kruglik
- M Ghomi
- J Raman
B. Hernández, Y.M. Coïc, F. Pflüger, S.G. Kruglik, M. Ghomi, J. Raman, Spectroscopy
47 (2016) 210-220.