Application In Forensic Analysis Research Articles

Enhanced detection of lysergic acid diethylamide using Ehrlich reagent and screen-printed electrodes: A hybrid method for application in forensic analysis

In forensic investigations, the presumptive identification of illicit substances, such as Lysergic Acid Diethylamide (LSD), is crucial. While the Ehrlich's colorimetric reagent (EHR) is commonly employed for LSD detection, producing a characteristic colour change, its lack of selectivity often leads to false-positive or misinterpreted results. Addressing this, we propose a novel method combining electrochemical detection with EHR, enhancing selectivity for LSD’s preliminary identification in forensic samples. This method utilizes a screen-printed carbon electrode (carbon-SPE) in a pH 12 phosphate buffer. We observed two irreversible oxidation processes for LSD at Epa= + 0.35 V (Ox1) and + 0.65 V (Ox2), and for EHR at + 0.62 V and + 0.83 V (vs Ag/AgCl). The LSD + EHR combination displayed three distinct irreversible oxidation processes at + 0.35 V, + 0.66 V, and + 0.86 V. This approach provides three analytical responses for LSD identification: (1) colour change post-EHR test; (2) voltammetric detection of LSD’s two oxidation processes on carbon-SPE; (3) decreased peak current of LSD at Ox1 post-reaction after EHR. Additionally, our method facilitates LSD quantification, exhibiting a low limit of detection (LOD) of 0.69 μmol/L, and consistent electrochemical responses (RSD < 3.0 %) using the same or different carbon-SPEs. Interference studies with other illicit drugs underscored the method’s reliability and selectivity in LSD detection. Moreover, addition-recovery studies on real seized samples approached 100 %, and LSD identification was corroborated by QTOF-LC/MS analyses. Therefore, combining voltammetry with carbon-SPE and EHR offers significant potential for a rapid, simple, and selective LSD screening test in forensic analysis.

Electrochemistry of the synthetic tryptamine 5-MeO-MiPT at glassy carbon and screen-printed electrodes: A rapid and simple screening method for application in forensic analysis

5-Methoxy-N-methyl-N-isopropyltryptamine (5-MeO-MiPT), also known as moxy, is a synthetic tryptamine analogue used recreationally as a hallucinogenic drug. This work investigates the electrochemical behaviour of 5-MeO-MiPT using carbon electrodes for the first time. Although 5-MeO-MiPT showed only one irreversible oxidation process at a glassy carbon electrode, many electrochemical processes were exhibited on a graphite screen-printed electrode (SPE-Gr). The oxidation reaction of 5-MeO-MiPT on both carbon electrode surfaces involves an adsorption-controlled process with the loss of one electron and one proton. A voltammetric screening method for 5-MeO-MiPT was performed in 0.1 mol L−1 phosphate buffer solution at pH 7.0 on the SPE-Gr using differential pulse adsorptive stripping voltammetry (DPAdSV). The proposed method showed a wide linear range (0.05–30.0 µmol L−1) and a sufficiently low limit of detection (0.015 µmol L−1) for application to seized forensic samples containing 5-MeO-MiPT. Good stability of the electrochemical responses for 5-MeO-MiPT detection on SPE-Gr was obtained, using the same or different electrodes (N = 3) with a relative standard deviation of less than 4.0%. Interference studies with other drugs demonstrated that the proposed sensor is selective for electrochemical screening of 5-MeO-MiPT. In addition, 5-MeO-MiPT was identified in a biological sample of synthetic urine and in real seized samples by the proposed method and confirmed by GC-MS. The analytical performance of SPE-Gr with DPAdSV for 5-MeO-MiPT detection shows great potential as a simple, fast, and selective screening method in forensic scenarios.

Electrochemistry of 5F-MDMB-PICA synthetic cannabinoid using a boron-doped diamond electrode with short anodic-cathodic pretreatment: A simple screening method for application in forensic analysis

This work presents, for the first time, the electrochemical detection of methyl(2S)-2-{[1-(5-fluoropentyl)-1H-indole-3-carbonyl]amino}-3,3-dimethyl butanoate (5F-MDMB-PICA), which is one of the most reported synthetic cannabinoids (SCs) in seized forensic samples. The 5F-MDMB-PICA detection is based on adsorptive stripping differential pulse voltammetry (AdSDPV) using a boron-doped diamond electrode (BDDE) with short anodic-cathodic pretreatment. This SC exhibited an irreversible oxidation process at around +1.2 V on a BDDE (vs. Ag|AgCl|KCl(sat.)) in 0.1 mol L−1 H2SO4. The proposed method presents a wide linear range (1.0 to 100 µmol L−1) for 5-MDMB-PICA determination and a low limit of detection (0.09 µmol L−1). The selectivity for 5F-MDMB-PICA detection at the BDDE using AdSDPV was evaluated using six other SCs and no interference was observed. In addition, the BDDE showed a good stability of 5F-MDMB-PICA electrochemical responses. Addition-recovery studies in real seized samples presented results close to 100%. Therefore, the combination of BDDE with AdSDPV demonstrates a great potential for a simple and fast screening of 5F-MDMB-PICA and an on-site application in forensic analysis.

Fast on-site screening of 3,4-methylenedioxyethylamphetamine (MDEA) in forensic samples using carbon screen-printed electrode and square wave voltammetry

The worldwide seizures of illicit synthetic drugs have been dramatically increasing over the past decade, when the quantity of seized amphetamine-type stimulants (ATS) quadrupled, while seized ecstasy (3,4–methylenedioxymethamphetamine or MDMA)-like substances doubled. In this work, a simple and fast methodology for the electrochemical screening of ecstasy analogue MDEA (3,4-methylenedioxyethylamphetamine) in forensic samples is presented, for the first time, using a carbon screen-printed electrode (C-SPE) and square wave voltammetry (SWV). The electrochemical behavior of MDEA was studied by cyclic voltammetry at different pH values (2 to 12), where an altered electrochemistry of this drug on C-SPE, with an unreported redox pair, was observed in comparison with previous works dealing with the voltammetric detection of other ATS with similar chemical structures. Based on the acquired electrochemical processes, a redox reaction mechanism for MDEA on C-SPE is proposed. The best conditions (sensitivity and selectivity) for MDEA screening were obtained by SWV (a: 40 mV, f: 30 Hz, and Estep: 4 mV) and 0.04 mol L−1 Britton Robinson buffer solution at pH 3.0 as the supporting electrolyte. The proposed method presents a wide linear range (2.5 to 30.0 µmol L−1, R2 > 0.99), high sensitivity (0.569 µA / µmol L−1), low theoretical limit of detection (0.03 µmol L−1), and good repeatability using the same C-SPE (RSD < 6%; n = 10). The inter-device reproducibility (n = 5) showed a minimal variation of peak potentials (RSD < 2.3%). The interference study was performed with some adulterants usually found in ecstasy tablets, such as paracetamol, caffeine, glucose, ketamine, cocaine, acetylsalicylic acid, amphetamine (A), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), MDMA, ethylone (bk-MDEA), n-ethylpentylone (bk-EBDP) and dibutylone (bk-DMDBD). The method was applied in real seized samples containing MDEA with addition-recovery studies close to 100%. The developed method is promising to be used as a preliminary test for the screening of MDEA in the ever-changing situation concerning seized forensic samples. The proposed sensor exhibits attractive features for application in forensic analysis, such as rapidness, simplicity, low-cost, user friendly and portability.

Identification of novel semen and saliva specific methylation markers and its potential application in forensic analysis

Differential DNA methylation in human tissues has been widely used to develop markers for body fluid identification in forensics. In the present study, identification of potential tissue specific differentially methylated regions (tDMRs) was based on mining differentially expressed genes in surrogate tissues for blood, saliva, semen and vaginal fluid. Genes specifically over expressed in one of the surrogate tissues viz: blood, salivary glands, testis, prostrate, cervix, uterus and ovary were identified from genome wide expression datasets. We hypothesized that over expression in surrogate tissues for body fluids could be correlated with differential methylation. Methylation information from two methylation datasets, NGSmethDB and ENCODE were integrated and heavily methylated gene body CpG islands (CGI) representing the body fluids were extracted. From a total of 53 potential genes the present study reports, two genes, ZNF282 and HPCAL1 which were preferentially expressed in cervix with comparatively reduced expression in other surrogate tissues. Methylated CGIs were targeted to design primers for methylation specific PCR (MSP) and bisulphite sequencing (BS). The ZNF282 CpG sites displayed semen-specific hypomethylation while HPCAL1 CpGs showed saliva-specific hypomethylation. Clone-based bisulphite sequencing also revealed significant hypomethylation in the target body fluids. To evaluate the stability of methylation profiles, the ZNF282 tDMR was tested and each body fluid was subjected to five different forensic simulated conditions (dry at room temperature, wet in an exicator, outside on the ground, sprayed with alcohol and sprayed with bleach) for 50 days. Under the condition “outside on the ground”, saliva showed a significant decrease in methylation level by bisulphite sequencing analysis over time. Complete methylation profiles were obtained only for vaginal fluid under all conditions and no differences in methylation levels were observed for this fluid after 50 days. Thus, ZNF282 and HPCAL1 tDMRs can be used as reliable semen and saliva identification markers respectively.

Electrochemical detection of the synthetic cathinone 3,4-methylenedioxypyrovalerone using carbon screen-printed electrodes: A fast, simple and sensitive screening method for forensic samples

In this work, the electrochemical detection of 3,4-methylenedioxypyrovalerone (MDPV), a synthetic cathinone used as a stimulant drug, is presented for the first time. The electrochemical behavior of MDPV was studied by cyclic voltammetry (CV) at the surface of an unmodified glassy carbon electrode and a carbon graphite screen-printed electrode (SPE-Gr), where three irreversible oxidation processes were identified. The quantification of MDPV in seized drug samples was optimized for the first oxidation process (at + 0.6 V vs Ag) in 0.1 mol L−1 Britton Robison (BR) buffer solution pH 6.0 at SPE-Gr, using adsorptive stripping differential pulse voltammetry (AdSDPV) detection. The proposed method exhibited a limit of detection (LOD) of 0.5 µmol L−1 and suitable electrochemical response stability using the same (N = 5) or different (N = 3) electrodes, both presenting a RSD lower than 1.6%. Additionally, interference studies and application to MDPV sensing in reference samples provided by United Nations Office on Drugs and Crime (UNODC) were performed, confirming the potential of the proposed sensor for application in forensic analysis as a simple, fast and cost-effective screening method for MDPV.

Electrochemical detection of 3,4-methylenedioxymethamphetamine (ecstasy) using a boron-doped diamond electrode with differential pulse voltammetry: Simple and fast screening method for application in forensic analysis

3,4-Methylenedioxymethamphetamine (MDMA) is an illicit stimulant drug also known as ‘ecstasy’ and is one of the most used amphetamines worldwide. Similar drugs to MDMA, so called as novel psychoactive substances (NPS), have been also found in seized samples. In this work, we present a simple and fast electrochemical method for MDMA detection in seized samples using a boron-doped diamond electrode (BDDE) with differential pulse voltammetry (DPV). The proposed method is based on the oxidation of the MDMA at a BDDE in Britton-Robinson buffer solution pH 10 as supporting electrolyte. A good linear range from 1.0 to 500 µmol L−1 and a low limit of detection (0.3 µmol L−1) were obtained for MDMA determination. We also present the interference study of the proposed method for other drugs, which can be found in seized samples of ecstasy-like tablets, such as caffeine and nine other synthetic drugs, including the own amphetamine, methamphetamine and N-methyldiethanolamine (MDEA). Analyses of seized samples with MDMA and very similar NPS such methylenedioxyamphetamine (MDA) and MDEA were successfully performed and compared by LC-MS and HPLC DAD. Therefore, the analytical performance of the BDDE with DPV for MDMA detection suggests a simple and fast screening method to detect this drug in forensic analysis.

Age Estimation Based on DNA Methylation Using Blood Samples From Deceased Individuals.

Age estimation using DNA methylation levels has been widely investigated in recent years because of its potential application in forensic genetics. The main aim of this study was to develop an age predictor model (APM) for blood samples of deceased individuals based in five age-correlated genes. Fifty-one samples were analyzed through the bisulfite polymerase chain reaction (PCR) sequencing method for DNA methylation evaluation in genes ELOVL2, FHL2, EDARADD, PDE4C, and C1orf132. Linear regression was used to analyze relationships between methylation levels and age. The model using the highest age-correlated CpG from each locus revealed a correlation coefficient of 0.888, explaining 76.3% of age variation, with a mean absolute deviation from the chronological age (MAD) of 6.08years. The model was validated in an independent test set of 19 samples producing a MAD of 8.84years. The developed APM seems to be informative and could have potential application in forensic analysis.

Human bone marrow as a tissue in post-mortem identification and determination of psychoactive Substances-Screening methodology.

The aim of this study was to apply a new instrumental approach to the analysis of human bone marrow for forensic purposes. A new screening method for the detection of more than 30 psychoactive drugs in bone marrow was developed and applied to case samples. The drugs used in this study belonged to the following groups: benzodiazepines (BZDs, n=16), tricyclic antidepressants (TCAs, n=5), selective serotonin reuptake inhibitors (SSRI, n=4), serotonin-norepinephrine reuptake inhibitors (n=1), anticonvulsants (n=1), imidazopyridines (n=1) and piperazines (n=3). The sample preparation procedure involved microwave-assisted extraction (MAE) and the experimental settings were optimized using the simplex method. Separation and detection was carried out using a UHPLC-TOF system. The method were validated using marrow samples, and further applied in the analysis of three case samples, in which diazepam, nordiazepam, citalopram, doxepin and paroxetine were successfully detected. Finally the presented method is a good example of an assay that could potentially find an application in forensic analysis.

Signature Verification for Banking Sector Based on SIFT

A person can be uniquely identified by evaluating one or more distinguishing biological traits. One such trait is scanned images of hand writing. It is useful biometric modality with application in forensic analysis, banking sector, document verification etc. This study focus on text-independent writer identification method based on scale invariant feature transform (SIFT). It consists of three phase: training, enrolment and identification phase. In all of these three phases an isotropic LoG filter is applied first. It is used to segment the handwriting image into word regions (WRs) and then, the SIFT descriptors (SDs) of word region and the corresponding scales and orientations (SOs) are extracted. In the first phase, an SD codebook is constructed by gathering the SDs training samples. In the second phase, SD signatures (SDS) are generated by looking up the SD codebook and SOs is used to generate a scale and orientation histogram (SOH). And finally in last phase, the SDS and SOH of the input handwriting are extracted and matched with the enrolled ones for identification. Here instead of analysing handwritten document we experiment on signature of an individual. Using SIFT algorithm we demonstrate that he/she is genuine or not.

Solid-phase synthesis of Rhodamine-110 fluorogenic substrates and their application in forensic analysis.

A novel synthetic route for the rapid and efficient preparation of fluorogenic substrates utilizing Rhodamine-110 or similar fluorophores is reported. Applicability of the synthesized peptide substrate within a forensic casework context is also presented.

High Performance Thin Layer Chromatography method for analysis of 3,4-methylenedioxymethamphetamine in seized tablets

Context: Consumption of synthetic drugs had increased in recent years, used as a recreational drug by young people who presume that consumption of this drug is harmless for health; however clinical studies have shown that this stimulant and its metabolites are toxic. Due to these reasons, chemical analysis of this illicit drug is crucial from the points of view of occupational medicine, toxicology, and law enforcement with the aim of pursuit the traffic of illegal drug. Aims: Implement and fully validate a rapid and simple method for detection and quantitation of MDMA by High-Performance Thin Layer Chromatography in seized samples. Methods: With the implemented method was analyzed 12 positive samples seized by Chilean police, to found the concentration of MDMA in ecstasy tablets. Results: The method was fully validated, the linearity of the method was evaluated by the calibration curve between 51.0 – 510.0 µg/band (R2 0.9977); limit of detection was 12.1 µg per band, and limit of quantitation was 36.8 µg per band. The precision of the method (RSD) was lower than 5.0%. Accuracy was evaluated by determination of the percentage of MDMA recovered by the assay (99.13%), and relative Uncertainty was 6.66%. With this method, it was analyzed real seized samples of MDMA, results showed that all samples contained MDMA and concentration was between 18.15 – 59.84 % w/w. Conclusions: The method is selective, sensitive, and specific, with possible application in forensic analysis. To the best of our knowledge, this is the first report about concentration of MDMA in ecstasy pills in Chile.

Analysis of Y chromosome haplogroups in Japanese population using short amplicons and its application in forensic analysis

We designed three mini multiplex PCR systems using single-base extension reactions to identify Japanese Y chromosome haplogroups. We selected a group of 22 Y chromosome single nucleotide polymorphisms (SNPs) from the haplogroups most commonly reported in East Asia. To make the systems more useful in analyzing degraded DNA samples, we designed primers to render amplicons of ≤ 150 bp. Applying these systems, we classified the Japanese population into major haplogroups and confirmed the applicability of these systems in forensic DNA analysis.

Improved GC method for the determination of the active principles of Catha edulis

The GC method previously reported by our research group for the analysis of the active principles of Catha edulis, i.e. cathine, cathinone and phenylpropanolamine, was considerably improved. N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) as derivatizing agent was employed, thus allowing an accurate determination of the analytes and a suitable internal standard for quantitative analyses (nicotinamide) was introduced. Moreover the chromatographic conditions were carefully studied to improve the separation of the alkaloids and sensitivity. To this end different chromatographic capillary columns and temperature gradients were investigated. The optimized GC method was validated and resulted adequate for the application in forensic analysis. Finally on behalf of the Tribunal, C. edulis vegetable material seized by the police in northern Italy was analyzed, the quantity of cathine ranging from 0.095 to 0.29%, the quantity of PPA from 0.010 to 0.21% and the quantity of cathinone from 0.025 to 0.374% of the weight of the vegetable material.

Assessment of palatal rugae pattern and their reproducibility for application in forensic analysis

Background:Rugae are the anatomical folds that are located on the anterior third of palate behind the incisive papillae. They are also known as “Plica palatine,” and the study of these patterns is called palatoscopy. It can be used in various fields such as sex determination, orthodontics and forensic odontology.Objective:To investigate palatal rugae patterns in females and males and to evaluate the stability of these patterns in pre- and post-operative orthodontic cases.Materials and Methods:Fifty patients were selected for this study (25 males and 25 females). From the above sample, 10 males and 10 females had undergone orthodontic treatment and their casts were retrieved for sex determination analysis and stability of rugae patterns pre- and post-treatment.Results:Changes occur in bony structures during fixed orthodontic treatment but rugae patterns remain stable. Kappa stats and Chi square test were used to analyze agreement between the two evaluators, and 95% correct matches were achieved.Conclusion:Palatal rugae are unique to every individual and can be used as an indicator in forensic odontology.

Amplified detection of cocaine based on strand-displacement polymerization and fluorescence resonance energy transfer

Cocaine is one of the most abused drugs in the United States and is potentially dangerous when consumed in excess. Its detection is thus important in many areas in the fight against drug trafficking. We have developed an amplified detection method for cocaine based on a strand-displacement polymerization reaction using aptamer recognition. The system mainly consists of a hairpin probe with Cy5 labeled on its 3′ end, a primer with FAM labeled on its 5′ end, and polymerase. The aptamer sequence is integrated into the 5′-section of the hairpin probe. The primer is designed complementary to the 3′ end of the hairpin probe, which is also part of the hairpin stem region. The cocaine induced reaction cycle generates product for detection and thus for signal amplification. The detection limit of this method is 200nM in about 16min and the specificity of this approach is excellent. We believe that this strategy will be useful for the development of analytical schemes for a variety of aptamers for small molecules, metal ions, and proteins. This simple scheme employing the strand-displacement polymerization reaction may find wide application in forensic analysis, environmental monitoring, and clinical diagnostics.

Plagiarism and authorship analysis: introduction to the special issue

1 Authorship attribution and plagiarism analysisThe Internet has facilitated both the dissemination of anonymous texts as well aseasy ‘‘borrowing’’ of ideas and words of others. This has raised a number ofimportant questions regarding authorship. Can we identify the anonymous author ofa text by comparing the text with the writings of known authors? Can we determineif a text, or parts of it, has been plagiarized? Such questions are clearly of bothacademic and commercial importance.The task of determining or verifying the authorship of an anonymous text basedsolely on internal evidence is a very old one, dating back at least to the medievalscholastics, for whom the reliable attribution of a given text to a known ancientauthority was essential to determining the text’s veracity. More recently, the problemof authorship attribution has gained greater prominence due to new applications inforensic analysis, humanities scholarship, and electronic commerce, and thedevelopment of computational methods for addressing the problem.Over the last century and more, a great variety of methods have been applied toauthorship attribution problems of various sorts. One can roughly trace the evolutionof methods through three main stages. In the earliest stage researchers sought asingle numeric function of a text to discriminate between authors. In a later stage,statistical multivariate discriminant analysis was applied to word frequencies andrelated numerical features. Most recently, machine learning methods and high-dimensional textual features have been applied to sets of training documents to

Ultrasensitive determination of cobalt in single hair by capillary electrophoresis using chemiluminescence detector

By use of the high separation capability of capillary electrophoresis (CE) and ultrasensitive chemiluminescence (CL) detection, a CE–CL method was proposed for the ultrasensitive determination of trace cobalt in a single hair, which is potentially useful in construction of the fingerprint of trace elements in the hair collected from crime scenes. In this work, the CE experimental conditions, CL experimental conditions and the digestion methods for the analysis of a single hair sample for cobalt were investigated in detail. The relative limit of detection (LOD, 3 σ) was 0.01 ng/mL, and the absolute LOD was 2.4 × 10 − 16 g considering the sampling volume of 24 nL. Using a dry digestion method, the analytical results for certified reference hair samples by the proposed method were in good agreement with the certified values. Finally, this method was successfully used to detect trace cobalt in a single hair from three adults. It has potential applications in forensic analysis.

Detection of human blood by immunoassay for applications in forensic analysis

The detection and confirmation of bloodstains as being human in origin is important in crime scene investigations. There are a number of blood detection methods currently available. The aim of this work was to develop an assay capable of detecting the presence of human blood from both liquid blood samples and dried bloodstains. A simple, direct competitive ELISA was developed utilising a polyclonal antibody against human IgG. Once optimised, the ELISA was found to be specific for human IgG, with no cross-reaction observed with pig, sheep, cow, goat, horse and rabbit IgG. The assay was also found to be sensitive, with a detection limit of 0.1 μg/mL. This compares favourably with leading blood detection methods. The assay was able to confirm the presence of human blood in blood mixtures, in stains on a variety of surfaces and also gave positive results with bloodstains that were up to 1 year old. The assay was simple to use, rapid and highly reproducible. The ELISA performance makes it suitable for development as a kit to rival currently used methods for the routine detection of human blood at crime scenes. Further applications of the anti-human IgG antibody are reported, including immunodot assays and a sandwich ELISA format. The methods described here are simple, reliable assays for the identification of human blood and are presented as viable alternatives to existing techniques for blood detection.

Single quantum-dot-based aptameric nanosensor for cocaine.

Recent advances in single-molecule detection, nanotechnology, and aptameric sensors hold exciting promise for many potential applications. By functionalizing the surface of a quantum dot (QD) with aptamers which can recognize cocaine, and taking advantage of single-molecule detection and fluorescence resonance energy transfer (FRET) between 605QD and Cy5 and Iowa Black RQ, we develop a single-QD-based aptameric sensor that is capable of sensing the presence of cocaine through both signal-off and signal-on modes. In comparison with the established aptameric sensors, this single-QD-based aptameric sensor has the significant advantages of simple sample preparation, high sensitivity, and extremely low sample consumption. With the advances in the development of varieties of aptamers for small molecules, nucleic acids, metal ions, and proteins, this single-QD-based aptameric sensor might find wide application in forensic analysis, environmental monitoring, and clinic diagnostics.