Mircea-Alexandru Comănescu

Benzodiazepines are psychoactive drugs with wide clinical applications. Unfortunately, due to their sedative effects, benzodiazepines are frequently used as date rape drugs or in drug-facilitated crimes. Considering the electroactive nature of benzodiazepines and the unique advantages of electrochemical techniques, this review presents a critical discussion of the state of the art of benzodiazepine electroanalysis. Aspects related to sample preparation as well as electrodes (from mercury electrodes to bare or modified solid electrodes and to disposable sensors) and techniques (mainly voltammetry) used for the quantification of benzodiazepines in different matrices (pharmaceuticals, body fluids, alcoholic and soft drinks) were discussed. Considering the actual achievements in the field, some general suggestions for possible further research were given.

Nicotine is a highly used addictive substance that has recently also become available through electronic cigarettes. Here we present a study of nicotine from e-cigarette liquids through reversed-phase (RP) and hydrophilic interaction (HILIC) liquid chromatography. Multiple aqueous mobile-phase additives are considered for the RP mechanism, focusing on chaotropic agents, mobile-phase concentrations and mixing ratios, and column temperature. Sample preparation was conducted by toluene liquid–liquid extraction of e-cigarette liquids diluted with aqueous 25 mM NaHCO₃/Na₂CO₃. Optimal RP results for retention and peak symmetry were obtained using aqueous 0.1% formic acid and 20 mM ammonium hexafluorophosphate with 0.1% formic acid in acetonitrile, using a gradient profile with a C18 column, exploited at 40 °C and a 1.5 mL/min flow rate. A dilute-and-shoot alternative with automated flow reversal after isocratic elution is presented. For HILIC, aqueous 100 mM ammonium formate and 0.1% formic acid in acetonitrile were used as mobile-phase components, using a gradient profile, on a Thermo Scientific™ Acclaim™ Mixed-Mode HILIC-1 column, operated at 25 °C with a 1 mL/min flow rate. UV detection was at 260 nm. Absolute limits of quantitation in the 1 μg/mL range were obtained for all tested alternatives, with 1 μL injection volumes.

Spectral peak purity evaluations are often used to control inadequate selectivity issues appearing in liquid chromatography separations coupled with UV-Vis photodiode detection, despite known limitations related to (a) the lack of characteristic absorption bands in UV-Vis for target analytes and overlapping related impurities; (b) increased similarity between the spectral characteristics of co-eluting compounds; (c) large concentration differences between overlapping compounds; (d) perfect co-elution cases. We propose an alternative protocol to evaluate differences between spectra collected over a peak’s elution interval. After normalizing the acquired spectra, linear regression was applied between each pair of spectra, resulting in slope, intercepts, and correlation coefficient sets, from each comparison. The means and standard deviations of each variable are thus computed. An ellipsoid in the 3D Cartesian space illustrates these computations, having the mean coordinates as center and 2 × standard deviations of the variables as the axes. The volume of the ellipsoid should be related to the similarity between the compared spectra; a smaller volume indicates a higher spectral similarity. This approach was evaluated with respect to the (a) concentration of the analytes; (b) spectral acquisition parameters (spectral resolution, spectral frequency acquisition); (c) spectral similarity between overlapping peaks; (d) perfect co-elution situation; (e) influence of spectral processing (derivation, wavelength rationing), using test solutions of carbamazepine (a,b), acetyl cysteine and enalapril maleate (c), or nitrazepam and diazepam (d,e).

Clozapine and its metabolites require close therapeutic monitoring (TDM) in patients due to poor correlation between the administrated doses and resulting plasma concentrations, the narrow therapeutic interval, high inter-individual variability, and the risk of serious side effects once toxic levels are exceeded. The aim of the study was to develop a simple (relatively cheap) LC-UV method for the quantification of clozapine and its metabolites in plasma and urine samples. For sample preparation, liquid-liquid extraction (LLE) in n-octanol was more efficient and less limiting in injection volumes compared to the in-situ formation of SUPRAS. When analyzing urine, an alkalinization step before extraction was required. The proposed method produced linear concentration responses with/without internal standard (IS) for the target analytes, with LLOQs within the targeted range of 50 ppb and %RSD within the acceptable 15% range. Furthermore, sample stability studies proved that pre-extracted samples were stable for the short term at room temperature and long-term when frozen.

In Europe, unaligned regulatory requirements between the EU and member states often require that researchers and educators undertake additional labor intensive activities to ensure that the institutions where they work do not fall short of meeting both requirements. Because manually introducing information piecemeal from thousands of Safety Data Sheets (SDSs) into other required lists is labor intensive, this project provides a stand-alone application that can populate the required information within minutes and be easily used by any employee. Though the application is currently limited to the Romanian language and there are certain improvements that can be addressed within the script, as it stands, the application can fulfill its purpose.

The logical first step in any traditional forensic visual examination of trace evidence samples is color comparison. However, comparing the color of two objects to determine if a common origin exists is largely subjective, unless the colors are far apart on the spectrum. To aid in the discrimination process, instrumental methods such as microspectrophotometry have been employed. A number of commercial units have been available over the years to make transmission, reflectance, and fluorescence measurements on these types of evidence, although many of these current and past units are quite costly. This paper describes the use of an Ocean Optics USB-2000+ fiber optic array detector (spectrometer) connected to existing laboratory microscopes and a laptop PC for such measurements. This spectrometer performed more than adequately for the determination of reflectance and transmission visible spectra of glass chips and dyed fibers.

The detection of fentanyl, a main culprit in opioid overdose deaths, has become critical. Although Raman spectroscopy is a valuable analytic tool for the detection of illicit drugs, the weak intensity of Raman scattering spectra makes it difficult to detect trace materials. This shortcoming is improved by application of surface‐enhanced Raman spectroscopy (SERS), which produces large signal enhancements when target compounds are near metal nanoparticles. This paper examines the use of a paper-based substrate impregnated with silver nanoparticles for the detection of trace quantities of fentanyl alone, or as an adulterant in heroin. In addition, a Langmuir isotherm calibration model was plotted using intensity-ratios of diagnostic peaks associated with each substance and allowing for quantitative analysis of fentanyl in various mixtures. Linearity was seen at concentrations < 6%, a significant finding as this is consistent with concentrations of fentanyl that are found in street-seized drugs. In addition, swabbing of surfaces with the paper-based SERS substrates allowed the recovery of fentanyl from surfaces, showing this approach may be applicable in crime scene analyses; however, assessment using a Langmuir model proved difficult for the swabbed samples. This work demonstrates a potentially simple and sensitive technique for the forensic detection and quantitation of fentanyl in trace amounts

Law enforcement agencies routinely sample for gunshot residue (GSR) by bulk techniques and often submit swabs taken from other surfaces besides the hands of the suspect shooter. This study aims to establish the prevalence of antimony, barium, and lead on normally handled automobile surfaces by graphite furnace atomic absorption analysis. No positives were determined on 50 sampled automobile surfaces above cutoff (positive) from background levels. Transfers of GSR particles from shooter hands to automobile surfaces were found to potentially allow for positive GSR determinations, but such transfers seem to be dependent on the shooting conditions and length of GSR exposure. We determined that our bulk analysis method yields an overall 87.94 ± 5.52% extraction efficiency from cotton swabs, while the LOQ determinations strengthening the fact that bulk analysis methods are valid and valuable tools for GSR investigations.