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Biodiesel is a fuel comprised of mono-alkyl esters of long-chain fatty acids derived from vegetable oils or animal fats. Biodiesel is designated B100 and is regarded as the major substitute for fossil diesel. Crambe abyssinica, a native plant from Ethiopia, has great potential for biodiesel production due to its higher calorific value and oxidative stability as compared to soybean oil biodiesel. Compared to fossil diesel, C. abyssinica oil biodiesel emits significantly less CO2 without efficiency loss. However, its crude oil only provides good results if it undergoes supercritical transesterification. Here, we aimed to produce ethyl and methyl esters from crambe oil under ambient conditions. Initially, we tested two methods to degum crambe oil: aqueous degumming and acid degumming. We subjected the degummed oil to transesterification through the methylic or the ethylic route, catalyzed by KOH. The methyl esters of the biodiesel obtained by esterification of crambe oil submitted to acid degumming had higher oxidative stability as compared to the methyl esters of the biodiesel obtained from crambe oil subjected to aqueous degumming: 15.7 h and 10.7 h, respectively, but the yield was lower: 70% vs. 80%, respectively. The ethyl esters of the biodiesel obtained from crambe oil submitted to aqueous degumming provided the highest yield and oxidative stability: 65% and 8.5 h, respectively. We also evaluated the oxidative stability of blends consisting of crambe oil methylic or ethylic biodiesel and soybean oil biodiesel.

Currently, marijuana or cannabis is the most consumed drug worldwide, and is also the one with the highest number of seizures, with 354 tons seized in Brazil in 2017. The increase in its consumption has been called attention, not only by the authorities, due to accidents caused when driving under the influence of the drug, but also by companies that carry out toxicological analyzes on their employees. For this, rapid tests, such as colorimetric tests, are generally used to analyze the urine of users. The need for agile and proper identification of drugs of abuse has encouraged the scientific community to improve and to develop new methodologies. Electrochemical methods appear as a cheap, portable and easy to use alternative. The use of biodegradable materials for the development of disposable electrodes has become paramount today. The use of 3D printers emerges as an alternative for the manufacture of these electrodes and the use of saliva instead of urine, has also been a priority because it is a less invasive sample and difficult to adulterate. In this work, a three dimensional device was created in an innovative way containing the three electrodes, working, counter and reference, in conductive material. The device was then used to detect the active principle present in cannabis, delta-9-tetrahydrocannabinol, in aqueous solution, and its metabolite, 11-nor-9-carboxy-THC, in samples of real saliva, both through cyclic voltammetry. The positive results show that the proposed device can be used, as well as those already found on the market, for the identification of drug use and in the forensic field.

3,4-Methylenedioxymethamphetamine (MDMA) is a popular illicit drug. Given its adverse effects, the growing abuse of MDMA worldwide, and the need for forensic chemistry methods that minimize environ...

The need for agile and proper identification of drugs of abuse has encouraged the scientific community to improve and todevelop new methodologies. The drug lysergic acid diethylamide (LSD) is still widely used due to its hallucinogenic effects. The use ofvoltammetric methods to analyze narcotics has increased in recent years, and the possibility of miniaturizing the electrochemical equipmentallows these methods to be applied outside the laboratory; for example, in crime scenes. In addition to portability, the search for affordable andsustainable materials for use in electroanalytical research has grown in recent decades. In this context, employing paper substrate, graphite pen-cil, and silver paint to construct paper-based electrodes is a great alternative. Here, a paper-based device comprising three electrodes was drawnon 300 g/m2watercolor paper with 8B pencils, and its efficiency was compared to the efficiency of a commercially available screen-printedcarbon electrode. Square wave voltammetry was used for LSD analysis in aqueous medium containing 0.05 mol/L LiClO4. The limits of detec-tion and quantification were 0.38 and 1.27 mol/L, respectively. Both electrodes exhibited a similar voltammetric response, which was alsoconfirmed during analysis of a seized LSD sample, with recovery of less than 10%. The seized samples were previously analyzed by GCMStechnique, employing the full scan spectra against the software spectral library. The electrode selectivity was also tested against 3,4-methylene-dioxymethamphetamine (MDMA) and methamphetamine. It was possible to differentiate these compounds from LSD, indicating that the devel-oped paper-based device has potential application in forensic chemistry analyses., Financial support provided by the Polícia Científica do Estado de São Paulo for the partnership, and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP - Process 2016/23825-3), Fundação para a Ciência e Tecnologia, FCT, Portugal, (UID/QUI/00686/2016 and UID/QUI/00686/2019), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Process Capes Pro Forenses 25/2014).

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.

Cocaine is an illicit drug that is being increasingly used worldwide. Therefore, the development of new methods to detect cocaine and to distinguish it from false positives is necessary. For the first time, we have investigated how cadmium telluride quantum dots (CdTe QDs) interact with cocaine, lidocaine or procaine, as hydrochloride salts, by fluorescence spectroscopy and by using the Stern–Volmer model at different temperatures (298, 304 and 311 K). The Stern–Volmer fluorescence quenching constant (KSV), binding constant (KB), number of binding sites (n) and the thermodynamic parameters (ΔGθ, ΔHθ and ΔSθ) were obtained for each compound through the fluorescence quenching data. The results showed differences that signalled distinct quenching mechanisms and demonstrated that the structure of the hydrochlorides influenced the way they interacted with CdTe QDs, which could lead to a promising method to distinguish between cocaine and its two potential false positives, procaine and lidocaine, in colorimetric forensic tests.

Cocaine is one of the most abused drugs worldwide. Therefore, it is crucial to develop and improve cocaine identification techniques. This article describes two new electrodes chemically modified with ([Co((±)-t-3MeOsalcn)] or ([Cu((±)-t-3MeOsalcn)] and their use in free-base cocaine (FB) and cocaine hydrochloride (HC) identification. The electrodes were not active toward FB, but cyclic voltammetry analysis revealed an increase of 0.1 V (vs Ag/AgCl) (Eoxi) for HC. The square-wave voltammetry results showed that FB@([Cu((±)-t-3MeOsalcn)] and HC@([Cu((±)-t-3MeOsalcn)] presented higher amperometric sensitivity than FB@([Cu((±)-t-3MeOsalcn)] and HC@([Cu((±)-t-3MeOsalcn)]. The limit of detection (LOD) and the limit of quantification (LOQ) for FB@([Cu((±)-t-3MeOsalcn)] were 0.61 μmol.L−1and 2.04 μmol.L−1, respectively. As for HC@([Cu((±)-t-3MeOsalcn)] the LOD and the LOQ were 0.58 μmol.L−1 and 1.92 μmol.L−1, respectively. The higher chemical stability of the cocaine@([Cu((±)-t-3MeOsalcn)] complexes and the lower binding energy of FB and HC with ([Cu((±)-t-3MeOsalcn)] predicted by theoretical calculations explain the results of the voltammetric analyses. Moreover, the topographic and compositional results confirmed that HC adsorbed onto the surface of the electrodes chemically modified with [Co((±)-t-3MeOsalcn)] or ([Cu((±)-t-3MeOsalcn)]. Overall, our results demonstrated that the electrodes chemically modified with [Co((±)-t-3MeOsalcn)] or ([Cu((±)-t-3MeOsalcn)] developed in this study have promising application in cocaine detection and quantification. At the end of the study, we propose a schematic mechanism for the HC oxidation process at the modified electrodes.

Made available in DSpace on 2022-04-28T19:41:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-10-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Nuclear Fuel Cycle and Supply Chain During laser-based powder bed fusion, the non-equilibrium solidification conditions promote local elemental segregation, leading to a characteristic microstructure composed of cellular walls. These walls can display either low carbon BCC martensite or FCC retained austenite crystal structures, thus affecting the subsequent isochronal or isothermal martensite to austenite phase transformation mechanisms. In the present study, the effect of the non-homogeneous as-built microstructure on the martensite-to-austenite reversion phenomena was studied for a 18Ni maraging steel fabricated by laser-based powder bed fusion. In-situ synchrotron X-ray diffraction was used to retrieve the austenite volume fraction and lattice parameter evolution during the physical simulation of continuous heating cycles to the austenitic field; and during isothermal tempering cycles throughout the inter-critical tempered martensite + austenite (α’ + γ) field. The as-built microstructure resulted in the expansion of the inter-critical α’ + γ field during very slow heating rates. This was associated to the synergic effects of compositional segregations (anticipating reversion) and pre-existing retained austenite (delaying solubilization). During conventional inter-critical tempering, the as-built microstructure did not fundamentally alter the austenite reversion kinetics, resulting in similar high temperature microstructures at the end of the isothermal stage relative to the solution treated state. Department of Materials Engineering University of Sao Paulo (USP), Av. Joao Dagnone, 1100 Jd. Sta Angelina São Paulo State University (UNESP) Campus of São João da Boa Vista, Av. Profa. Isette Corrêa Fontão, 505, Jardim das Flores Universidad Autónoma de Occidente (UAO), Cali, Calle 25, Vía Cali - Puerto Tejada #115-85 Km 2, Cali Metallurgical and Materials Engineering Department University of São Paulo, 10 Av.Prof. Mello Moraes 2463 UNIDEMI Department of Mechanical and Industrial Engineering NOVA School of Science and Technology NOVA University Lisbon Institute of Materials Physics Helmholtz-Zentrum Hereon, Max-Planck-Str. 1 São Paulo State University (UNESP) Campus of São João da Boa Vista, Av. Profa. Isette Corrêa Fontão, 505, Jardim das Flores CNPq: 142440/2019 Nuclear Fuel Cycle and Supply Chain: UID/EMS/00667/2019

Given the fast-growing demand for anti-trafficking measures, this article investigates the development of voltammetric sensors for the oxidation of cocaine hydrochloride on the surface of carbon paste electrodes chemically modified with Schiff base complexes and their potential use for cocaine detection and quantification in seized samples. Voltammetric analyses revealed that [CoII(salen)] displayed amperometric and thermal stability, was uniformly distributed on the electrode surface, was only degraded at temperatures above 300 °C, and did not undergo passivation in acid medium. The [CoII(salen)]-modified voltammetric sensor gave error below 10%, an improvement on HPLC. SIMCA chemometric analyses predicted the group belonging to cocaine hydrochloride and its interferents effectively, attesting to the good selectivity and specificity of the developed sensor. The sensor has potential application in forensic investigations: its LOD and LOQ, intra and inter-day precision, accuracy, linearity ranges, selectivity, specificity, and sensitivity are better as compared to other chemically modified electrodes. Finally, the Density Functional Theory (DFT) method confirmed the oxidation–reduction mechanisms proposed in the literature.

In recent years, practical, inexpensive, and highly specific electroanalytical methods based on modified electrodes have been increasingly developed for forensic science. Simple modification of the carbon paste electrode with Schiff base complexes has become a promising strategy to detect and quantify narcotics. In this context, we aimed to develop voltammetric methods to quantify lysergic acid diethylamide (LSD) by using a carbon paste electrode modified with the complex [UO2(Ac-ophen)]·H2O. The use of an aqueous solution of KCl as supporting electrolyte makes the methodology less polluting, which contrasts with methods that still employ toxic solvents. The developed method for Differential Pulse Voltammetry provides a linear response at various concentrations of LSD and affords analytical curves with standard deviation, detection, and quantification limits around 2.45, 0.625, and 2.08 μmol L-1, respectively. The recovery values of 103 and 108% prove that the developed method is suitable for application in forensic science.

MDMA is the abbreviation for 3,4-methylenedioxymethamphetamine, which is commonly found in “ecstasy” pills. The psychoactive and euphoric effects that MDMA causes make this substance an illicit drug that is constantly seized by police forces. We describe a low-cost and fast voltammetric methodology that requires a carbon paste electrode (working electrode) in aqueous solution containing 0.1 mol L-1 LiClO4 as the supporting electrolyte. We conducted cyclic and square wave voltammetry and obtained limits of detection of 0.33 μg mL-1 and 0.36 μg mL-1, respectively, as others figures of merit for a complete validation. It includes the analysis main interfering substances, and results for seized samples were compared to those obtained by chromatography, which were close. An extended study of robustness were carried out by Youden’s test, that is inedited to electrochemical techniques when applied to forensic analysis. This test contributes to complete methodology validation and study of electrode cost and efficiency during electrochemical measurements involving a carbon paste electrode. In the end, this work presents a full validated methodology able to be applied in forensic laboratories.

The consequences of consuming and commercializing illicit drugs including cocaine, con­stitute a serious problem for authorities and the whole society. Cocaine is usually identified in the laboratory conditions by chromatographic or spectroscopic methods. Electro­che­mical techniques have also gained prominence because they are fast and easy to use, have many applications, and provide reproducible and reliable results. Therefore, in the present study, a voltammetric method was developed to detect freebase cocaine using carbon paste electrode and methanol as the main cocaine solvent. The developed method was applied to detect cocaine in the artificial saliva by the square wave voltammetry (SWV). The current values increased linearly with the concentration of cocaine, which afforded construction of the analytical curve. The limit of detection (LoD) and the limit of quantify­cation (LoQ) were determined as 0.90 µg/mL and 2.41 µg/mL, respectively. For compa­rison purposes, HPLC-DAD chromatographic method was also applied to detect cocaine. The corresponding analytical curve gave LoD = 0.043 µg/mL and LoQ = 0.130 µg/mL. Although showing better analytical results, HPLC-DAD method could not detect cocaine in saliva samples without previous treatment, what makes the electrochemical method much more attractive for this type of detection.

This article describes a method that uses a carbon paste chemically modified with N,N’-ethylene-bis-(salicylideneiminato) manganese(II) to detect cocaine hydrochloride by linear sweep voltammetry (LSV) in aqueous medium containing 0.1 mol L−1 KCl as supporting electrolyte. The potential scans were run from 0.4 to 0.9 V (vs Ag/AgCl), at 100 Mv s−1. The carbon paste chemically modified with the [Mn(salen)] complex had to be heated at 60 °C for paste agglutination. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were conducted to assess the thermal stability of the [Mn(salen)] complex, which remained stable up to 300 °C. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analyses showed that the [Mn(salen)] complex was evenly and homogeneously distributed on the chemically modified electrode surface. The possible mechanism of electronic exchange between cocaine hydrochloride and the electrode surface was proposed: cocaine hydrochloride reduction at the working electrode surface produced the radical •C–OH due to reduction of the carbonyl group (C=O) stabilized by interaction of its free electron with orbital d electrons present in the manganese(II) Schiff base complex. Cathodic activity was verified at 0.8 V (vs Ag/AgCl). Cocaine hydrochloride detection presented linear dependence from 1 to 100 μmol L−1 with linear correlation coefficient of 0.9995 ± 0.0006, average amperometric sensitivity of 0.3367 μmol L−1, limit of detection (LOD) of 0.9349 μmol L−1, and limit of quantification (LOQ) of 3.11 μmol L−1. Notably, the [Mn(salen)] complex used in herein presented higher amperometric sensitivity than the complexes published so far, which is an important contribution to the development of techniques for cocaine detection.

The consumption of ecstasy has increased in recent years due to the psychostimulating effects of MDMA (3,4-methylenedioxymethamphetamine), its main active ingredient. With that, there is a great concern on the part of the authorities, mainly for the control of drivers who drive under the influence of drugs. The verification of the drug use is usually made by the presence of its metabolites in blood or urine, but alternative matrices such as oral fluid, sweat and hair have been investigated over past decades. For the oral fluid the collection is simple, noninvasive, and less susceptible to adulteration and can be used to show recent use of the drug. Portable equipment such as Drugwipe®, Cozart RapiScan, and Ora-Check are routinely used because they easy and simple to operate and give the result quickly. Another technique that features portability and easy handling is electrochemistry. This work demonstrates that it is possible to identify MDMA in oral fluid using the carbon paste electrode, as working and auxiliary electrodes, and the screen printed carbon electrode (SPCE) with cyclic and square wave voltammetry. The presence of the drug could also be identified in real saliva, mixed with 0.1 mol L−1 LiClO4 as supporting electrolyte, in a concentration of 2.53 µg mL−1, demonstrating that it can be applied to identify the recent use of the drug, as well as the rapid tests already commercialized. Also, SPCE was used for the detection and quantification of MDMA in seized samples, using aqueous solution of 0.1 mol L−1 LiClO4, with limits of detection and quantification of 1.75 and 5.82 µg mL−1, respectively, and a linear range of 1.75 – 19.98 µg mL−1. These results support the use of these procedures in forensic laboratories as simple, rapid, and alternative methods for detecting MDMA in saliva and for analyzing seized drugs.

The HPLC technique with UV-Vis detection was employed in the analysis of cocaine content in apprehended samples of cocaine and crack. A peak signal for cocaine was obtained in 3.5 minutes run by using acetonitrile/water (95:5v/v) as a mobile phase. Optimized spectrophotometric signal was obtained at a wavelength of 224 nm. The analytical curve from 1.0 to 40.0 ppm of cocaine was obtained, showing a linear correlation coefficient of 0.9989, with detection and quantification limits of 0.75 ppm and 3.78 ppm, respectively. This methodology was employed at the dosage of confiscated samples of cocaine and crack in the Scientific Police Laboratory of Ribeirão Preto-SP city

Rapid screening of seized drugs is a continuing problem for governmental laboratories and customs agents. Recently new and cheaper methods based on electrochemical sensing have been developed for the detection of illicit drugs. Screen printed electrodes are particularly useful in this regard and can provide excellent sensitivity. In this study, a carbon screen printed electrode for the voltammetric analysis of D9-THC was developed. The analysis was performed using cyclic voltammetry with 0.15 mol×L-1 potassium nitrate as a supporting electrolyte. In the analysis, a D9-THC standard solution was added to the surface electrode by a drop coating method. A study of scan rate, time of pre-concentration, and concentration influence parameters showed versatility during the investigation. The high sensitivity, quantitative capability and low limit of detection (1.0 µmol×L-1) demonstrate that this electrochemical method should be an attractive alternative in forensic investigations of seized samples.

Schiff bases and their transition metal complexes are inexpensive and easy to synthesize. These compounds display several structural and electronic features that allow their application in numerous research fields. Over the last three decades, electroanalytical scientists of various areas have developed electrochemical sensors from many compounds. The present review discusses the applicability of Schiff bases, their transition metal complexes and new materials containing these compounds as electrode modifiers in sensors to detect analytes of forensic, pharmaceutical and environmental interest. In forensic sciences, Schiff bases are mainly used to analyze illicit drugs: chemical reactions involving Schiff bases can help to elucidate illicit drug production and to determine analytes in seized samples. In the environmental area, given that most methodologies provide Limit of Detection (LOD) values below the values recommended by regulatory agencies, Schiff bases constitute a promising strategy. As for pharmaceutical applications, Schiff bases represent an approach for analysis of complex biological samples containing low levels of the target analytes in the presence of a large quantity of interfering compounds. This review will show that new highly specific materials can be synthesized based on Schiff bases and applied in the pharmaceutical industry, toxicological studies, electrocatalysis and biosensors. Most literature papers have reported on Schiff bases combined with carbon paste to give a chemically modified electrode that is easy and inexpensive to produce and which displays specific and selective sensing capacity for different applications.

An empirical method is developed, based on the calculated theoretical elastic-strain energy, to predict the phase formation and its stability for complex concentrated alloys. The method prediction quality is compared with the traditional empirical rules based on the atomic-size mismatch, enthalpy of mixing, and valence-electron concentration for a database of 235 alloys. The “elastic-strain energy vs. valence-electron concentration” criterion shows an improved ability to distinguish between single-phase solid solutions, and mixtures of solid solutions and intermetallic phases when compared to the available empirical rules used to date. The criterion is especially strong for alloys that precipitate the µ phase. The theoretical elastic-strain-energy parameter can be combined with other known parameters, such as those noted above, to establish new criteria which can help predict the design of novel complex concentrated alloys with the on-demand combination of mechanical properties.

The illegal use of formalin (commercial formaldehyde) in cosmetic products harms the health of individuals exposed to this substance. Over the last years, the commercial availability of these products, especially those containing irregular dosage of formaldehyde, has increased in Brazil. This work analyzes some products for hair treatment available in the Brazilian market and verifies their safety. The adopted analytical methodology involved sample derivatization with 2,4‐dinitrophenylhydrazine, followed by high‐performance liquid chromatography with ultraviolet detection (UV–VIS) at λ = 365 nm. The limit of quantification is 2.5 × 10−3% w/w, and the recovery tests were around 93%. Some of the samples contained high and illegal formaldehyde levels ranging from 9% to 19% (w/w) and others presented suitable concentrations of the analyte. On the basis of the results, this work discusses the efficiency and practicality of this analytical method for forensic purposes.

The worldwide attention for illicit drug consumption is known, mainly cocaine and marijuana, which were the most commonly apprehended drugs. In this study, we adapted conventional systems for voltammetric analysis for identifying these drugs using screen-printed electrode (SPE) devices in a portable potentiostat. For cocaine determination, a commercial platinum screen-printed electrode (Pt-SPE) with a cobalt hexacyanoferrate film (CoHCFe) presented the best results in comparison to other available models, and for Δ9-tetrahydrocannabinol (Δ9-THC), no chemical modification was required on the carbon screen-printed electrodes (C-SPEs). The results allowed the use of the adapted systems with good analytical parameters: cocaine and Δ​9-THC determination presented a sensibility equal to 2.02 × 10−2 and 2.65 × 10−7 A L mol−1 , respectively. Finally, the developed procedures showed an application for electrochemical analysis in forensic context, besides the results obtained to comply with reliable results which forensic analysis must have.