RESUMO

A solvothermal synthesis of ultrasmall cerium oxide nanoparticles (USCeOxNPs) with an average size of 0.73 ± 0.07 nm using deep eutectic solvent (DES) as a stabilizing medium at a temperature of 90 ºC is reported. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were used to morphologically characterize the USCeOxNPs. These revealed approximately spherical shapes with emission lines characteristic of cerium. Selected area electron diffraction (SAED) was used to determine the crystalline structure of the cerium oxide nanoparticles (CeO2NPs), revealing the presence of crystalline cubic structures. The USCeOxNPs-DES/CB film was characterized by scanning electron microscopy (SEM), which demonstrated the spherical characteristic of CB with layers slightly covered by DES residues. DES was characterized by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR), indicating its formation through hydrogen bonds between the precursors. An electrochemical sensor for dopamine (DA) determination in biological fluids was developed using the USCeOxNPs together with carbon black (CB). An enhanced current response was observed on DA voltammetric determination, and this can be attributed to the USCeOxNPs. This sensor displayed linear responses for DA in the range 5.0 × 10-7 mol L-1 to 3.2 × 10-4 mol L-1, with a limit of detection of 80 nmol L-1. Besides detectability, excellent performances were verified for repeatability and anti-interference. The sensor based on USCeOxNPs synthesized in DES in a simpler and environmentally friendly way was successfully applied to determine DA in biological matrix.

Assuntos

RESUMO

This study presents the development of a simple, fast, and inexpensive approach for the direct analysis of new psychoactive substances (NPS) in seized tablets and blotter paper, with improved sample preservation and increased analytical frequency. Paper triangles were gently rubbed against the surface of the samples containing synthetic drugs and then subjected to analysis by paper spray ionization mass spectrometry (PS-MS). Seized samples containing lysergic acid diethylamide (LSD) and several other substances from the classes of amphetamines, N-benzyl-substituted phenethylamines, synthetic cathinones, and synthetic cannabinoids, were analysed. Three types of paper were tested (filter paper, blotter paper, and synthetic paper) and several combinations of spray solvents were studied for the optimization. All samples were weighed and photographed before and after sequences of analysis in order to attest to the sample preservation. The results revealed that the approach is excellent for sample preservation, with less than 5% of mass loss even after 27 consecutive analyses. Moreover, no significant signal decreases were observed in mass spectrometry (MS) even after the experiments. It was possible to unequivocally identify illicit substances from seized samples (pills and blotter paper). By overcoming the solubilization and wet extraction process used for sample preparation, the waste was restricted to a volume of only 10 µL of solvent for the PS-MS analysis. The main advantage of our approach over existing methods is the sample preparation, which is simple and quick since the samples are just rubbed against the PS paper. This brings enormous benefits in terms of analytical frequency, economy of time and low consumption of solvents. Another important point is that the sample can remain intact for further analysis, which is crucial in forensic analysis.

Assuntos

RESUMO

This work presents a data survey regarding the qualitative chemical analysis of drugs seized by the Police in the state of Minas Gerais between July 2017 and June 2022, including an evaluation of labeling of 265 samples of anabolic androgenic steroids (AAS) seized in 2020. The Active Pharmaceutical Ingredients (API) present in the samples were identified through chemical analysis and classified by system Anatomical Therapeutic Chemical (ATC) methods. Analysis of the labeling information for 265 samples of AAS followed the guidance of legislation RDC 71 (2009) from ANVISA. For this study 6355 seized pharmaceuticals underwent qualitative chemical analysis that corresponded to 7739 APIs successfully identified and classified. Among the components studied AAS, psychostimulants, anesthetics, and analgesics were the most commonly examined. AAS seized and tested increased by over 100% and for the majority of the samples analyzed were found to not match the labeling on the packaging. In the meantime, anti-obesity drugs presented a prominent increase of 400% from 2020/1 to 2021/2, during covid-19 quarantine. Seized pharmaceuticals and tests can support information in the planning of public health and safety policies.

Assuntos

RESUMO

This paper presents the combination of wooden-tip electrospray ionization mass spectrometry (WTESI-MS) and multivariate pattern recognition methods (principal component analysis, PCA and partial least squares discriminant analysis, PLS-DA) for the rapid and reliable discrimination, via chemical fingerprints, of garlic origin. A total of 312 garlic samples grown in different countries (Brazil, China, Argentina, Spain, and Chile) were studied. The methodology was based on a direct sampling approach, which relies on loading the sample by penetrating the garlic cloves with a pre-wetted wooden tip, followed by direct prompt analysis by WTESI-MS. Thus, no sample preparation is needed, which prevents the degradation of important metabolites and increases the analytical throughput. Parameters that affects the WTESI were optimized and the best performance in terms of signal stability and intensity was achieved using the positive ion mode. Most of the ions in WTESI mass spectra were assigned to amino acids, sugars, organosulfur compounds, and lipids. The discriminative model showed good performance (accuracy rates between 81.9% and 98.6%) and enabled identifying diagnostic ions for garlic samples from different origins. The differentiation and classification of garlic origin is of major importance as this food flavoring product is widely consumed, with worldwide trade representing billions of dollars every year, and is very often the subject of fraud.

Assuntos

RESUMO

The recent developments on fieldable miniature mass spectrometers require efforts to produce easy-to-use and portable alternative tools to assist in point-of-care analysis. In this paper, the reagent-pencil (RP) technology, which has been used for solvent-free deposition of reagents in paper-based microfluidics, was combined with paper spray ionization mass spectrometry (PS-MS). In this approach, named RP-PS-MS, the PS triangular piece of paper was written with the reagent pencil, consisting of mixtures of graphite and bentonite (used as a support) and a reactive compound, and allowed to react with a given analyte from a sample matrix selectively. We conducted typical applications as proof-of-principles to verify the methodology's general usefulness in detecting small organic molecules in distinct samples. Hence, various aldehydes (2-furaldehyde, valeraldehyde, and benzaldehyde) in spiked cachaça samples (an alcoholic drink produced from fermentation/distillation of sugarcane juice) were promptly detected using a reagent pencil doped with 4-aminophenol (the reactive compound). Similarly, we recognized typical ginsenosides and triacylglycerols (TAGs) in ginseng aqueous infusions and soybean oil samples, respectively, using lithium chloride as the reactive compound. The results indicate that the reagent-pencil methodology is compatible with PS-MS and provides an easy and fast way to detect target analytes in complex samples. The advantage over the usual solution-based deposition of reagents lies in the lack of preparation or carrying different specific solutions for special applications, which can simplify operation, especially in point-of-care analysis with fieldable mass spectrometers.

RESUMO

This paper presents a novel coupling between a four-phase electroextraction (EE) system and paper spray mass spectrometry (PS-MS) for the extraction, pre-concentration, and direct analysis of target compounds in different samples. The approach, EE-PS-MS, is based on the sorption of analytes directly on the tip of a triangular-shaped chromatographic paper, with subsequent prompt analysis by PS-MS. Thus, no off-line extraction step is required before the PS analysis, improving the protocol efficiency and reducing the analysis time. In addition to functioning as a porous material to absorb the target compounds, the chromatographic paper also served as the support for one of the aqueous phases of the optimized four-phase electroextraction system. Extraction conditions, such as the composition of the donor and organic phases, applied electric potential, and extraction time, were optimized. Three different applications, involving biofluid, food, and water quality analysis, were evaluated as a proof-of-concept. These applications involved the determination of (i) cocaine and lidocaine in saliva, (ii) malachite green in tap water, and (iii) bisphenol A (BPA) in red wine. When compared with direct PS-MS, the novel EE-PS-MS protocol improved the sensitivities by factors ranging from 14 to 110, depending on the analyte and the sample. The electroextraction procedures were performed on a laboratory-built 66-well plate, which offered the functionality of simultaneous sample handling and, most importantly, improved analytical throughput.

RESUMO

A novel methodology using liquid-liquid extraction with low temperature partitioning (LLE-LTP) and paper spray mass spectrometry (PS-MS) was developed to identify and quantify benzodiazepines in beverages. Four types of alcoholic beverages usually consumed in parties and bars were spiked with 5 distinct benzodiazepines (diazepam, alprazolam, bromazepam, clonazepam, and cloxazolam) simulating a drug-facilitated crime occurrence. The direct PS-MS analysis of the spiked beverages revealed a remarkable matrix effect with an unclear detection of protonated benzodiazepines. However, by the application of the LLE-LTP using liquid nitrogen, a prompt and doubtless detection of such compounds was achieved. The quantification potential of the LLE-LTP/PS-MS methodology was demonstrated by using beer as matrix, diazepam as target analyte and cloxazolam as an internal standard. Figures of merit (linearity, limit of detection, linear dynamic range, relative standard deviation, and recovery) were determined and adequate values were obtained. In conclusion, we demonstrated herein that the LLE-LTP/PS-MS methodology has potential to be applied directly at the crime scene through of a portable mass spectrometer and a thermal container for the transport of liquid nitrogen.

Assuntos

RESUMO

A direct method based on the application of paper spray mass spectrometry (PS-MS) combined with a chemometric supervised method (partial least square discriminant analysis, PLS-DA) was developed and applied to the discrimination of authentic and counterfeit samples of blended Scottish whiskies. The developed methodology employed the negative ion mode MS, included 44 authentic whiskies from diverse brands and batches and 44 counterfeit samples of the same brands seized during operations of the Brazilian Federal Police, totalizing 88 samples. An exploratory principal component analysis (PCA) model showed a reasonable discrimination of the counterfeit whiskies in PC2. In spite of the samples heterogeneity, a robust, reliable and accurate PLS-DA model was generated and validated, which was able to correctly classify the samples with nearly 100% success rate. The use of PS-MS also allowed the identification of the main marker compounds associated with each type of sample analyzed: authentic or counterfeit.

Assuntos

RESUMO

This article describes the use of paper spray mass spectrometry (PS-MS) for the direct analysis of black ink writings made with ballpoint pens. The novel approach was developed in a forensic context by first performing the classification of commercially available ballpoint pens according to their brands. Six of the most commonly worldwide utilized brands (Bic, Paper Mate, Faber Castell, Pentel, Compactor, and Pilot) were differentiated according to their characteristic chemical patterns obtained by PS-MS. MS on the negative ion mode at a mass range of m/z 100-1000 allowed prompt discrimination just by visual inspection. On the other hand, the concept of relative ion intensity (RII) and the analysis at other mass ranges were necessary for the differentiation using the positive ion mode. PS-MS combined with partial least squares (PLS) was utilized to monitor changes on the ink chemical composition after light exposure (artificial aging studies). The PLS model was optimized by variable selection, which allowed the identification of the most influencing ions on the degradation process. The feasibility of the method on forensic investigations was also demonstrated in three different applications: (1) analysis of overlapped fresh ink lines, (2) analysis of old inks from archived documents, and (3) detection of alterations (simulated forgeries) performed on archived documents. Graphical Abstract ᅟ.

RESUMO

Paper spray mass spectrometry (PS-MS) combined with partial least squares discriminant analysis (PLS-DA) was applied for the first time in a forensic context to a fast and effective differentiation of beers. Eight different brands of American standard lager beers produced by four different breweries (141 samples from 55 batches) were studied with the aim at performing a differentiation according to their market prices. The three leader brands in the Brazilian beer market, which have been subject to fraud, were modeled as the higher-price class, while the five brands most used for counterfeiting were modeled as the lower-price class. Parameters affecting the paper spray ionization were examined and optimized. The best MS signal stability and intensity was obtained while using the positive ion mode, with PS(+) mass spectra characterized by intense pairs of signals corresponding to sodium and potassium adducts of malto-oligosaccharides. Discrimination was not apparent neither by using visual inspection nor principal component analysis (PCA). However, supervised classification models provided high rates of sensitivity and specificity. A PLS-DA model using full scan mass spectra were improved by variable selection with ordered predictors selection (OPS), providing 100% of reliability rate and reducing the number of variables from 1701 to 60. This model was interpreted by detecting fifteen variables as the most significant VIP (variable importance in projection) scores, which were therefore considered diagnostic ions for this type of beer counterfeit.

Assuntos