Eloilson Domingos

Quantification of cocaine and its adulterants (lidocaine and levamisole) using the Dragendorff reagent allied to paper spray ionization mass spectrometry

Thin layer chromatography is a simple, easy and cheap technique widely used in Brazilian forensic laboratories, being a screening test for the separation and identification of illicit drugs, such as cocaine and its adulterants. Herein, paper chromatography using the Dragendorff reagent (revealing agent) was employed to analyze cocaine and its adulterants (levamisole, lidocaine, caffeine, and phenacetin). Positive results, i.e. visualization of the orange color, were only observed for cocaine, lidocaine and levamisole. Paper spray ionization mass spectrometry (PS-MS) was applied on revealed spots for the construction of a quantification model, for which some figures of merit were determined such as linearity, limit-of-detection (LOD), limit-of-quantification (LOQ) and accuracy. The results showed that PS-MS in positive-ion ionization mode, PS(+)-MS, is an efficient technique for direct analysis of the chromatographic spots on office-type paper revealed by the Dragendorff reagent. The method presented linearity greater than 0.98, and LODs of 6.51 μg mL−1 and 13.53 μg mL−1 for cocaine and levamisole, respectively, and 0.35 mg mL−1 for lidocaine. PS(+)MS was also applied to quantify cocaine in ten street crack samples, where there was no statistically significant difference between PS(+)MS and gas chromatography with flame ionization detection (GC-FID) data at a significance level of 5%.

Rapid screening of agrochemicals by paper spray ionization and leaf spray mass spectrometry: which technique is more appropriate?

Paper Spray Ionization (PSI) and Leaf Spray (LS) are two new sources of ambient ionization mass spectrometry. In PSI, the sample is deposited on a triangular paper and ions are generated by applying a high voltage on a moistened paper with an organic protic solvent. The LS technique is a variant of PSI, where the paper is now substituted by the matrix itself to be studied, a triangular leaf. Both methods allow rapid and inexpensive analyses compared to traditional API techniques. In this work, both sources were applied to identify and quantify agrochemicals which are widely used in fruits and vegetables. The analytical performance of PS and LS techniques was evaluated from the construction of calibration curves in the positive ionization mode (PSI(+) and LS(+)) using atrazine, diuron and methomyl agrochemicals in arugula, basil, cabbage, lettuce and kale vegetable samples. The concentration ranged from 10 to 1000 ppb. Atrazine and diuron were used as internal standards, not requiring the use of deuterated standards. Both analytical methods demonstrated similar performance for the three agrochemicals with R2 > 0.99, and values of LOD and LOQ ranging from 1.23 to 25.00 and 4.12 to 83.33 ppb for PSI(+)-MS and from 0.03 to 36.00 and 0.11–120.00 ppb for LS(+)-MS. In almost all cases, these values were lower than the established MRLs (Maximum Residue Limits), which are 250 ppb for atrazine and 100 ppb for diuron and methomyl.

Paper spray ionization mass spectrometry applied to forensic chemistry – drugs of abuse, inks and questioned documents

With the advent of a new family of ionization techniques, ambient mass spectrometry (or ambient MS) was introduced as a simple way of generating ions in MS. Among them, the paper spray ionization (PS-MS) technique has demonstrated to be versatile to solve numerous problems in many areas of science. In this work, the PS-MS technique in the positive ionization mode (PS(+)-MS) was applied in two subareas of forensic chemistry: drugs of abuse and documentoscopy. In the first, the PS(+)MS technique was applied to obtain the chemical profiles of illicit drugs such as blotter papers containing 25I-NBOMe, extracts and leaves of natural cannabinoids (Δ9-tetrahydrocannabinol) and synthetic cannabinoids (naphthalen-1-yl-(1-butylindol-3-yl)methanone, (JWH-073); n-(adamantan-1-yl)-1-(4-fluorobutyl)-1H-indazole-3-carboxamide (5F-AKB48); 4-methyl-1-naphthyl-1-pentylindol-3-yl-methanone (JWH-122); 2-(2-methoxyphenyl)-1-(1-pentylindol-3-yl)ethanone (JWH-250); and 4-ethylnaphthalen-1-yl-(1-pentylindol-3-yl)methanone (JWH-210)) as well as to determine the authenticity in weight-loss herbal samples. Finally, an analytical method has been developed to quantify eight illicit drugs (3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy-N-methylamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), meta-chlorophenylpiperazine (m-CPP), methamphetamine (MA), cocaine, lysergic acid diethylamide (LSD), and dimethoxybromoamphetamine (DOB)) where their limit-of-detection ranged from 0.17 to 1 ppb, with linearity R2 > 0.99. The performance of the PS(+)-MS technique was also compared to other ionization sources: leaf spray mass spectrometry (LS-MS), and electrospray ionization mass spectrometry (ESI-MS). In the second part of this study, the PS(+)MS technique was successfully able to obtain the chemical profiles of different commercial blue pens. The relative intensity (RII372) of the methylene blue dye was monitored to discriminate crossings of traces, and to date questioned documents. The chemical profile of the second generation of Brazilian banknotes (R

Portable near infrared spectroscopy applied to quality control of Brazilian coffee

, reais) was also explored. In general, the PS(+)-MS technique was proved to be an excellent analytical tool in forensic chemistry, acting like a “Swiss army knife”.

Identification of Alkaloids from Hippeastrum aulicum (Ker Gawl.) Herb. (Amaryllidaceae) Using CGC-MS and Ambient Ionization Mass Spectrometry (PS-MS and LS-MS)

The use of portable micro-spectrometers such as a micro near infrared region (microNIR) spectrometer is a promising technique for solving analytical problems in several areas of science. This work evaluated the potential of microNIR in quality control of Arabica coffee. Arabica coffee has a high commercial value product, motivating the development of analytical methods with high sensitivity and accuracy for detection of its adulteration. Herein, microNIR was successfully used to determine the quality of Arabica coffee by identification and quantification of adulterations such as Robusta coffee (in different roasting levels), as well as corn, peels, and sticks. MicroNIR was combined with multivariate calibration by partial least squares (PLS) and principal component analysis (PCA). A total of 125 blends were produced, containing thirteen different concentrations of the adulterants (corn and peels/sticks, and the Robusta coffee) ranging from 1 to 100wt%. Developed PCA and PLS models were also applied to monitor the quality of sixteen commercial coffee samples. The results obtained using microNIR proved the ability of the method to be efficient and capable in the prediction of adulterations with minimum quantification levels (LOQs of 5-8wt%), being able to be applied to quality control of commercial coffee samples. Therefore, microNIR can reduce and simplify the time of analysis and sample preparation step, as well as to guarantee the efficiency of real-time data acquisition owing to its portability.

Portable near infrared spectroscopy applied to fuel quality control.

Amaryllidaceae alkaloids are well-known isoquinolines which have demonstrated a wide range of biological activities such as antiviral, anticancer, acetylcholinesterase inhibition, antimalarial, among others. Mass spectrometry (MS) studies based on capillary gas chromatography (CGC), paper spray (PS), and leaf spray (LS) ionization were carried out for alkaloid investigation of the native Brazilian species Hippeastrum aulicum, along with nuclear magnetic resonance (NMR) techniques. Thirty-one alkaloids were identified including the new compound haemanthamine N-oxide. The results from PS- and LS-MS techniques were consistent with those observed in CGC-MS analysis. To the best of our knowledge, it is the first study combining NMR, CGC-MS and the ambient ionization-mass spectrometry (PS- and LS-MS) on Amaryllidaceae plants.

Monitorando a degradação da poliamida 11 (PA-11) via espectroscopia na região do infravermelho médio com transformada de fourier (FTIR)

Fuel quality control has gained interest in many countries owing to the potential damage of low-quality fuel to engines, the environment, and economy. Thus, the application of analytical techniques to verify quality control of fuels has become crucial. The portable micro-spectrometer in the near infrared region (microNIR) has gained credibility as a successful analytical technique in several quality control sectors. The possibility of real-time analysis using a nondestructive and reliable method is the main advantage of this methodology. In this work, chemometric models (PLS) were developed using microNIR data to determine the amount of biodiesel in diesel (LODBio = 0.5wt%; LOQBio = 1.8wt%; and RMSEPBio = 1.8wt%); sulfur in diesel (LODS = 2.4mgL-1; LOQS = 8.0mgL-1; and RMSEPS = 13.2mgL-1); gasoline, ethanol, and methanol in C-type gasoline (LODgas = 0.55wt%; LOQgas = 1.84wt%; and RMSEPgas = 0.81wt%; LODeth = 0.75wt%; LOQeth = 2.5wt%; and RMSEPeth = 3.81wt%; and LODmet = 0.85wt%; LOQmet = 2.84wt%; and RMSEPmet = 1.80wt%); and water, methanol, and ethanol in ethanol-hydrated fuel (EHF) (LODH2O = 0.04wt%; LOQH2O = 1.29wt%; and RMSEPH2O = 1.05wt%; LODmet = 0.52wt%; LOQmet = 1.73wt%; and RMSEPmet = 2.78wt%; and LODeth = 1.22wt%; LOQeth = 4.07wt%; and RMSEPeth = 4.41wt%). A total of 181 blends were prepared, with biodiesel and sulfur contents ranging from 0 to 100wt% and 10-500mgL-1, respectively. For gasoline blends, the gasoline, ethanol, and methanol contents ranged from 0.0 to 75.0wt%, 25.0-75.0wt%, and 0.0-50.0wt%, respectively. In the EHF control, the ethanol, water, and methanol contents ranged from 0.0 to 100.0wt%, 0.0-50.0wt%, and 0.0-50.0wt%, respectively. The proposed method presented high precision and accuracy in all cases, and the results showed that the microNIR technique had excellent performance in fuel quality control.

Portable near infrared spectroscopy applied to abuse drugs and medicine analyses

O potencial da tecnica de espectroscopia de infravermelho com transformada de Fourier e acessorio de reflexao total atenuada (FTIR-ATR) foi avaliado para o monitoramento da degradacao da poliamida 11 (PA-11) usada em dutos flexiveis. As amostras foram submetidas a envelhecimento em reatores com pressao controlada e atmosfera inerte. Os corpos de prova foram imersos em agua deionizada (pH 7), nas temperaturas de 110, 120 e 140 ÂoC por um periodo de ate 50 dias. A tecnica recomendada para monitoramento da degradacao da PA-11 e a viscosimetria, atraves de medidas da viscosidade inerente corrigida (VIC) e a analise termogravimetrica (TGA). O comportamento observado para a VIC e TGA durante o envelhecimento possibilitou a construcao de modelos que correlacionam com a tecnica de FTIR-ATR. A partir dos resultados de FTIR-ATR, a variacao na intensidade da banda atribuida a fase amorfa, 1161 cm-1, possibilitou o monitoramento do envelhecimento quando associamos a tecnica a modelos quimiometricos como o de regressao dos minimos quadrados parciais, PLS. Portanto, a tecnica FTIR-ATR pode ser uma nova alternativa no monitoramento da degradacao hidrolitica da PA-11, eliminando assim o uso de solventes orgânicos toxicos e reduzindo, consequentemente, o tempo de analise.

Monitoring the polyamide 11 degradation by thermal properties and X‐ray fluorescence spectrometry allied to chemometric methods

Near infrared (NIR) spectroscopy using a portable instrument (microNIR) associated with chemometrics models (partial least squares regression (PLS), principal component analysis (PCA) and hierarchical cluster analysis (HCA)) was applied to quantify cocaine, and to classify synthetic drugs by their functional chemical composition in 19 ecstasy tablets, 22 seals of designer drugs and 23 medicine samples. Cocaine content in the range of 0 to 100 wt% was quantified by PLS model with root mean square error of prediction of 6 wt%. Then, the PLS model was applied in 38 seized cocaine samples and the results were compared to results from liquid chromatography with a diode array detector. MicroNIR spectroscopy was able to discriminate between the seal samples between LSD and NBOMes derivatives, while for the ecstasy tablets, five groups were formed containing (1) MDMA; (2) amphetamine, ATS, methamphetamine, MDMA, 2C–B; (3) amphetamine and caffeine; (4) MDMA; and (5) ethylone and ketamine. Finally, the results of the medicine analysis indicated either a lack of quality control (with distinct dosages other than specified on the packaging) or falsification.