Desenvolvimento de novos métodos analíticos em química forense e petroleômica por espectrometria de massas ambiente (Paper Spray) e espectroscopia portátil na região do infravermelho próximo (MICRONIR)
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Data
2017-11-30
Autores
Domingos, Eloilson
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Universidade Federal do Espírito Santo
Resumo
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 ionizationmode (PS(+)-MS) was applied in three subareas of forensic chemistry: drugs of abuse, documentoscopy, and herbal medicines. In the first, the PS(+)MS technique was applied to obtain the chemical profiles of illicit drugs such as drug stamps containing 25I-NBOMe, extracts and leaves of natural cannabinoids (?9-tetrahydrocannabinol) and synthetic cannabinoids (JWH-073; 5F-AKB48; JWH-122; JWH-250; e JWH-210). In all cases, molecules were easily detected in their protonated form ([M + H]+) with resolution of m/?m50%=67,000 and a mass precision <2 ppm. The performance of the PS(+)-MS technique was compared with other sources of ionization: leaf spray (LS-MS) and electrospray (ESI-MS). In addition, a method was developed to quantify a series of illicit drugs (from 1 to 110 ??g L-1, with linearity of R2> 0.99). In documentoscopy, the PS(+)-MS technique was able to successfully obtain the chemical profile of different pens commercially sold in stores. The relative intensity (RII372) of the methylene blue dye was monitored to discriminate crossing pen traces and, to date, questioned documents. The chemical profile of second-generation Brazilian notes of R$ 100.00 (reais) was also explored. The PS(+)-MS technique was able to classify notes into either authentic or counterfeit. Finding that fake samples have a chemical profile similar to the homemade notes of the Deskjet® printer. Finally, PS-MS was applied to verify the authenticity of herbs used for weight loss. Fifteen different herbal medicines were analyzed by PS(+)-MS, substances such as: sibutramine (m/z280), caffeine (m/z195), and glucose (m/z203 [M + Na], m/z219 [M + K] and sucrose (m/z381 [M + K]) were found in samples where they were not listed in the herbal medicine label. In general, the PS(+)-MS technique proved to be an excellent analytical tool in chemistry forensic. A second study developed wasquality control of fuel with the application of the portable micro-spectrometer inthe near infrared region (MICRONIR), which has proven to be an excellent analytical technique in the quality control of several products. In this work, the potential of the MICRONIR in the control of fuel quality was verified. Thus, chemometric models (PLS-Partial Least Squares regression) were developed using near-infrared data acquired in the MICRONIR to determine the amount of biodiesel in Diesel (LOD=0.5wt%; LOQ=1.8 wt%, RMSEP=1.8 wt%); sulfur in Diesel (LOD=2.4 mg L-1; LOQ=8.0 mg L-1, RMSEP=13.2 mg L-1); gasoline, ethanol and methanol in gasoline type C (LODgas=0.55 wt%; LOQgas=1.84 wt%, RMSEPgas=0.81 wt%; LOQgas=2.50 wt%, RMSEPeth=3.81 wt%, LODmet= 0.85 wt% LOQmeth= 2.84 wt%, RMSEPmeth=1.80 wt% ; and water, methanol and ethanol in ethanol hydrated fuel (LODH2O=0.04 wt%; LQH2O=1.29 wt%, RMSEPH2O=1.05 wt%; , LOQmeth=1.73 wt%, RMSEPmeth=2.78 wt%). The proposed method presented high precision and accuracy in all cases, and the results showed that the MICRONIR technique had excellent performance in the control of fuel quality.
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Paper Spray , Droga de abuso , Documentoscopia , PLS , MICRONIR