Adelir Aparecida Saczk

Cathodic stripping voltammetric determination of arsenic in sugarcane brandy at a modified carbon nanotube paste electrode

We have developed an eletroanalytical method that employs Cu(2+) solutions to determine arsenic in sugarcane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and polymeric resins. We used linear sweep (LSV) and differential-pulse (DPV) voltammetry with cathodic stripping for CNTPE containing mineral oil or silicone as binder. The analytical curves were linear from 30 to 110μgL(-1) and from 10 to 110μgL(-1) for LSV and DPV, respectively. The limits of detection (L.O.D.) and quantification (L.O.Q.) of CNTPE were 10.3 and 34.5μgL(-1) for mineral oil and 3.4 and 11.2μgL(-1) for silicone. We applied this method to determine arsenic in five commercial sugarcane brandy samples. The results agreed well with those obtained by hydride generation combined with atomic absorption spectrometry (HG AAS).

Determination of ethyl carbamate in cachaça produced from copper stills by HPLC

Ethyl carbamate (EC) is a common substance in fermented foods and drinks, and its quantification is important because of its carcinogenic nature and its usually presence in alcoholic beverages. The present work involved the development and validation of an analytical method for the evaluation of EC in cachaça by HPLC-FLD after previous derivatization with xanthydrol. The method presented a mean recovery of 94.88%, an intra-day precision of 4.19% (30.0 μgL(-1)) and 3.32% (75.0 μgL(-1)), a coefficient of determination (r(2)) equal to 0.9985, and limits of detection and quantification equal to 6.39 and 21.32 μgL(-1), respectively. The results show that the analytical method is accurate, reproducible and linear over the concentration range from 5.0 to 160 μg of EC per litre. The method was applied to the analysis of EC in cachaça, the analyses being rapid and efficient.

Anthocyanins, pigment stability and antioxidant activity in jabuticaba [Myrciaria cauliflora (Mart.) O. Berg]

Diferentes solventes foram avaliados para a extracao de pigmentos antociânicos da jabuticaba, identificacao, quantificacao e verificacao da estabilidade das antocianinas, assim como a conducao de tres testes de atividade antioxidante e determinacao dos niveis de vitamina C. A maceracao com etanol acidificado com HCl 1.5 mol L-1 (85:15) promoveu melhor extracao e estabilidade dos pigmentos. As cascas sao ricas em pigmentos antociânicos, apresentando 1,59 e 2,06 g 100 g-1 de materia seca (MS) nas variedades Paulista e Sabara, respectivamente. Cyanidina 3-glucosideo e o pigmento majoritario nas cascas, seguido pela delphinidina 3-glucosideo. Os niveis de vitamina C foram mais altos nas cascas e sementes de ambas as variedades. Foi verificado que as cascas apresentaram maior atividade antioxidante, tanto na captura de radical livre, quanto no retardo do processo de oxidacao lipidica.

Caracterização e quantificação de contaminantes em aguardentes de cana

The objective of the present study was the evaluation of the presence of organic and inorganic contaminants in samples of aged cachaca from the South of the state of Minas Gerais. Furfural, methanol and copper were determined by colorimetric reactions, while the analyses of ethyl carbamate and acrolein were performed by GC/MS and HPLC, respectively. High levels of furfural and copper were obtained. All samples showed concentrations below the established by legislation for the ethyl carbamate, and for acrolein, only one sample showed higher levels. Methanol was not detected in the samples.

Evolution of the concentration of phenolic compounds in cachaça during aging in an oak (Quercus sp.) barrel

A cachaca, tradicional e popular bebida brasileira, e obtida por meio da destilacao do mosto fermentado de cana de acucar. Dentre as etapas do processo de producao da bebida, o envelhecimento natural consiste em armazena-la em recipientes de madeira apropriados por um tempo determinado, onde ocorrem alteracoes na composicao quimica, aroma, sabor e cor da bebida. Este trabalho teve como objetivo realizar um acompanhamento da composicao fenolica em diferentes periodos de envelhecimento da cachaca em tonel de carvalho (Quercus sp.). Foram realizadas coletas periodicas durante o periodo de envelhecimento da cachaca em tonel de carvalho e realizaram-se analise de treze compostos fenolicos utilizando a tecnica de cromatografia liquida de alta eficiencia com detector de arranjo de diodos (HPLC-DAD). Foi constatado um aumento progressivo na concentracao dos compostos analisados ao longo do periodo analisado, sendo que os compostos encontrados em maior concentracao foram siringaldeido e acido galico.

Voltammetric determination of Δ9-THC in glassy carbon electrode: An important contribution to forensic electroanalysis.

A new voltammetric method for the determination of Δ(9)-tetrahydrocannabinol (Δ(9)-THC) is described. The voltammetric experiments were accomplished in N-N dimethylformamide/water (9:1, v/v), using tetrabutylammonium tetrafluoroborate (TBATFB) 0.1mol/L as supporting electrolyte and a glassy carbon disk electrode as the working electrode. The anodic peak current was observed at 0.0V (vs. Ag/AgCl) after a 30s pre-concentration step under an applied potential of -1.2V (vs. Ag/AgCl). A linear dependence of Δ(9)-THC detection was obtained in the concentration range 2.4-11.3ng/mL, with a linear correlation coefficient of 0.999 and a detection limit of 0.34ng/mL. The voltammetric method was used to measure the content of Δ(9)-THC in samples (hemp and hashish) confiscated by the police. The elimination of chemical interferences from the samples was promptly achieved through prior purification using the TLC technique, by employing methanol/water (4:1, v/v) as the mobile phase. The results showed excellent correlation with results attained by HPLC.

Identificação do carbamato de etila durante o armazenamento da cachaça em tonel de carvalho (quercus sp) e recipiente de vidro

The objective of the present study was the identification and quantification of ethyl carbamate (EC), by HPLC-FLD, after different periods of storage in an oak (Quercus sp) barrel and a glass vessel. The concentration of EC in the cachaca samples varied from <LD to 17.46 µg L-1, for the period during which the cachaca was stored in an oak barrel, and <LQ to 18.51 µg L-1 for the cachaca stored in a glass recipient. The storage of the beverage in both the oak barrel and the glass vessel resulted in a significant increase in the concentration of this contaminant.

Contamination of cachaça by PAHs from storage containers.

Cachaça is a distiled beverage obtained from the fermentation of sugar cane syrup that, depending on the production procedures, may be susceptible to contamination by polycyclic aromatic hydrocarbons (PAHs). These compounds present carcinogenic and/or mutagenic properties and offer a risk to human health. Sixteen PAHs were determined in cachaças that had been stored in glass bottles and in polyethylene tank by gas chromatography coupled with mass spectrometry. The quantification of the PAHs utilised an internal standard. The limits of detection and quantification varied from 0.05 to 0.10μgL(-)(1) and 0.20 to 0.30μgL(-)(1), respectively. A total PAH concentration of 51.57μgL(-)(1) was found in the beverages that were stored in the tank, while the concentration in the cachaça stored in glass jugs was 6.07μgL(-)(1). These results indicate that the polyethylene tank is a source for PAHs in cachaça.

Ácidos orgânicos de baixa massa molar em solos e materiais orgânicos

Determination of organic acids in soils and organic materials is important due to the important role they play in improving the soils physical, chemical and microbiological conditions. This study identified and quantified low molecular weight organic acids (LMWOA) in soils (dystroferric Red Latosol, dystrophic Red-Yellow Latosol and Quartzarenic Neosol) and organic materials (cow, pig, chicken, quail and horse manures, sawdust, coconut fiber, pine bark, coffee husks, biochar, organic substrate, sewage sludges 1 and 2, garbage compost, pig slurry compost). The following acids were identified: acetic, citric, D-malic, formic, fumaric, maleic, malonic, oxalic, quinic, shikimic, succinic and tartaric.

Determination of Phenolic Compounds and Coumarins in Sugar Cane Spirit Aged in Different Species of Wood

The identities and quantities of the phenolic compounds and coumarins in twelve samples of sugar cane spirit aged in Quercus sp., Amburana cearensis, Cariniana legalis, Castanea sativa Mill, Ocotea sp., Cotyledon orbiculata L., and Hymenaea sp. casks were determined. These compounds have a direct influence on the sensory characteristics of aged beverages; some of them are considered to be markers for the aging process. The analysis of phenolic compounds was performed by HPLC. Solid phase extraction (SPE) was also used for the determination of coumarins. The concentrations of the principal compounds extracted varied according to the species of wood. The concentrations of total phenolic compounds ranged from 0.08 for a sample stored in a 4000-L jatobá barrel for a period of six months to 40.9 mg · L−1 for a sample aged in a 50000-L oak barrel for a period of 48 months. The use of the SPE technique removed interfering compounds from the samples, thereby improving the detection of coumarin.