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1.
Food Chem ; 419: 136027, 2023 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-37031537

RESUMO

Aging aroma is an intriguing but an understudied phenomenon in baijiu. The aromatic characteristics of Qingxiangxing (QXX) baijiu stored for 45 years (aged) were investigated using the sensomics approach and were compared with those of young baijiu (0 year-old). Aroma extract dilution analysis revealed 59 odorants, with many long-retained components exhibiting greater flavor dilution values in the aged than the young sample. The analysis of variance of the quantitative data showed significant differences between the young and aged baijiu for 26 compounds. Based on the variations in the content of these compounds, QXX baijiu aged for 0, 5, 15, 20, and 45 years was analyzed and twelve compounds were significantly correlated with aging duration. Finally, eight positively correlated compounds were omitted from the recombinant model, and sotolon, methional, vanillin, dimethyl trisulfide, benzaldehyde, and 3-hydroxy-2-butanone were confirmed to primarily contribute toward the aging aroma of QXX baijiu.


Assuntos
Odorantes , Compostos Orgânicos Voláteis , Odorantes/análise , Cromatografia Gasosa-Espectrometria de Massas , Compostos Orgânicos Voláteis/análise , Técnicas de Diluição do Indicador , Extratos Vegetais
2.
J Agric Food Chem ; 71(1): 690-699, 2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36573803

RESUMO

Large-leaf yellow tea (LYT) is a yellow tea product with a specific aroma characteristic and is enjoyed with increasing enthusiasm in China. However, its key odorants are still unknown. In this study, 46 odorants in the headspace and vacuum-distillate of the tea infusion were identified via aroma extract dilution analysis. Sixteen compounds were newly found in LYT infusion. They were present in the highest flavor dilution factors together with 2-ethyl-3,5-dimethylpyrazine. All odorants were quantitated to evaluate their own odor activity values (OAVs). High OAVs were found for 2-methylbutanal (malty, 210), (E,E)-2,4-heptandienal (fatty/flowery, 170), 2-methylpropanal (malty, 120) and 2,3-diethyl-5-methylpyrazine (earthy/roasty, 110). An aroma recombinate consisting of 17 odorants (all OAVs ≥ 1) in an odorless nonvolatile LYT matrix mimicked the overall aroma of the original infusion, verifying the successful characterization of key aroma components in a LYT beverage. The knowledge of key odorants obtained showed potential for simplifying industrial flavor optimization of the LYT product.


Assuntos
Camellia sinensis , Compostos Orgânicos Voláteis , Odorantes/análise , Técnicas de Diluição do Indicador , Folhas de Planta/química , Chá , Compostos Orgânicos Voláteis/análise , Aromatizantes/análise , Olfatometria
3.
J Environ Manage ; 326(Pt B): 116702, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36395534

RESUMO

Dairy processing sludge (DPS) and DPS-derived secondary products such as struvite, biochar, hydrochar and ash (collectively known as SRUBIAS) are emerging as alternatives to fertilizers produced from mined rock phosphate. However, little is known about how these products affect soil P availability and daily P turnover rates.. A lack of such information prevents precision nutrient management planning using these products out on farms. This study used a novel isotope dilution technique (IPD) with 33P as a tracer to compare P turnover in soils amended with chemically (alum-treated DPS and struvite) and thermally (biochar, hydrochar, ash) treated DPS. Results showed that thermally treated products exhibited poor agronomic performance as P fertilizers, potentially inhibiting P availability when applied to soils. For example, a P deficient soil amended with hydrochar treatment at the highest application rates did not record a build-up of available P to agronomic target values. In ash and biochar treated P deficient soils, available P increased but only with very high application rates of 150 and 80 mg P kg -1. The application of these products as fertilizers could have negative implications for both environmental and agronomic goals. Conversely, chemically treated fertilisers demonstrated better agronomic performance. The same agronomic target value was reached with application rates of only 20 mg P kg -1 soil for DPS and 50 mg P kg -1 soil for struvite. However, the techniques deployed revealed that these products exhibited slower rates of available and exchangeable P build-up when compared with chemical fertilisers. This suggests that these bio-based alternatives require higher application rates or earlier application times compared to conventional chemical fertilizers. Regulations providing advice on P use in agricultural soils need to account for slower P turnover in soils receiving recycled fertilizers. The IPD technique is transferrable to all wastes to examine their performance as fertilizers.


Assuntos
Fósforo , Solo , Fertilizantes/análise , Estruvita , Esgotos , Isótopos , Técnicas de Diluição do Indicador
4.
Talanta ; 252: 123786, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36027616

RESUMO

In the search for a normalized procedure to replicate and compare single cell-inductively coupled plasma-mass spectrometry (SC-ICP-MS) experiments, SELM-1, a certified reference material containing selenium enriched yeast cells has been used. Selenium concentrations (both, intra- and extracellular) have been measured using either sequential or simultaneous procedures. Regarding quantitative results, the sequential procedure involving cell washing followed by freeze drying of the washed material and intracellular Se quantification using SC-ICP-MS provided best results. In this case, intracellular Se accounted for 1304 ± 48 mg kg-1 (corresponding to 64% of the certified Se content). The average mass of Se per yeast cell was 41.6 fg Se with a dispersion of 1.6-279 fg Se/cell. In the isolated extracellular Se fraction, the Se concentration accounted for 412 ± 48 mg kg-1 (about 21% of the total Se). Thus, the sequential procedure provided a total Se recovery of about 85% with respect to the certified value. The direct dilution and simultaneous measurement of intra- and extracellular Se by SC-ICP-MS provided results of 1024 ± 42 mg kg-1 for intracellular and 316 ± 30 mg kg-1 for extracellular Se representing a total recovery of about 66%. In both cases, an initial thorough characterization of the cell density per solid weighed material was conducted by flow cytometry and the cell integrity ensured using confocal microscopy. These results clearly demonstrated that with appropriate sample preparation, SC-ICP-MS is a unique tool, which is capable of providing quantitative information about intracellular and extracellular Se. In addition, SELM-1 seems the ideal tool to enable data normalization at the single cell level to replicate, benchmark, and improve new SC-ICP-MS studies by using the same material for data validation.


Assuntos
Saccharomyces cerevisiae , Selênio , Saccharomyces cerevisiae/química , Selênio/análise , Espectrometria de Massas/métodos , Análise Espectral , Técnicas de Diluição do Indicador
5.
Anal Bioanal Chem ; 413(26): 6479-6488, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34458946

RESUMO

In the present study, a method for quantitation of the pharmaceutical peptide oxytocin (OT) and its diselenide-containing analogue (SeOT) in human plasma was developed using gradient elution LC-ICP-MS/MS. Plasma samples were precipitated with acetonitrile containing 1.0% TFA in a volume ratio of 1+3 (sample+precipitation agent) before analysis. Post-column isotope dilution analysis (IDA) was applied for quantitation and was compared with external calibration. Both calibration methods appeared to be fit for purpose regarding figures of merit including linearity, precision, LOD, LOQ and recovery. Analysis of OT and SeOT showed that selenium-based analysis is considerably more sensitive and selective compared to the sulfur-based analysis. Despite the relatively simpler setup of external calibration, IDA can be advantageous because it compensates for instrument drift and changes in organic solvent concentration. The method was applied for a stability study showing the degradation of OT and SeOT in plasma. The degradation of SeOT was faster than the degradation of OT in plasma. Thus, possible stability effects should be considered before replacing a disulfide bridge with a diselenide bridge or introducing a diselenide label in a potential drug.


Assuntos
Ocitócicos/sangue , Ocitocina/sangue , Selênio/sangue , Calibragem , Cromatografia Líquida/métodos , Humanos , Técnicas de Diluição do Indicador , Limite de Detecção , Ocitócicos/análise , Ocitocina/análogos & derivados , Selênio/análise , Espectrometria de Massas em Tandem/métodos
6.
Homeopathy ; 110(4): 277-282, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-33979844

RESUMO

Active ingredients are unlikely to be present in homeopathic dilutions that surpass the Avogadro limit. Yet responses of biological systems to these substances-chemically equivalent to water and indistinguishable from one another-are specific to the materials that are diluted away. This article addresses this challenging problem of homeopathy by identifying its underlying cause through a quantum electrodynamics-based "structural model" stated as: Succussed serial dilutions in water carry information about the solute via solute-specific water structures. The model is verifiable by our three-stranded set of experiments-nuclear magnetic resonance spectroscopy, anomalous dielectric dispersion, and atomic force microscopy. The results, some of which are presented here, directly or indirectly indicate that even extremely diluted solutions, devoid of any gross presence of the solutes, contain solute-reminiscent water structures. Apart from contributing to understanding high-dilution phenomena, these findings are expected to create an impact in the areas of medicine, pharmacopeia, and biology. Succussed aqueous dilutions acquire altered water structures with change of starting material: thus, their altered properties may be ascribed to these water structures, akin to allotropes of carbon. This theory justifies water structures as potential information carrier through succussed serial dilutions.


Assuntos
Homeopatia , Técnicas de Diluição do Indicador , Espectroscopia de Ressonância Magnética , Teoria Quântica , Soluções , Água
7.
Nutrients ; 13(1)2021 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-33406595

RESUMO

BACKGROUND: Exclusive breastfeeding during the first six months of an infant's life is an important factor for their optimal growth and health. Breastfeeding also has maternal benefits and can assist with postpartum weight loss. As shown by previous studies, postpartum weight retention can contribute to obesity. OBJECTIVE: To quantify the human milk and evaluate the effect of breastfeeding on maternal weight loss during the 12 months postpartum. METHOD: This study included 70-mother-baby pairs. Infants' intake of human milk and water from other sources, as well as the body composition of the mothers, were measured at the 1st, 3rd, 6th, 9th and 12th month postpartum by using the deuterium oxide dose-to-mother technique. RESULTS: There was a significant change in the mothers' body composition between the first and twelfth months in exclusive breastfeeding women compared to not-exclusive ones. Similarly, the difference between the quantities of human milk intake was highly significant in exclusive breastfeeding women compared to women who were not exclusively breastfeeding. CONCLUSION: Our results showed that exclusive breastfeeding for twelve months has a significant effect on postpartum weight loss among Moroccan women and that it is an effective way to control overweight and obesity among lactating women.


Assuntos
Composição Corporal , Aleitamento Materno , Técnicas de Diluição do Indicador , Fenômenos Fisiológicos da Nutrição do Lactente , Lactação , Adolescente , Adulto , Índice de Massa Corporal , Óxido de Deutério/administração & dosagem , Ingestão de Alimentos , Feminino , Humanos , Lactente , Leite Humano , Mães , Período Pós-Parto , Gravidez , Fatores Socioeconômicos , Inquéritos e Questionários , Redução de Peso , Adulto Jovem
8.
Artigo em Inglês | MEDLINE | ID: mdl-33301371

RESUMO

The matrix effect in complex spices and herbs presents a great challenge to the simultaneous, rapid, quantitative analysis of multiple pesticides by mass spectrometry. The aim of this work was to develop and validate an effective UPLC-MS/MS multi-residue method for the analysis of pesticide residues to reduce matrix effects in four spices and one herb and infer which component caused the matrix effect in black pepper. In this paper, we highlight the importance of reducing matrix effects. SPE and dilution factors combined with d-SPE were two approaches to reduce matrix effects compared with d-SPE, and dilution (5-fold) combined with d-SPE was more effective than SPE in reducing matrix effects. With the validated d-SPE method combined with dilution (5-fold), 22 pesticides showed satisfactory recovery (77 to 114%) and RSDs (1.4%-19.1%) at three spiked concentrations in dried chilli pepper, star anise, mint, and cinnamon skin, but not in black pepper. Compared to the other three spices and one herb, black pepper appeared to have a stronger matrix effect. D-SPE method combined with dilution (5-fold) was not suitable for black pepper and required more efficient purification methods and higher dilution factors. With the validated SPE method combined with 10-fold dilution, 19 pesticides showed satisfactory recovery (71% to 113%) and RSDs (2.1%-18.2%) at three spiked concentrations in black pepper. We ascertained that piperine was the component contributing most to the matrix effect in black pepper. The method was used to monitor 15 market samples.


Assuntos
Técnicas de Diluição do Indicador , Resíduos de Praguicidas/análise , Plantas Medicinais/química , Especiarias/análise , Interações Hidrofóbicas e Hidrofílicas , Espectrometria de Massas em Tandem
9.
Toxins (Basel) ; 12(9)2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32942568

RESUMO

Alternaria toxins are emerging mycotoxins, candidates for regulation by European Authorities. Therefore, highly sensitive, confirmatory, and reliable analytical methodologies are required for their monitoring in food. In that context, an isotope dilution LC-MS/MS method was developed for the analysis of five Alternaria toxins (Altenuene, Alternariol, Alternariol monomethylether, Tentoxin, and Tenuazonic Acid) in a broad range of commodities including cereals and cereal-based products, tomato-based products, tree nuts, vegetable oils, dried fruits, cocoa, green coffee, spices, herbs, and tea. Validation data collected in two different laboratories demonstrated the robustness of the method. Underestimation of Tenuazonic Acid level in dry samples such as cereals was reported when inappropriate extraction solvent mixtures were used as currently done in several published methodologies. An investigation survey performed on 216 food items evidenced large variations of Alternaria toxins levels, in line with data reported in the last EFSA safety assessment. The analysis of 78 green coffee samples collected from 21 producing countries demonstrated that coffee is a negligible source of exposure to Alternaria toxins. Its wide scope of application, adequate sample throughput, and high sensitivity make this method fit for purpose for the regular monitoring of Alternaria toxins in foods.


Assuntos
Alternaria/metabolismo , Café/microbiologia , Micotoxinas/análise , Sementes/microbiologia , Cromatografia Líquida , Qualidade de Produtos para o Consumidor , Exposição Dietética/efeitos adversos , Microbiologia de Alimentos , Técnicas de Diluição do Indicador , Lactonas/análise , Micotoxinas/efeitos adversos , Peptídeos Cíclicos/análise , Medição de Risco , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem , Ácido Tenuazônico/análise
10.
Artigo em Inglês | MEDLINE | ID: mdl-32364029

RESUMO

In this work, we describe a method developed to quantify persistent organic pollutants (POPs) including polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in dietary supplement samples using stir-bar sorptive extraction (SBSE)-GC-MS/MS-isotope dilution mass spectrometry (IDMS). This method enables accurate, precise, and sensitive quantification of POPs in plant-extract based dietary supplement products commercially available in the United States. When compared with calibration curves, IDMS provided more accurate and precise measurements. The mean error of measurements using this method was 7.24% with a mean RSD of 8.26%. The application of GC-MS/MS enabled approximately two-order-of-magnitude lower limit of quantifications compared with GC-MS. 12 commercially available plant-extract based dietary supplement samples were analysed using this method. PAHs including naphthalene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene, chrysene, and benzo[a]pyrene were detected in most of the products and had average concentrations over 1 ng/g. OCPs were detected less frequently than PAHs in these products, and none of the OCPs had mean concentrations over 1 ng/g. The mean toxin concentration of each product was calculated, and the highest value was 3.20 ng/g. These results were compared with existing guidelines and none of the analytes in the samples were found to be above the daily allowable limits.


Assuntos
Suplementos Nutricionais/análise , Hidrocarbonetos Clorados/análise , Praguicidas/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Cromatografia Gasosa , Monitoramento Ambiental , Técnicas de Diluição do Indicador , Marcação por Isótopo , Espectrometria de Massas
11.
J Nutr ; 150(6): 1644-1651, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32135013

RESUMO

BACKGROUND: Retinol isotope dilution (RID) and model-based compartmental analysis are recognized techniques for assessing vitamin A (VA) status. Recent studies have shown that RID predictions of VA total body stores (TBS) can be improved by using modeling and that VA kinetics and TBS in children can be effectively studied by applying population modeling ("super-child" approach) to a composite data set. OBJECTIVES: The objectives were to model whole-body retinol kinetics and predict VA TBS in a group of Mexican preschoolers using the super-child approach and to use model predictions of RID coefficients to estimate TBS by RID in individuals. METHODS: Twenty-four healthy Mexican children (aged 3-6 y) received an oral dose (2.96 µmol) of [13C10]retinyl acetate in corn oil. Blood samples were collected from 8 h to 21 d after dosing, with each child sampled at 4 d and at 1 other time. Composite data for plasma labeled retinol compared with time were analyzed using a 6-component model to obtain group retinol kinetic parameters and pool sizes. Model-predicted TBS was compared with mean RID predictions at 4 d; RID estimates at 4 d were compared with those calculated at 7-21 d. RESULTS: Model-predicted TBS was 1097 µmol, equivalent to ∼2.4 y-worth of VA; using model-derived coefficients, group mean RID-predicted TBS was 1096 µmol (IQR: 836-1492 µmol). TBS at 4 d compared with a later time was similar (P = 0.33). The model predicted that retinol spent 1.5 h in plasma during each transit and recycled to plasma 13 times before utilization. CONCLUSIONS: The super-child modeling approach provides information on whole-body VA kinetics and can be used with RID to estimate TBS at any time between 4 and 21 d postdose. The high TBS predicted for these children suggests positive VA balance, likely due to large-dose VA supplements, and warrants further investigation.


Assuntos
Vitamina A/farmacocinética , Carga Corporal (Radioterapia) , Criança , Pré-Escolar , Feminino , Humanos , Técnicas de Diluição do Indicador , Masculino , México , Estado Nutricional , Vitamina A/metabolismo
12.
Anal Bioanal Chem ; 412(7): 1483-1495, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31965244

RESUMO

The focus of this study was the analysis of the complex chemical composition from different parts of Buddleja davidii, whose species are commonly known as ornamental plants and herbal medicines in many countries. As an herbal medicine, it has been utilized for stroke treatments, headache, wound healing, neurological disorder, etc. However, the understanding of its chemical matrices is still insufficient. Therefore, an online two-dimensional reversed phase liquid chromatography x hydrophilic interaction liquid chromatography (RPLCxHILIC) system coupled with mass spectrometry was applied for further detailed investigation of the chemical constituents in Buddleja dividii. In this two-dimensional liquid chromatography (2D-LC) method, a new at-column dilution (ACD) modulator was introduced in the 2D-LC system to solve the incompatibility problem of the mobile phase between two dimensions, which resulted in a 2D-LC analysis with high orthogonality. For the root extract, as one of the analyzed samples, the optimization of the 1D and 2D gradients was carried out carefully. With this new modulator, much better peak separation and better peak shape were achieved compared to two-dimensional liquid chromatography system using a traditional standard (TS) modulator. With a similar approach, the other four parts of Buddleja davidii were well separated. Comparing the different analyzed parts, flowers and leaves showed the most complex profiles. MS and MS/MS data were obtained successfully, which demonstrated the potential of the proposed RPLCxHILIC-MS system in the constituents' analysis of herbal medicine. However, due to the lack of reported reference information, 24 compounds could be tentatively identified.


Assuntos
Buddleja/química , Cromatografia de Fase Reversa/métodos , Medicamentos de Ervas Chinesas/química , Interações Hidrofóbicas e Hidrofílicas , Técnicas de Diluição do Indicador , Espectrometria de Massas em Tandem/métodos
13.
Food Chem ; 312: 126081, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31901831

RESUMO

We analyzed the aroma of aged garlic extract (AGE) using a sensomics approach to elucidate the effect of the aging process on AGE aroma. Sensory analysis showed a high intensity of the "acid", "seasoning," and "metallic" odor in AGE. The aroma of AGE exhibited more complex notes compared to those of fresh garlic which were characterized as "pungent." Aroma components of AGE were evaluated using aroma extract dilution analysis. Thirty-nine odorants were detected as key odorants in AGE. Allyl methyl sulfide (sulfury), 2-methoxyphenol (smoky), 4,5-dimethyl-3-hydroxy-2(5H)-furanone (seasoning-like), eugenol (spicy) and ethyl butanoate (fruity), which were mostly absent in fresh garlic, contributed to the AGE aroma. These results suggest that chemical reactions that occur during the aging process of garlic are important for the development of the characteristic aroma of AGE.


Assuntos
Alho/química , Odorantes/análise , Extratos Vegetais/química , Técnicas de Diluição do Indicador , Fatores de Tempo , Compostos Orgânicos Voláteis/análise
14.
J Appl Lab Med ; 4(3): 415-421, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31659079

RESUMO

BACKGROUND: Oral biotin supplementation is known to interfere with biotin-streptavidin-based immunoassays, including Roche's fifth-generation cardiac troponin T (cTnT) assay, which plays a critical role in the diagnosis of myocardial infarction (MI). The utility of dilution, a quick and easy method to detect and remove interferences, has not been published for biotin interference. METHODS: Concentrations of cTnT were measured in pooled serum from clinical samples. Serum samples were supplemented with biotin to known concentrations, then cTnT concentrations were remeasured to assess for biotin interference. Samples were then diluted to assess for effective removal of biotin interference. RESULTS: At cTnT values near the critical reporting range for our institution (100 ng/L) we observed significant interference in measured values with added biotin concentrations above 50 ng/mL. In specimens without added biotin, autodilution at a 1:10 ratio yielded a mean 157% capture of measured cTnT, precluding the use of autodilution for detecting and mitigating biotin interference. A 1:10 dilution with serum containing 20-30 ng/L cTnT yielded a mean capture of 107%, which was suitable for detecting underlying biotin interference in supplemented samples. CONCLUSIONS: Biotin interference, at supraphysiologic concentrations, may create an artifactual reduction in measured cTnT to levels that could lead to delayed detection of an MI. Dilution with serum of known cTnT concentration of 20-30 ng/L is a fast and effective method to mitigate the analytical consequences of biotin interference.


Assuntos
Imunoensaio/métodos , Técnicas de Diluição do Indicador , Infarto do Miocárdio/sangue , Infarto do Miocárdio/diagnóstico , Troponina T/sangue , Humanos , Imunoensaio/normas , Técnicas de Diluição do Indicador/normas , Sensibilidade e Especificidade
15.
J AOAC Int ; 102(6): 1725-1731, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31277723

RESUMO

Background: Coffee is an important agricultural commodity with technical barriers for exportation because of possible contamination with ochratoxin A (OTA), a mycotoxin nephrotoxic and carcinogenic. The maximum limit for OTA in roasted coffee is 5.0 µg/kg in the European Union and 10 µg/kg in Brazil, and the use of certified reference materials (CRM) is required for reliable measurements. Objective: This paper describes the development of a candidate CRM of OTA in roasted coffee following the requirements of ISO 17034 and ISO Guide 35. Methods: A primary method of isotope dilution MS was developed and validated using (13C20)-OTA as internal standard. The sample preparation was based on AOAC Official Methods of AnalysisSM using immunoaffinity column. Results: The linear working range is 2.0-15.0 µg/kg, with recoveries of 92.2-110.8% and relative SDs lower than 12.4%. The method was successfully applied to the feasibility study, which defined the procedure for preparation of a large batch around 5 µg/kg. It was produced by spiking blank roasted coffee with OTA standard, mixing and filling in amber flasks with 50 g of coffee, and storing at -80°C. The homogeneity study showed an acceptable degree of heterogeneity of 1.44%, and the short-term-stability study defined the conditions for transportation as maximum temperature of 50°C up to 28 days. Conclusions: These results show that certification is possible. Highlights: The long-term stability study at -20°C is in progress, and the characterization will be conduzed by a interlaboratory comparison. This material will be an important tool for QC in laboratories.


Assuntos
Contaminação de Alimentos/análise , Ocratoxinas/análise , Ocratoxinas/normas , Brasil , Isótopos de Carbono , Cromatografia de Afinidade/métodos , Café/química , Estudos de Viabilidade , Técnicas de Diluição do Indicador , Padrões de Referência
16.
Bioresour Technol ; 278: 26-33, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30669028

RESUMO

Washing pretreatments of rice straw were performed using three different solutions, namely water, dilute hydrochloric acid solution (HCl solution, pH = 2.9), and aqueous phase bio-oil (APBO, pH = 2.9). The raw and pretreated samples were pyrolyzed at 550 °C in a fixed bed reactor. Results showed that among the three pretreatments, washing with APBO had the highest removal efficiency of alkali metal and alkaline earth metals (AAEMs). Among the pyrolysis products, bio-oil from APBO washed sample had the highest mass, energy, and carbon yields, lowest water content of 36.9%, highest HHV of 17.2 MJ/kg, and highest relative content of anhydrosugars of 31.2%. Its biochar had the lowest ash content of 27.3% and highest specific surface area of 98.6 m2/g, and its non-condensable gases had the highest HHV of 11.9 MJ/m3. Therefore, APBO washing was effective in improving the quality of biomass and its subsequent pyrolysis products.


Assuntos
Biomassa , Carbono/química , Temperatura Alta , Técnicas de Diluição do Indicador , Metais Alcalinos/isolamento & purificação , Metais Alcalinoterrosos/isolamento & purificação , Oryza/química , Óleos de Plantas/química , Polifenóis/química , Pirólise , Água/química
17.
J AOAC Int ; 102(6): 1651-1656, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30305203

RESUMO

Background: Mycotoxin contamination in oils remains an important food safety issue. To monitor the occurrence of mycotoxins in edible oils, it is important to develop analytical methods that can determine multiple mycotoxins in oil products. A stable isotope dilution LC-tandem MS (LC-MS/MS) method for the simultaneous determination of 12 mycotoxins in five edible oil matrixes (canola, corn, olive, peanut, and soybean oil) was developed and validated. Methods: Prior to extraction, the oil samples were fortified with ¹³C uniformly labeled internal standards (¹³C-IS) for 12 target mycotoxins, followed by extraction and LC-MS/MS analysis. Quantitation was achieved using solvent-only calibration standards, relative response factors of ¹³C-IS, and target mycotoxins. Results: The majority of recoveries in oil for ochratoxin A and aflatoxins B1, B2, G1, and G2 fortified at 1, 10, and 100 ng/g as well as deoxynivalenol; fumonisins B1, B2, and B3; T-2 toxin; HT-2 toxin; and zearalenone fortified at 10, 100, and 1000 ng/g ranged from 80 to 120% with RSDs of <20%. The method LOQs ranged from 0.1 ng/g (aflatoxin B1) to 6.4 ng/g (zearalenone). Among 16 U.S. market samples, zearalenone was detected in three corn oil samples at 37, 185, and 317 ng/g, respectively. T-2 toxin was found in two corn oil samples at 7 and 10 ng/g, respectively. Conclusions: The method provides sufficient selectivity, sensitivity, accuracy, and repeatability to screen edible oils for regulated mycotoxins such as aflatoxins at low nanogram per gram concentrations without using conventional standard addition or matrix-matched calibration standards to correct for matrix effects.


Assuntos
Cromatografia Líquida/métodos , Contaminação de Alimentos/análise , Micotoxinas/análise , Óleos de Plantas/análise , Espectrometria de Massas em Tandem/métodos , Isótopos de Carbono/química , Técnicas de Diluição do Indicador , Limite de Detecção
18.
Homeopathy ; 107(4): 244-263, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30144789

RESUMO

BACKGROUND: Homeopathy is controversial due to its use of very highly diluted medicines (high potencies/dynamisations). METHODS: We used a multi-technology approach to examine dilutions of two commonly used homeopathic medicines: an insoluble metal, Cuprum metallicum, and a soluble plant tincture, Gelsemium sempervirens, for the presence of nanoparticles (NPs) of original substance. The homeopathic medicines tested were specially prepared, according to the European pharmacopoeia standards. We compared the homeopathic dilutions/dynamisations with simple dilutions and controls. RESULTS: Using Mass Spectrometry (Single Particle-Inductively Coupled Plasma-Mass Spectrometry) and Dynamic Light Scattering (DLS) we could not find the expected copper in the 4cH potentisation and could not confirm the results previously obtained by Chikramane et al (2010). For Gelsemium medicines, using sensitive chromatography (HPLC-UV) up to a dilution level of 6 dH (3cH = dilution 10e-6), there was no significant difference in alkaloid content between a simple dilution and a homeopathic potency.For higher potentisations, however, NP tracking analysis findings revealed the presence of particles in all samples (except for pure water). The measurements showed large differences in particle quantities, mean particle sizes and standard deviations of the mean sizes between manufacturing lines of different starting material.There was always more material in potentised medicines than in potentised pure water. Gelsemium yielded the largest quantity of material (36 times more than that from copper at the same potentisation, 30 cH). The shapes and the chemical composition of the material are differentiable between different medicines and controls. CONCLUSION: Potentisation influences specifically the nature of NPs detected. This material demonstrates that the step-by-step process (dynamised or not) does not match with the theoretical expectations in a dilution process. The Avogadro/Loschmidt limit is not relevant at all. It was not possible to reproduce the findings of Chikramane et al (2010) using inductively coupled plasma-mass spectrometry with copper. Copper NPs could not be detected at 4cH and above.


Assuntos
Cobre/isolamento & purificação , Homeopatia/normas , Jasminum , Extratos Vegetais/isolamento & purificação , Difusão Dinâmica da Luz/métodos , Homeopatia/métodos , Humanos , Técnicas de Diluição do Indicador , Espectrometria de Massas/métodos , Nanopartículas/química
19.
Homeopathy ; 107(3): 155-156, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-30053764
20.
Homeopathy ; 107(3): 189-195, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29871024

RESUMO

We discuss questions related to the 'Benveniste Affair', its consequences and broader issues in an attempt to understand homeopathy. Specifically, we address the following points: 1.: The relationship between the experiments conducted by Benveniste, Montagnier, their collaborators and groups that independently tested their results, and 'traditional' homeopathy. 2.: Possible non-local components such as 'generalised entanglement' as the basis of the homeopathic phenomenon and experimental evidence for them. 3.: The capability of highly diluted homeopathic remedies to provoke tangible biological changes in whole organisms and cellular experimental systems. 4.: Aspects of the similia principle related to the above. 5.: Suggestions that can lead to experimental verifications of the non-local hypothesis in homeopathy.


Assuntos
Homeopatia/métodos , Técnicas de Diluição do Indicador , Materia Medica/farmacologia , Extratos Vegetais/farmacologia , Medicina Baseada em Evidências , Humanos
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