Analytical interference of 4-hydroxy-3-methoxymethamphetamine with the measurement of plasma free normetanephrine by ultra-high pressure liquid chromatography-tandem mass spectrometry.

OBJECTIVES: The diagnosis of pheochromocytoma relies on the measurement of plasma free metanephrines assay whose reliability has been considerably improved by ultra-high pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Here we report an analytical interference occurring between 4-hydroxy-3-methoxymethamphetamine (HMMA), a metabolite of 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy"), and normetanephrine (NMN) since they share a common pharmacophore resulting in the same product ion after fragmentation. DESIGN AND METHODS: Synthetic HMMA was spiked into plasma samples containing various concentrations of NMN and the intensity of the interference was determined by UPLC-MS/MS before and after improvement of the analytical method. RESULTS: Using a careful adjustment of chromatographic conditions including the change of the UPLC analytical column, we were able to distinguish both compounds. HMMA interference for NMN determination should be seriously considered since MDMA activates the sympathetic nervous system and if confounded with NMN may lead to false-positive tests when performing a differential diagnostic of pheochromocytoma.

First detection of Waddlia chondrophila in Africa using SYBR Green real-time PCR on veterinary samples.

Waddlia chondrophila is a strict intracellular microorganism belonging to the order Chlamydiales that has been isolated twice from aborted bovine fetuses, once in USA and once in Germany. This bacterium is now considered as an abortigenic agent in cattle. However, no information is available regarding the presence of this bacterium in Africa. Given the low sensitivity of cell culture to recover such an obligate intracellular bacterium, molecular-based diagnostic approaches are warranted. This report describes the development of a quantitative SYBR Green real-time PCR assay targeting the recA gene of W. chondrophila. Analytical sensitivity was 10 copies of control plasmid DNA per reaction. No cross-amplification was observed when testing pathogens that can cause abortion in cattle. The PCR exhibited a good intra-run and inter-run reproducibility. This real-time PCR was then applied to 150 vaginal swabs taken from Tunisian cows that have aborted. Twelve samples revealed to be Waddlia positive, suggesting a possible role of this bacterium in this setting. This new real-time PCR assay represents a diagnostic tool that may be used to further study the prevalence of Waddlia infection.

Determination of patulin in apple juice by HPLC using a simple and fast sample preparation method

The goal of this work was to develop a simple and rapid preparation method for patulin analysis in apple juice without previous clean-up. This method combined sonication and liquid extraction techniques and was used for determination of patulin in 37 commercial apple juices available on the market in the South of Brazil. The method performance characteristics were determined using a sample obtained in a local market fortified at five concentration levels of patulin and done in triplicates. The coefficient of variation for repeatability at the fortification level of 20.70µg.L-1 was 3.53 % and the recovery 94.63 %, respectively. The correlation coefficient was 0.9996 and agrees with the requirements for a linear analytical method value. The detection limit was 0.21µg.L-1 and the quantification limit 0.70 µg.L-1. Only three of the analyzed samples were upper the allowed level of 50.00 µg.L-1 recommended for the World Health Organization.

A method to determine volatile contaminants in polyethylene terephthalate (PET) packages by HDC-GC-FID and its application to post-consumer materials

A simple and low cost method to determine volatile contaminants in post-consumer recycled PET flakes was developed and validated by Headspace Dynamic Concentration and Gas Chromatography-Flame Ionization Detection (HDC-GC-FID). The analytical parameters evaluated by using surrogates include: correlation coefficient, detection limit, quantification limit, accuracy, intra-assay precision, and inter-assay precision. In order to compare the efficiency of the proposed method to recognized automated techniques, post-consumer PET packaging samples collected in Brazil were used. GC-MS was used to confirm the identity of the substances identified in the PET packaging. Some of the identified contaminants were estimated in the post-consumer material at concentrations higher than 220 ng.g-1. The findings in this work corroborate data available in the scientific literature pointing out the suitability of the proposed analytical method.

Quantification of catechins and caffeine from green tea (Camellia sinensis) infusions, extract, and ready-to-drink beverages

This study aimed to quantify the levels of catechins and caffeine in various forms of presentation of green tea: infusion tea bags, extract, and ready-to-drink beverage and, based on their content, identify the most suitable for consumption. High Performance Liquid Chromatography (HPLC) analytical method was used for the quantification of catechins and caffeine. The tea bags had the highest concentration of total catechins with 5 to 9.5% followed by the extract with 3.64 to 4.88%, and ready-to-drink green tea beverage showed low levels of catechins, from 0.14 to 0.26%. As for caffeine content, green tea extract had higher concentration (1.96 to 3.54%) compared to the tea bags (1.39 to 1.57%). Tea bags were found the most suitable for consumption because it contains higher amounts of catechins and smaller amounts of caffeine.

METHOXYPYRAZINES AND LADYBUG TAINT IN WINES

Methoxypyrazines are aroma active compounds found in many wine varietals. These compounds can be of either grape-derived nature or can be introduced into wines via Coccinellidae beetles. Regardless of their origin, methoxypyrazines can have either a beneficial role for wine quality, contributing to the specificity of certain wine varietals (Cabernet sauvignon, Cabernet franc, Sauvignon blanc) or a detrimental role, particularly at higher concentrations, resulting in overpowering green, unripe and herbaceous notes. When methoxypyrazines of exogenous nature are responsible for these unpleasant characteristics, wines are considered to be affected by what is generally known as Ladybug taint (LBT). This is work is a collection of studies seeking to create a sensitive analytical method for the detection and quantification of methoxypyrazines in wines; to investigate the role of different Coccinellidae species in the tainting of wines with LBT and identify the main compounds in ladybug tainted wines responsible for the typical green herbaceous characteristics; to determine the human detection threshold of 2,5-dimethyl-3-methoxypyrazine in wines as well as investigate its contribution to the aroma of wines; and finally to survey methoxypyrazine concentrations in a large set of wines from around the world. In the first study, an analytical method for the detection and quantitation of methoxypyrazines in wines was created and validated. The method employs multidimensional Gas Chromatography coupled with Mass Spectrometry to detect four different methoxypyrazines (2,5-dimethyl-3-methoxypyrazine, isobutyl methoxypyrazine, secbutyl methoxypyrazine and isopropyl methoxypyrazines) in wine. The low limits of detection for the compounds of interest, improved separation and isolation capabilities, good validation data, as well as the ease of use recommend this method as a good alternative to the existing analytical methods for methoxypyrazine detection in wine. In the second study the capacity of two Coccinellidae species, found in many wine regions – Harmonia axyridis and Coccinella septempunctata - to taint wines is evaluated. Coccinella septempunctata is shown to be as capable as causing LBT in wines as Harmonia axyridis. Dimethyl methoxypyrazine, previously thought to be of exogenous nature only (from Coccinellidae haemolymph), is also detected in control (untainted) wines. The main odor active compounds in LBT wines are investigated through Aroma Extract Dilution Assay. These compounds are identified as isopropyl methoxypyrazine, sec- and iso- butyl methoxypyrazine. In the third study, the human detection threshold for dimethyl methoxypyrazine in wine is established to be 31 ng/L in the orthonasal modality and 70 ng/L retronasally. After wines spiked with various amounts of dimethyl methoxypyrazine are evaluated sensorally, dimethyl methoxypyrazine causes significant detrimental effects to wine aroma at a concentration of 120 ng/L. The final study examines methoxypyrazine (dimethyl methoxypyrazine, isopropyl methoxypyrazine, secbutyl methoxypyrazine and isobutyl methoxypyrazine) concentrations in 187 wines from around the world. Dimethyl methoxypyrazine is detected in the majority of the red wines tested. Data are interpreted through statistical analyses. A new measure for predicting greenness/herbaceousness in wines - methoxypyrazine “total impact factor” is proposed.

Evaluation of curcumin and cisplatin-induced DNA damage in PC12 cells by the alkaline comet assay

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Development and Validation of a UV-Spectrophotometric Method for Determination of Flucloxacillin Sodium in Capsules

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

An Environmentally Friendly Reflectometric Method for Bumetanide Determination in Pharmaceuticals

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Valor nutritivo e desempenho de leitões alimentados com rações contendo silagem de grãos úmidos de milho

Um ensaio de digestibilidade (experimento 1) foi conduzido para determinar os coeficientes de digestibilidade aparentes da matéria seca (CDMS), proteína bruta (CDPB), amido (CDAM) e energia bruta (CDEB) e o coeficiente de metabolização da energia bruta (CMEB) da silagem de grãos úmidos de milho (SGUM). Foram utilizados 12 suínos mestiços (Landrace, Large-White e Duroc) machos castrados, alojados em gaiolas de metabolismo, distribuídos em um delineamento experimental inteiramente casualizado. O método utilizado foi o da coleta total de fezes e urina. Os valores de matéria seca digestível (MSD), proteína digestível (PD), amido digestível (AD), energia digestível (ED) e energia metabolizável (EM), na matéria natural (60,18% de MS), foram, respectivamente, 48,70; 3,77; 42,35%; 2.389 e 2.327 kcal/kg de SGUM. O experimento 2 foi conduzido para avaliar o desempenho de leitões e a viabilidade econômica da utilização das rações com diferentes níveis de substituição do milho seco por SGUM. Foram utilizados 48 suínos mestiços (Landrace, Large White e Duroc), distribuídos em um delineamento inteiramente casualizado, com seis repetições e dois animais por unidade experimental. Os tratamentos consistiram de uma ração à base de milho e farelo de soja e outras três com 33, 66 e 100% de substituição do milho seco por SGUM com base nos valores de energia digestível. Não houve efeito da inclusão de SGUM sobre o ganho de peso e o consumo de ração, porém ocorreu redução linear na conversão alimentar e no custo da ração por quilograma de peso vivo ganho. Os dados indicam que o milho seco pode ser totalmente substituído pela SGUM em rações para leitões em fase de creche, com melhora nos índices produtivos e econômicos.

Colorimetric assay of ethanol using alcohol dehydrogenase from dry baker's yeast

Alcohol dehydrogenases (ADHs) are oxidoreductases present in animal tissues, plants, and microorganisms. These enzymes attract major scientific interest for the evolutionary perspectives, afforded by their wide occurrence in nature, and for their use in synthesis, thanks to their broad substrate specificity and stereoselectivity. In the present study, the standardization of the activity of the alcohol dehydrogenase from baker's yeast was accomplished, and the pH and temperature stability showed, that the enzyme presented a high stability to pH 6.0-7.0 and the thermal stability were completely maintained up to 50 degrees C during 1 h. The assays of ethanol (detection range 1-5 mM or 4.6 x 10(-2) to 23.0 x 10(-2) g/L) in different samples in alcoholic beverages, presented a maximum deviation of only 7.2%. The standard curve and the analytic curve of this method meet the conditions of precision, sensitivity, simplicity, and low cost, required for a useable analytical method. (c) 2006 Elsevier B.V. All rights reserved.

Fontes de fibra para leitões recém desmamados

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Rapid turbidimetric assay to potency evaluation of tigecycline in lyophilized powder

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Rapid turbidimetric assay to determine the potency of daptomycin in lyophilized powder

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development and validation of first derivative spectrophotometric method for quantification of darunavir in tablets

Aims: Darunavir is widely used in HIV/AIDS therapy. It is a HIV protease inhibitor that has excellent efficacy against the virus. The aim of this study is to develop and validate an analytical method fast and free of interferences for determination of darunavir ethanolate as raw material and tablet dosage form. Methodology: As the formulation excipients show high interference in darunavir determination by a direct UV absorption measurement a derivative spectrophotometry was applied. A selective, easy and fast method was achieved employing simple and cheap instrumentation by using first-order derivative spectrophotometry. Results: The first-derivation of spectrum of the drug measured between 200 and 400 nm allowed identification of the analyte and showed absence of placebo interference. The assay was based on the absorbance at 276nm. The linear concentration range was established from 11 to 21 μg/mL. The intra-day and inter-day precision expressed as RSD was 0.06% and 3.75% respectively with mean recovery of 99.84%. Conclusion: The proposed analytical method is able to quantify darunavir as raw material and tablets and can be used routinely by any laboratory applying a spectrophotometer with a derivative accessory. The great difference of the method proposed here is that it proves to be free of placebo interferences as well as simple, fast and low cost.