A fast and low-cost approach for the discrimination of commercial aged cachaças using synchronous fluorescence spectroscopy and multivariate classification.

BACKGROUND: Cachaça is the distilled beverage typical of Brazil and can be subjected to the aging process in wooden barrels. In addition to oak barrels, cachaça is also aged in barrels of different Brazilian native woods, resulting in a wide variety of its sensory characteristics. In this work, 172 cachaças aged in bálsamo, jequitibá, oak, and umburana barrels were analyzed by synchronous fluorescence spectroscopy and by the classification methods of principal component analysis and partial least squares discriminant analysis. Spectra were preprocessed by the first derivative by Savitzky-Golay smoothing, using a filter width and polynomial order determined through face-centered central composite designs. Multivariate analysis was realized using the spectra recorded at different wavelength differences, and models were compared by the classification errors in the test sets. RESULTS: The principal component analysis applied to the synchronous fluorescence spectra presented a tendency of separation by the wood used in the aging process, and the partial least squares discriminant analysis model constructed using the fluorescence spectra recorded at a wavelength difference of 30 nm provided better performance parameters (efficiency 91-97%, sensitivity 81-100%, and specificity 91-100%). CONCLUSION: Synchronous fluorescence spectroscopy offers a promising approach for the classification of cachaças aged in bálsamo, oak, jequitibá, and umburana barrels, and the discriminant model can be used for routine analysis as a screening method. © 2022 Society of Chemical Industry.

Synchronous fluorescence spectroscopy and multivariate classification for the discrimination of cachaças and rums.

Although cachaça and rum are distilled beverages obtained from the same raw material, they present differences in their chemical compositions. In this study, synchronous fluorescence spectroscopy was used combined with supervised classification models based on the partial least squares discriminant analysis to develop a rapid and low-cost model for discriminating between 50 cachaça and 40 rum samples. Partial least squares discriminant analysis models were constructed using synchronous fluorescence spectra recorded at wavelength differences of 10-100 nm. Initially, spectra were preprocessed by the first derivative with the Savitzky-Golay smoothing, and filter width and polynomial order were selected through face-centered central composite designs. For the construction and validation models, the spectra data were split into two datasets: the training and the test sets containing 60 (C, n = 33; R, n = 27) and 30 (C, n = 17; R, n = 13) samples, respectively. The best discrimination was achieved using fluorescence spectra recorded at wavelength difference 10 nm, allowing the discrimination of cachaça and rum with a classification efficiency of 98%. These results indicate that synchronous fluorescence spectroscopy offers a promising approach for the authentication of cachaças and rums.

Spectrofluorimetric analyzes of thiamine and riboflavin in monofloral honey varieties of africanized bees (Apis mellifera).

This research aimed to study the validation of a viable and low-cost spectrofluorimetric method, capable of detecting and quantifying B vitamins in floral varieties of bee honey. The analyzes were performed using chemical and operational methods of pre-defined solutions and standards, performed in triplicate and the results expressed as mean ± standard deviation. The data were recorded in a Microsoft Office Excel spreadsheet (version 2013) and studied using the statistical program Bioestatic version 3.0. The calibration curves of the vitamins showed the linearity and precision of the method. Subsequently, a descriptive analysis of the data was performed, being considered normal in the Lilliefors normality tests. Finally, the data were subjected to Pearson's correlation test, showing positive and strong correlations, with r (Pearson) ranging from 0.7619 to 1. Honey had positive results regarding the detection and quantification of vitamins B1 and B2 through the spectrofluorimetric method.

Exploitation of a short monolithic column for in-line separation and preconcentration: Environmental friendly determination of the emerging pollutant salicylic acid in natural waters.

Salicylic acid is an emerging environmental contaminant, usually found at ng/L concentrations in natural waters. Its quantification usually involves liquid chromatography-tandem mass spectrometry, which requires complex and costly instrumentation as well as time-consuming sample pretreatment, typically involving large solvent volumes. In this work, sequential injection chromatography was exploited to develop a fast, green, cost-effective, and highly sensitive procedure for fluorimetric determination of salicylic acid in natural waters. Analyte preconcentration directly on the chromatographic column (on-column preconcentration) was exploited to improve detectability, yielding an enrichment factor of 122 (1.75 mL of sample) and takes only 8.5 min per determination. A detection limit of 20 ng/L, a linear response range from 0.06 to 5.00 µg/L, coefficients of variation lower than 3.0% (n = 10), and recoveries within 86 and 114% were estimated. The procedure was applied for the analyses of freshwater samples and results agreed with those obtained by liquid chromatography-tandem mass spectrometry at the 95% confidence level. The proposed procedure encompasses in-line concentration, isolation/separation, and detection, without the need for sample clean-up, thus minimizing the consumption of organic solvents and risk of analyte losse.

A novel fluorimetric method for glyphosate and AMPA determination with NBD-Cl and MCR-ALS.

We report the development of a new analytical method for the quantification of N-(phosphonomethyl)glycine (glyphosate) and (aminomethyl)phosphonic acid (AMPA) by combining spectrofluorimetry and multivariate calibration. In this study, fluorescence spectroscopy was used to quantify glyphosate and AMPA, which were previously derivatized with the fluorogenic reagent: 4-chloro-7-nitrobenzofurazan (NBD-Cl). Fluorescence excitation-emission matrices (EEM) were recorded by exciting between 400 and 500 nm, and measuring the emission between 500 and 610 nm. The second-order data obtained were processed using the Multivariate Curve Resolution with Alternating Least Square (MCR-ALS) methodology. The developed method was used to predict different concentrations of glyphosate and AMPA in validation samples. In addition, the presence of the herbicide was evaluated in real samples: a commercial formulation and a water sample from a cultivated area. For this purpose, the standard addition method was used to study the matrix effect in each case. The ranges of working concentrations obtained for this new method are in agreement with the amounts found in surface water samples near a direct sowing soybean growing region in Argentina.

Development of on-line spectrofluorimetric methodology for selenium monitoring in foods and biological fluids using Chrome azurol S quenching.

A novel, simple and accurate on-line green methodology for Se(IV) monitoring by molecular fluorescence has been developed. Because the analyte does not exhibit fluorescence, the organic dye Chrome azurol S (CAS) has been chosen to allow detection. The effect of metal-quenching on CAS excitation and emission conditions (λex=300nm; λem=407nm) was used as criterion for analyte quantification in presence of sodium cholate bile salt (NaC). The quenching mechanism was explored, and it can be classified as a collisional type with a Stern-Volmer constant value of 3.0×107molL-1. To improve the sampling rate, minimize the reagent consumption and generated wastes, an on-line configuration was designed. Experimental variables that affect the fluorimetric sensitivity were optimized using uni-variation assays. Under optimal experimental conditions, the limit of detection was 0.27µgL-1 with a lineal range for Se(IV) concentration from 0.84 to 6.00µgL-1. The developed methodology is low cost and fast sampling, allowing Se(IV) quantification in the presence of other common ions. Bulbous vegetables and biological samples were successfully analyzed with an average recovery close to 100%.

Novel spectrofluorimetric method for boldine alkaloid determination in herbal drugs and phytopharmaceuticals.

A new green on-line method for Boldine determination (BOL) in herbal drugs and phytopharmaceuticals, using its native fluorescence in acid media (λex=282nm; λem=373nm) has been developed. The presented methodology involves for the first time, a flow injection (FI) strategy using a mini-column of multiwalled carbon nanotubes as retention agent coupled with molecular fluorescence. Different parameters influence as sample pH and flow rate, eluent flow rate and composition; on BOL sensitivity and elution time was investigated by multifactorial techniques. Adequate dynamic calibration range (r2=0.9993) was obtained over a concentration interval of 0.029-27.0µgmL-1 BOL. The limits of detection (LOD) and quantification (LOQ) were 0.008 and 0.029µgmL-1, respectively. The average recoveries in explored samples ranged from 95% to 103%. Under optimized conditions, the throughput sample as high as 30h-1 was achieved with high repeatability performance (99%). The proposed development represents a useful and valuable tool emulating the analytical efficiency of the official methodologies for quality control of herbal and phytopharmaceutical drugs containing BOL. Moreover, this approach shows advantages respect to low cost, simplicity and environmental and analyst friendly.

Antioxidant activity and protective role on protein glycation of synthetic aminocoumarins

Background: Synthesized aminocoumarins are heterocyclic compounds possessing potential for the treatment of insulin-dependent diabetes mellitus with unexplored anti-glycative action. Results: In this study 4-aminocoumarin derivatives (4-ACDs) were evaluated in vitro for antiglycation (AG) activities by using the human serum albumin (HSA)/glucose system, for 8 weeks of incubation. The glycation and conformational alteration of HSA in the presence of the tested compounds were evaluated by Congo red assay, fluorescence and circular dichroism spectroscopy. The antioxidant (AO) capacity were also tested by four different assays including: DPPH (2,2'-diphenyl-1-picrylhydrazyl radical), ABTS (2,2-azinobis (3-ethylbenzothiazoline-6-sulphonate) diammonium salt), FRAP (ferric reducing antioxidant power) and β-carotene-linoleic acid assay. The tested compounds showed AG and AO effects. The intensity of the accomplished AO potential is related to the type of the used assay. Significant alterations in the secondary (monitored by CD spectropolarimetry) and tertiary structure (assessed by spectrofluorimetry) of HSA upon glycation were mitigated by the 4-ACDs, suggesting their suppressive role in the late stage (post-Amadori) of the HSA glycation. Conclusions: By the analogues, in vitro ascertained AO and AG properties of 4-ACD may be recognized as rationale for their protective role against oxidative changes of proteins, thereby precluding diabetic complications in humans.

Chemometrics-assisted cyclodextrin-enhanced excitation-emission fluorescence spectroscopy for the simultaneous green determination of bisphenol A and nonylphenol in plastics.

The aim of this work was to quantify two relevant priority chemicals, bisphenol A (BPA) and 4-nonylphenol (NP), coupling the sensitivity of fluorescence in organized media and the selectivity of multivariate calibration, measuring excitation-emission fluorescence matrices in an aqueous methyl-ß-cyclodextrin solution. The studied priority pollutants are two of the most frequently found xenoestrogens in the environment, and are therefore of public health concern.The data were successfully processed by applying unfolded partial least-squares coupled to residual bilinearization (U-PLS/RBL), which provided the required selectivity for overcoming the severe spectral overlapping among the analyte spectra and also those for the interferents present in real samples. A rigorous International Union of Pure and Applied Chemistry (IUPAC)-consistent approach was applied for the calculation of the limits of detection. Values in the ranges of 1-2 and 4-14 ng mL(-1) were obtained in validation samples for BPA and NP, respectively. On the other hand, low relative prediction errors between 3% and 8% were achieved. The proposed method was successfully applied to the determination of BPA and NP in different plastics. In positive samples, after an easy treatment with a small volume of ethanol at 35°C, concentrations were found to range from 26 to 199 ng g(-1) for BPA, and from 95 to 30,000 ng g(-1) for NP.

Evaluation of transformer insulating oil quality using NIR, fluorescence, and NMR spectroscopic data fusion.

Power transformers are essential components in electrical energy distribution. One of their most important parts is the insulation system, consisting of Kraft paper immersed in insulating oil. Interfacial tension and color are major parameters used for assessing oil quality and the system׳s degradation. This work proposes the use of near infrared (NIR), molecular fluorescence, and (1)H nuclear magnetic resonance (NMR) spectroscopy methods combined with chemometric multivariate calibration methods (Partial Least Squares - PLS) to predict interfacial tension and color in insulating mineral oil samples. Interfacial tension and color were also determined using tensiometry and colorimetry as standard reference methods, respectively. The best PLS model was obtained when NIR, fluorescence, and NMR data were combined (data fusion), demonstrating synergy among them. An optimal PLS model was calculated using the selected group of variables according to their importance on PLS projections (VIP). The root mean square errors of prediction (RMSEP) values of 2.9 mN m(-1) and 0.3 were estimated for interfacial tension and color, respectively. Mean relative standard deviations of 1.5% for interfacial tension and 6% for color were registered, meeting quality control requirements set by electrical energy companies. The methods proposed in this work are rapid and simple, showing great advantages over traditional approaches, which are slow and environmentally unfriendly due to chemical waste generation.

Fluorescence method using on-line sodium cholate coacervate surfactant mediated extraction for the flow injections analysis of Rhodamine B.

An on-line surfactant mediated extraction method in a flow injection analysis format with fluorescence detection was developed for the determination of Rhodamine B (RhB) in food condiments. The sample was extracted using the phase separation behavior exhibited by the bile salt surfactant, sodium cholate (NaC), upon addition of sodium dodecylsulfate (SDS) in the presence of acid at room temperature. The RhB in the sample was incorporated into the NaC/SDS coacervate phase which was then collected on a glass-wool packed mini column from which it was subsequently eluted using a 1.00 mol L(-1) HCl solution. The inherent fluorescence (λex=555 nm; λem=575 nm) of RhB was employed for detection. Good linearity (r(2)=0.9933) was obtained over the concentration range 0.4-4794-479.0 µg L(-1) RhB. The detection (LOD) and quantification (LOQ) limits were 0.12 and 0.40 µg L(-1), respectively. The method was successfully applied for analysis of RhB in food condiments and spiked samples. The average recoveries ranged from 95.3% to 118.9% at spiked concentration levels of 1.19 and 2.39 µg L(-1). Under optimized conditions, a throughput of 50 samples per hour was achieved. The proposed method may be a valuable tool not only for quality control of food condiments and similar food confectioneries but for the analysis of a variety of other RhB-containing samples as well.

O-(ß-hydroxyethyl)rutosides determination by micellar flow injection (FI)-spectrofluorimetry.

A simple, eco-friendly, sensitive and economic flow injection spectrofluorimetric method was developed for the determination of O-(ß-hydroxyethyl)rutosides. The procedure was based on the use of an anionic surfactant such as sodium dodecyl sulfate to provide an appreciable O-(ß-hydroxyethyl)rutosides fluorescence enhancement, increasing considerably the sensitivity of detection. All the variables affecting the fluorescence intensity were studied and optimized. The flow rate was 5 mL/min with detection at 450 nm (after excitation at 346 nm). A linear correlation between drug amount and peak area was established for O-(ß-hydroxyethyl)rutosides in the range of 0.01-200 µg/mL with a detection limit of 0.001 µg/mL (s/n=3). Validation processes were performed by recovering studies with satisfactory results. The new methodology can be employed for the routine analysis of O-(ß-hydroxyethyl)rutosides in bulks as well as in commercial formulations.

Development of dissolution test method for a telmisartan/amlodipine besylate combination using synchronous derivative spectrofluorimetry

The dissolution process is considered an important in vitro tool to evaluate product quality and drug release behavior. Single dissolution methods for the analysis of combined dosage forms are preferred to simplify quality control testing. The objective of the present work was to develop and validate a single dissolution test for a telmisartan (TEL) and amlodipine besylate (AML) combined tablet dosage form. The sink conditions, stability and specificity of both drugs in different dissolution media were tested to choose a discriminatory dissolution method, which uses an USP type-II apparatus with a paddle rotating at 75 rpm, with 900 mL of simulated gastric fluid (SGF without enzymes) as the dissolution medium. This dissolution methodology provided good dissolution profiles for both TEL and AML and was able to discriminate changes in the composition and manufacturing process. To quantify both drugs simultaneously, a synchronous first derivative spectrofluorimetric method was developed and validated. Drug release was analyzed by a fluorimetric method at 458 nm and 675 nm for AML and TEL, respectively. The dissolution method was validated as per ICH guidance.

O processo de dissolução é considerado como uma importante ferramenta in vitro para avaliar a qualidade do produto e o comportamento de liberação do fármaco. Prefere-se um ensaio único de dissolução para formas farmacêuticas contendo associação de fármacos pela simplificação dos testes de controle de qualidade. O objetivo do presente trabalho foi desenvolver e validar um teste de dissolução único para forma farmacêutica comprimidos contendo telmisartana (TEL) e besilato de anlodipino (AML) associados. Condições "sink", estabilidade e especificidade de ambos os fármacos nos diferentes meios de dissolução foram avaliadas para selecionar um método de dissolução discriminatório, que utiliza um aparato do tipo II da USP, com pás girando a 75 rpm e 900 mL de fluido gástrico simulado (SGF sem enzima) como o meio de dissolução. Estas condições proporcionaram bons perfis de dissolução para ambos, TEL e AML, sendo capaz de discriminar as mudanças na composição e processo de fabricação. Para quantificar os dois fármacos simultaneamente, um método de fluorescência derivada sincronizado foi desenvolvido e validado. A quantidade de fármaco liberado foi analisada pelo método fluorimétrico em 458 e 675 nm para a AML e TEL, respectivamente. O método de dissolução foi validado de acordo com a orientação da ICH.

Optimization of a spectrofluorimetric method based on a central composite design for the determination of potassium losartan in pharmaceutical products

Here, a spectrofluorimetric method for the determination of potassium losartan (PL) in pharmaceutical products is described. The effects of critical parameters, pH, acid molarity, and temperature, on the fluorescence intensity of PL were analyzed, and these parameters were optimized using a central composite design (CCD). The highest fluorescent intensity at excitation (λex) and emission (λem) wavelengths of 248 nm and 410 nm, respectively, was achieved using 0.01 M sulfurous acid (pH 2) at 21.6 °C. Under optimum conditions, the method was linear from 0.025-0.5 µg/mL, with a reasonably high correlation coefficient (0.9993). Furthermore, the method was very sensitive (LOQ, 0.006), accurate (RE, ≤7.06), and precise (%RSD, ≤6.51). After development and validation of the method, samples containing PL were analyzed with this method, and the obtained data were statistically compared with those obtained with a previously published reference method using a two one-sided equivalence test (TOST). According to the data, the results from the proposed and reference assays were equivalent.

Descreve-se método espectrofluorométrico para a determinação de losartana potássica (PL) em produtos farmacêuticos. Os efeitos de parâmetros críticos (pH, molaridade ácida e temperatura) na intensidade da fluorecência foram otimizados usando o planejamento de componente central (DCC). A mais alta intensidade fluorescente com λex=248 nm e λem= 410 nm foi obtida usando ácido sulfúrico 0.01 M (pH 2) e 21.6 ºC. Nas condições ideais, a linearidade do método foi estabelecida na faixa de concentração de 0.025-0.5 µg/mL com coeficiente de correlação bastante elevado (0.9993). Além disso, o método foi muito sensível com valor de LOQ 0.006, exato (RE≤7.06) e preciso (RSD%≤6.51). Depois do desenvolvimento e validação do método, amostras de medicamentos contendo PL foram analisadas com este método e os resultados obtidos foram comparados estatisticamente com método de referência, publicado anteriormente, usando o Teste de equivalência TOST (Teste de Equivalência Unilateral). De acordo com os dados estatísticos, os resultados do ensaio de referência e do método proposto foram equivalentes.

Biochemical characterization of recombinant nucleoside hydrolase from Mycobacterium tuberculosis H37Rv.

Tuberculosis (TB) is a major global health threat. There is a need for the development of more efficient drugs for the sterilization of the disease's causative agent, Mycobacterium tuberculosis (MTB). A more comprehensive understanding of the bacilli's nucleotide metabolic pathways could aid in the development of new anti-mycobacterial drugs. Here we describe expression and purification of recombinant iunH-encoded nucleoside hydrolase from MTB (MtIAGU-NH). Glutaraldehyde cross-linking results indicate that MtIAGU-NH predominates as a monomer, presenting varied oligomeric states depending upon binding of ligands. Steady-state kinetics results show that MtIAGU-NH has broad substrate specificity, accepting inosine, adenosine, guanosine, and uridine as substrates. Inosine and adenosine displayed positive homotropic cooperativity kinetics, whereas guanosine and uridine displayed hyperbolic saturation curves. Measurements of kinetics of ribose binding to MtIAGU-NH by fluorescence spectroscopy suggest two pre-existing forms of enzyme prior to ligand association. The intracellular concentrations of inosine, uridine, hypoxanthine, and uracil were determined and thermodynamic parameters estimated. Thermodynamic activation parameters (Ea, ΔG(#), ΔS(#), ΔH(#)) for MtIAGU-NH-catalyzed chemical reaction are presented. Results from mass spectrometry, isothermal titration calorimetry (ITC), pH-rate profile experiment, multiple sequence alignment, and molecular docking experiments are also presented. These data should contribute to our understanding of the biological role played by MtIAGU-NH.

Comparison of thin-layer chromatography, spectrofluorimetry and bright greenish-yellow fluorescence test for aflatoxin detection in corn

In this study the bright greenish-yellow fluorescence test, widely used by the corn milling industry, was compared to the thin-layer chromatography (TLC) and spectrofluorimetry methods for aflatoxin detection in 40 corn samples naturally contaminated by the Aspergillus section Flavi. According to the corn processing industry criteria, all the samples were adequate for human and animal consumption by the bright greenish-yellow fluorescence test, but TLC and spectrofluorimetry analysis detected aflatoxins above the maximum tolerated limit (20 µg/kg) in 7 and 8 samples, respectively. Aflatoxins were detected in 16 (40 percent) corn samples by TLC, with levels ranging from 4.0 to 54.0 µg/kg (mean 19.97 ± 15.97 µg/kg), and in 25 (62.5 percent) samples by spectrofluorimetry, with levels ranging from 1.0 to 58.66 µg/kg (mean 17.14 ± 17.81 µg/kg). The results indicated a good correlation (ρ = 0.97) between TLC and spectrofluorimetry for aflatoxin determination in naturally contaminated corn. The bright greenish-yellow fluorescence test was simple and quick, but it showed 20 percent false-negative results, suggesting its use only as screening method for detecting the suspected lots of grains that should be tested further for aflatoxin by more sensitive methods.

Neste trabalho a contagem de fluorescência luminosa amarelo-esverdeada, amplamente utilizada pela indústria de processamento de milho, foi comparada à cromatografia em camada delgada (CCD) e espectrofluorimetria para detecção de aflatoxinas em 40 amostras de milho naturalmente contaminadas por Aspergillus section Flavi. De acordo com os critérios da indústria processadora de milho, todas as amostras estavam adequadas para o consumo humano e animal pela contagem de fluorescência luminosa amarelo-esverdeada (CFLAE), porém as análises por CCD e espectrofluorimetria detectaram aflatoxinas acima do limite máximo tolerado (20 µg/kg) em 7 e 8 amostras, respectivamente. As aflatoxinas foram detectadas em 16 (40 por cento) amostras por CCD, com níveis variando de 4,0 a 54,0 µg/kg (média 19,97 ± 15,97 µg/kg) e, em 25 (62,5 por cento) amostras por espectrofluorimetria, com níveis variando de 1,0 a 58,66 mg/kg (média 17,14 ± 17,81 µg/kg). Os resultados indicaram uma boa correlação (ρ=0,97) entre CCD e espectrofluorimetria para detecção de aflatoxinas em amostras de milho naturalmente contaminadas. A CFLAE, apesar da simplicidade e rapidez, apresentou 20 por cento de resultados falso-negativos, sugerindo seu uso apenas como método de triagem para detecção de lotes de grão suspeitos de contaminação que devem ser avaliados posteriormente por métodos mais sensíveis.

Emission fi lter design to detect poultry skin tumorsusing fl uorescence hyperspectral imaging / Diseño del filtro de emisión para detectar tumores cutáneos en canales de aves usandoimagenes de fluorescencia hiperespectral / Desenho de um filtro de emissão para detectar tumores cutâneos em carcaças de avesusando imagens de fluorescência hiperespectral

This paper presents an optimal emission filter of the fluorescence imaging system to detect skintumors on poultry carcasses. The secure production of disease-free meat is crucial in the mass productionenvironment. The fluorescence spectra have been gaining the practical use in many areas because thefluorescence response is very sensitive in detecting trace elements. The spectral features of the specimenare embedded across broad spectral bands and have been analyzed in various methods. We apply thelinear discriminant analysis to determine the emission filter of fluorescence imaging system. It providesthe optimal attenuation of emission wavelengths in terms of discriminant power. The attenuation valuesprioritize wavelengths to select significant spectral bands. With the optimal filter, skin tumor parts ofchicken carcasses are enhanced saliently in resultant fluorescence images.

La producción de carne libre de enfermedades es crucial en producción pecuaria intensiva. Losespectros de fluorescencia se han estado usando en forma práctica en muchas áreas, ya que la respuestade fluorescencia es muy sensible para detectar elementos traza. Este artículo presenta un óptimo filtrode emisión para el sistema de imágenes de fluorescencia utilizado para detectar tumores cutáneos encanales de pollo. Las características espectrales de la muestra --insertas en bandas espectrales amplias- sehan analizado por varias metodologías. En este artículo aplicamos el análisis lineal discriminante paradeterminar el filtro de emisión del sistema de imágenes por fluorescencia, mediante el cual se obtiene laatenuación optima de las ondas de emisión en términos de poder discriminante. Los valores de atenuaciónpriorizan las longitudes de onda para seleccionar las bandas espectrales más significativas. Gracias a lautilización de este filtro optimizado, los tumores cutáneos existentes en la canal de pollo son magnificados,de modo que se alcanzan a diferenciar perfectamente en las imágenes de fluorescencia resultantes.

A produção de carne livre de doenças é crucial em produção pecuária intensiva. Os espectros defluorescência temse estado utilizando em forma prática em muitas áreas, já que a resposta da fluorescênciaé muito sensível para detectar elementos traça. Este artículo apresenta um óptimo filtro de emissão parao sistema de imagens de fluorescência utilizado para detectar tumores cutâneos em carcaças de frangos.As características espectrais da amostra, insertas em bandas espectrais amplas são utilizadas por variasmetodologias. Neste artículo aplicamos a análises linear discriminante para determinar o filtro de emissãodo sistema de imagens por fluorescência, mediante o qual obtém-se a atenuação óptima das ondas deemissão em termos de poder discriminante. Os valores de atenuação dão prioridade às longitudes deonda para seleccionar as bandas espectrais mais significativas. Graças à utilização do filtro optimizado,os tumores cutâneos existentes na carcaça de frango são magnificados, de fato que são diferenciadosperfeitamente nas imagens de fluorescência resultantes.

Ochratoxin A detection by spectrofluorimetry compared with high performance liquid c hromatography in coffee / Espectrofluorimetria comparada à cromatografia líquida de alta eficiência na detecção de ocratoxina A em café

The Brazilian coffee production plays important role both in the national and oversea trade. The quality and sanity of coffee depend on fungal contamination, with emphasis on ochratoxin A (OTA) producing species, which is a nephrotoxin with hazardous effect in public health. The exigency on continuous monitoring and control of OTA in agricultural commodity requires a simple, rapid and accessible analytical methodology. The objective of this research was to set up the spectrofluorimetric method for OTA detection intended for monitoring in coffee, which was developed in data-correlation with high efficiency liquid chromatography (HPLC). The performance of spectrofluorimetric analysis was evaluated using artificially contaminated coffee (10, 20 and 50 ng/g), and the data compared with HPLC. Although of the fault of former technique, with recovery of 40.14 % and correlation coefficient of 0.79 when compared to HPLC, i.e. low reliability and inadequate efficiency, the data showed perspective to follow the improvement inserting new tool, and further standardization and certification.

A cafeicultura brasileira apresenta grande importância ao mercado interno e comércio exterior. A qualidade e sanidade do café dependem da contaminação fúngica, com ênfase as espécies produtoras de ocratoxina A (OTA), uma nefrotoxina de efeito deletério à saúde pública. A necessidade de contínuo monitoramento e controle de OTA em produtos agrícolas requer metodologia analítica simples, rápida e acessível. O trabalho teve como objetivo padronizar um método espectrofluorimétrico para detecção de OTA visando monitoramento em grãos de café, correlacionando-o com a cromatografia líquida de alta eficiência (CLAE). A aplicabilidade da espectrofluorimetria foi avaliada em café artificialmente contaminado com OTA (10, 20 e 50 ng/g), comparando os resultados obtidos com a CLAE. Embora a fluorimetria tenha apresentado resultados insatisfatórios, com recuperação de 40,14 % e coeficiente de correlação de 0,79 em relação a CLAE, i.e. baixa confiabilidade e eficiência inadequada, a técnica constitui perspectiva para prosseguir o estudo inserindo novos ensaios referentes à sua padronização e certificação.

Ochratoxin A detection by spectrofluorimetry compared with high performance liquid c hromatography in coffee / Espectrofluorimetria comparada à cromatografia líquida de alta eficiência na detecção de ocratoxina A em café

The Brazilian coffee production plays important role both in the national and oversea trade. The quality and sanity of coffee depend on fungal contamination, with emphasis on ochratoxin A (OTA) producing species, which is a nephrotoxin with hazardous effect in public health. The exigency on continuous monitoring and control of OTA in agricultural commodity requires a simple, rapid and accessible analytical methodology. The objective of this research was to set up the spectrofluorimetric method for OTA detection intended for monitoring in coffee, which was developed in data-correlation with high efficiency liquid chromatography (HPLC). The performance of spectrofluorimetric analysis was evaluated using artificially contaminated coffee (10, 20 and 50 ng/g), and the data compared with HPLC. Although of the fault of former technique, with recovery of 40.14 % and correlation coefficient of 0.79 when compared to HPLC, i.e. low reliability and inadequate efficiency, the data showed perspective to follow the improvement inserting new tool, and further standardization and certification.

A cafeicultura brasileira apresenta grande importância ao mercado interno e comércio exterior. A qualidade e sanidade do café dependem da contaminação fúngica, com ênfase as espécies produtoras de ocratoxina A (OTA), uma nefrotoxina de efeito deletério à saúde pública. A necessidade de contínuo monitoramento e controle de OTA em produtos agrícolas requer metodologia analítica simples, rápida e acessível. O trabalho teve como objetivo padronizar um método espectrofluorimétrico para detecção de OTA visando monitoramento em grãos de café, correlacionando-o com a cromatografia líquida de alta eficiência (CLAE). A aplicabilidade da espectrofluorimetria foi avaliada em café artificialmente contaminado com OTA (10, 20 e 50 ng/g), comparando os resultados obtidos com a CLAE. Embora a fluorimetria tenha apresentado resultados insatisfatórios, com recuperação de 40,14 % e coeficiente de correlação de 0,79 em relação a CLAE, i.e. baixa confiabilidade e eficiência inadequada, a técnica constitui perspectiva para prosseguir o estudo inserindo novos ensaios referentes à sua padronização e certificação.

Pesquisa de toxina paralisante dos moluscos em pescado / Investigation of paralyzing toxin from molluscs in fish

A toxina paralisante dos moluscos foi pesquisada em amostras de ostras, mariscos e peixes, colhidas em diferentes praias do litoral paulista. Foram empregados dois procedimentos analíticos: o químico e o bioensaio. Em decorrência do aparecimento de manchas avermelhadas nas águas e mortalidade de peixes na região, no período de agosto a setembro de 1983, suspeitou-se do fenômeno de "maré vermelhra". A toxina não foi detectada em nenhuma das amostras, pelos dois métodos empregados, que permitem segurança dos resultados, considerando que os testes foram realizados com o padrão de saxi toxina (AU).