The annatto carotenoids and the norbixin absorption coefficient / Carotenoides de urucum e o coeficiente de absorção da norbixina

Annatto seeds present cis-bixin as the major carotenoids, but the norbixin salt is the mainpigment present in dyes obtained from the alkaline extraction process. For analyzing the norbixin,the absorptions are obtained in the two spectral peaks with higher intensity, but discrepanciesin the published extinction values have led to serious doubts. Taking into account the use ofabsorption coefficient for evaluating the norbixin concentration in annatto seeds and extracts, thepresent study evaluated the absorption coefficient in various solvents and the total uncertaintyassociated with this value was determined. The norbixin standard was prepared from annattoseeds, purified by column chromatography and the purity of norbixin was evaluated by HPLC-DAD.The absorption coefficients were determined for norbixin in different solvents and the uncertaintywas evaluated. The 0.5% potassium hydroxide, the main solvent used for marketing the annattoseeds and extracts, showed the absorption coefficients of 2887 at 454nm and of 2546 at 483nm,and the estimation of expanded uncertainty (K=2) was ±86 and 85 g 100 mL-1, respectively.

O principal carotenoide em sementes de urucum é a cis-bixina, mas o sal de norbixina torna-seo principal pigmento presente em corantes obtidos pelo processo de extração alcalino.Para a análise de norbixina as absorbâncias são obtidas nos dois picos espectrais de maiorintensidade, mas discrepâncias no valor de absortividade levam a sérias dúvidas. Levando-se emconta o uso do coeficiente de absorção na avaliação da concentração de norbixina em sementesde urucum e extratos, este trabalho teve como objetivo avaliar o coeficiente de absorção emvários solventes e determinar a incerteza expandida associada a esse valor. Para a execução doestudo, um padrão de norbixina foi preparado a partir de sementes de urucum, purificado emcoluna aberta e a pureza da norbixina foi avaliada por HPLC-DAD. O coeficiente de absorçãoda norbixina foi determinado pela construção de curvas analíticas em diferentes solventes e aincerteza expandida foi avaliada. O hidróxido de potássio a 0,5%, principal solvente utilizadona comercialização de sementes de urucum e extratos, apresentou o coeficiente de absorçãodeterminado em 2887 a 454nm e 2546 a 483nm e a estimação da incerteza expandida (K=2) foi86 e 85 g 100 mL-1, respectivamente.

The annatto carotenoids and the norbixin absorption coefficient / Carotenoides de urucum e o coeficiente de absorção danorbixina

Annatto seeds present cis-bixin as the major carotenoids, but the norbixin salt is the main pigment present in dyes obtained from the alkaline extraction process. For analyzing the norbixin, the absorptions are obtained in the two spectral peaks with higher intensity, but discrepancies in the published extinction values have led to serious doubts. Taking into account the use of absorption coefficient for evaluating the norbixin concentration in annatto seeds and extracts, the present study evaluated the absorption coefficient in various solvents and the total uncertainty associated with this value was determined. The norbixin standard was prepared from annatto seeds, purified by column chromatography and the purity of norbixin was evaluated by HPLC-DAD. The absorption coefficients were determined for norbixin in different solvents and the uncertainty was evaluated. The 0.5% potassium hydroxide, the main solvent used for marketing the annatto seeds and extracts, showed the absorption coefficients of 2887 at 454nm and of 2546 at 483nm, and the estimation of expanded uncertainty (K=2) was ±86 and 85 g 100 mL-1, respectively.

O principal carotenoide em sementes de urucum é a cis-bixina, mas o sal de norbixina torna-se o principal pigmento presente em corantes obtidos pelo processo de extração alcalino.Para a análise de norbixina as absorbâncias são obtidas nos dois picos espectrais de maior intensidade, mas discrepâncias no valor de absortividade levam a sérias dúvidas. Levando-se em conta o uso do coeficiente de absorção na avaliação da concentração de norbixina em sementes de urucum e extratos, este trabalho teve como objetivo avaliar o coeficiente de absorção em vários solventes e determinar a incerteza expandida associada a esse valor. Para a execução do estudo, um padrão de norbixina foi preparado a partir de sementes de urucum, purificado em coluna aberta e a pureza da norbixina foi avaliada por HPLC-DAD. O coeficiente de absorção da norbixina foi determinado pela construção de curvas analíticas em diferentes solventes e a incerteza expandida foi avaliada. O hidróxido de potássio a 0,5%, principal solvente utilizado na comercialização de sementes de urucum e extratos, apresentou o coeficiente de absorção determinado em 2887 a 454nm e 2546 a 483nm e a estimação da incerteza expandida (K=2) foi86 e 85 g 100 mL-1, respectivamente.

Quantifying Uncertainties in the Modelled Estimates of Extreme Precipitation Events at Upper Thames River Basin.

Assessment of climate change impact on hydrology at watershed scale incorporates downscaling of global scale climatic variables into local scale hydrologic variables and evaluation of future hydrologic extremes. The climatological inputs obtained from several global climate models suffer the limitations due to incomplete knowledge arising from the inherent physical, chemical processes and the parameterization of the model structure. Downscaled output from a single AOGCM with a single emission scenario represents only one of all possible future climate realizations; averaging outputs from multiple AOGCMs might underestimate the extent of future changes in the intensity and frequency of climatological variables. These available methods, thus cannot be representative of the full extent of climate change. Present research, therefore addresses two major questions: (i) should climate research adopt equal weights from AOGCM outputs to generate future climate?; and (ii) what is the probability of the future extreme events to be more severe? This paper explores the methods available for quantifying uncertainties from the AOGCM outputs and provides an extensive investigation of the nonparametric kernel estimator based on choice of bandwidths for investigating the severity of extreme precipitation events over the next century. The Sheather-Jones plug-in kernel estimate appears to be a major improvement over the parametric methods with known distribution. Results indicate increased probabilities for higher intensities and frequencies of events. The applied methodology is flexible and can be adapted to any uncertainty estimation studies with unknown densities. The presented research is expected to broaden our existing knowledge on the nature of the extreme precipitation events and the propagation and quantification of uncertainties arising from the global climate models and emission scenarios.