DAN - Posters/abstracts em congressos internacionais
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Browsing DAN - Posters/abstracts em congressos internacionais by Subject "Accuracy"
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- Accuracy evaluation in thiamin quantification in food matricesPublication . Flores, Cristina; Dias, M. Graça; Santos, MarianaThe performance evaluation of an RP-HPLC method to determine thiamine using different food matrices and reference materials, showed the method suitability to its purpose and to be submitted to accreditation. Intermediate precision evaluate through the relative standard deviation (RSD%) was under 8% for all food matrices tested an all the z-scores obtained for the reference materials were < 1.5.The estimated expanded measurement uncertainty was 13%.
- Accuracy in niacin quantification in food matrices, by an RP-HPLC methodPublication . Flores, Cristina; Dias, M. Graça; Santos, MarianaAim: This work intended to evaluate accuracy of niacin quantification in food matrices, by an RP-HPLC method, in order to validate it for four different food groups: legumes, grains, dairy products and fish. Material and methods: Analytical methodology The analytical method was a RP-HPLC with fluorometric detection, based on EN 15652:2009. Samples (1 to 10 g) were submitted to an acid hydrolysis with 0.1 mol/l HCl for 30 min in an autoclave at 121ºC. After filtration, 50 µl of the solutions, were injected and separated at 37 ºC on a HPLC system. The stationary phase was the Fortis C18 5 µm (150 x 4,6 mm) column and the mobile phase consisted of 0.07 mol/l phosphate buffer, 0.075 mol/l hydrogen peroxide and 5x10-6 mol/l copper sulphate, at a flow rate of 1 ml/min. Excitation and emission wavelengths were 322 nm and 380 nm, respectively. Quantification was made with five external standards. Results were expressed in mg/100g. Accuracy evaluation To evaluate precision, at least one matrix of each food group was chosen: roasted peanuts, canned green peas, wheat bran, powder milk and canned tuna. Method trueness was assessed by testing five different reference materials from FAPAS and NIST. Each of the FAPAS samples 2160, 2166, 2172, 2176 (Breakfast Cereals) were tested once over a period of 14 months and, NIST 1849 (Infant/Adult Formula) was tested twice in the same period. In the precision study, the five matrices were tested in triplicate in four different days. Repeatability and intermediate precision standard deviations (Sr and SPi) were calculated, for each matrix, trough ANOVA (p < 0.05). Repeatability and Intermediate precision limits; r and Pi were calculated using the following formulas: r=2.8*S_r and Pi=2.8*S_Pi . Trueness was evaluated from the z-scores obtained. Results: The values of niacin concentration obtained were: peanuts – 13.4 mg/100 g, green peas – 0.59 mg/100 g, wheat bran – 18.2 mg/100 g, powder milk – 0.73 mg/100 g and tuna – 9.5 mg/100 g. The Sr and SPi (mg/100g) were respectively 0.52 / 1.25 (peanuts), 0.02 / 0.05 (green peas), 0.23 / 0.78 (wheat bran), 0.02 / 0.06 (powder milk) and 0.24 / 0.60 (tuna). The r and Pi values obtained ranged from 0.05 to 1.46 for r and 0.14 to 3.50for Pi. All the │z-scores│ obtained for FAPAS samples were < 1 and, the │z-scores│ obtained for NIST reference material were both < 2. Conclusion: The repeatability data obtained in this study, for niacin in different food matrices were in accordance with the ones presented in the method standard EN 15652:2009. Trueness evaluation using breakfast cereals and formulas revealed a good method/laboratory performance. Accuracy evaluation, using representative matrices and niacin contents, showed the method suitable to its purpose and fit to be submitted to accreditation by an external entity.
- Prepacked processed foods: accuracy of the labelled informationPublication . Albuquerque, T.G.; Nunes, M.A.; Oliveira, M.B.P.P.; Costa, H.S.Introduction: The accuracy of nutritional labelling is important to establish health food policies. The European Commission on 25 October 2011, the Regulation (EU) No. 1169/2011 on the provision of food information, setting common definitions, principles and procedures was published. Above all, food information should not mislead consumers about the nature, characteristics, and food effects. Aim: The compliance between the declared and the determined values of prepacked processed foods, selected from the Portuguese market, considering the permitted tolerance limits for salt, fat and saturated fatty acids, was explored in this work.