The pet food industry for dogs and cats has grown extensively. This growth has been reflected from the requirements of the owners of these animals by products with different characteristics and which are suitable nutritional quality, according to the need of the animal. Therefore, we emphasize the importance in determining the mineral composition of these foods, especially in the sense of possible contaminants. In this work, a method proposed for determination of mineral composition (S, Al, Ca, Cu, K, Mg, Mn, P, Zn, Sr, V, Fe, Ni, Cr and Ba) in dog and cat foods by inductively coupled plasma optical emission spectrometry (ICP-OES). The samples were digested by microwave-assisted digestion method using dilute HNO3 (2.0 mol L-1) and H2O2 (6% m/v). The ratio of the reagents used in digestion was established by a full-two level factorial design. The optimum conditions for RF power was 1.2 kW and nebulization gas flow rate of 1.0 L min-1, which were established by a 32 factorial design with two variables, evaluating these conditions the methodology of response surface analysis. To evaluate the precision and accuracy of the proposed method, five certified reference materials (CRM) were analyzed: wheat flour (NIST 1567a), bovine liver (NIST 1547), peach leaves (NBS 1577), oyster tissue (NIST 1566b) and fish proteins (DORM-3). The analysis of the CRM has shown that the values are in agreement with the certified values ranged between 80 (Cr) and 117% (Cd), with relative standard deviations (% RSD) lower than 5%, except for Ni and Cr which exceeded 15%. The limits of quantification (LOQ) were obtained between 0.075 (Ba, 233.527 nm) and 87 ìg g-1 (Ca, 373.690 nm). The method was applied to analysis of 17 cat food samples with concentrations varying between 2.3 mg kg-1 for Ba and 2.8 g kg-1 for Ca and 24 of dog food samples ranging between 3.8 mg kg-1 for Cu and 3.4 g kg-1 for Ca collected in supermarkets of cities the of State of Sergipe, Brazil. The exploratory techniques of data using hierarchical cluster analysis (HCA) and principal components analysis (PCA), can conclude that the ration for the pet foods were uniform, since there was no trend in the formation of distinct groups for possible rating, according to their mineral composition, except the brand "F2", which clustered with the presence of concentrations of aluminum and copper in feed composition for dog. / A industria de racoes destinadas a caes e gatos tem crescido amplamente. Este crescimento tem sido reflexo das exigencias dos donos desses animais por produtos com caracteristicas diferenciadas e que apresentem qualidade nutricional adequada, de acordo com a necessidade do animal. Diante disso, ressalta-se a importancia na determinacao da composicao mineral desses alimentos, principalmente no sentido de possiveis contaminantes. Neste trabalho foi proposto um metodo analitico para determinacao da composicao mineral (S, Al, Ca, Cu, K, Mg, Mn, P, Zn, Sr, V, Fe, Ni, Ba e Cr) em racoes de caes e de gatos por espectrometria de emissao optica com plasma indutivamente acoplado (ICP OES). As amostras foram digeridas por aquecimento assistido por micro-ondas utilizando HNO3 diluido (2,0 mol.L-1) e H2O2 (6% v/v). A condicao da proporcao entre os reagentes utilizados na digestao foi estabelecida por um planejamento fatorial em dois niveis. As condicoes otimas para potencia de radiofrequencia foi de 1,2 kW e vazao do gas de nebulizacao da amostra, de 1,0 L min-1, as quais foram estabelecidas por um planejamento fatorial 32 com duas variaveis, avaliando-se estas condicoes pela metodologia de analise de superficie de resposta. Para avaliar a precisao e a exatidao do metodo proposto foram analisados cinco materiais de referencia certificados (MRC): farinha de trigo (NIST 1567a), figado bovino (NIST 1547), folhas de pessegueiro (NBS 1577), tecidos de ostra (NIST 1566b) e proteinas de peixe (DORM-3). Apos analise dos MRC, os valores encontrados foram concordantes com os valores certificados e informados variaram entre 80 (Cr) e 117% (Cd), com desvios padrao relativos (%RSD) menores do que 5%, exceto para Ni e Cr que excederam 15%. Os limites de quantificacao (LQ) obtidos estiveram entre 0,075 (Ba, 233,527 nm) e 87 Êg g-1 (Ca, 373,690 nm). O metodo foi aplicado na analise de 17 amostras de racoes de gatos, com concentracoes variando entre 2,3 mg Kg-1 para o Ba e 2,8 g Kg-1 para o calcio, e 24 amostras de racoes de caes, variando entre 3,8 mg Kg-1 para o Cu e 3,4 g Kg-1 para o Ca, coletadas em municipios do Estado de Sergipe. A partir das tecnicas exploratorias de dados utilizando PCA e HCA, pode-se concluir que as racoes destinadas aos animais de estimacao apresentaram uniformidade, uma vez que nao houve tendencia na formacao de grupos distintos para uma possivel classificacao conforme a sua composicao mineral, exceto a marca gF2 h, que aglomerou-se atraves da presenca das concentracoes de aluminio e cobre na sua composicao para caes.
| Identifer | oai:union.ndltd.org:IBICT/oai:ri.ufs.br:riufs/6082 |
| Date | 05 February 2013 |
| Creators | Costa, Silvânio Silvério Lopes da |
| Contributors | Araújo, Rennan Geovanny Oliveira |
| Publisher | Pós-Graduação em Química |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | Portuguese |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFS, instname:Universidade Federal de Sergipe, instacron:UFS |
| Rights | info:eu-repo/semantics/openAccess |
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