Eloiza Guimarães

Qualitative and quantitative monitoring of methyl cotton biodiesel content in biodiesel/diesel blends using MIR spectroscopy and chemometrics tools.

This paper presents methodologies for monitoring the quality of methyl cotton biodiesel in biodiesel/diesel blends using mid-infrared spectroscopy (MIR) and chemometrics tools. The first method relates to the construction of multivariate control charts with the aim of qualitatively monitoring the samples according to the Brazilian specification for biodiesel in the biodiesel/diesel blends (7.00 ± 0.5% v/v of biodiesel). The second concerns the construction of partial least squares (PLS) to determine the content of the biodiesel in the biodiesel/diesel blend. The PLS model was validated from multivariate figures of merit according to the guidelines of ASTM E1655-05 and IUPAC. The results from both methods were satisfactory for both qualitative and quantitative monitoring. Therefore, the proposed methodologies for monitoring the quality of biodiesel in biodiesel/diesel blends are fast, practical, economical and efficient and can be used by industries and service stations.

Use of Mass Spectrometry with Electrospray Ionization and Exploratory Analysis for Classification of Extra Virgin Olive Oil Adulterated with Vegetable Oils

Due to the economic value and health benefits of the extra virgin olive oil (EVOO), this product is mainly the subject of adulteration by addition of cheaper vegetable oils. Thus, this study evaluated the detection of extra virgin olive samples oil adulterated with oils of canola, sunflower, corn and soybeans through exploratory multivariate analysis. The oil fingerprints were obtained by mass spectrometry with electrospray ionization in positive ion mode (ESI(+)-MS). The mass spectrometry data were analyzed by Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). Through the analysis of the loadings obtained in the PCA, it was possible to identify the ratio m/z most important for distinguishing authentic and adulterated oils, as well as the composition related with these samples. Authentic and adulterated samples were classified into different groups by the two methods, indicating that the developed methodologies are alternatives for the quality control of extra virgin olive oils.

Development and Validation of PLS Models for Quantification of Biodiesels Content from Waste Frying Oil in Diesel by HATR- MIR

Resumo: Este trabalho apresenta o desenvolvimento e a validacao de dois modelos PLS para quantificacao de biodiesel metilico e biodiesel etilico provenientes de oleos de fritura em misturas com diesel empregando dados de espectroscopia no infravermelho medio. A exatidao dos modelos PLS mostraram excelente desempenho com baixos valores de RMSEC, RMSECV e RMSEP. Alem disso, a exatidao foi comprovada pela avaliacao da regiao de elipse de confianca. O metodo foi validado de acordo com as diretrizes internacionais e nacionais pela estimativa de figuras de merito, tais como exatidao, precisao, linearidade, seletividade, sensibilidade analitica, limites de deteccao e quantificacao e erro sistematico. Uma excelente correlacao foi observada entre os valores reais e previstos do conjunto de previsao (R = 0,9999) e os modelos nao apresentaram erros sistematicos conforme a norma ASTM E1655. Os modelos propostos utilizam uma unica faixa espectral permitindo a determinacao de biodiesel em mistura com diesel na faixa de concentracao entre 1,00 e 30,00% (v/v), em ambos os modelos. Assim, as metodologias propostas foram validadas sem a necessidade de escolher faixas espectrais se comparado com as normas pertinentes que regulamentam a determinacao do teor de biodiesel em mistura com diesel. Palavras-chave: Biodiesel; oleo de fritura; espectroscopia no infravermelho; calibracao multivariada; PLS; validacao analitica.