RESUMO
Waste cooking oil (WCO) is a valuable feedstock for the synthesis of biodiesel but the product exhibits poor oxidative stability. Techniques available for assessing this parameter are generally expensive and time-consuming, hence the purpose of this study was to develop and validate a rapid and reliable predictive system based on signals from the sensors of a commercial hand-held e-nose instrument. Biodiesels were synthesized from soybean oil and six samples of WCO, and their physicochemical characteristics and oxidative stabilities determined before and after storage in different types of containers for 30 or 60 days at room temperature or 43 °C. Linear regression models were constructed based on principal component analysis of the signals generated by all 32 e-nose sensors and stochastic modeling of signal profiles from individual sensors. The regression model with principal components as predictors was unable to explain the oxidative stability of biodiesels, while the regression model with stochastic parameters (combining signals from 11 sensors) as predictors showed an excellent goodness of fit (R2 = 0.91) with a 45-sample training set and a good quality of prediction (R2 = 0.84) with a 18-sample validation set. The proposed e-nose system was shown to be accurate and efficient and could be used to advantage by producers/distributors of biodiesel in the assessment fuel quality.
RESUMO
El consumo de alcohol durante la gestación está asociado con un amplio espectro de efectos adversos conocidos como trastornos del espectro alcohólico fetal (TEAF). Así es como a través del dosaje de los esteres etílicos de ácidos grasos (FAEEs) en meconio, como biomarcadores de exposición prenatal al consumo de etanol, nos brinda una herramienta importantísima en el screening de los recién nacidos, facilitando la confi rmación del diagnóstico y la intervención clínica adecuada en los individuos afectados por esta problemática con una mejora en las expectativas y calidad de vida. El síndrome alcohólico fetal (SAF) representa el clásico síndrome y la manifestación más grave inducido por el alcohol de forma repetida durante el embarazo. Dado el carácter heterogéneo de las alteraciones clínicas presentes en los recién nacidos expuestos a etanol, la mayoría de los cuales no son específi cos, conlleva a un diagnóstico del TEAF extremadamente difícil.
Alcohol consumption during pregnancy is associated with a wide range of adverse effects known as fetal alcohol spectrum disorders (FASDs). Through the measurement of Fatty Acid Ethyl Esters (FAEEs) in meconium, as biomarkers of prenatal alcohol exposure, we have a very important tool in the screening of newborns, facilitating the confi rmation of diagnosis and adequate clinical intervention in individuals affected by this problem with improvements in life quality and expectancy. Fetal Alcohol Syndrome (FAS) represents the classic syndrome and the most serious condition is caused by repetitive alcohol consumption during pregnancy. Due to the heterogeneous characteristics of clinical alterations of newborns exposed to ethanol, most of which are not specifi c, diagnosis of FASDs is extremely diffi cult.
O consumo de álcool durante a gravidez é associado a um amplo espectro de efeitos adversos conhecidos, tais como transtornos do espectro do alcoolismo fetal (TEAF). É assim como através da dosagem dos ésteres etílicos de ácidos graxos (FAEEs) em mecô- nio, como biomarcadores de exposição pré-natal ao consumo de etanol, fornece uma ferramenta importantíssima na triagem de recém-nascidos, aprimorando a confi rmação do diagnóstico e a intervenção clínica adequada em indivíduos afectados por este problema com uma melhoria das expectativas e qualidade de vida. Síndrome alcoólica fetal (FAS) representa a síndrome clássica e a mais grave manifestação induzida frequentemente pelo álcool durante a gravidez. Dada a heterogeneidade das alterações clínicas em recémnascidos expostos ao etanol, a maioria das quais são não-específi cas, esta situação gera um diagnóstico de TEAF extremamente difícil.