Desenvolvimento e validação de metodologia analítica baseada em cromatografia gasosa rápida (fast GC) para determinação do teor de fame em biodiesel

Abstract

An analytical method based on fast gas chromatography with a response factor (Fast GCRF) and flame ionization detector was developed and validated In this study. It was used an apolar capillary column, polydimethylsiloxane, (10 m x 0.10 mm x 0, 10 μm), submitted to temperature programming with a single heating ramp (60 - 360 ° C) at a 60 ° C min-1 speed and total analysis time of 5 min. The Fast GCRF method was applied to quantify total fatty acid methyl esters (FAME) in fifteen biodiesel samples types. The FAME mixtures (C8 - C20) were produced from cottonseed oil, peanuts, almonds, canola, chia, coconut, palm oil, sesame, sunflower, macauba, corn, castor bean, soy, residual frying oil and chicken fat. hexane was used to dissolve the biodiesel samples and the internal standard (tricapriline). The validated methodology is selective and it able to identify and quantify total alkyl esters. Changing sample preparations conditions like hexane changed for an isopropyl alcohol and toluol mixture or adding NaCl in the at sample dissolving didn't affects the Fast GCRF method robustness. The maximum values of relative standard deviation (RSD) of 2.3%, 3.6% and 2.8%, were calculated for instrumental precision, repeatability and intermediate precision, respectively, by successive analyzes in different days and different analysts. In comparison with other methods, the values of r2 = 0.9953 and slope = 0.99725 (for Fast GCRF versus GCEN14103 standard), r2 = 0.9962 and slope = 1.00337 (for Fast GCRF versus GC methodology with short column and response factor – GCSCRF) indicating accuracy and agreement between the results in the three methodologies. The recovery tests are within the range of 86.16% to 119.12% and the RSD values between 0.4% - 4.49%.