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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Liquid-liquid microextraction in sequential injection analysis for the direct spectrophotometric determination of acid number in biodiesel

Full text
Author(s):
Batista, Alex D. [1] ; Amais, Renata S. [1] ; Rocha, Fabio R. P. [1]
Total Authors: 3
Affiliation:
[1] Univ Sao Paulo, Ctr Energia Nucl Agr, BR-13400970 Piracicaba, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Microchemical Journal; v. 124, p. 55-59, JAN 2016.
Web of Science Citations: 10
Abstract

Sequential injection analysis (SIA) is used here for acid number determination in biodiesel exploiting liquid-liquid microextraction and spectrophotometric detection. Free fatty acids (FFA) from biodiesel are partially extracted to an aqueous bromocresol green (BCG) aliquot placed in between two aliquots of biodiesel without any pretreatment. Microextraction is favored by using holding coils and transmission lines made of Teflon due to the formation of biodiesel film in the tube walls. Detection was performed in a glass tube coupled to a fiber-optic spectrophotometer and analytical signals were related to the discoloration of the BCG after FFA microextraction. A linear response was observed up to 0.6 mg KOH g(-1), with detection limit, coefficient of variation, and sampling rate estimated at 0.0074 mg KOH g(-1) 2.9% (n = 10) and 12 h(-1), respectively. The procedure is a fast, reliable, and mechanized alternative for acid number determination, which requires only 250 mu L of sample, 10 mu g BCG and 500 mu L. of ethanol. A reference procedure based on visual titration was used for comparison and results agreed at the 95% confidence level. (C) 2015 Elsevier B.V. All rights reserved. (AU)

FAPESP's process: 13/26857-5 - Total concentrations and chemical speciation of As, Cr and Se using low pressure monolithic columns and inductively coupled plasma techniques
Grantee:Renata Stábile Amais
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 14/19115-5 - Development and application of two-dimensional sequential injection chromatography
Grantee:Alex Domingues Batista
Support Opportunities: Scholarships in Brazil - Post-Doctoral