TY - JOUR
T1 - New FTIR method for the determination of FFA in oils
AU - Al-Alawi, Ahmed
AU - Van de Voort, Frederick R.
AU - Sedman, Jacqueline
N1 - Funding Information:
The authors would like to thank Sultan Qaboos University, Oman, for the support of Ahmed Al-Alawi, and the Natural Sciences and Engineering Research Council (NSERC) of Canada for financial support of this research. The technical assistance of Claudia Muc-ciardi is also acknowledged.
PY - 2004/5
Y1 - 2004/5
N2 - A rapid, practical, and accurate FTIR method for the determination of FFA in edible oils was developed. Analogous to the AOCS titration procedure, the FTIR FFA determination is effected by an acid/base reaction but directly measures the product formed rather than utilizing an end point based on an electrode potential or color change. A suspension of a weak base, potassium phthalimide (K-phthal) in 1-propanol (1-PrOH), is used to convert the FFA present in oils to their carboxylate salts without causing oil saponification, and differential spectroscopy is used to circumvent matrix effects. Samples are first diluted with 1-PrOH, then split, with one-half treated with the K-phthal reagent and the other half with 1-PrOH (blank reagent), their spectra collected, and differential spectra obtained to ratio out the invariant spectral contributions from the oil sample. Quantification of the percentage of FFA in the oil, expressed as %oleic acid, based on measurement of the peak height of the v (COO-) absorption of the FFA salt formed, yielded a calibration with an SE of <0.020% FFA over the range of 0-4%. The method was validated by standard addition and the analysis of Smalley check samples, the results indicating that the analytical performance of the FTIR procedure is as good as or better than that of the standard titrimetric procedure. As structured, the FTIR procedure is a primary method, as calibration is not dependent on reference values provided by another method, and has performance criteria that could lead to its consideration as an instrumental AOCS procedure for FFA determination. The FTIR portion of the analysis is automatable, and a system capable of analyzing ∼60 samples/h was developed that could be of benefit to laboratories that carry out a large number of FFA analyses per day.
AB - A rapid, practical, and accurate FTIR method for the determination of FFA in edible oils was developed. Analogous to the AOCS titration procedure, the FTIR FFA determination is effected by an acid/base reaction but directly measures the product formed rather than utilizing an end point based on an electrode potential or color change. A suspension of a weak base, potassium phthalimide (K-phthal) in 1-propanol (1-PrOH), is used to convert the FFA present in oils to their carboxylate salts without causing oil saponification, and differential spectroscopy is used to circumvent matrix effects. Samples are first diluted with 1-PrOH, then split, with one-half treated with the K-phthal reagent and the other half with 1-PrOH (blank reagent), their spectra collected, and differential spectra obtained to ratio out the invariant spectral contributions from the oil sample. Quantification of the percentage of FFA in the oil, expressed as %oleic acid, based on measurement of the peak height of the v (COO-) absorption of the FFA salt formed, yielded a calibration with an SE of <0.020% FFA over the range of 0-4%. The method was validated by standard addition and the analysis of Smalley check samples, the results indicating that the analytical performance of the FTIR procedure is as good as or better than that of the standard titrimetric procedure. As structured, the FTIR procedure is a primary method, as calibration is not dependent on reference values provided by another method, and has performance criteria that could lead to its consideration as an instrumental AOCS procedure for FFA determination. The FTIR portion of the analysis is automatable, and a system capable of analyzing ∼60 samples/h was developed that could be of benefit to laboratories that carry out a large number of FFA analyses per day.
KW - 1-propanol
KW - Automated analyses
KW - Edible oils
KW - FFA
KW - FTIR
KW - Potassium phthalimide
UR - http://www.scopus.com/inward/record.url?scp=3042559677&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=3042559677&partnerID=8YFLogxK
U2 - 10.1007/s11746-004-0920-9
DO - 10.1007/s11746-004-0920-9
M3 - Article
AN - SCOPUS:3042559677
SN - 0003-021X
VL - 81
SP - 441
EP - 446
JO - JAOCS, Journal of the American Oil Chemists' Society
JF - JAOCS, Journal of the American Oil Chemists' Society
IS - 5
ER -