New FTIR method for the determination of FFA in oils

Ahmed Al-Alawi, Frederick R. Van de Voort, Jacqueline Sedman

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)441-446
Number of pages6
JournalJAOCS, Journal of the American Oil Chemists' Society
Volume81
Issue number5
Publication statusPublished - May 2004

Fingerprint

Fourier Transform Infrared Spectroscopy
Oils
oils
Salts
Calibration
Saponification
1-Propanol
calibration
phthalimide
Oleic acid
salts
Propanol
1-propanol
Oleic Acid
sampling
Oils and fats
methodology
Titration
saponification
Potassium

Keywords

  • 1-propanol
  • Automated analyses
  • Edible oils
  • FFA
  • FTIR
  • Potassium phthalimide

ASJC Scopus subject areas

  • Food Science
  • Chemistry (miscellaneous)

Cite this

New FTIR method for the determination of FFA in oils. / Al-Alawi, Ahmed; Van de Voort, Frederick R.; Sedman, Jacqueline.

In: JAOCS, Journal of the American Oil Chemists' Society, Vol. 81, No. 5, 05.2004, p. 441-446.

Research output: Contribution to journalArticle

Al-Alawi, Ahmed ; Van de Voort, Frederick R. ; Sedman, Jacqueline. / New FTIR method for the determination of FFA in oils. In: JAOCS, Journal of the American Oil Chemists' Society. 2004 ; Vol. 81, No. 5. pp. 441-446.
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