TITLE:
Use of Ultrasound Bath in the Extraction and Quantification of Ester-Linked Phenolic Acids in Tropical Forages
AUTHORS:
Mellina Damasceno Rachid Santos, Aline de Paula Vitor, Jailton da Costa Carneiro, Domingos Sávio Campos Paciullo, Renato Camargo Matos, Maria Auxiliadora Costa Matos
KEYWORDS:
Ultrasound Bath, Phenolic Acids, Forage, Internal Calibration
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.2 No.3,
July
8,
2011
ABSTRACT: A method was developed for the analysis of ester-linked phenolic acids in forage samples using extraction by an ultrasound-assisted treatment and quantification by HPLC with a UV-VIS detector. A reversed-phase C18 column was used for developing the method and the optimal condition was established with isocratic elution using acetonitrile/methanol/H3PO4 pH 2.08 (13:12.5:74.5) as the mobile phase. To reduce the time of sample processing, the extraction of ester-linked phenolic acids was studied using ultrasound bath and the results were then compared with those from an extraction usual using alkaline hydrolysis (20°C for 24 h). The method was valued through external and internal calibration. Internal calibration using o-coumaric acid as internal standard and m-coumaric acid as surrogate internal standard showed better results. The detection limits were of 0.09 and 0.04 mg●L-1 for p-coumaric and ferulic acids, respectively. The proposed method showed a good linear dynamic range (3.00 - 30.00 mg●L-1) for the analytes. The usefulness of the methodology was demonstrated by addition-recovery experiments using forage samples and values were in the 83 to 99% range. The extraction of ester-linked phenolic acids by 120 minutes of ultrasound bath was faster and more reproducible than alkaline hydrolysis (20°C for 24 h).