Chromatography White Wine

Analysis and Separation of Organic Acids in White Wine Using High Performance Liquid Chromatography

Atis, Arnelson Arwin G. and Gaitos, Gerald M. Institute of Chemistry, University of the Philippines, Diliman, Quezon City Performed: December 9, 2011 Submitted: December 15, 2011

RESULTS AND DISCUSSION solutions containing increasing amounts of the organic acid. These solutions were contained in flasks numbered 5, 6, 7, 8, and 9. (Refer to the Appendix to see components of each flask). Tables 2, 3, 4, and 5 show the peak areas and the equation of the calibration curve obtained for each organic acid in the chromatograms obtained for flasks 5 to 9. Table 2. Peak Areas of Tartaric Acid in Flasks 5, 6, 7, 8,
The peak areas of the acids were then obtained through chromatograms and plotted against the concentrations of the standard solutions of the organic acids to construct a calibration curve. Finally, the calibration curves obtained were used to determine the concentration of the organic acids in samples of white wine. Standard solutions of various organic acids commonly found in white wine (tartaric, malic, lactic, citric) were assigned to be contained in flasks 1, 2, 3, and 4, respectively, and were run through the chromatograph. The mobile phase used for the analytes was H3PO4 at pH 3, to prevent dissociation of the organic acids. The resulting chromatograms of each standard were then analyzed to obtain the retention times of the organic acids. Table 1 shows the experimental retention times of the different organic acids. Table 1. Experimental Retention Times of Organic Acids Organic Acid Retention Time (min) Tartaric 3.088 Malic 3.812 Lactic 3.620 Citric 3.568 Since there were no clear peaks from the chromatograms obtained for the tartaric, malic, and lactic acid samples, the retention time at which the peak height is greatest was obtained as the experimental retention time of the organic
Peak Areas of Citric Acid in Flasks 5, 6, 7, 8, and 9 Flask Retention Peak Area Concentration time (min) (g/L) 5 3.140 361 921 0.05 6 3.208 907 232 0.1 7 3.306 4 736 427 0.5 8 3.325 7 508 481 0.75 9 3.347 9 612 454 1 Calibration Curve Equation: y = 9 836 731.501x + 96 328.12036 R2 = 0.9994 The equations of the calibration curves were then used to calculate the concentration of each organic acid in the white wine samples. The peak area corresponding to each organic acid was first obtained, and substituted in the calibration curve equation. The concentration of each acid is shown in Table 6. Table 6. Experimental Concentration of Various Organic Acids in White Wine Samples. Organic Retention Peak Area Concentration Acid Time (min) (g/L) Tartaric 2.966 2 675 651 2.499 Malic 3.752 3 576 021 4.506 Lactic 3.393 4 709 737 3.303 Citric 3.144 794 394 0.091 The results indicate that malic acid is the major component of white wine. But in reality, this is not the case. The major component of white wine is found to be tartaric acid. The chromatograms (See Appendix) of flasks 1 to 9, and of the sample are not well resolved. This discrepancy may be caused by several factors. These factors include