Organic acids are naturally present in many food products, including fruits, vegetables, and wine. Further, they are also commonly used in the food and beverage industry as preservatives and stabilizers. Besides analytical methods involving colorimetric reaction and enzyme assays, chromatographic techniques allow simultaneous analysis of most of the organic acids. HPLC is the most popular method of choice for analyzing organic acids because of its simplicity, speed, and stability. Hence, an HPLC method was developed for the simultaneous analysis of the nine organic acids.
This application illustrates the separation of nine polar organic acids (Figure 1) on the Ascentis Express® AQ-C18 column using a 100% aqueous mobile phase at low pH. In this method, a column length of 250 mm was selected to provide satisfactory resolution with a reasonable run time for the analysis of this mixture of polar organic acids.
Figure 1a. Chemical structure of Oxalic acid
Figure 1b. Chemical structure of Tartaric acid
Figure 1c. Chemical structure of Malic acid
Figure 1d.Chemical structure of Ascorbic acid
Figure 1e.Chemical structure of Lactic acid
Figure 1f.Chemical structure of Acetic acid
Figure 1g.Chemical structure of Citric acid
Figure 1h.Chemical structure of Succinic acid
Figure 1i.Chemical structure of Fumaric acid
Figure 2.Chromatogram showing peaks obtained for the analysis of nine Organic acids (Oxalic Acid, Tartaric Acid, Malic Acid, Ascorbic Acid, Lactic Acid, Acetic Acid, Citric Acid, Succinic Acid, and Fumaric Acid) on Ascentis® Express AQ-C18 column
The Ascentis® Express AQ-C18 column, based on Fused-Core® particles, is a C18 bonded phase prepared using a proprietary procedure that incorporates a small amount of polar silane which makes the phase resistant to de-wetting. This allows the users of the AQ-C18 phase to run highly aqueous (up to 100%) mobile phases without the risk of phase collapse. The modified C18 phase exhibits enhanced retention of polar compounds under 100% aqueous conditions, there by efficient separation of organic acids.
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