Characterization of Sorbic Acid and Its Oxidation Degradants Using HPLC-ESI-MS, and HPLC-MALDI-TOF MS
Publication Date: 2001-Oct-16
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In this study the combination of GPC and HPLC with ESI and MALDI time of flight (TOF) MS are used to elucidate oxidative products and polymeric materials formed from degradation of sorbic acid. Degradation products from aqueous model systems and pharmaceutical products are compared. To date we have verified the degradation products of sorbic acid to have a copolymer composition of acrolein and -carboxy acrolein monomers.
Title: Characterization of Sorbic Acid and Its Oxidation Degradants Using HPLC-ESI-MS, and HPLC-MALDI-TOF MS
Sorbic acid (2,4-hexadienoic acid) is known to be a safe anti-microbial preservative that has been widely used in a variety of commercial pharmaceutical, food, and cosmetic products. Although notably stable in the solid state, sorbic acid is known to have limited stability in aqueous solutions due to oxidative degradation. Such degradation causes the aqueous sorbic acid solution to turn a yellow/brown color. Although this oxidative decomposition occurs after prolonged storage at ambient temperature, it can be accelerated by exposure to heat and/or certain transition metals. Historically the molecular composition of the yellow/brown material is proposed to be polymer products of sorbic acid degradation; namely acrolein and -carboxyl acrolein. However there has been no direct analytical data to verify these polymer products.
In this study, a combination of high performance liquid chromatography (HPLC), aqueous gel permeation chromatography (GPC), matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and electrospray (ESI) mass spectrometry are used to characterize sorbic acid and its oxidative degradants. The root cause of the yellowing/browning effect from aged sorbic acid solutions are also investigated using GPC/MALDI-TOF mass spectrometry.
Recently soft ionization techniques such as matrix assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) mass spectrometry (MS) have been used for polymer analysis. With this analysis the mass of each n-mer within the polymeric distribution is directly measured, thus enabling repeat unit sequence and end gro...