Determination of Octenylsuccinic Acid in Nutritional Products

Abstract

A quantitative method for the direct LC/UV determination of octenylsuccinic acid (OSAc) in nutritional products formulated with octenylsuccinic anhydride-modified starch (MS) is described. The cis-2-OSAc and trans-2-OSAc released from the MS by a mild alkaline hydrolysis are separated by reversed phase chromatography and are detected by UV at 192 nm. Method suitability has been defined by assessments of linearity (R 2 average = 0.99991 ± 0.00008, n = 12, and the relative calibration error average <1 % at each OSAc concentration level), intermediate precision (RSD values [each of four batches tested on each of 3 days] ranged from 1.1 to 2.5 % for total OSAc concentrations at 235 to 266 mg per kg in a hydrolyzed protein-based nutritional product [HP]), accuracy (spike recovery average = 97.9 ± 0.7 %, for four batches of HP spiked with MS at the 100 % MS level), selectivity (peak purity verification as HP analyte 192 nm/200 nm peak area ratio vs the corresponding ratio for the OSAc reference solutions), and the limits of quantification and detection (30 and 10 mg, respectively, per kg of nutritional product). The method provides for a simple and reliable quantification of free and/or total OSAc in nutritional products formulated with MS and is suitable for the routine verification of proper MS fortification of nutritional products and for the verification of MS stability during nutritional product processing and over shelf life.