Comprehensive analysis of complicated chlorination products in sucralose production: Separation, purification,...

As a new generation of safe sweeteners, sucralose (TGS) has been extensively used in food and beverages. However, the comprehensive identification and quantification of chlorination products have never been conducted, which renders the difficulty in mechanism study and hinders further technology upgrading. Herein, by using preparative liquid chromatography (PLC), comprehensive separation and purification have been executed on complicated chlorination products after undergoing acylation/chlorination reactions. Consequently, 29 chlorinated products classified into eight kinds of positional isomers (purity > 97 % wt) have been prepared for the first time. They were further structurally determined by 1D/2D nuclear magnetic resonance (NMR) and high-resolution mass spectrum (HR-MS). Furthermore, a fast/convenient analysis method on chlorinated products using high-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD) has been established, in which main-product 4,1',6'-trichlorosucrose-6-acetate (TSA-6) and other by-products could be quantified simultaneously. Upon optimization on the HPLC conditions, the standard curves of 29 compounds exhibit good linear degree (R² > 0.9992) and excellent spiked recoveries (97.8 %∼102.4 %), hinting at its high accuracy, sensitivity (detection limit: 0.5∼2.0 μg/mL), repeatability (intra-day and the inter-day deviations RSD < 3.10 %, n = 6). It can detect 38 chlorination by-products in 42 min with excellent separation efficiency (Rs > 1.5). Finally, based on the structural determination of 28 by-products, the generation pathways of TSA-6 and by-products were proposed: the multi-step chlorination on sucrose-6-acetate (SA-6), gradient carbonization, and polymerization. The proposal of the quantification method and the determination of by-products can be beneficial for high-quality TGS production.