Study On Determination Of Sweetener Additives And Organic Acids In Food With High Performance Liquid Chromatography And Their Application

Objective The simultaneous determination methods for four sweeteners of acesulfame-K, aspartame, sodium cyclamate, sodium saccharine and for nine organic acids including oxalic acid,tartaric acid,ascorbic acid,malic acid,lactic acid,acetic acid,citric acid,succinic acid,propanoic acid in food with high performance liquid chromatography were established. The proposed methods will provide the monitoring technique for food safety and anaerobic bacteria.Methods The analytical procedure was involved in preparation of samples and Chromatographic analysis. After precipitation of protein for dilute sample of yoghourt, filtration of the mincing preserved szechuan pickle which was extracted ultrasonically with water for 30min, centrifugalization of metabolites of anaerobic bacteria, the extracts were respectively filtrated with membrane of 0.45μm for HPLC analysis.1. The separation for 4 sweeteners was achieved on C₁₈ column with the mobile phase 5mmol/L tris(hydroxymethyl) aminomethane aqueous solution (pH 4.5, adjusted by 4mol/L acetic acid) at flow rate of 1.20mL/min and the analytical detection wavelength was 205nm.2. The analysis for 9 organic acids was fmished on C18 column with the mobile phase 0.01mol/L(NH4)zHPO4 aqueous solution (pH 2.8, adjusted by phosphate acid) at flow rate of 0.70mL/min and the analytical detection wavelength was 215nm.Results 1. Under the optimized conditions, the correlation coefficients of the calibration curves were better than 0.998.The linear range were 0.13μg/mL～60μg/mL for acesulfame-K, 0.10μg/mL～60μg/mL for aspartame, 0.07μg/mL～60μg/mL for sodium saccharine and 0.007mg/mL～4.0mg/mL for sodium cyclamate,respectively.The limits of detection were 0.04μg/mL for acesulfame-K; 0.03μg/mL for aspartame; 2.0μg/mL for cyclamate; 0.02μg/mL for sodium saccharine. The contents of the target compounds were determined by HPLC-UV and compared with those obtained by national standard method and there was no significant difference between the two methods.The recoveries of yoghourt, beverage were 82.1%～108.6% for acesulfame-K,91.3%～112.0% for aspartame,99.0%～107.4% for sodium cyclamate,94.6%～106.4% for sodium saccharine with RSD of 1.16%～6.95%.2. The 9 organic acids were separated and showed good lineafity under the optimized conditions. The linear range was 0.01mg/mL～1.0mg/mL with correlation coefficients greater than 0.998. The limits of detection were 0.01μg/mL (oxalic acid and tartaric acid); 0.04μg/mL (malic acid and citric acid) ; 0.002μg/mL (ascorbic acid) ; 0.10μg/mL (lactic acid,acetic acid,succinic acid,propanoic acid) at a signal-to-noise ratio (S/N) of3. Recoveries of yoghourt and metabolites of anaerobic bacteria were between 80.0%～110.0% with RSD of 0.62%～45.69%.Conclusion 1. The Ion-pair high performance liquid chromatography was applied for the determination of the 4 sweetener additives in food for the first time, without derivation.The method was simple and rapid.2. Simultaneous determination methods of nine organic acids in food and metabolites of anaerobic bacteria were established by high performance liquid chromatography with ultraviolet detector rapidly. And the pretreatments for samples were simple and rapid.The methods were applied to monitor the concentrations of organic acids in yoghourt and ratios of organic acids in metabolites of anaerobic bacteria.