Application Studies To The Determination Of Food Samples By Ion Chromatography

IC based on thoery of ion exchange and IC is one kind of LC methods which is used to detect negion and cation in solution. It has been developed rapidly since invented in 1975 and widely used in spheres of environment monitor, agriculture, biology, pharmacy, industry and food because of simplicity, quickness, high sensitivity and selectivity. IC marked by simultaneous determination of multi-component has became the ideally method for detecting negion and ion-type compound and it play a very important role in the security research that bearing the significance of hygiene and nutrition of food ingredients and additives. Recently, IC as an offical standard method is intoduced more frequently and food analysis by IC has been one of the main application.This thesis contains two sections. One is review related to development of IC detection and application of food analysis.The other is research report which is composed as follows:1)Ion Chromatography in the application of food composition analysis. First, IC method for herbs is studied, suppressed conductivity detector and pulsed amperometric detector are introduced to detect inorganic anions and organic acid and water-soluble carbohydrate in herbs. Secondly, appoach to detect fluoride, nitrate and nitrite in tea and tea beverage is studied.2) Aplication of IC in the security of food additives. First, the method of simultaneously determination of benzoic acid, sorbic acid, saccharin sodium and sodium tripolyphosphate is established. Secondly, the content of sodium formaldehyde sulfoxylate in food is detected by suppressed conductivity detector, the outcomes show satisfactory.1.Study on Determination of Chinese Herbal Medicine Ingredients using Ion ChromatographyHigh-performance anion-exchange chromatography was optimized for determination of inorganic anions, organic acid and sugars in Chinese herbal medicine. METROSEP A Supp4-250 was selected as the separation column,1.8 mmol/L Na₂CO₃,1.7 mmol/L NaHCO₃and 2% acetone were used as the eluent and suppressed conductivity detection, separation and determination of inorganic anions and organic acid including fluoride ion, chloride ion, bromide ion, nitrite ion, nitrate ion, phosphate ion, sulfate ion and oxalic acid, malic acid and fumaric acid. METROSEP CARB 1(150×4.0 mm) was selected as the separation column,10.0 mmol/L NaOH were used as the eluent and pulsed amperometric detection, separation and determination of sugars including arabinose, galactose, glucose, mannose and fructose. Chinese herbal medicine ingredients were fast determined effectively, and the results of the determination were satisfied.2. Determination of Fluoride, Nitrate and Nitrite in Tea by Ion ChromatographyTo develop an ion chromatogram method for determination of fluoride, nitrate and nitrite in tea. METROSEP A Supp4-250 was selected as the separation column, On-line dialysis injection,15 mmol/L Na₂B₄O₇ and 2 mmol/L NaHCO₃ were used as the eluent with suppressed conductivity detection. The linear range was 1-50 mg/L, the relative coefficient was 0.9979～0.9999, the detection limit was 0.015～0.079 mg/L, the relative standard deviation was 1.76%～2.12%, the recovery rates were 96.9%-103.1%.This method presents a good effect of pretreatment and chromatographic peak separation and with a satisfactory recovery rate, accuracy and precision. This method can be applied to determination of content analysis of tea.3.Determination of Four Kinds of Additives in Food by Ion ChromatographyA method was developed for the determination of additives in food including benzoic acid, sorbic acid, saccharin sodium and sodium tripolyphosphate by ion chromatography. Sample was pretreated by deposition, METROSEP A Supp4-250 was selected as the separation column,15 mmol/L KOH were used as the eluent and suppressed conductivity detection. The detection limits of 0.082～0.188 mg/L were achieved under the optimal conditions. The relative standard deviation for the eight consecutive determinations were 2.10%～2.88%. The average recovery percentages of the sample detection were 96.2%-101.1%.Four kinds of additives were fast determined effectively, and the results of the determination were satisfied.4. Determination of Sodium Formaldehyde Sulfoxylate in Food by Ion ChromatographyAn ion chromatogram method is developed for determination of sodium formaldehyde sulfoxylate in food. METROSEP A Supp4-250 was selected as the separation column, On-line dialysis injection, 10 mmol/L NaOH were used as the eluent with suppressed conductivity detection. The linear range was 0.10～100.0 mg/L, the relative coefficient was 0.9998, the detection limit was 0.04 mg/L, the relative standard deviation was 3.14%, the recovery rates were 99.6%-101.4%. The method, which is used to determine sodium formaldehyde sulfoxylate in yuba etc., is sensitive, accurate, quick and suitable for routine food analysis.