Determination Of Organic Acid In Food And Biological Samples By IC

In this thesis, four methods of determination of organic acids were established by using high selective and sensitive ion chromatography(IC). The main achievements of the research were listed below.A method for simultaneous determination of lactic acid, formic acid and acetic acid in ethanol reclaimed from the purification process of phospholipid by ion chromatography was proposed in Chapter 2. The separation was carried out on an anion exchange column with 4 mmol/L NaHCO3 as mobile phase. Lactic acid, formic acid and acetic acid can be separated in 13 minutes. The detection limits of the three organic acids were 0.03-0.04 mg/L by a suppressed conductivity detector. The recoveries of the method were 87.5%～102.4%. This method can be used to monitor the phospholipid purification process and control the quantity of phospholipid with high selectivity and sensitivity.A simple, fast, precise and eco-friendly analytical method for the determination of UA in human urine by IC is described in Chapter 3. Only centrifugation and filtration were needed in the sample pretreatment. The separation was carried out on a cation exchange column with 2.0 mmol/L nitric acid as mobile phase at the flow-rate 1.0 mL/min. The IC analysis time for one run was within 10 min under the optimized IC condition. The detection limits were 0.5μg/L (S/N=3) for uric acid. The recovery was 100.1% while the relative standard deviation (RSD) was 1.8% from ten measurements. A simple, precise and eco-friendly anion exchange chromatography (AEC) method for the determination of HA in human urine was proposed in Chapter 4. The separation was carried out on an anion exchange column with 2.0 mmol/L Na2CO3+2.0 mmol/L NaHCO3 as mobile phase at the flow-rate 0.7 ml/min. A suppressed conductivity detector was used and the detection limit was 1.0μg/L (S/N=3) for hippuric acid. The analysis time for one run was 30 min under the optimized IC condition. The recovery of hippuric acid was 93.2-98.0% while the relative standard deviation (RSD) was 1.4-2.3% by seven measurements.A simple, fast, precise and eco-friendly anion exchange chromatography (AEC) method for the determination of BA in milk was established in Chapter 5. The chromatographic separation was accomplished by using an anion exchange column eluted with 3.2 mmol/L Na2CO3+1.0 mmol/L NaHCO3 at a flow-rate of 0.7 ml/min. The method validation provided excellent results with respect to linearity (correlation coefficient up to 0.9997), limit of detection (1.0μ/L), recovery values (ranging from 88.0% to 93.0%) and relative standard deviation (RSD) (below 2.2%, n=7).