| Iron is an essential trace element to life. Due to iron deficiency, the body will be suffering from iron deficiency anemia and other diseases. Excessive levels of iron can cause iron poisoning. The excess iron and iron deficiency can both do harm to people’s health. Exceed the standard problem of iron has not been widely concerned. With the gradual establishment of healthy diet and food safety concept, people are beginning to realize the harm of excess iron elements on the human body. Therefore, it is very necessary to establish a fast, accurate and simple determination method of iron content.There are several methods for determination of iron content. Spectrophotometric method is one of the most commonly used methods of them. The method is simple, rapid, no need of special equipment, low price, easy to realize and many other advantages. But the spectrophotometric method has some disadvantages, such as poor sensitivity and accuracy. In order to avoid these disadvantages, people began to build a lot of determination methods of iron element, but these methods also have their advantages and disadvantages.The experiment was based on the principle of phenylfluorone and ferric iron to form a blue complex in alkaline environment. Tween-80as reaction sensitizer was joined into the reaction system. Tween-80microemulsion improved the sensitivity and accuracy of conventional spectrophotometry.Tween-80was selected as surfactant in this experiment. The common cosurfactant and oil phase were selected and optimized. Comparing the ability of forming microemulsion of different alcohols and different oil phases, the Tween-80/ethanol/isoamyl acetate/water was the best component to form a microemulsion system. Analyzing the external conditions of microemulsion, the optimum conditions of the formation of microemulsion were determined.3mL phenylfluorone reagent,4mL Tween-80microemulsion was selected as the best proportion of preparation of chromogenic agent in this experiment. Regression equation of standard curve was y=0.1359x+0.009(R2=0.9993), When ferric iron concentration fluctuated in the range of0-0.6μg·mL-1, Ferric iron concentration and absorbance values showed a good linear relationship. The detection limit was0.0065μg·mL"’. The relative standard deviation ranged from2.46%to6.30%. The recovery rate ranged from96.01%to98.15%. It indicated that the method had good accuracy and precision.Compared with the conventional phenylfluorone spectrophotometric method, absorbance values of Tween-80microemulsion phenylfluorone spectrophotometric was bigger, sensitivity was improved significantly in the same conditions. The accuracy,precision and detection limit experiments of two methods were carried out. The results showed that the recovery and the relative standard deviation of microemulsion method were better than the conventional method, and the detection limit was smaller than the conventional method.This method was used for the determination of iron element in kelp, pure milk and peanut. Compared with atomic absorption spectrophotometry (AAS), the results of two methods were analyzed by variance analysis of statistical methods, The results showed that there was little difference between measurements of two methods(All P values were more than0.05). It indicated that testing results of this method had a good reliability.This study optimized the phenylfluorone reagent formula. When the microemulsion was added to the phenylfluorone reagent. Solubilization and sensitizing characteristics of microemulsion overcame the disadvantages of low sensitivity and poor accuracy of the conventional method. In addition to, the phenylfluorone microemulsion spectrophotometry was simple, less interferences, with good repeatability. After improvements, the method became more perfect, practical and can be applied to the detection of trace iron element. This paper laid a solid theoretical foundation for further study. |
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