A Study Of Molybdenum Blue Spectrophotometric Determination Of Phosphorus In Food

Phosphorus is essential for life,a chemical element in human bones and teeth as well as a component of DNA,RNA,ATP,and phospholipids.Phosphorus plays a major role in the normal metabolism,kidney and cerebral functions.Amorphous form of calcium phosphate is the main component of bone.Phosphorus deficiency or excessive intake is harmful.Hence,the determination of phosphorus in food is vital to understand the baseline levels of the chemical of daily diet and to provide a technical measure in the evaluation of food safety.So far,methods for determining phosphorus include Molybdenum blue,Vanadium Molybdenum and ICP-OES.Taking into account the authenticity and availability of methods for the determination,this article will base on GB5009.87—2016 “China's national standards for the determination of phosphorus in food” to improve its first method and to to compare their accuracy,reproducibility,test period and operational definition.Use the two methods to test 31 food samples to further measure the amount of phosphorus in Chinese diet.The research results of this article are as follow:Compare the first 2 steps in the first method in GB5009.87—2016 “China's national standards for the determination of phosphorus in food”,and recovery rate of wet digestion is better than that of dry ashing method.Apply Microwave digestion Molybdenum blue method.Improve the preparation in the microwave digestion step by using 6 mL of nitric acid under 2.4MPa for 20 min with up to 1200 W.The accuracy and precision meet the requirements for determining phosphorus in food.Apply variance analysis to compare the accuracy and precision of wet digestion Molybdenum blue and microwave digestion Molybdenum blue.No difference in accuracy of sample determination.Regarding the precision,difference is observed “F=6.43,F crit=3.95,F>F crit,P<0.05”,when a=0.05.Microwave digestion is more precise and has advantage in the terms of test period and operational definition.Apply Wet digestion Molybdenum blue and microwave digestion Molybdenum blue to determine phosphorus in 31 food samples.The amount of phosphorus is between 0.935~201mg/100 g.Conclusion: The use of microwave digestion in the preparation for determining phosphorus in food could ensure accuracy of test results and have the advantages of better reproducibility,shorter test period,easies operation and less reagent,which will increase work efficiency and reduce environmental pollution.