1 Scope
This standard specifies spectrophotometric method and inductively coupled plasma atomic emission spectrometry for determining the content of phosphorus in foods.
Method I and Method III of this standard are applicable to the determination of phosphorus in various foods; Method II is applicable to the determination of phosphorus in foods for infants and young children, milk and milk products.
Method I Molybdate Blue Spectrophotometric Method
2 Principle
After the specimen is digested, phosphorus combines with ammonium molybdate in acidic condition to generate ammonium phosphomolybdate which is restored to blue compound molybdate blue by hydroquinone, sodium sulfite or stannous chloride, hydrazine sulfate. The absorbance value of molybdate blue at 660nm is directly proportional to the concentration of phosphorus. The absorbance of specimen solution is determined with spectrophotometer and quantitation is realized by comparing with standard series.
3 Reagents and Materials
Unless otherwise specified, analytically-pure reagents and Grade III water (defined in GB/T 6682) are adopted for the purposes of this method.
3.1 Reagents
Foreword i
1 Scope
2 Principle
3 Reagents and Materials
4 Apparatuses
5 Analysis Procedures
6 Expression of Analysis Results
7 Accuracy
8 Others
9 Principle
10 Reagents and Materials
11 Apparatuses
12 Analysis Procedures
13 Expression of Analysis Results
14 Accuracy
15 Others
