1 Scope
This standard specifies the liquid chromatography method for the determination of lutein in foods.
This standard is applicable to the liquid chromatography method for the determination of lutein in infant formula, milk products, frozen drinks, rice & flour products, bakery products, jam, jelly and beverage.
2 Principle
Saponify the foods with high fat content (the fat content, calculated in dry basis, is not less than 3%) at room temperature by using potassium hydroxide solution to dissociate the lutein; extract it with ethyl ether -normal hexane -cyclohexane (volume ratio: 40+40+20), separate with liquid chromatography method, examine it with ultraviolet detector or diode array detector, then quantify with external standard method.
Extract the lutein in the samples of other foods directly with ethyl ether - normal hexane - cyclohexane (volume ratio: 40+40+20). After purifying the extracting solution with Alumina N neutral alumina solid phase extraction column, separate it with liquid chromatography method, examine it with ultraviolet detector or diode array detector, and quantify it with external standard method.
During the extraction and analysis of the samples, the trans-lutein may be isomerized and transformed to cis-lutein. The cis-lutein generated by such transformation may be qualified according to the retention time and quantified by peak area adduction.
Foreword i
1 Scope
2 Principle
3 Reagents and Materials
4 Instruments and Apparatus
5 Analysis Steps
6 Expression of Analysis Result
7 Precision
8 Others
Appendix A Calibration Method for Concentration of Standard Solution
Appendix B Liquid Chromatogram of Standard Solution