Keywords
carotenoid analysis
certified reference material
intralaboratory evaluation
accuracy
precision
How to Cite
Abstract
Carotenoid analysis is inherently challenging, requiring the analysts’ expertise and attention to many details. To guarantee the reliability of carotenoid data generated in our laboratory, aside from method development, optimization and validation, periodic evaluation of the analysts’ performance is carried out. This paper reports the results obtained in one of our evaluations, using a certified reference material. Five analysts with varying experience in carotenoid analysis participated. The same liquid chromatograph and standard curves were used, restricting the evaluation to the analysts’ performance. The HPLC method consisted of extraction with acetone, partition to petroleum ether, saponification with 10 % methanolic KOH, washing with water, concentrating in a rotary evaporator, drying with nitrogen, dissolving in acetone, separation, identification and quantification. The z-score for each carotenoid was calculated. There was very good agreement in terms of the carotenes and b-cryptoxanthin for the five analysts. For lutein and zeaxanthin, the analyst with little experience in carotenoid analysis obtained lower values, but the z-scores were still satisfactory. One analyst who had experience only with carotene analysis also got lower concentrations for the xanthophylls. This was due to the fact that ethyl ether was not used in partitioning the carotenoids from the extracting solvent to petroleum ether.
References
1. Olson JA. Carotenoids and human health.Arch Latinoam Nutr.1999;49:7-11.
2. Tapiero H, Townsend DM, Tew KD. The role of carotenoids in the prevention of human pathologies. Biomed Pharmacother. 2004;58:100-10.
3. Krinsky NI, Johnson EJ. Carotenoid actions and their relation to health and disease. Mol Aspects Med. 2005;26:459-516.
4. Young AJ, Lowe GM. Antioxidant and prooxidant properties of carotenoids. Arch Biochem Biophys. 2001;385:20-7.
5. Stahl W, Sies H. Antioxidant activity of carotenoids. Mol Aspects Med. 2003;24:345-51.
6. Kiokias S, Gordon MH. Antioxidant properties of carotenoids in vitro and in vivo. Food Rev Int. 2004;20:99-121.
7. Stahl W, Ale-Agha N, Polidori MC. Non-antioxidant properties of carotenoids. Biol Chem. 2002;383:553-8.
Thompson M, Ellison SLR, Wood R. The international Harmonized Protocol for the Proficiency Testing of Analytical Chemistry Laboratories. Pure Appl Chem. 2006;78:145-96.
9. Sharpless KE, Margolis S, Thomas JB. Determination of vitamins in food-matrix Standard Reference Materials. J Chromatogr. 2000; 881:171-81.
10. Phillips KM, Wolf WR, Patterson KY, Sharpless KE, Holden JM. Reference materials to evaluate measurement systems for the nutrient composition of foods: results from USDA’s National Food and Nutrient Analysis Program (NFNAP). Anal Biochem. 2007;389:219–29.
11. Kimura M, Rodriguez-Amaya DB. A scheme for obtaining standards and HPLC quantification of leafy vegetable carotenoids. Food Chem. 2002;78:389-98.
12. Kimura M, Kobori CN, Rodriguez-Amaya DB, Nestel P. Screening and HPLC methods for carotenoids in sweetpotato, cassava and maize for plant breeding trials. Food Chem. 2007;100:1734-46.
13. Kimura M, Rodriguez-Amaya DB, Godoy HT. Assessment of the saponification step in the quantitative determination of carotenoids and provitamin A. Food Chem. 1990;35:187-95.
14. Rodriguez-Amaya DB. A guide to carotenoid analysis in foods. Washington, D. C.: International Life Sciences Institute Press; 1999.
15. Scott KJ, Finglas PM, Seale R, Hart DJ, de Froidmont-Görtz I. Interlaboratory studies of HPLC procedures for the analysis of carotenoids in foods. Food Chem. 1996;57:85-90.
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