Determination of Available Lysine by Planar Chromatography: A Useful Tool for Protein Quality Evaluation in Fish Feed
Abstract:Due to the essentiality of lysine for fish, its availability is commonly used as a predictor of the protein nutritional quality of fish feed. The objective of this work was to establish a high-throughput analytical method for protein quality control in fish feed through the measurement of available lysine by planar chromatography. Sample was first incubated with 1-fluoro-2,4-dinitrobenzene to obtain the dinitrophenyl-lysine derivative and then hydrolyzed with hydrochloric acid in order to release the derivative from proteins. Chromatography was performed on silica gel 60 F254 HPTLC plates using n-propanol25 ammonia (7 + 3, v/v) as mobile phase. Quantitative analysis was performed by densitometry in the absorbance mode at 360 nm. Calibration showed a polynomial relationship with an R2 of 0.9991 in the range of 25 to 125.0 ng/band. Repeatability relative standard deviation (RSD) and intermediate precision (RSD) in matrix were 0.8 and 3.6, respectively. Recoveries of spiked samples at two levels ranged from 72 to 85 with RSD from 3 to 8. This method provides the salmon feed industry with a reliable, high-throughput, and low-cost means for routine quality control of available lysine.
Document Type: Research Article
Affiliations: University of Concepcion, Faculty of Pharmacy, Department of Food Science, Nutrition and Dietetic, Barrio Universitario s/n Casilla 237, PO 403-0249 Concepcion, Chile.
Publication date: 2009-05-28
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- The Journal of AOAC INTERNATIONAL publishes refereed papers and reviews in the fields of chemical, biological and toxicological analytical chemistry for the purpose of showcasing the most precise, accurate and sensitive methods for analysis of foods, food additives, supplements and contaminants, cosmetics, drugs, toxins, hazardous substances, pesticides, feeds, fertilizers and the environment available at that point in time. The scope of the Journal includes unpublished original research describing new analytical methods, techniques and applications; improved approaches to sampling, both in the field and the laboratory; better methods of preparing samples for analysis; collaborative studies substantiating the performance of a given method; statistical techniques for evaluating data. The Journal will also publish other articles of general interest to its audience, e.g., technical communications; cautionary notes; comments on techniques, apparatus, and reagents.
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