Uncertainty in the Determination of Glucose and Sucrose in Solutions with Chitosan by Enzymatic Methods

Berta N Estevinho,Fernando Rocha,Amélia Ferraz,Lúcia Santos,Arminda Alves

doi:10.5935/0103-5053.20130119

Abstract

The purpose of this work was to evaluate the applicability of two enzymatic methods to quantify glucose and sucrose in aqueous solutions with chitosan. The analytical methods were validated and the main parameters, as limit of detection, linearity range, precision and accuracy were determined. The global uncertainty for glucose enzymatic method was less than 10% for concentration levels between 700 and 2000 mg L-1, and for the sucrose enzymatic method, the global uncertainty showed values less than 3% for all concentration levels analyzed (100-1000 mg L-1). Despite the similarities of performances with respect to other analytical methods, the enzymatic method proved to be better than others, in particular high performance liquid-chromatography (HPLC), mainly if a great number of samples needs to be analyzed, allowing a quick result, and because the mucoadhesive properties of chitosan make difficult the HPLC analytical methodology, creating stability problems in the chromatographic column.

Highlights

Chitosan is a polycationic polymer obtained commercially by alkaline deacetylation of chitin.[1,2] The chitosan molecule is a copolymer of N-acetylD-glucosamine and D-glucosamine and differs in the degree of N-acetylation (40-98%) and molecular weight (50‐2000 kDa).[1,2,3] Chitin is the second most abundant natural polymer in nature after cellulose and is found in the structure of a wide number of invertebrates among others
The objective of this work was to evaluate the applicability of an enzymatic method to quantify glucose and sucrose in solution with chitosan, minimizing the effects of the chitosan interactions, the time of analysis and the problems associated to the use of high performance liquid-chromatography (HPLC) methods with chitosan
Few enzymatic methods have a study of validation method, and from our knowledge, no one including the determination of uncertainty

Summary

Introduction

Chitosan is a polycationic polymer obtained commercially by alkaline deacetylation of chitin.[1,2] The chitosan molecule is a copolymer of N-acetylD-glucosamine and D-glucosamine and differs in the degree of N-acetylation (40-98%) and molecular weight (50‐2000 kDa).[1,2,3] Chitin is the second most abundant natural polymer in nature after cellulose and is found in the structure of a wide number of invertebrates (crustaceans, exoskeleton insects, cuticles) among others. Chitosan can be considered as a biodegradable and a nontoxic product and is currently receiving a great deal of. Other properties with special interest for food industry are related to the anticholesterolemic,[7,8] antioxidant[9] and antimicrobial properties[9] of chitosan. Chitosan is an attractive biomacromolecule, presenting, a disadvantage: it is a water-insoluble material. Chitosan is soluble only in acidic solutions because of its rigid crystalline structure and deacetylation, which limits its application. It is possible to modify the chitosan

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