ANALYTICAL METHODOLOGY FOR THE STUDY OF THE INTERACTION OF CADMIUM AND LEAD WITH SOME PRESENT AMINO ACIDS IN SOLUTIONS OF PARENTERAL NUTRITION / METODOLOGIA ANALÍTICA PARA O ESTUDO DA INTERAÇÃO DE CÁDMIO E CHUMBO COM ALGUNS AMINOÁCIDOS PRESENTES EM SOLUÇÕES DE NUTRIÇÃO PARENTERAL

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The patients health under treatment by Parenteral Nutrition (PN) is directly associated to the quality of the solutions used during the procedures and thus, a rigorous quality control is necessary. Among possible contaminants, toxic metaIs like cadmium and lead, found in constituents of contaimers, raw materiaIs and manufacturing procedures of the pharmaceutical products may contaminate PN solutions. The development of appropriate methodologies to the quantification of these metaIs is of great importance. The PN solutions are shared according the volume in two groups, Small Parenteral Volume (SPV) constituted basicaUy by saline solutions and Large Parenteral Volume (LPV)- To verify the presence of metallic contaminants in the solutions of PN through voltammetric determinations, after sample pretreatment. - To investigate the interaction of cadmium and lead with some quantification of the amino acids alanine, glycine, serine, methionine, threonine, histidine, phenylalanine, glutamic acid and aspartic acid in aqueous solutions and in PN solutions. Additionally, the interaction of amino acids in aqueous solutions and commercial solutions ofPN. The study was divided in three parts. In the first, different types of samples pretreatments of PN solutions were investigated to enable voltammetric determinations. In the second, the interaction of cadmium and lead with some amino acids in aqueous solutions was studied by using high performance liquid chromatography (HPLC) with fluorimetric detection. In the third, the HPLC methodology was applied to PN samples. Voltammetric determination of zinc, cadmium, lead and copper in SPV solutions, was also investigated by solid phase extraction in columns filled with polyethylene powder. This pretreatment allowed the separation and preconcentration of the metaIs with good preconcentration factors, limits of detection by ng L-I, recoveries around 100% and relative standard deviations up to 8%. For LPV solutions, the determination of zinc, cadmium, lead and copper by anodic stripping voltammetry (ASV) was possible after sample pretreatment with ultraviolet (UV) or microwave (MW) irradiations. The concentrations determined by ASV, after UV or MW irradiations ranged from 16,9 to 260 ~g L-I for zinc; 0,68 to 4,44 ~g L-I for cadmium; 0,53 to 16,8 ~g L-I for lead and 0,95 to 40,8 ~g L-I for copper. Relative standard deviation ranged from O, 5-10%. The HPLC system with gradient elution, post-column derivatization and fluorimetric detection was appropriated for the separation and quantification of the amino acids alanine, glycine, serine, methionine, threonine, histidine, phenylalanine, glutamic acid and aspartic acid in aqueous solutions and in PN solutions. Additionally, the interaction of cadmium and lead with the amino acids was also investigated through the chromatographic signals with and without the metaIs. For the aqueous solutions, the order of interaction metal - amino acid agreed with the complex constants of formation. On the other hand, for PN samples the results were different from the obtained in aqueous solutions.

ASSUNTO(S)

quimica analítica analytical chemistry quimica analitica

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