Rapid method for monitoring chitosan coagulation using low-field NMR relaxometry

Autor(es)

Crizostomo Kock, Flavio Vinicius ^[1] ; Colnago, Luiz Alberto ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, Ave Trabalhador Sao Carlense 400, BR-13566590 Sao Carlos, SP - Brazil

^[2] Embrapa Instrumentacao, Rua 15 Novembro 1452, BR-13560970 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Carbohydrate Polymers; v. 150, p. 1-4, OCT 5 2016.
• Citações Web of Science: 5

Resumo

Time-domain NMR relaxometry was proposed as a simple, rapid method to monitor chitosan (CS) coagulation as a function of pH. The longitudinal (T-1) and transverse (T-2) relaxation times of three CS concentrations (0.022, 0.22, and 2.2 g L-1) were simultaneously measured by CP-CWFPx-x pulse sequences in a 0.47T spectrometer. T-1 and T-2 were shown to be independent of pH as well as to assume values similar to the relaxation time of water (2.7 s) at the lowest tested CS concentration. At the highest concentration, T-1 increased whereas T-2 decreased as pH varied from 6.0 to 7.0. This indicates a remarkable effect of CS on water relaxation at pH values higher than the pKa of CS amino groups (6.5). Therefore, CS reduced the water mobility at the highest CS concentration and greatest pH values, suggesting a CS supramolecular structure (gel) that entraps the solvent in confined regions. The method proposed here can be further used to study the coagulation of other polysaccharides. (C) 2016 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 12/23169-8 - Estudo in situ da ação do biopolímero quitosana na descontaminação de metais e herbicidas em sistemas aquosos por eletroquímica acoplada com RMN de alto e baixo campo
• Beneficiário: Flavio Vinicius Crizostomo Kock
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 14/22126-9 - Desenvolvimento de instrumentação e métodos de RMN no domínio do tempo para análise química, em campo
• Beneficiário: Luiz Alberto Colnago
• Modalidade de apoio: Auxílio à Pesquisa - Regular