Extraction of residual heavy metals from commercial chitosan and approach to preparation of oligochitosan hydrochloride

Boris B Berezin; Evgeniya A Bezrodnykh; Inesa V Blagodatskikh; Igor A Yamskov; Vladimir E Tikhonov

doi:10.1016/j.carbpol.2019.03.072

Extraction of residual heavy metals from commercial chitosan and approach to preparation of oligochitosan hydrochloride

Carbohydr Polym. 2019 Jul 1:215:316-321. doi: 10.1016/j.carbpol.2019.03.072. Epub 2019 Mar 30.

Authors

Boris B Berezin¹, Evgeniya A Bezrodnykh¹, Inesa V Blagodatskikh¹, Igor A Yamskov¹, Vladimir E Tikhonov²

Affiliations

¹ A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Russia.
² A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Russia. Electronic address: tikhon@ineos.ac.ru.

PMID: 30981360
DOI: 10.1016/j.carbpol.2019.03.072

Abstract

For biomedical applications, chitosan and oligochitosan must be appropriately characterized and meet pharmacological requirements in terms of contamination by residual heavy metals. In this work, a series of commercial chitosans was analyzed by ICP-MS method, and high concentration of Fe (44-382 ppm), Cr (3.1-35.5 ppm) and Ni (0.33-7.91 ppm) exceeding pharmacologically acceptable level was found. It was shown that as a chelating agent EDTA was an ineffective remedy for solid-phase extraction of residual heavy metals from chitosan. It was proposed that corrosion of stainless steel apparatus in the process of chitin deacetylation contributed to chitosan contamination by heavy metals. A two-step treatment of chitosan with hydrochloric acid allowed remediation of chitosan and preparation of oligochitosan hydrochloride with molecular weight 5-16 kDa and acceptable level of Fe<10, Cr<1 and Ni<1 ppm.

Keywords: Chitosan; Heavy metals; ICP-MS; Oligochitosan; Pharmacopeia.