Chitin characterization by SEM, FTIR, XRD, and ¹³C cross polarization/mass angle spinning NMR

TLDR

The study reports a comprehensive characterization of chitin extracted from squid, shrimp, prawn, lobster, and king crab. Chitin was isolated by alternating hydrochloric acid and sodium hydroxide, then characterized by elemental analysis, TEM with EDX, 13C CP/MAS NMR, FTIR, and X‑ray diffraction. α‑Chitin exhibited two NMR signals at 73.7 and 75.6 ppm, amide I bands at 1660 and 1627 cm⁻¹, and an orthorhombic crystal structure, whereas β‑chitin showed a single NMR signal at 75.2 ppm, an amide I band at 1656 cm⁻¹, and a monoclinic dihydrated structure. © 2004 Wiley Periodicals, Inc., J Appl Polym Sci 93:1876–1885.

Abstract

Abstract The full characterization of chitin obtained from squid, shrimp, prawn, lobsters, and king crab is reported. Elemental analysis, including metals such as Ca, Mg, Zn, Cd, Hg, Cr, Mn, Cu, and Pb, was performed, which is quite relevant because the skeleton composition is slightly different for each species. The morphology was studied by means of TEM and their compositions were determined by energy‐dispersive X‐ray analysis. 13 C cross polarization/magic angle spinning NMR was applied to determine the chemical shift of all the carbons and the difference between them. Chitin was isolated by using chemical methods, alternating hydrochloric acid and sodium hydroxide. The α‐chitin from shrimp, prawn, lobsters, and king crabs showed two signals at 73.7 and 75.6 ppm. Meanwhile, the β‐chitin from squid exhibited one signal at 75.2 ppm. FTIR studies were used to analyze α‐chitin from shrimp and β‐chitin from squid. The α‐chitin exhibited amide I vibration modes at 1660 and 1627 cm −1 , whereas the β‐chitin showed one band at 1656 cm −1 . X‐ray diffraction showed that α‐chitin is orthorhombic ( a = 4.74 Å, b = 18.86 Å, and c = 10.32 Å) and β‐chitin had a monoclinic dihydrated form ( a = 4.80 Å, b = 10.40 Å, c = 11.10 Å, and β = 97°). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1876–1885, 2004