Varian gemini

Lyophilized CHOS (10 mg) were dissolved in deuterium oxide (D₂O) (0.5 mL) and the pH was adjusted to 4.2 with sodium deuteroxide (NaOD) prior to lyophilization. The lyophilized CHOS was redissolved in D₂O and lyophilized again to secure that all the H₂O had been removed. Finally the lyophilized CHOS were dissolved in D₂O (700 μL) and ¹H-NMR analysis was performed on a 300 MHz Varian Gemini instrument (Varian, USA) at 85°C. The DP_n was calculated by the equation (Dα+Dβ+D+Aα+Aβ+A)/(Dα+Dβ+Aα+Aβ), where Dα, Dβ, Aα and Aβ are the integrals of the reducing end signals of the α and β anomers of the deacetylated (D, GlcN) and acetylated (A, GlcNAc) units respectively, D is the integral of the signals from GlcN in internal positions and non-reducing end positions, and A is the integral of the signals from GlcNAc in internal and non-reducing end positions [14] (link).

The initial compound (Apollo Scientific, Bredbury, UK) and all reagents and solvents (Sigma-Aldrich, Darmstadt, Germany) were of analytical grade. Thin-layer chromatography was performed on Merck silica gel 60F₂₅₄ plates and visualized using UV light. The stationary phase in column chromatography was high-purity Merck silica gel (pore size 60 Å, 70–230 mesh). Elemental analyses (%C, H, N) of all synthesized compounds in the solid form were carried out using a PerkinElmer PE 2400 Series II CHNS analyzer (Perkin-Elmer, Shelton, CT, USA), the results of which were in agreement with the calculated values within the ±0.4% range. IR spectra were recorded as KBr pellets of the solids using a Satellite FT-IR spectrophotometer (Bruker, Madison, WI, USA). The ¹H and ¹³C NMR spectra in DMSO-d₆ were recorded using Varian Unity Plus (500 MHz) and Varian Gemini (200 MHz) instruments (Varian Medical Systems, Palo Alto, CA, USA). Melting points were determined using a Stuart SMP30 apparatus (Stone, Staffordshire, UK) and were uncorrected.