An Efficient Method for Determining the α-, β-, and γ-Cellulose Content in Fully Delignified Pulps by Reaction-Based Headspace Gas Chromatography

Abstract

This article reports on a headspace gas chromatographic (HS-GC) technique for determining the content of α-, β-, and γ-cellulose in fully delignified pulps. In this method, the pulp sample was extracted by 17.5% and 9.45% NaOH solutions (25°C), respectively, to obtain two soluble fractions; i.e., the sum of β- and γ-cellulose and γ-cellulose. By reacting with potassium dichromate in a strong-acidic medium at 100°C for 60 min in a sealed headspace sample vial, these soluble celluloses in the filtrates were quantitatively converted to carbon dioxide. With the headspace equilibration at 60°C for 7 min, the formed carbon dioxide was measured by HS-GC and thus the content of β- and γ-cellulose in the pulp samples can be determined, from which the content of α-cellulose can also be calculated. The results showed that the present method had a good measurement precision (a relative standard deviation <2.1%) and accuracy (relative differences of <10% compared to the reference); the limit of quantification (LOQ) was 1.71%. In summary, the present method is simple, practical, and is particularly suitable for use in the batch sample analysis for determining α-, β-, and γ-cellulose content in fully delignified pulps.

KEYWORDS:

• α-
• β-
• and γ-cellulose
• delignified pulps
• carbon dioxide
• oxidation reaction
• headspace gas chromatography