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LOGO: Journal of Cotton Science


Novel Studies of Non-Aqueous Volatiles in Lint Cotton Moisture Tests by Complementary Thermal Methods

Authors: Sherwin Y. Cheuk, Joe G. Montalvo Jr., and Terri M Von Hoven
Pages: 179-188
Textile Technology

A preliminary study of non-aqueous volatiles (NAVs) in lint cotton moisture tests by thermal methods suggested that oxidation occurs during standard oven-drying conditions (105o to 110oC in ambient air). The thermal methods in that study included thermogravimetric analysis-quadrupole mass spectrometry (TGA-QMS). Surprisingly, no specific volatile organics were detected. The objective of the current study was to investigate further the nature of the NAVs with the following complementary thermal methods: distillation, direct injection of the carrier gas in a closed system, and colorimetry after oven drying. Fifty g samples of cotton were distilled at 105oC with dry air, nitrogen or argon as carrier gas. Distillates were analyzed for total organic carbon (TOC) content and the residue from the interior walls of the glassware was collected. The distillates were essentially pure water, regardless of carrier gas, supporting the earlier TGA-QMS results. However, the trace amounts of TOC and residue found were greater for samples distilled in dry air, suggesting that the NAV material is of low volatility and/or exists as fine particulate matter, not sensed by a mass spectrometer. Direct injection of the carrier gas (dry air, nitrogen, argon or helium) into sealed vials containing cotton samples heated at 105oC produced similar findings. Within an hour of drying, samples heated in air resulted in a higher dry weight than nitrogen, suggesting oxidation of the sample material, helium and argon absorbed on the dry cotton. Colorimetry data on oven-dried cotton in ambient air at 105°C also implied oxidation.