Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 7/7/2008
Publication Date: 7/30/2008
Citation: Funk, P.A., Eiceman, G.A. 2008. Detecting plastics in seedcotton. Proceedings of the American Society of Agricultural and Biological Engineers (ASABE) 2008 Annual International Meeting. June 29 - July 2, 2008, Providence, RI. Paper No. 083601. Interpretive Summary: To keep the US cotton industry competitive on the world market, plastic materials contaminating raw seedcotton needs to be removed before ginning so that it is not dispersed through large volumes of cotton lint. This paper presents advances in detection of plastic material in a background of seedcotton; detection is a necessary prerequisite to removal. It shows how ion mobility spectrometers modified for the purpose can detect small amounts of plastic, distinguishing between types of plastic, in a large volume of seedcotton. The modest cost of this technology has the potential to pay for itself many times over by assuring a premium for contaminant-free natural fiber and preserving market reputation for years to come.
Technical Abstract: The US cotton industry wants to increase market share and value by supplying pure cotton. Removing contamination requires developing a means to detect plastics in seedcotton. This study was conducted to determine if Ion Mobility Spectrometry (IMS) could be used to find small amounts of plastic in a matrix of heated seedcotton. Commercial IMS analyzers equipped with membrane inlets sampled air displaced from heated flasks containing seedcotton and five common plastic contaminants; bale twine, new and weathered polypropylene tarp, polyethylene film and plastic film shopping bags. In the first of two sets of experiments the temperature was varied from 85 to 115°C to determine its influence on vapor emissions; in the second, air samples were taken from seedcotton containing various amounts of each plastic. Vapors from plastics associated with cotton contamination were detected with IMS in negative polarity; different plastics were distinctive. Vapor molecules and product ions from plastics and seedcotton both increased with temperature. Seedcotton vapors spectra coincided with plastics vapors spectra but had different slope characteristics at specific drift times. Digital signal processing may be used to detect plastic contamination, triggering an alarm or control action. Spectra from new and old polypropylene tarp were nearly identical suggesting detection will be possible after weathering. IMS detection of plastics vapors in seedcotton works in the laboratory. The next step is developing IMS systems for commercial cotton gins.