Measurement comparison of cotton fiber micronaire and its components by portable near infrared spectroscopy instruments

Micronaire is a key cotton fiber quality assessment property, and changes in fiber micronaire can impact fiber processing and dyeing consistency. Micronaire is a function of two fiber components—maturity and fineness. Historically, micronaire is measured in a laboratory under tightly controlled environmental conditions. There is increased interest by the cotton and textile industry to measure key fiber properties both in the laboratory and in-field (non-controlled conditions), using small portable near infrared (NIR) spectroscopy instruments. A program was implemented to determine the feasibility of using portable NIR instruments to monitor fiber micronaire, maturity, and fineness. Prior to outside the laboratory measurements (field, warehouse, etc.), laboratory feasibility was performed to assess the NIR instruments’ capabilities. Comparative evaluations for fiber micronaire, maturity, and fineness were performed on three portable NIR instruments. Instrumental, sampling, and operational procedures and protocols for each instrument were established. Although representing different measurement technologies, very good spectral agreement was observed between the portable NIR instruments and a bench-top NIR unit used as a comparison. Rapid (less than 3 minutes per sample), easy to use, and accurate measurements of fiber micronaire and maturity were achieved, with regressions (R values) greater than 0.85, low residuals, and a low number of outliers observed for each NIR instrument. Improvements are required for the accurate measurement of fiber fineness by portable NIR instruments. Thus, for well-defined cotton fiber samples, the universal nature of the NIR measurement of cotton fiber micronaire and maturity by portable NIR instruments was validated.