Fast detection of cotton content in silk/cotton textiles by handheld near-infrared spectroscopy: a performance comparison of four different instruments

Its extraordinary chemical and physical properties have made silk one of the most versatile and comfortable fiber fabrics for a multiplicity of customers and industrial applications. However, this development has led to fraud and adulteration attempts for a multitude of consumer goods. In these respects, the potential and increasing affordability of handheld near-infrared (NIR) spectrometers makes them an attractive tool for customers to fight these evils efficiently. In this work, the rapid quantitative analysis of the purity level of silk adulterated with cotton by four different handheld NIR instruments, the NeoSpectra Scanner, Viavi MicroNIR 1700, Spectral Engines NR 2.0-W, and SenoCorder Solid, and their detection performances were compared with a benchtop NIR instrument (Thermo Antaris II). With these instruments, samples with 0–100% (w/w) cotton content were measured, spectral pretreatment methods were performed, and partial least squares calibration models were developed. The results showed that while the root mean square error values of approximately 1.9%(w/w) cotton were obtained with the benchtop instrument, the corresponding values for the handheld instruments varied in the range from 2.5% to 4.0%(w/w) cotton. Generally, a large signal-to-noise ratio and an extended available wavelength/wavenumber range had a beneficial effect on the prediction performance of the developed calibration model. Notwithstanding the diversity of instrumental parameters of the tested instruments, it can be concluded that all handheld spectrometers under investigation qualified as suitable tools for the detection of cotton adulterations in silk materials.