The relationship between instrumental leaf grade and Shirley Analyzer trash content in cotton lint

Abstract

With the increasing acceptance of high volume instrument (HVI™) instrumental leaf grade index in both domestic and international trading, there is a continued interest in the relationship between instrumental leaf grade and equivalent trash gravimetric content (% percent by mass) from cotton customers and regulators. Due to the complexity of not only trash type, size, and its weight distribution but also the nature of HVI and gravimetric methods, it is an on-going challenge to examine such a relationship. In this study, the Shirley Analyzer (SA) was used to determine the gravimetric cotton trash in percent by mass (%). This system is the traditional cotton trash reference method that is still utilized as a routine tool in the cotton industry, despite being a destructive process that is both labor-intensive and time-consuming. This study first investigated the correlations between three SA trash readings (SAvisible, SAinvisible, and SAtotal) and respective leaf grade categories, and it revealed a general trend of increasing SAvisible and SAtotal trash content with elevating leaf grade. Then, comparison of SAvisible trash content in the current study to that in separate studies indicated a good agreement for low leaf grade cottons (<4). Next, the principal component analysis of near infrared spectra from SAvisible trash portions revealed a different pattern in PC1 score between low leaf grade (1–4) and high leaf grade (5 and 6) SA visible trash remains, implying a general change of more leaf-related trash in low leaf grade cottons to more non-leaf-related trash in high leaf grade cottons.

Effect of Instrumental Leaf Grade On HVI Micronaire Measurement In Commercial Cotton Bales

“…However, this trend is difficult to interpret because the harvest history or production region of each of these fiber samples is unknown. The pattern in Figure 5 is similar to a previous report (Liu and Delhom, 2018), in which the first principal component (PC1) scores from principal component analysis (PCA) of near infrared (NIR) spectra of SA visible trash remains representing six leaf grade samples were related to leaf grade.…”

“…Table 1 summarizes the range, mean, and standard deviation (STDEV) of SA total trash content (%) for six instrumental leaf grade cottons, in which 30 and 15 samples were selected randomly from a set of 50 cotton lint samples and tested by Shirley Analyzer in 2016 (Liu and Delhom, 2018) and 2017, respectively. Like SA total trash content increased from 3.41 to 6.64 % in 2016 (Liu and Delhom, 2018), SA total trash content increased from 4.68 to 8.20 % with instrumental leaf grade in 2017. Notably, SA total trash of 15 samples in 2017 measurement is about 1.2 ~ 2.4 % higher than that of 30 samples in the 2016 test.…”

“…A total of 90 commercial cotton bale lint samples (15 samples / leaf grade x 6 leaf grades) and their official instrumental leaf grade one through six assignments were provided by a collaborator. These fibes were part of an earlier report demonstrating the potential of visible and near infrared (NIR) spectroscopy in the determination of instrumental leaf grade (Liu and Foulk, 2013), but they were different from those 150 samples used to explore the relationship between instrumental leaf grade and Shirley Analyzer trash content (Liu and Delhom, 2018). All cotton samples and SA resultant clean fibers were conditioned at a constant relative humidity of 65 ± 2% and temperature of 21 ± 1°C for at least 24 h, prior to routine SA and HVI micronaire measurement.…”

“…After averaging the Shirley Analyzer visible trash (SA visible ) values for samples having identical HVI area or HVI particle count (HVI count ), a better correlation relating HVI area or HVI count to SA visible in lower-trash cottons compared to higher-trash cottons was reported (Liu et al, 2012). More recently, HVI instrumental leaf grade was reported to increase with percent trash content determined by gravimetric instruments such as the Micro Dust and Trash Analyzer III (MDTA 3) (Whitelock et al, 2016) and Shirley Analyzer (SA) (Liu and Delhom, 2018).…”