Applications Of Multivariate Spectral Analysis On The Testing Of Paper-Related Materials

The existing analytical methods used for paper products and related materials are usually not only very complicated and time-consuming in the sample preparation, but also with poor measuring accuracy and reliability. In this work, four analytical methods have been proposed for rapid determination or detection of the average fiber-length in wood pulps, migratable fluorescent whitening agents(m-FWA) in the printing paper material, barium sulfate in antifake papers, and pre-polymer in UV printing gloss oil by the visible, UV, and infrared spectroscopic analysis, respectively. The details of these methods are described below:1. The new method for the determination of average fiber-length in wood pulp is based on measuring the absorbance at whole visible wavelength range, assisted by chemometrics. The results showed that there is a good correlation between the spectral signals(absorbance) and the average fiber-length at a fixed fiber consistency(0.3g/L). The square of regression coefficient(R2) is > 0.98, for an optimized model, indicating that the present method can proved a good prediction in the average fiber-length measurement.2. The new method for the m-FWA in textbook paper material was based on a UV spectroscopy assisted by a dual-wavelength calculation technique. The spectral interference of the ink, filling, and coating materials in the textbook printing sample extracts could lead to a significant measurement error in the m-FWA quantification. By introducing a tracer(potassium chromate), measuring the extracts with and without adding this tracer, and using a dual-wavelength calculation technique, the above spectral interference can be minimized. The results showed that the relative standard deviation and the recovery of present method are 2.17% and 98%-104%, respectively, indicating that the method can be used to accurately determine the m-FWA in textbook samples.3. The method for the determination of trace amount of barium sulfate in anti-fake paper was based on the inferred spectroscopy. The result showed that the sample pretreatment procedures, i.e., calcined to be ash followed by acidic washing(with 1mol/L hydrochloric acid) is mandatory to improve the detection sensitivity of the method for the qualitative determination of trace barium sulfate content in the relevant paper samples.4. A new method for the determinate the pre-polymer in UV printing gloss oil was based on infrared spectroscopy on measuring the characteristic transmittance peaks at 732 and 767 cm-1 for the epoxy groups and 1727 and 1736 cm-1 for the ester carbonyl groups. The present method is very simple and suitable to be used for rapidly selecting the UV printing gloss oil according to materials’ requirement.