Authenticity Identification Of The Melamine Material And Products Using Near Infrared Spectroscopy

Melamine material has been widely used in our daily lives, owing to their good characteristics of beauty, firmness and durableness. Melamine tableware must be made from melamine-formaldehyde resin (MF) according to the Chinese National Standard. However, a large number of inferior melamine tableware made from urea-formaldehyde resin (UF) or UF-MF mixture appeared in the market, which are very harmful to health and has caused severe safety problems about melamine tableware. At present the melamine identification still relies on the physical and chemical indices, with which the ingredients of melamine cannot be authenticated effectively. Therefore, the development of fast screen method is very meaningful to the supervision and control on melamine tableware market.Near infrared spectroscopic (NIR) technology has been applied in agricultural and petrochemical fields in virtue of its merits of fast and nondestructive analysis for long. There are many successful examples about distinguishing materials with NIR. In this paper, a rapid method to identify melamine tableware with near infrared reflectance spectroscopy was proposedIn this thesis, more than 112 melamine tableware samples were collected from the markets around Beijing. An optimal condition suitable for measuring spectra of melamine table-wares was studied, and identification models using Mahalanobis distance and SIMCA methods was built. The results showed that melamine tableware and the fake ones can be discriminated by NIR, and the recognition rates of up to 100% have been obtained. In order to determine the MF-UF content in melamine tableware, many polymer samples with different contents of MF-UF powder were prepared in Lab. Feasibility of establishing quantitative model for determining MF-UF content in melamine table-wares were studied. The SECV and SEP are 0.06 and 0.28, respectively. Although orthogonal signal correction, OSC, is very effective for improving correlation curve of spectra -property, the over-fitting phenomenon in building PLS model using OSC has been not resolved yet. In the quantitative analysis study the reason to bring about the over-fitting has been discussed..An effective application method of OSC has been found using MLR modeling, which can avoid the over fitting occurred in PLS modeling.