微波等离子体炬质谱技术快速鉴别天然石材与人造石材

天然石材主要有大理石、花岗岩等;人造石材多以不饱和聚酯树脂为基料,添加适量的无机物粉料和添加剂固化制成。由于石材种类繁多,并且各种石材的岩体所含矿物成分也有差异,当前很少应用化学成分分析方法准确、快速鉴别天然和人造石材,仅有的红外光谱法由于对待测物纯度的要求较高而具局限性。本文基于微波等离子体炬源(MPT)同时具有热解吸与强电离能力,能在短时间内离子化待测物的特点,采用微波等离子体炬质谱(MPT-MS)技术,无需样品复杂预处理直接对天然与人造石材进行分析,获得正离子检测模式下在m/z 50~1000之间的石材的指纹谱图,并运用化学计量学的主成分分析(PCA)方法处理所获取的数据,实现了不同建筑石材的区分。结果表明,MPT-MS能够获得石材丰富的指纹谱图,结合PCA方法能够快速鉴别天然石材与人造石材,天然石材中解吸出的物质主要为CO₂和H₂O的团簇分子;而人造石材中解吸出的主要成分为有机物(人为添加的黏合剂等)。本研究采用的MPT-MS技术无需采用喷雾、激光、基质和加热等方法辅助,并且无需对石材进行任何复杂的处理即可进行质谱分析,从而获取石材表面及内部物质的质谱信息,为快速直接鉴定石材样品提供了一种新的质谱分析方法。

Microwave Plasma Torch Mass Spectrometry for Rapid Differentiation of Natural and Artificial Construction Stones

The distinction between natural stones such as marble and granite, and artificial stones formed mostly by unsaturated polyester resin with the addition of disintegrating slag of natural stone and some additives is difficult to determine accurately and quickly by chemical composition. Consequently, the development of Infrared Reflection Spectroscopy (IRS) has been established for for this purpose, but has limitations due to the high purity requirement of samples. Based on the high ability of thermal desorption and ionization of Microwave Plasma Torch (MPT), analyte could be ionized in a short time. In this study, Microwave Plasma Torch Mass Spectrometry (MPT-MS) was used to directly analyze natural and artificial stone without sample pretreatment. The fingerprint mass spectra of these stones were obtained in the mass range of m/z 50-1000. All data from artificial stones and natural stones were analyzed by principal component analysis (PCA) for differentiation of artificial and natural stones. The results show that abundant fingerprints of stones were acquired by MPT-MS. With the application of PCA, natural stones were successfully and rapidly differentiated from artificial stones. CO₂ and H₂O molecular clusters were desorbed from natural stones, however, organics (i.e. adhesives) were desorbed from artificial stone. Herein, MPT-MS is a new mass spectrometry technology under atmospheric pressure. Without the assistance of spray, laser, matrix and heat, the stones can be analyzed by MPT-MS directly. The method has high analytical speed (1 min per sample), high sensitivity, and does not require sample pretreatment. The results indicate that direct MPT-MS analysis allows rapid differentiation of untreated solid materials, such as construction stones, at the molecular level.