Abstract
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is an analytical technique that can be used to characterize the surface and near surface region of solids and the surface of some liquid sample without volatility. TOF-SIMS could be detected including single- and multi-atomic ions, and organic fragments with different polarity. In this thesis, bisphenol A (BPA) in thermal paper, the effect of boron concentration in process water for silicon device and species of edible oil on foods were investigated by TOF-SIMS or SIMS couple with other related analytical techniques. BPA has widely been used in a variety of consumer products including thermal papers (TPs) as a color developer. The health risk associated with dermal penetration of BPA as a result of the finger contact with TPs warrants the need of a new analytical method for direct analysis of BPA in TP surface. Techniques of surface analysis such as TOF-SIMS was helpful to fulfill this need. Fragment ions of BPA on the TP surface were readily detected by TOF-SIMS. Quantification of BPA was performed by establishing curves based on the intensity of the BPA fragment ions versus the concentration of BPA in the prepared BPA/stearamide solid sample which exhibits acceptable correlation coefficient. The content of BPA in the surface of BPA-positive TPs agrees well to bulk BPA concentration by high-performance liquid chromatography-fluorescence detector analysis. The amount of BPA transferred from TP-positive TPs to the holding fingers (last for 30 seconds) was found to be ~2.4 g and highly related to the surface BPA concentration. Direct analysis of BPA in TPs by TOF-SIMS is useful for screening purpose of TPs as well as for provides an opportunity for estimating BPA exposure from TPs. Recently, the boron concentration in desalination plants and fabrication process has become most critical issue due to high cost and adverse effect on the performance of semiconductor devices (SD) since the presence of boron might causes poor P-N junction and lowers the production yield. In this study, SIMS and inductively coupled plasma-mass spectrometer (ICP-MS) coupled with semiconductor parameter analyzer were used to determining the effect of boron contaminants in SD. The main aim for the present study was to identify boron spatial distribution and concentration in SD as well as an investigation of relevant electrical properties. Spatial locality of boron and various metal species that may affect electrical property was determined at the interface of silicon dioxide layer and Si wafer in SD. The amount of boron was found in SDs is proportional to the boron concentration inIV process water. When the boron concentration in process water was higher than 125 ng/L, the related electrical properties were significantly decreased. The result of analyses clearly indicates the pronounced effect of boron on a semiconductor. Edible oils play an essential role for human body since they provide lipids. There have been a lot of safety issues about edibles oils in recent years such as misbranding of blended oils and the products that made from inedible oils. These scandals indicate that the existing food examination methods are unable to meet the demand nowadays. Therefore, it is necessary to come up with more suitable methods to figure out this problem. In this research, a rapid method for classifying edible oils on foods was established by applying TOF-SIMS to detect the acylglycerols with limit pretreatment. TOF-SIMS data were subsequently analyzed by principal component analysis (PCA) to make a clear classification between various oils, showing its potential in differentiating the fakes quickly. Further quantification of mixing ratio was studied by estimating known and unknown compositions of blend oils according to the curves of intensities of selected ions versus adulterant concentrations. This fast and effective method is of great advantage to authenticate edible oils. Molecular imaging (MI) is a noninvasive, real-time visualization of biochemical events at the cellular and molecular level that can be advantageously applied in the areas of diagnostics, therapeutics, drug discovery, and development in understanding the nanoscale reactions including enzymatic conversions and protein–protein interactions. Consequently, over the years, great advancement has been made in the development of a variety of MI agents such as peptides, aptamers, antibodies, and various nanomaterialsincluding single-walled carbon nanotubes. Recently, graphene, a material popularized by Geim & Novoselov, has ignited considerable research efforts to rationally design and execute a wide range of graphene-based NMs making them an attractive platform for developing highly sensitive MI agents. Owing to their exceptional physicochemical and biological properties combined with desirable surface engineering, graphene-based NMs offer stable and tunable visible emission, small hydrodynamic size, low toxicity, and high biocompatibility and thus have been explored for in vitro and in vivo imaging applications as a promising alternative of traditional imaging agents. This chapter is review form which begins by describing the intrinsic properties of graphene and the key MI modalities. We provide an overview on the recent advances in the design and development as well as physicochemical properties of the different classes of graphene-based NMs being used as MI agents for potential applications. Finally, the major challenges and future directions in the field will be discussed.