Organic thin-film devices consist of highly oriented π-conjugated molecules, which have attractive features, such as mechanical flexibility and controllability of the optical and electrical functions stemming from the molecules. Among them, we believe that organic thin-film transistors (OTFTs) are some of the most suitable platforms to develop on-site sensors for environmental pollutants or biomarkers, owing to their low-manufacturing costs and easy fabrication processes. In this regard, we have developed extended gate-type OTFT-based chemical sensors, which are able to detect various sizes and types of chemical species (i.e. small ionic molecules, electrically neutral ones, and proteins). We believe that our proposed sensing system will open up a new aspect of organic thin-film devices for chemical analysis applications.

In order to improve the lower detection limit of solvent polymeric membrane ion-selective electrodes (ISEs), a flow-through system with an ISE based on a highly selective and lipophilic Pb²⁺ ionophore, ETH5435, was constructed. This flow-through system has a function to remove most Pb²⁺ remaining at the phase boundary of the ISE membrane with feeding EDTA chelating solutions just before sample feeding. By feeding a trace level of Pb²⁺ solutions into the flow-through system, transient potentiometeric responses for Pb²⁺ were observed in the concentration range of 1 × 10⁻⁹ mol L⁻¹ to 1 × 10⁻⁶ mol L⁻¹ which was lower than the detection limit of conventional Pb²⁺-ISEs. The observed transient potential responses were analyzed based on an ion-flux model across the membrane/sample solution interface. As a result, it was found that plotting the gradient of the transient potential response immediately after sample feeding provides a calibration curve with good linearity from a sub-ppb to ppb Pb²⁺ concentration range.

Inarguably, one of the major issues concerning ICP-MS is spectral interferences. Around the year of 2000, some ICP-MS manufactures developed collision/reaction cells (CRCs) so as to cope with this issue. Since then, CRCs have undergone continual refinments and improvement for nearly two decades, and eventually became vital devices in today’s quadrupole ICP-MS. In this paper, the latest technological aspects of CRCs are reviewed and their fundamental limitations are clarified. Then follows a discussion about the mechanism for overcoming some of these limitaions by triple quadrupole ICP-MS (ICP-MS/MS). Particulary, this new technology enhances the capability of reaction cells by minimizing the cell-formed interferences and making the mass-shift method truly useful. Many of the interference problems that have remained unresolved for long in ICP-MS are now being resolved. The principles and applications of ICP-MS/MS are described in detail.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been used as a powerful tool for the structural characterization of polymeric materials. However, the presence of components having a highly ionization efficiency, such as polyethyleneoxide (PEO)-type surfactants, significantly suppresses the ionization of interesting target compounds in the sample. This study was proposed a simple sample pretreatment to selectively remove PEO components from the surface on the sample/matrix co-crystal. In this procedure, PEO components can be washed away by adding and aspirating an aliquot of aqueous methanol. A key point of this procedure is the use of water-insoluble matrix reagents, such as 2,4,6-trihydroxyacetophenone (THAP), which can retain the sample/matrix co-crystal during the removal procedures. This technique was first applied for characterizing the composition of a commercial shampoo. By removing sodium laureth sulfate (SLS), which is a typical PEO-type anionic surfactant, many mass spectral peaks suppressed by SLSs could be observed. After conversion of the mass spectral data to a Kendrick mass defect (KMD) plot, the compositional distribution of various PEO-type non-ionic surfactants and PEO hydrogenated castor oil could be depicted. An urethane/acrylate-based UV-curable coating material was then characterized. By removing PEO-type nonionic surfactants, it could be speculated that the remaining components contained isophorone diisocyanate (IPDI) and pentaerythritol (di/tri)acrylate units. This method will be a useful sample-pretreatment technique for screening formulation information concerning industrial polymeric materials.

Aluminium (Al) species in prepared polyaluminium chloride (PAC) solutions and in a commercial PAC coagulant were investigated by Electrospray Ionization Mass Spectrometry (ESI-MS) and Capillary Electrophoresis hyphenated with ESI-MS (CE/ESI-MS) in this study. Al tridecamers (Al₁₃) have seemed to be one of the most important species for coagulant efficiency; however, to date, there is not much “direct evidence” to show which Al species exist precisely in commercial PAC coagulants, and which ones literally work to make flocs in the process of coagulations in wastewater. The main aim in this study was to detect Al₁₃ species and others in a commercial PAC coagulant as a first step to reveal of “what exactly commercial PAC coagulant is composed” in the end. As the results of some experiments, Al monomers were found to be the main species, and Al₁₃ was characterized with CE/ESI-MS, although very small amounts of Al₁₃ species were detected with ESI-MS because of its suppression effect.