Ion mobility spectrometry
Ion mobility spectrometry (IMS) applies ionization and analysis of the ions formed at ambient temperature and pressure. It can be used to analyze numerous compounds but is mainly used in various demanding applications, including the field or on-site detection of vapor phase species such as chemical weapons, explosives and drugs. Ion mobility spectrometers are similar to time-of-flight mass spectrometers though operation at ambient pressure has its own pros and cons. Our instrumentation enables exact and accurate measurements.
IMS Humidity
The presence of water is the most important single factor affecting to the IMS measurements: usually it causes some problems. The sensitivity and the selectivity are decreasing, as the detection limits are increasing. Thus the identification of the unknown analyte is getting more difficult and even a well-known analyte may produce different response. Our measurements indicated that even ppm levels of humidity are significant (due to changes occurring in gas-phase ion-molecule chemistry). In the field of IMS this is basic research with the exception that the effect of humidity has not been systematically studied.
IMS Quantitative Analysis
IMS can be used for qualitative and quantitative analysis of both organic and inorganic compounds. The aim of quantitative studies is to systematically investigate the dependency between the analyte concentration and response generated by the IMS device. In quantitative analyses additives called dopants will either increase or decrease the sensitivity of detection. The relation between the concentration of the analytes and the corresponding peak intensities varies with the dopants. This research has the ambition for IMS to be total analytical device instead of being qualitative warning system. This objective is possible to achieve with certain samples in laboratory conditions, but not in in-field analyses.
IMS preconcentration SPME
SPME is a straightforward technique to concentrate organic compounds from liquid samples. The aim of the study in our laboratory is to develop a method for fast sampling and detection of methyl tert-butyl ether (MTBE) from water. Only in few studies SPME has been combined with IMS. As combined with SPME, ion mobility spectrometry (IMS) can be a feasible early-warning technique for detection of hazardous substances from environmental matrices. In some applications (combinations like IMS– MS or IMS– GC) the IMS itself works as sample introduction/separation/preconcentration method.
IMS ionization
Currently, ionization by radioactive Ni63 (or Am241) produces ions of the analyte. However, due to strict regulations of radioactive materials new ionisation methods are required. The hottest area considering IMS instrument manufacturing is to get rid of radioactive ion sources. Future instruments will use non-radioactive methods of ionization (UV, corona, ESI etc.) Our current research consist ionization studies with SMAC (surface discharge microplasma aerosol charger) ion source.
IMS ionic liquids
Room temperature ionic liquids (ILs) are a versatile class of low melting point (generally below 100 °C) salts composed of organic cations combined with organic or inorganic anions. In general, this is relatively novel field of research related to green chemistry or to electrochemical applications. They are considered as practically nonvolatile substances but some recent studies have demonstrated that some thermally stable ILs can vaporize at elevated temperatures. We have studied thermal evaporation of several imidazolium-based ionic liquids.. They are difficult to study with IMS, but there are no competitors in this field.
Novel materials and electrodes
Carbonized cellulose films
Carbon materials provide excellent electrode materials due to their good electrical conductivity, mechanical strength, and featureless capacitive background. The main idea of this research is to use widely available cellulose and especially its nano-structures to produce thin films which can then be pyrolysed to carbon films on electrodes and therefore produce cheaply and easily new carbon electrodes to sensors.
Composite films of cellulose and TiO2
TiO2 is an interesting semiconductor material and it is widely studied for example for photovoltaic applications. The research is to produce a new material that would have enhanced electrochemical properties of TiO2 nanoparticles with carbonised cellulose material.
Ion sensing on junction electrodes
Processes at liquid–liquid interfaces are of importance in analytical applications and in many biological processes. Electrochemical polarisation of liquid–liquid interfaces allows extraction of thermodynamic and kinetic data for ion transfer processes. Especially the array electrodes where several microelectrodes are arranged next to each other and connected improve the signal to noise ratio in the measurements. Junction electrodes increase the sensitivity of the measurements even further, and the ion sensing on the interdigitated array electrodes with oil droplets settled on them in the aqueous system may produce in future sensitive and selective sensors for various ions.
DNA investigations
DNA damage
Structurally damaged DNA can lead to mutations and malignant transformations that may cause appearance of diseases such as cancer or cystic fibrosis. Detection of DNA damage induced by environmental mutagens and carcinogens, industrial pollutants and their metabolically activated products are therefore of great importance for human health protection. Current trend is to investigate the mechanisms how chemical agents (hydroxyl radicals and other reactive oxygen species, chemical nucleases, carcinogens or antitumor drugs) as well as ionizing radiation can damage DNA. Research is focused to antioxidant activity of tea extracts.
DNA sensors
Electrochemical DNA biosensors consist of DNA recognition layer immobilized at the surface of electrochemical transducer representing a relatively new type of affinity biosensors. Their usage is based on detection of specific interactions such as hybridization, DNA association with low molecular weight compounds (drugs, risk chemicals) as well as damage to DNA. Research includes testing of nanomaterials to prepare more sensitive DNA biosensors for detection of DNA damage.
DNA sensors in environmental analysis
DNA interacts with majority of pollutants. When th pollutants interact with the DNA components (DNA bases, phosphate groups) usually the cause change in DNA electroactivity. Current trend is to study of mechanism of DNA damage caused by pollutants, development of DNA biosensors for fast monitoring and “alarm tests” applicable directly in terrain, detection of pollution by drugs such as antibiotics and their metabolities. Research includes detection of heavy metals by DNA biosensors and study of their interaction with DNA.
Water quality of the “Water Tower of Asia”
– Tibetan Plateau
The Tibetan Plateau is called the “Water Tower of Asia” as it is the source of the eight largest rivers in Asia. There is very little information on water quality of these rivers draining in the Plateau exists, even though these rivers play a significant role in lives of more than one third of world’s population! This is partially because of the environment in the Tibetan Plateau has traditionally been considered pristine. In addition, limited accessibility to these rivers has led to a restricted number of studies. There is growing public concern about the potential effects of the rapidly increased mining activities and demographic changes on the Plateau’s fragile aquatic environment. Furthermore, there is a fast increasing interest internationally regarding the river water quality on the Plateau, particularly due to possible important impacts of climate change and its impact on the melting glaciers of the Himalayas.
The results reveal that the spatial distributions of major solutes in the Tibetan rivers are relatively homogenous and are mainly controlled by the lithology and climatic conditions. The amounts of these solutes in the Tibetan rivers are on average twice that of rivers in rest of the world. In spite of alkaline nature of these waters, the average levels of dissolved trace elements in the Tibetan rivers are high compared to the world’s average. Nevertheless, from a drinking-water point of view, the levels of most of toxic metals are negligible in all studied waters. Based on dissolved matter studied in this work, these Asian major rivers in the Plateau can in general be considered as pristine. However, poorly regulated mining operations have caused severe heavy metal contamination in one particular major tributary of the Yarlung Tsangpo near Lhasa city. The rapidly increased mining activities pose therefore a future high risk of heavy metal pollution for the local environment and a potential threat to the downstream water quality.
Water quality, case study
Case: Protection of Waters in Egypt
The study is covering the water quality evaluation of surface water bodies. The focus is the water quality upgrading of Lake Qarun (Egypt) and its recharge sources using constructed wetland and desalination processes. In addition, second task is the evaluation of applicable treatment methods for re-use of water in irrigation, in industry or even in water supply purposes.
Environmental organics
VOC’s, PAH’s, chlorophenols, hydrocarbons in range C10 to C40 are ubiquitous because of the fact that they are released in appreciable quantities every year into the environment through the combustion of organic materials such as coal, fuel, oils, petrol, wood, refuse and plant materials. Some of these are carcinogenic or mutagenic, their presences in the environment are regularly monitored and controlled. We are developing more efficient methods for analysis of these organic compounds.