LOW-COST CAPILLARY ELECTROPHORESIS INSTRUMENTATION FOR ASSESSMENT OF RAIN WATER IONIC COMPOSITION

The objective of this Short Term Scientific Mission was to test the suitability of capillary electrophoresis for determination of rain water chemical composition. The fully functional, open-hardware, low-cost instrument was assembled and tested. An original protocol for determination of the chemical content of rain water was established and validated in the pilot test. Capillary electrophoresis proofed its highest suitability for the detection and quantification of ions in different samples, indicating substantial differences between clean and dirty snow waters. The hydrostatic sample injection method has been found very efficient and straightforward in manual and laboratory routines. An important deliverable of the Short Term Scientific Mission was a set of multimedia materials for the promotion of CE technique and especially low-cost CE instrumentation

Green analytical chemistry

xii, 319 p.; 24 c

Capacitance-to-digital : a single chip detector for capillary electrophoresis

Online ISSN: 1522-2683A capacitance-to-digital converter integrated circuit was implemented in an automated CE device as a single chip detector. In this paper, design and hardware issues related to the fabrication and application of a miniature detector for contactless measurement of complex impedance are discussed. The capacitance-to-digital converter integrated circuit was used as the whole detector. The advantage of this setup is that the single integrated circuit provides digital data and neither additional signal conditioning nor analog-to-digital converter is required. Different separation conditions were used to evaluate the detection characteristics of the constructed detection unit. A 1 μM LOD for sodium and a 1.6 μM LOD for potassium ions were revealed for the detector. The detection system designed is competitive with miniaturized contactless conductivity detectors or UV absorbance detectors with respect to overall parameters (sensitivity, resolution, power consumption properties, and size). The obtained separation and detection results show that such detection technique can be used as an extremely low power consuming and space saving solution for CE detection with potential applications in environmental monitoring, process control, and various analytical measurementsBiochemijos katedraVytauto Didžiojo universiteta

Recent advancements in portable and autonomous analytical instrumentation

Portable analytical instrumentation is interesting due to its applicability for in situ analysis. What is more important, current scientific trends show that it is possible to develop autonomous (performing all necessary functions without the intervention of the operator) instrumentation from portable systems. One of the perspective directions of investigations in chemical analysis are separation techniques due to their versatility analysing different origin substances and capability of determining multiple analytes simultaneously. In this group of works special attention will be given to capillary electrophoresis and (digital-droplet) microfluidics. During the presentation advances, peculiarities and applications developing portable and autonomous instrumentation will be reviewed. Software, hardware, sampling, signal compensation, sensitivity enhancement, automation and integration aspects will be discussedInstrumentinės analizės APCVytauto Didžiojo universiteta

In situ monitoring of kinetics of metabolic conversion of ATP to ADP catalyzed by MgATPases of muscle Gastrocnemius skinned fibers using micellar electrokinetic chromatography.

International audienceA method for the in situ measurement of the kinetics of ATP metabolic transformation using capillary electrophoresis (CE) has been developed. The depletion of ATP and formation of ADP were monitored in situ by using saponin-permeabilized muscle fibers. The method of micellar electrokinetic chromatography, employing reversed electroosmotic flow by cationic surfactant and reversed-polarity mode, provided an efficient and reproducible separation of nucleotides and enabled kinetic analysis of the reaction to be performed in a large range of nucleotide concentrations that approaches physiological concentrations of ATP in the muscle cells, without the need for precipitation of proteins prior to sample application. The analytes were detected at a nM level with a reproducibility of about 7%. This reproducibility enabled the comparison of different competing kinetic models of ATP conversion to ADP and the results show that the MgATPase activity in the fast-twitch gastrocnemius muscle followed biphasic kinetics that corresponds to the allosteric character of regulation of the enzyme(s) activity at physiological ATP concentrations. The results also confirmed that the combination of minimal sample volume requirements, rapid measurement and reproducibility makes the micellar CE a valuable tool for the analysis of biological fluids and understanding the processes of biological interest

Analysis of corrosion inhibitors, used in fertilizers industry, by high performance liquid chromatography - electrospray ionization mass spectrometry

Liquid fertilizers are stored, manufactured, and transported in metallic tanks which can completely corrode if corrosion inhibitor is not added. Corrosion inhibitors form a protection layer which protects metallic surface from corrosion. The use of these protecting compounds in fertilizers industry has a huge economical importance. Depending on the chemical origin of fertilizers, different composition corrosion inhibitors are used. Usual ingredients of corrosion inhibitors are fatty acids, amines, surfactants, glycols. Amines are very difficult to analyze by high performance liquid chromatography (HPLC), because they strongly interact with column packing and separation of compounds becomes impossible. In order to determinate these compounds a derivatization is needed. Fatty acids and surfactants can be separated by HPLC-MS without any derivatization. In some cases, when the mixture is not complex (contains up to 5 compounds) it is useful to apply direct injection electrospray ionization and mass spectrometry (ESITOF- MS). It provides a possibility of direct injection and covers a broader scope of analytesBiochemijos katedraVytauto Didžiojo universiteta

Capillary Electrophoresis Time-of-Flight Mass Spectrometry for Comparative Metabolomics of Transgenic versus Conventional Maize

In this work, capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS) is proposed to identify and quantify the main metabolites in three lines of genetically modified (GM) maize and their corresponding nontransgenic parental lines grown under identical conditions. The shotgun-like approach for metabolomics developed in this work includes optimization of metabolite extraction from GM and non-GM maize, separation by CE, online electrospray-TOF-MS analysis, and data evaluation. A large number of extraction procedures and background electrolytes are tested in order to obtain a highly reproducible and informative metabolomic profile. Thus, using this approach, significant differences were systematically observed between the detected amounts of some metabolites in conventional varieties (Aristis, Tietar, and PR33P66 maize) compared with their corresponding transgenic lines (Aristis Bt, Tietar Bt, and PR33P66 Bt maize). Results point to some of these metabolites as possible biomarkers of transgenic Bt maize, although a larger number of samples needs to be analyzed in order to validate this point. It is concluded that metabolomics procedures based on CE-TOF-MS can open new perspectives in the study of transgenic organisms in order to corroborate (or not) their substantial equivalence with their conventional counterparts.Peer reviewe

Capillary electrophoresis sensitivity enhancement based on adaptive moving average method

This research was funded by a grant (No. 09.3.3-LMT-K-712-02- 0202) from the Research Council of LithuaniaIn the present work, we demonstrate a novel approach to improve the sensitivity of the “out of lab” portable capillary electrophoretic measurements. Nowadays, many signal enhancement methods are (i) underused (nonoptimal), (ii) overused (distorts the data), or (iii) inapplicable in fieldportable instrumentation because of a lack of computational power. The described innovative migration velocity-adaptive moving average method uses an optimal averaging window size and can be easily implemented with a microcontroller. The contactless conductivity detection was used as a model for the development of a signal processing method and the demonstration of its impact on the sensitivity. The frequency characteristics of the recorded electropherograms and peaks were clarified. Higher electrophoretic mobility analytes exhibit higher-frequency peaks, whereas lower electrophoretic mobility analytes exhibit lower-frequency peaks. On the basis of the obtained data, a migration velocity-adaptive moving average algorithm was created, adapted, and programmed into capillary electrophoresis data-processing software. Employing the developed algorithm, each data point is processed depending on a certain migration time of the analyte. Because of the implemented migration velocity-adaptive moving average method, the signal-to-noise ratio improved up to 11 times for sampling frequency of 4.6 Hz and up to 22 times for sampling frequency of 25 Hz. This paper could potentially be used as a methodological guideline for the development of new smoothing algorithms that require adaptive conditions in capillary electrophoresis and other separation methodsInstrumentinės analizės APCSistemų analizės katedraVytauto Didžiojo universiteta