Analytical Chemistry

Kalina Kamenova completed her Bachelor of Science degree in Computer Chemistry at Sofia University Kliment Ohridskia. In 2015, she obtained Master of Science degree in Medicinal Chemistry from Sofia University “St. Kliment Ohridskiâ€. Presently, she is a regular PhD student in Department of Analytical Chemistry. She is a co-author of five scientific papers and she has participated in eight national and six international conferences. She is a member of an interdisciplinary team of 11 national and two international projects. She received two Alma Mater Awards from the Rector of Sofia University for her achievements in science.

Lead (Pb) is a toxic metal, found in nature in the form of sulphide ores. Pb enters into the human body through the respiratory system and gastrointestinal tract. More than 1/3 of the absorbed Pb spreads to the organs and tissues. Lead exerts toxicity on the central nervous system, haematopoiesis, excretory, cardiovascular, and endocrine and immune systems, gastrointestinal tract, and reproductive functions in men and women. One of the possible mechanisms by which lead causes its toxic effects involves alteration of bio-metal ions homeostasis. The aim of our study was to evaluate the effects of Pb on the bio-distribution of calcium (Ca), copper (Cu), iron (Fe), lead (Pb) and zinc (Zn) in mice, subjected to sub-acute Pb-poisoning. 60-day-old male ICR mice were randomized into two groups - control group (untreated animals) and toxic group exposed to Pb(II) nitrate treatment in an maverage daily dose of 80 mg/kg b.w. for two weeks. Treatment of mice with Pb(II) nitrate increased significantly the concentration of the toxic metal ion in their spleen, lungs, kidneys, heart, liver, testes and brain compared to the untreated control animals. In this study, we found that the intoxication of mice with Pb(II) nitrate for 14 days increased significantly the concentration of Ca in spleen, of Cu and Fe in heart, compared to control group. Our study demonstrates that Pb(II) intoxications caused a significant depletion of concentrations of Ca in kidneys, lungs and testes, of Cu in spleen and testes, of Zn in lungs and Fe in spleen, liver and heart, compared to untreated animals. Herein we present for the first time a detailed study on the effect of lead on the biodistribution of essential metal ions in mice.

Adebimpe Esther Ofusori is currently studying at School of Chemistry and Physics-University of KwaZulu-Natal, South Africa.

Celosia trigyna L which belongs to the plant family Amaranthaceae, is a medicinal plant used in orthodox medicine to treat several diseases such as sores, boils, costal pains diarrhoea, chest related complications and menstrual cramps. In this study, the concentration of the elements in the plants and growth soil from the western region of Nigeria was investigated. The, soil organic matter (SOM), pH and cation exchange capacity (CEC) in the growth soil was also determined in order to validate the soil quality effects on elemental uptake. The elemental concentration in the leaves were found to be in decreasing order of Ca>Mg>Fe>Mn>Zn>Cu>Pb>As>Ni but variation of Pb and Ni was observed within the plant parts. The proximate analysis in the leaves were ash (22±0.58%), crude fibre (1.4±0.2%) protein (25.6±1.05%) and fat (1.6±0.57%) P<0.05. Calcium and Zn were found to contribute between 13.3-17.3% and 6.1-8.4%, respectively, towards their recommended dietary allowance. However, Fe and Mn contribute above 50% towards its RDA for these elements which makes the plant suitable for treating deficiencies of these elements. Hierarchical cluster analysis indicated that some elements absorbed by the plant were from common sources. Also, correlation coefficient shows synergistic and antagonistic relationships between soil parameters and elements across the plant parts. Efficient translocation of nutrients was observed in the leaves compared to the stem as the translocation factor (TF>1) for most of the elements. Cadmium was not detected in the leaves but lead and arsenic were observed at low concentrations well below the tolerable upper intake level (ULs), making them safe and beneficial for human consumption.

Tu Yifeng has completed his PhD in Analytical Chemistry at Nanjing University. He has worked as Professor of Analytical Chemistry at Soochow University, China. He has published more than 100 papers in reputed journals and has been serving as a Director of PhD in the field of “Electrochemical biosensing and electrochemiluminescent analysis”.

Cellular metabolism monitoring plays a critical role in cell therapy; clinical transplantation and effective drug screening since high quality control of cultivated cells are required. Cellular metabolism state can be reflected by the parameters including pH, oxygen, glucose, and carbon dioxide etc. In particular, cellular oxygen metabolism is more important, it not only directly relates to adenosine triphosphate production and energy consumption, but is also probably to trigger the cell oxidative stress (OS) in abnormal conditions. The OS is a condition of the imbalance between the systemic manifestation of reactive oxygen species (ROSs), e.g. O2− (superoxide radical), OH• (hydroxyl radical) and H2O2 (hydrogen peroxide), etc., and the ability to detoxify them or to repair the resulting damage. The aim of this study is to develop a novel sensing platform for the investigation of cell oxygen metabolism. With chitosan@TiO2 nanocomposites decorated on the surface of indium tin oxide glass to act as sensor substrate which can effectively absorb A549 cells, and to sensitize the electrochemiluminescence (ECL) of luminol, the cell-based sensor can be built up. On this sensing platform, the ECL output is dependent on the level of ROSs, which was evidenced by the injection of resveratrol, a typical antioxidant. The results indicated that the ECL sensing signal was quenched by the resveratrol within its concentration range from 0.1 nM to 2.97 μM. Thus, it is believable that the ECL of luminol is sensitively responding to oxygenic matters on this cell biosensing platform, will be powerful for cell oxygen metabolism monitoring.

Yuliya Petrova has completed her PhD in Analytical Chemistry from Moscow State University, Russia. She works as an Associate Professor of Analytical Chemistry at Surgut State University, Russia. She has published more than 15 papers in reputed journals and serves as a Director of Institute of Natural Science and Engineering. Her research interests are related to hybrid sorption- kinetic methods of analysis, and recently to surface molecular imprinting on inorganic carriers. Currently, she is working on a project on creation of highly selective sorbents, based on molecular imprinted polymer films on the surface of inorganic materials (TiO2, SiO2, layered double oxides etc.) for extraction and determination of biologically active natural compounds.

Surface molecular imprinting is the technology of obtaining films with fingerprints of molecules on the surface of carriers. It has several advantages in comparison with traditional molecular imprinting through the bulk synthesis: increasing the availability of molecular fingerprints for target molecules and sorption capacity, as well as reducing the cost of sorbent material. In this work, glutathione–silica hybrid monolithic polymer was proposed to produce molecularly imprinted films on the surface of silica microparticles. A monolithic polymer was prepared by thiolene click reaction between glutathione and 3-methacryloxypropyltrimethoxysilane initiated by azobisisobutyronitrile on heating in the presence of methylene blue as a template. Firstly, the samples were washed several times with ethanol and a mixture of methanol: acetic acid. However, the degree of methylene blue removal did not exceed 20%. Optimization of the solution composition allowed increasing the degree of removal up to 27%. For this purpose, seven mobile phases used in HPLC for determination of methylene blue were studied. After washing with a mixture of methanol: formic acid the rebinding was studied: the maximum imprinting factor was 2.9, and the maximum sorption capacity was 29 μmol/g. It was shown that after washing the samples with ethanol, these values were significantly less and amounted to 1.2 and 15, respectively. The binding kinetics of methylene blue to molecularly imprinted and non-imprinted films obeys a pseudo-first-order model with a rate constant of about 2·10-3 min-1. However, the degree of recovery in case of rebinding the template with molecular imprinted samples was 1.5 times higher than with un-imprinted ones and went up to 42%. The surface imprinting was compared with imprinting by bulk synthesis. The maximum imprinting factor in this case amounted to 2.5, and the maximum sorption capacity was 22 μmol/g, which is 24% less than one of the surface imprinted polymer.

Jin Gyeong Son has completed her PhD in Analytical Chemistry from Korea Advanced Institute of Science and Technology and Postdoctoral studies from Korea Research Institute of Standard and Science. She has published more than 58 papers in reputed journals and has been serving as a Director of spin off Tx Biotechnology Enterprise.

25-hydroxyvitamin D (25-OHD) is known to be the best indicatorof vitamin D status in the body. There are two major vitamin D metabolites in the circulation, 25-hydroxyvitamin D3 (25-OHD3) mainly derived from vitamin D3 produced by sunlight in the skin and 25-hydroxyvitamin D2 (25-OHD2) derived from plants in the diet. Severe vitamin D deficiency below 20 nmol/L causes rickets in children and osteomalacia in adults. Less severe deficiency, where the 25-OHD concentration is between 20 and 30 nmol/L, causes secondary hyperparathyroidism and increases in bone turnover and bone loss. Furthermore vitamin D insufficiency has been implicated in an extremely wide range of clinical disorders. Quantitative analysis of 25-hydroxyvitamin D, used as a bio marker for disease judgment, is a necessary process to find these risk factors. Here, we report the development of a precise and sensitive method to determine 25-hydroxyvitamin D (25- OHD3) using Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) after derivatization with a Betaine Aldehyde (BA). The method involves the use of deuterated [2H3]-25-OHD3 as an internal standard compound for 25-OHD3. We conclude that this novel ToF-SIMS method would be useful for the evaluation of the vitamin D provide useful information in the diagnosis of vitamin D insufficiency/deficiency, as well as for the treatment and prevention of osteoporosis with vitamin D.

Yasumasa Kanekiyo completed his BSc and MSc from Nagoya University in 1993 and 1995, respectively. He obtained his PhD in Chemistry from Kyushu University under the supervision of Prof. Seiji Shinkai in 2001. From 2001 to 2006, he worked as Postdoc at National Institute of Advanced Industrial Science and Technology (AIST), Japan. Since 2006, he has worked as an Associate Professor at Kitami Institute of Technology, Japan.

Novel colorimetric sensing mechanisms toward various reactive oxygen species such as hydrogen peroxide, hypochlorite, etc., have been developed. By copolymerizing boronic acid and tertiary amine monomers with acrylamide and a cross-linker on a glass plate, a boronic acid-containing thin film was obtained. After immersing in aqueous solutions containing various concentration of hydrogen peroxide, the thin film was successively immersed in an anionic dye solution. The amount of adsorbed dye increased with increasing hydrogen peroxide concentration, whereas the dye was scarcely adsorbed in the absence of hydrogen peroxide. These phenomena should be derived from a change in the charge state of the thin film in response to the conversion of negativelycharged boronate group into non-charged phenol group by the reaction with hydrogen peroxide. Thus the thin film changed from colorless to color in response to hydrogen peroxide. Various pattern of color change was achieved by changing conditions such as monomer composition of the thin film, charge and color of dyes, etc. For the sensing of hypochlorite, thin films containing hydroxyl groups were also utilized. It was revealed that thin films having tertiary amino or hydroxyl groups but not have boronic acid group are effective for the selective detection of hypochlorite. Since hypochlorite is highly oxidative, these functional groups are converted into negatively-charged carboxylate group. As the results, the thin films become possible to adsorb cationic dyes after reaction with hypochlorite.

E Sadeghi received BS degree in Applied Chemistry from Khajeh Nasir Toosi University of Technology and was started Analytical Chemistry at Shahid Beheshti University under the Guidance of Professor Alireza Fakhari in 2015. He has experiences in the field of several extraction and purification techniques such as electromembrane extraction, headspace solid-phase and dispersive liquid–liquid microextraction in real samples such as urine and plasma and waste water. His current research interests include “Evaluation and separation of achiral and chiral drug by variety chiral selector such as cyclodextrin, maltodextrin, antibiotic compounds and so on as additive to background electrolyte in CE-based analysis’’.

Electromembrane extraction (EME) is a sample preparation technique in pharmaceutical, chemical, clinical and environmental analysis. This technique uses electromigration across artificial liquid membranes for selective extraction of analytes and sample enrichment from complex matrices. This method has many advantages such as simplicity, rapid, low-cost, low LOD, high preconcentration factor and high recovery. In the present work, simultaneous preconcentration and determination of two basic drugs namely metoclopramide (MCP) and ondansetron (OSN) were studied using EME as a suitable extraction method, followed with capillary electrophoresis (CE) using ultraviolet (UV) detection as separation technique. The drugs were extracted from 4 ml sample solutions, through a supported liquid membrane (SLM) consisting 2-nitrophenyloctylether (NPOE) impregnated in the walls of a polypropylene hollow fiber, and into a 20 μL acidic aqueous acceptor solution resent inside the lumen of the hollow fiber with a potential difference applied over the SLM. The variables of interest, such as chemical composition of the organic liquid membrane, stirring speed, extraction time and voltage, pH of donor and acceptor phases and salt effect in the EME process were investigated and optimized. Under optimal conditions NPOE as SLM, stirring rate of 1000 rpm, 200 V potential differences, 20 min as the extraction time, acceptor phase HCl (pH 1.0) and donor phase HCl (pH 1.5). After the microextraction process, the extracts were analyzed by CE with optimum conditions phosphate running buffer (pH 2.0), applied voltage of 20 kV and 25°C. Under the optimum conditions, limits of detection (LOD) and quantification (LOQ) for MCP and OSN were 2.31-2.68 and 7.72-8.91 ng mL-1 respectively. Preconcentration factor and RSD for five replicates of each drugs were calculated to be 200 and 4.06-3.93 respectively. Finally, the applicability of this method was studied by the extraction and determination of these drugs in urine samples with recovery percentages of 87–92%..