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Qualitative and quantitative research on pesticide chemical admixture in liquids
Abstract
Express electric monitoring of a chemical composition is proposed to be conducted by identifying an electric index that corresponds to regulatory chemical threshold concentration and is selective for the monitored substance. Theoretical and experimental possibilities of combining the known classical methods have been scrutinized in order to improve the characteristics of an output signal for determining the monitored substance concentrations - the pollutants in liquids (juices, vegetable and fruit samples or wastewaters). The monitor-technique implies the measurement of a reactive immitance component (a component of complex conductivity) at the defined frequency value selective for copper sulfate that is compared to the relevant regulatory value identified in the process of studying a standard pattern with the given ThC.
... Instrumentation and measurements play a very important role in the modern economy [1]. The accuracy of measurements predetermines the quality of the production [1] and its reliability [2][3][4], safety [5], and service lifespan [2]. Modern industry and scientific research requires even better and more-accurate sensors, data acquisition units, and systems [6]. ...
The best method to prevent error due to inhomogeneity is to use a new thermocouple design—the thermocouple with controlled temperature field (TCTF). It uses the auxiliary furnace to control the temperature field along its legs. Such a design allows setting and maintaining the temperature field along the thermocouple (TC) legs for the sensor. Error due to inhomogeneity of TCs cannot appear in a stable temperature field. However, the auxiliary furnace and TCs, to control the temperature field, have errors, so the temperature field along the main TC is maintained with some error. This leads to residual error due to acquired inhomogeneity of the TCTF. We constructed the mathematical models to fit the experimental data of error due to drift for the type K TC. The authors used the constructed models to study error due to inhomogeneity of the TCTF and the conventional type K TC under considerable changes in temperature field. The main results of modelling are as follows: (i) if the changes in temperature field exceed 7 °C, error due to inhomogeneity of the TCTF is lesser than that of the conventional TC; (ii) the maximum error due to inhomogeneity of the conventional type K TC is 10.75 °C; (iii) the maximum error due to inhomogeneity of the TCTF is below 0.2 °C.
... 4. It is established that the modified electrode of carbon electrodes achieves the amplification of the electrical signal in the presence of copper salts in the liquid, which allows the measured value of the reactive component of conductivity, at a certain frequency, to quickly and selectively control the presence and small concentrations (from thousandths of g/l) of vitriol in a multicomponent fluid of unknown composition [4][5][6][7][8][9][10]. Table 1 illustrates the measurement results, which confirm the points 1 and 2 above. ...
The authors substantiated the relevance of scientific studies of the electrical properties of multicomponent liquids. Such liquids are real objects that require stock control during operation. This applies to many areas of human activity: environmental monitoring, the chemical and food industries, medicine, and the like. Laboratory methods are unable to meet the following requirements.
The electrical properties of substances, including liquids, have been well studied by scientists. In addition, the high level of modern experimental technology allows to combine theoretical and practical achievements, in this case chemical and physical-electrical sciences.
In the theoretical provisions regarding the electrical methods for the study of the composition of liquids, the authors, based on the classical knowledge of dielectric conductivity physics, argue for their use for applied chemical measurements. After all, physico-chemical electrical measurements have long been used for the study of two-component standard solutions. The authors propose to improve such measurements and use them for multicomponent liquids. At the same time, it is proposed to use the developed primary converters and a new informative parameter - complex conductivity components (admittance).
On the basis of the obtained experimental results, the research conditions are formulated. The measuring system consists of a primary capacitive transducer (carbon electrodes in vessels with the test liquid); multi-frequency current generator (RLC meter) and computer.
The dependences of the values of the complex components of conductivity on the frequency of the electromagnetic field between the electrodes for liquids with dissolved substances of different chemical nature and concentrations were investigated. Some individual properties have been established for such substances, which allow to develop methods and methods of operational control of the composition of multicomponent liquids by electrical parameters.
The article discusses the scientific and practical results of research and the advantages of the developed methods and methods of composition control for real liquids. Also, some of the scientific facts obtained allow to further develop and develop methods of electro-chemical research with a wider range of constituents, for low concentrations and without complex laboratory manipulations.
... Thus the problem of creating and evolving the methods free from the above mentioned disadvantages is of significance. An admittance method, one of the most promising, is based on the measurement of active G (conductance) and reactive B (susceptance) components of complex conductivity Y [3,4]. ...
In recent years, a significant increase in the application of chemotherapeutic
drugs is observed, along with their appearance in the environment (Santos et al.,
2018; Souza et al., 2018).
For many years, there were no standards regulating the limitations on the
introduction of medicines to the environment. Significant amounts of these
pollutants were discharged with municipal wastewater to treatment plants, which
were not adapted for their removal. It was shown that the standard technologies
are characterized by low efficiency in terms of removing active substances of
drugs and their metabolites. Therefore, it is necessary to implement additional
steps in the technological system of treatment plants, based on advanced oxidation
processes such as ozonation and UV irradiation (Olalla et al., 2018). Moreover,
numerous substances negatively impact the biotechnological processes, inhibiting
biochemical reactions and multiplication of utilized microorganisms. Many studies
on micropollutants focus only on the efficiency of their removal, not accounting
for the hindrance of the entire process (Avella et al., 2010).
Determinations of cisplatin, oxaliplatin, and carboplatin as well as their
derivatives was carried out with ICP-MS method, using Agilent 8900 apparatus.
The standard curve method and an external standard will be used. Mineralization
in aqua regia will be performed in Mars microwave digestion system. In the case
of the samples with high organic substances content, additional oxidizing media
will be used if necessary (H2O2, HClO4).
Concentration levels ranging from 0.7 to 185,7 μg·L-1 were obtained as a sum
of analysed compounds.
Determinations of iphosphamide and cyclophosphamide was carried out with
HPLC-MS/MS method, using Agilent 1200 series HPLC and Q-trap 4000
MS/MS system. Results showed that cyclophosphamide was present in hospital
wastewater in the range 375–5141 ng·L-1, while iphosphamide was present in
some months in effluents from only one wastewater treatment plant and hospital
effluents in the range 56–1413 ng·L-1.
Results of our investigations (12 samples) are similar to the results presented.
The ability to determine and control the normalized concentrations has been established using the experimentally obtained dependencies of the active and reactive constituents of conductivity in the wide frequency range of the electromagnetic field on the composition of the multicomponent fluid and the impurity concentrations. For high-aqueous substances dissolved in water (cooling liquids), a method for controlling the qualitative and quantitative composition is developed. It is based on the comparison of the measured and experimentally established active conductivity component and the comparison of the corresponding dependencies in the frequency field of the reactive component of conductivity. The developed electric method allows quantitative and qualitative estimation of the composition of the coolant on the contents of controlled components in the short time (up to 2 seconds) in a non-laboratory environment and to ensure uninterrupted operation of the equipment.
The results of experimental investigations fostering the performance of efficient measurement of liquid characteristics are proposed in the article. The experiments made within the vast range of electromagnetic frequencies have proved the dependences of imitance parameters on substance concentrations in multicomponent liquid which enables us to determine and control the standardized characteristics, according to those parameters.
With rising healthcare costs and to improve patient health, diagnostic laboratories have been challenged to develop new tests that are easy, reliable, cost-effective and accurate and to optimize existing protocols by making them faster and more beneficial. Determination of ascorbic acid in sample is one of the most vital biochemical parameters in healthcare. With the availability of new materials used for developing new sensing techniques has led to remarkable innovations in the design and construction of ascorbic acid biosensors. The present review describes the specifications of most of the electrochemical ascorbic acid biosensors reported till date.
In this paper an electrochemical sensor was prepared by modification of carbon paste electrode with a nanostructured mesoporous material. The electrooxidation of norepinephrine (NE), paracetamol (AC) and folic acid (FA) was studied at this electrode by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). CV experiments showed that the oxidation overpotential of these substances decreased and their oxidation current increased sharply at the modified electrode rather than bare carbon paste electrode. The overlapped DPV peaks of NE, AC and FA has been resolved into three separated peaks by the electrochemical sensor. DPV peak currents increased linearly with concentration over the range of 7.0 × 10−8 to 2.0 × 10−3, 5.0 × 10−7 to 2.2 × 10−3 and 5.0 × 10−6 to 2.0 × 10−3 M for NE, AC, and FA, respectively. Also, the proposed electrochemical sensor was used for the determination of these substances in some real samples.
A graphene, chitosan and 1-ethyl-3-methylimidazolium tetrafluoroborate composite was prepared and modified on the surface of a carbon molecular wire electrode. The fabricated electrode was characterized by different methods such as scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical behaviors of guanosine-5′-triphosphate (GTP) were carefully studied on the modified electrode. The electrochemical parameters such as the charge transfer coefficient (α) and the electrode reaction standard rate constant (ks) were calculated with the results as 0.57 and 1.56 × 10−4 s−1. Under the optimized conditions, the oxidation peak current was proportion to the GTP concentration in the range from 0.007 to 70.0 μmol/L with the detection limit of 0.232 nmol/L (S/N = 3). Moreover, the proposed method showed good selectivity to the GTP detection without the interference of coexisting substances, and was further applied to the artificial samples determination with satisfactory results.
Electric sensors for express-method of liquid quality level monitoring
- P Stolyarcuk
- V Yatsuk
- M Mikhalieva
Results of experimental exploring the model water solutions after a new electric impedance method Digest of 'Lviv Polytechnic' National University on Automatics, Measurement andManagement
- M Mikhaleva
Application of capacitance sensors in the rapid control of multicomponent solution parameters
- J Majewski
- P Malacziwskyj
- V Yatsuk