Method For Determination Of Concentration Research Articles

Study on Calibration Method for Ion Concentration Measurement Parameters of Ion Selective Electrode Based on Multiple Linear Regression

In the drilling industry, the change of ion concentration of drilling fluid can provide a basis for judging whether it enters the target layer and whether there is a layer penetration phenomenon during the drilling process. Traditional ion concentration determination methods require manual operation, time-consuming and labor-intensive, and most of them have problems such as large measurement errors, measurement cycles and in-line measurements, so for these problems, there is an urgent need for a fast and real-time measurement measurement method. The ion-selective electrode method allows accurate and real-time measurement of chloride, sulfur and potassium ions, but due to the mechanism of the ion selective electrode method, mutual interference occurs when multiple ions coexist. Aiming at the problem of low efficiency of traditional measurement methods and multi-ion interference with each other in ion-selective electrode method. In this paper, an ion concentration calibration method based on multiple linear regression is proposed, and the error cause of the ion selective electrode method is analyzed first, and the measurement value is calibrated in combination with the multiple linear regression model, and finally the ion concentration experimental platform is established, and the results of the measurement accuracy of chlorine, sulfur and potassium ions are improved by more than 90%, which proves the effectiveness of the proposed method.

Interaction between Chinese medicine and digoxin: Clinical and research update.

Background: Digoxin is one of the most widely and commonly used cardiac drug, which plays an irreplaceable role in treating heart failure and arrhythmia. The 2010 Edition of Pharmacopoeia of the People's Republic of China stipulates that the effective range of digoxin plasma concentration is 0.5-2.0ng/mL and it is toxic at plasma concentration >2ng/mL. Its effective plasma drug concentration is close to the toxic concentration, and large individual differences in the effects of the drug have been observed. It is often used in combination with other drugs, but drug interactions have a great impact on the plasma concentration of digoxin and lead to adverse reactions (ADRs), such as poisoning. Most of the reported drug interactions are with Western drugs. However, there are many combinations of traditional Chinese medicine (TCM) and Western drugs, TCM interacting with digoxin comprises monomer components, single medicines, and Chinese patent medicines. Aim of the study: We aimed i) to provide an overview of the TCM formulations affecting the pharmacology of digoxin and their mechanisms of action and ii) to provide a theoretical reference for the safe and rational use of digoxin in combination with TCM in clinical practice and to avoid ADRs. Methods: A literature search of electronic databases, including PubMed, MEDLINE, Cochrane Library, Web of Science, China National Knowledge Infrastructure, and WANFANG Data, was performed to search for articles published between 1 January 1960, and 1 August 2022. Search terms used included "digoxin," "traditional Chinese medicine," "Chinese patent medicine," and "adverse reactions" and their combinations. Results: A total of 49 articles were obtained, including clinical reports, pharmacological experiments and in vitro experiments. The mechanisms of action affecting the pharmacology of digoxin are complex. TCM formulations may affect the pharmacology of digoxin in vivo by influencing gastrointestinal motility or gastric juice pH, regulating P-glycoprotein levels, exerting cumulative pharmacological effects, and enhancing the sensitivity of the heart to digoxin. Although studies have shown that some TCM formulations interact with digoxin, they may be influenced by the complexity of the composition and the pharmacological effects of the TCM, the sensitivity of digoxin concentration determination methods, etc. The results of existing studies are controversial and further in-depth studies are required. Conclusion: Combinations of digoxin and TCM formulations are commonly used. This article serves as a reference to understand the interactions between TCM formulations and digoxin to avoid the occurrence of ADRs and improve the efficacy and safety of digoxin.

Application of Optical Methods for Determination of Concentration of Doxorubicin in Blood and Plasma.

The aim of presented research is to develop a simple and quick method of spectrophotometric detection for the determination of doxorubicin hydrochloride in blood and plasma. Anthracycline antibiotics are among the most effective antineoplastic agents. However, despite their high efficacy in the treatment of various types of cancer, their administration is limited primarily because they exhibit myocardial toxicity. This may be a limiting factor in the dosage of medications; nevertheless, drugs exhibiting this mechanism of action constitute a very important group of chemotherapeutics. One of the more widely studied antibiotics from the anthracycline group is doxorubicin. It exhibits the highest antineoplastic activity from among a number of derivative compounds. Because of the adverse effects of doxorubicin, especially cardiotoxicity, it is important to maintain control of its concentration in body fluids. The method in the study consists of extraction doxorubicin from the plasma or blood and measurements of the absorbance of light in the visible light range in a DOX solution with respect to a reference sample. The research used blood and plasma samples spiked with doxorubicin to give concentrations in the range of 0.2–10 µg/mL. Obtained LODs were 1.6 µg/mL and 1.2 µg/mL, respectively.

Comparative analysis of pharmacokinetics and intestinal absorption of six alkaloids between Sanmiao Pills and Simiao Pills in rats

The present study investigated the differences in pharmacokinetics and intestinal absorption of six alkaloids in Sanmiao Pills and Simiao Pills in rats and explored the different efficacies of the two formulae. After oral administration of Sanmiao Pills and Simiao Pills in rats, blood samples were collected at different time points. Samples were prepared for the determination of six alkaloids in plasma by UPLC-MS/MS. The chromatography was performed on an ACE Excel 3 C_(18 )column with acetonitrile-0.1% formic acid in water as the mobile phase for gradient elution. Analytes were detected in the positive ion mode. Plasma concentrations and pharmacokinetic parameters were calculated. Intestinal absorption of alkaloids was investigated by single-pass intestinal perfusion and absorption parameters of ingredients were calculated. The results showed that the UPLC-MS/MS method for simultaneous determination of concentrations of six alkaloids in plasma was developed and validated by methodological investigations, such as specificity, calibration curves, precision, accuracy, recovery, matrix effect, and stability. The results of the pharmacokinetic assay revealed that C_(max) and AUC values of phellodendrine, berberine, magnoflorine, berberrubine, and jatrorrhizine in Simiao Pills were significantly increased, and CL/F values were reduced as compared with those in Sanmiao Pills, which indicated the increase in plasma concentrations of alkaloids. The intestinal absorption parameters K_(a )and P_(eff) values of phellodendrine, berberine, and jatrorrhizine in Simiao Pills were higher than those in Sanmiao Pills. The intestinal absorption and plasma concentrations of alkaloids in Simiao Pills were significantly higher than those in Sanmiao Pills, suggesting that the composition of Simiao Pills was more conducive to the alkaloids into the blood to resist inflammation and lower uric acid.

Rapid Algae Identification and Concentration Prediction Based on Discrete Excitation Fluorescence Spectra

In this paper, an algal identification and concentration determination method based on discrete excitation fluorescence spectra is proposed for online algae identification and concentration prediction. The discrete excitation fluorescence spectra of eight species of harmful algae from four algal categories were assessed. After determining typical excitation wavelengths according to the distribution of photosynthetic pigments and eliminating strongly correlated wavelengths by applying the hierarchical clustering, seven characteristic excitation wavelengths (405, 435, 470, 490, 535, 555, and 590 nm) were selected. By adding the ratios between feature points (435 and 470 nm, 470 and 490 nm, as well as 535 and 555 nm), standard feature spectra were established for classification. The classification accuracy in pure samples exceeded 95%, and that of dominant algae species in a mixed sample was 77.4%. Prediction of algae concentration was achieved by establishing linear regression models between fluorescence intensity at seven characteristic excitation wavelengths and concentrations. All models performed better at low concentrations, not exceeding the threshold concentration of red tide algae outbreak, which provides a proximate cell density of dominant algal species.

Ionometric Method for Determination of Concentrations of Microelements in Research of Digital Medicine

Ionometric Method for Determination of Concentrations of Microelements in Research of Digital Medicine

Establishment and evaluation of UPLC method for concentration determination of vancomycin in serum

Establishment and evaluation of UPLC method for concentration determination of vancomycin in serum

Quality evaluation method of Lepidium meyenii using UPLC-UV-Q-TOF-MS

In order to evaluate the quality of different varieties of Maca(Lepidium meyenii), the main chemical components in Maca were investigated and a method for simultaneous determination of the main chemical components in Maca was established. UPLC-UV-Q-TOF-MS technology and reference materials were used to identify the structures of 19 main components in Maca. Seven compounds with UV absorption and high contents were selected to establish a simultaneous concentration determination method. The method was employed with a Waters Acquity I-Class~(TM) liquid chromatographic system coupled with a PDA detector and a Waters Acquity Cortecs C_(18)~+ column(2.1 mm×100 mm, 1.6 μm), and acetonitrile-0.2% phosphoric acid water was used as mobile phase(0.45 mL·min~(-1)). The detection wavelength was 195 nm and the column temperature was maintained at 40 ℃. There was efficient separation of seven compounds, p-hydroxybenzylglucosinolate, benzylglucosinolate, N-benzyl-9Z,12Z,15Z-octadecatrienamid, N-benzyl-9Z,12Z-octadecadienamide, N-(3-methoxybenzyl)-hexadecanamide, N-benzyl-hexadecanamide, and N-benzyl-9Z-octadecenamide. The stan-dard calibration curves were good(R~2>0.999). The precision, stability and repeatability were also good. The linearity ranges were 0.197-4.980 μg·mL~(-1) to 193.67-796.8 μg·mL~(-1), and the average recovery rate was 96.71%-103.9%. The average concentration of glucosinolates and macamides in Maca were 1.20% and 0.20%, respectively. Among four kinds of Maca grown in China, the concentration of glucosinolates in yellow Maca and black Maca were relatively high(1.55%), followed by white Maca(0.93%), and purple Maca(0.76%). The concentration of macamides in yellow, purple and white Maca was similar(0.23%-0.29%), however black Maca had significantly lower concentration(0.15%). Peru Maca tested in this study had the lowest concentration of these compounds. This qua-lity evaluation method was fast, accurate, and comprehensively reflects the concentration of the main chemical components in Maca, which provides a useful reference for the quality control and evaluation of Maca.

Optimization and validation of a chiral CE-LIF method for quantitation of aspartate, glutamate and serine in murine osteocytic and osteoblastic cells

Asp, Glu, and D-Ser are chiral amino acids and neurotransmitters binding to the N-methyl-D-aspartate receptor (NMDA) and they participate in glutamate signalization. D-amino acids are increasingly being recognized as important signaling molecules and variations in their levels are considered a marker of different pathologies, however, there is still a lack of knowledge about the role of most of D-amino acids in living organisms such as bone cells. A method for determination of concentrations of L/D-Asp, L/D-Glu and L/D-Ser in two types of bone cell lines: murine osteocytes (MLOY4) and osteoblasts (MC3T3-E1) is presented. It is based on capillary electrophoresis coupled to laser-induced fluorescence detection in normal polarity with 4-fluoro-7-nitro-2,1,3-benzoxadiazole as derivatizing agent suitable for an Argon ion laser source. The electrolyte consists of 137.5 mM borate buffer and 12.5 mM β-cyclodextrins as chiral selectors and the separation lasts 25 min. The method was optimized and validated for specificity, sensitivity, linearity, accuracy, and precision in murine osteocytes and osteoblasts. LLOQ was 0.25 µmol L−1 for the three D-amino acids and linearity was confirmed with r > 0.995 for all D-and L-amino acids. Accuracy ranged between 81.9% and 111.7% and intra-day precision ranged between 1.8% and 10.9%. Concentrations of D- and L- Asp, Glu, and Ser are given and statistical differences between osteocytes and osteoblasts were found. The highest differences corresponded to L- and D-Glu. This method could play a fundamental role in the study of therapeutic targets in the treatment of bone diseases.

Ex-vivo Sensitivity of Plasmodium falciparum to Common Anti-malarial Drugs: The Case of Kéniéroba, a Malaria Endemic Village in Mali.

BackgroundIn 2006, the National Malaria Control Program in Mali recommended artemisinin-based combination therapy as the first-line treatment for uncomplicated malaria. Since the introduction of artemisinin-based combination therapy, few reports are available on the level of resistance of Plasmodium falciparum to the most common anti-malarial drugs in Mali.MethodsFrom 2016 to 2017, we assessed the ex-vivo drug sensitivity of P. falciparum isolates in Kéniéroba, a village located in a rural area of southern Mali. We collected P. falciparum isolates from malaria-infected children living in Kéniéroba. The isolates were tested for ex-vivo sensitivity to commonly used anti-malarial drugs, namely chloroquine, quinine, amodiaquine, mefloquine, lumefantrine, dihydroartermisinin, and piperaquine. We used the 50% inhibitory concentration determination method, which is based on the incorporation of SYBR® Green into the parasite’s genetic material.ResultsPlasmodium falciparum isolates were found to have a reduced ex-vivo sensitivity to quinine (25.7%), chloroquine (12.2%), amodiaquine (2.7%), and mefloquine (1.3%). In contrast, the isolates were 100% sensitive to lumefantrine, dihydroartermisinin, and piperaquine. A statistically significant correlation was found between 50% inhibitory concentration values of quinine and amodiaquine (r = 0.80; p < 0.0001).ConclusionsPlasmodium falciparum isolates were highly sensitive to dihydroartermisinin, lumefantrine, and piperaquine and less sensitive to amodiaquine (n = 2), mefloquine (n = 1), and quinine (n = 19). Therefore, our data support the previously reported increasing trend in chloroquine sensitivity in Mali.

Carboxymethyl cellulose/diclofenac bioactive coatings on AISI 316LVM for controlled drug delivery, and improved osteogenic potential

This work reports on the preparation and systematic testing of a novel multi-layered coating, comprised of the non-steroid anti-inflammatory drug diclofenac and biopolymer carboxymethyl cellulose. Drug release testing was performed on an Automated Transdermal Diffusion Cells Sampling System in combination with UV-VIS spectroscopy as the released drug concentration determination method. The results showed that most of the drug is released in the first six hours, whereas the overall released amount could be tailored through changes in the multi-layered coating composition. Biocompatibility tests performed on human osteoblast cells, showed cell viability improvement between 7% and 17% compared to the control sample. The expression of proteins playing important roles in extracellular matrix production and functioning was performed in order to obtain additional proof of the prepared materials’ osteointegration boosting capacity. Finally, electrochemical measurements confirmed that the coatings do not influence the corrosion susceptibility of AISI 316LVM stainless steel.

Synergistic-antagonistic antibacterial potential of chitosan composites with &lt;i&gt;Moringa oleifera&lt;/i&gt; leaf powder

Chitosan is very useful in everyday life in adsorption, cosmetics, pharmaceuticals, flocculants, anticancer and antimicrobial.In this study, chitosan was synthesized from chitin extracted from crayfish. The methods such as deproteinization, demineralization, and deacetylation respectively were used in the synthesis of chitosan from crayfish. Antimicrobial activity was studied and it was found that chitosan and Moringaleaf powder were good in inhibiting the growth of microorganisms; confirmed by the results obtained from the experiments. In evaluating the antimicrobial activity, the serial dilution method was used towards Escherichia coli, Staphylococcus aureus, Salmonella typhi, Proteus bulgaris and Streptococcus pneumonia. The antibacterial activity of chitosan composite with the leaf powder of Moringa oleifera Lam., was determined, using well diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration determination method. The composites show the synergistic effect at the higher chitosan to lower Moringa concentration and antagonistic effect at higher Moringa to lower chitosan concentrations in all the test organisms. The consequences of this research suggest that the chitosan, Moringa leaf powder, and their composites can be used to discover an antibacterial agent for developing new pharmaceuticals to control studied human pathogenic bacteria responsible for severe illness. Moringa oleiferais widely used in food and folk medicine; while chitosan is widely useful in food, detergents, textiles, leather, paper, pharmaceuticals, and cosmetics industries. Synergism/antagonism of Moringa-chitosan composites was based on concentrations on the tested organisms.Keywords: Antimicrobial, Biopolymer, Health, Synergism/antagonism

Silver – soluble compounds. Determination in workplace air

Silver compounds are generally insoluble in water. The few soluble silver compounds include, e.g. silver nitrate, silver fluoride, silver perchlorate. These compounds are used in chemical analysis and organic catalysis to produce other silver compounds (e.g. halides), explosives, antiseptics (in medicine ), mirrors; they are also used in classical photographic technique. Soluble silver compounds are irritating and corrosive to the skin and mucous membranes of the eyes; they also cause permanent damage to the eyes and dysfunction of the respiratory and nervous systems. Maximum admissible concentrations (MAC) for soluble silver compounds, expressed as silver, was set at 0,01 mg/m3. The aim of the study was to develop a method for determination of concentrations of soluble silver compounds in the air at workstations in the range from 1/10 to 2 MAC value. The developed method of determination consists in: taking an air sample on a membrane filter, washing out soluble silver compounds from the filter with deionized water and determination of these compounds as silver by flame (air-acetylene) atomic absorption spectrometry (F-AAS). The method enables the determination of silver in the concentration range of 0.070÷2.00 µg/ml. The obtained silver calibration curve is characterized by a correlation coefficient R2 = 1.0000. The limit of silver detection (LOD) is 0.009 µg/ml, the limit of quantification (LOQ) is 0.027 µg/ml, and the recovery rate is 0.99. The developed method allows the determination of soluble silver compounds in the air at workstations in the concentration range of 0.001÷0.028 mg/m3 (for an air sample with a volume of 720 l), which corresponds to 0.1÷2.8 times the MAC value. The method is characterized by good precision and accuracy and meets the requirements of the European standard PN-EN 482 for chemical determination procedures. The method for the determination of soluble silver compounds has been recorded in the form of the analytical procedure set out in the Annex.

Water absorption of fine recycled aggregates: effective determination by a method based on electrical conductivity

The high absorption of fine recycled aggregates is indicated as the main difference with respect to fine natural aggregates. This property determines the extra amount of water to be added during mixing to avoid a loss in workability when these aggregates are used for making concrete. Although several methods have been proposed for its determination, none of them has been standardized or has achieved full consensus. In this paper, a method for the determination of absorption based on electrical conductivity is applied. The results from this method and other particular methods proposed in the literature for this type of aggregate are analyzed and compared regarding their representativeness. The outcomes of this study show the suitability of the conductivity method for the effective determination of water absorption of fine recycled concrete aggregate, with relatively low variation and incidence of the operator.

Monolith affinity chromatography for the rapid quantification of a single-chain variable fragment immunotoxin.

We developed a novel analytical method for concentration determination of tandem single‐chain antibody diphtheria toxin (immunotoxin). The method is based on polymethacrylate monoliths with Protein L ligands as the binding moiety. Different buffers were tested for elution of the Protein L‐bound immunotoxin and 4.5 M guanidinium hydrochloride performed best. We optimized the elution conditions and the method sequence resulting in a fast and robust method with a runtime <10 min. Fast determination of immunotoxin is critical if any process decisions rely on this data. We determined method performance and a lower limit of detection of 27 μg/mL and a lower limit of quantification of 90 μg/mL was achieved. The validity of the method in terms of residual analysis, precision, and repeatability was proven in a range from 100 to 375 μg/mL. The short runtime and ease of use of a high‐performance liquid chromatography method is especially useful for a process analytical tool approach. Bioprocesses related to immunotoxin where fermentation or other process parameters can be adjusted in accordance to the immunotoxin levels will be benefited from this method to achieve the highest possible purity and productivity.

Real-time monitoring of nanoscale TiO2 concentration by spectrophotometry: implications of agglomeration due to natural organic matter and multivalent ions

ABSTRACTThe study of the environmental fate of nanoscale TiO2 (n-TiO2) is a major recent research focus which requires a rapid and accurate on-site concentration determination method. Inductively coupled plasma mass spectroscopy (ICP-MS) has been the most widely used method for determining the concentration of n-TiO2 in environmental samples; however, poses many challenges, such as hazardous hydrofluoric acid pre-treatment and clear limitations in mobile on-site measurement and monitoring. This study demonstrates that industrial wastewater containing natural organic matter (NOM) can present a major challenge to the analysis of n-TiO2 by ICP-MS, and introduces a spectrophotometry technique that can be used as an alternative. The results suggest that spectrophotometry methods can be more accurate than slurry nebulization ICP-MS for measuring the concentrations of n-TiO2 in wastewater containing NOM under low salt conditions. Furthermore, this study demonstrates the use of a portable flow-through spectrophotometer for use in applications of wastewater treatment and environmental monitoring with real-time feedback of n-TiO2 concentrations. The ability to detect and monitor n-TiO2 will greatly assist in improving the understanding of hazards and risks that emerging nanomaterials pose to the environment and the public health.

ВОПРОСЫ ПРИМЕНЕНИЯ ДИСТАНЦИОННЫХ МЕТОДОВ ОПРЕДЕЛЕНИЯ КОНЦЕНТРАЦИИ ФОСФОРА В ПОЧВЕ

ВОПРОСЫ ПРИМЕНЕНИЯ ДИСТАНЦИОННЫХ МЕТОДОВ ОПРЕДЕЛЕНИЯ КОНЦЕНТРАЦИИ ФОСФОРА В ПОЧВЕ

2-Ethylhexan-1-ol Determination in working air

2-Ethylhexan-1-ol (2-EH) is a colorless liquid that is poorly soluble in water but soluble in most organic solvents. On an industrial scale, 2-Ethylhexanol is produced in the aldol condensation of n-butyraldehyde. It is mainly used as an alcohol component in manufacturing ester plasticizers for soft poly(vinyl chloride) (PVC). The aim of this study was to develop a method for determining concentrations of 2-ethylhexan-1-ol in workplace air in the range from 0.54 to 10.8 mg/m3, in accordance with the requirements of Standard No. EN 482. The study was performed using a gas chromatograph (GC) with a flame ionization detector (FID) equipped with a capillary column Stabilwax (60 m × 0.32 mm, 0.5 μm). The method is based on the adsorption of 2-ethylhexan-1-ol vapours on activated charcoal, desorption with dichloromethane and GC-FID analysis. The use of Stabilwax column enabled selective determination of 2-ethylhexan-1-ol in the presence of other substances. The measurement range was from 0.013 to 0.26 mg/ml for a 24-L air sample. The limit of detection was 8.05 ng/ml and the limit of quantification was 24.14 ng/ml. This method is precise, accurate and it meets the criteria for procedures for measuring chemical agents listed in Standard No. EN 482. The method can be used for assessing occupational exposure to 2-ethylhexan-1-ol and associated risk to workers’ health. The developed method of determining 2-ethylhexan- 1-ol has been recorded as an analytical procedure (see appendix).

2,2’-Oxydiethanol Determination in workplace air

2,2’-Oxydiethanol (DEG) is a colorless and oily liquid. 2,2’-Oxydiethanol is a by-product of ethylene glycol production. 2,2’-Oxydiethanol is used in the production of unsaturated polyester resins, plasticizers, acrylate and methacrylate resins, and urethanes. 2,2’-Oxydiethanol is a mild irritant. The aim of this study was to develop a method for determining concentrations of 2,2’-Oxydiethanol (inhalable fraction) in workplace air in the range from 1/10 to 2 MAC values. The study was performed using a gas chromatograph (GC) with a flame ionization detector (FID) equipped with a capillary column Stabilwax (60 m × 0.32 mm, 0.5 μm). This method is based on the adsorption of 2,2’-oxydiethanol on a polypropylene filter, extraction with methanol and chromatographic analysis of the obtained solution. The masurement range was from 1 to 20 mg/m3 for a 720-L air sample. Validation of the method was performed in accordance with Standard No. EN 482. The following validation parameters were determined: detection limit – 0.5 μg/ml, determination limit – 1.5 μg/ml, the overall accuracy of the method – 5.25%, the relative total uncertainty of the method – 11.5%. This analytical method enables selective determination of 2,2’-Oxydiethanol in workplace air in the presence of other alcohols at concentrations from 1 mg/m³ (1/10 MAC value). The method is precise, accurate and it meets the criteria for procedures for measuring chemical agents listed in Standard No. EN 482. The developed method of determining 2,2’-oxydiethanol has been recorded as an analytical procedure (see appendix).

X-ray fluorescence-based method for the quantitative determination of uranium in the aqueous solutions

Currently, one of the important issues in the field of nuclear technology is providing special handling with respect to nuclear materials, due to their energy and commercial significancy, as well as their potential radiation contamination threat. There is a necessity to have information about the full qualitative and quantitative composition of the sample as a part of special handling with nuclear materials. Spectrometric methods solve this problem effectively. One of these methods is the X-ray fluorescence analysis, which is fast, nondestructive and environmentally friendly with a high accuracy and reproducibility of the results. Development of uranium quantitative determination method in aqueous solutions to solve the problems of accounting and control of nuclear materials is the subject of research in this article. The development of the uranium concentration determination method in the aqueous solutions of uranyl nitrate UO2(NO3)2 was carried out using Spectroscan MAKC-G – wavelength dispersive crystal diffraction XRF spectrometer.