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Pharmacokinetics of isocorynoxeine in rat plasma after intraperitoneal administration by UPLC–MS/MS
Authors: Haichao Zhan, Zhen Wei, Ke Ren, Shuhua Tong, Xianqin Wang and Qing Wu

Isocorynoxeine is one of the main alkaloids in Chinese medicinal herbs, and has pharmacological activities such as antihypertensive, sedative, anticonvulsant, and neuronal protection. It is an effective component of Uncaria for the treatment of hypertension. In this study, we used a fast and sensitive ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) to detect isocorynoxeine in rat plasma and investigated its pharmacokinetics in rats. Six rats were given isocorynoxeine (15 mg/kg) by intraperitoneal (i.p.) administration. Blood (100 μL) was withdrawn from the caudal vein at 5 and 30 min and 1, 2, 4, 6, 8, 12, and 24 h after administration. Chromatographic separation was achieved using a UPLC BEH C18 column using a mobile phase of acetonitrile–0.1% formic acid with gradient elution. Electrospray ionization (ESI) tandem mass spectrometry in the multiple reaction monitoring (MRM) mode with positive ionization was applied. Intra-day and inter-day precisions (relative standard deviation, %RSD) of isocorynoxeine in rat plasma were lower than 12%. The method was successfully applied in the pharmacokinetics of isocorynoxeine in rats after intraperitoneal administration. The t 1/2 of isocorynoxeine is 4.9 ± 2.1 h, which indicates quick elimination.

Open access

The authorities have identified an emerging trend where over-the-counter products, represented as dietary supplements, contain hidden active ingredients that could be harmful. Consumers may unknowingly take products laced with varying quantities of approved prescription drug ingredients, controlled substances, and untested and unstudied pharmaceutically active ingredients. Hidden ingredients are increasingly becoming a problem in products promoted for sexual enhancement, weight loss, or bodybuilding. The tests have revealed the presence of some undesired substances like sildenafil, tadalafil, vardenafil, and their analogues in tainted sexual enhancement products. The content of these substances is usually around the daily curative dose. A simple high-performance liquid chromatography (HPLC) method for simultaneously determination of sildenafil, vardenafil, tadalafil, dapoxetine, yohimbine, and sibutramine was developed and validated. InfinityLab Poroshell 120 EC-C18 (150 '4.6 mm '4 μm particles) was used, as well as a diode-array detector (DAD) at 230 nm, and a gradient flow with 0.030 М ammonium acetate buffer and acetonitrile. The method is linear in the following range: 2.5–37.5 μg/mL for yohimbine, 2.06–30.9 μg/mL for vardenafil, 2.0–30.0 μg/mL for sildenafil, 3.1–46.5 μg/mL for tadalafil, 1.98–29.7 μg/mL for dapoxetine, and 2.2–66.0 μg/mL for sibutramine. The linearity coefficient is R 2 = 1 for all substances. Model matrices were spiked, and the analytical recoveries for all substances are in the range 97.5%–99.5%. The method exhibited an upper hand compared with previously reported methods in terms of speed and simplicity. Additionally, the mobile phase (also used as extracting, column washing, and diluting solvent) was composed of only buffer and acetonitrile, which rendered the method much cheaper than others.

Open access
Determination of diosmetin-7-o-β-d-glucoside in rat plasma by UPLC–MS/MS
Authors: Jianbo Li, Zheng Yu, Cheng Han, Zhening Wang, Yujie Hu, Congcong Wen and Chongliang Lin

In this study, we used UPLC–MS/MS to determine diosmetin-7-o-β-d-glucoside in rat plasma and investigated its pharmacokinetics in rats. Six rats were given diosmetin-7-o-β-d-glucoside (5 mg/kg) by intravenous (i.v.) administration. The blood (150 μL) was withdrawn from the caudal vein after administration. Diazepam was used as an internal standard (IS), and a one-step acetonitrile precipitation method was used to process the plasma samples. Chromatographic separation was achieved using a UPLC BEH C18 column using a mobile phase of acetonitrile–0.1% formic acid with gradient elution. Electrospray ionization (ESI) tandem mass spectrometry in multiple reaction monitoring (MRM) mode with positive ionization was applied, 463.1 → 301.0 for diosmetin-7-o-β-d-glucoside, m/z 285.1 → 193.0 for diazepam (IS). Intra-day and inter-day precision of diosmetin-7-o-β-d-glucoside in rat plasma were less than 14%. The method was successfully applied in the pharmacokinetics of diosmetin-7-o-β-d-glucoside in rats after intravenous administration. The t 1/2 of diosmetin-7-o-β-d-glucoside is 1.4 ± 0.4 h, which indicates the quick elimination.

Open access

In reversed-phase liquid chromatography, in case of the absence of additives, cationic basic compounds give rise to asymmetrical and broad peaks as a result of interactions of analyte cations with residual free silanols on silica-based stationary phases. Ionic liquids, added to the mobile phase, have been suggested as alternatives to amines to block the activity of free silanols. The different parameters affecting the retention behavior, symmetry of peak, system efficiency, and separation selectivity of selected psychotropic drugs, especially the effect of concentration of ionic liquid, kind and concentration of organic modifiers of mobile phases, and kind of stationary phases were investigated. The most selective and efficient systems are used for separations of psychotropic drug standards' mixture and for determination of selected psychotropic drugs in human serum.

Open access
Augmentation of Vortex Cavitator Performance by the Use of Co-Directional Swirl of the Flux after Vortex Chamber
Authors: Evgeniy Gennadievich Ivanov, Boris Ivanovich Gorbunov, Alexander Valentinovich Pasin, Boris Alexandrovich Aryutov and Alexei Ivanovich Novozhilov

Abstract

Background: Acoustic cavitation is the creation and collapse of cavitation caverns in liquid in an acoustic field with a frequency of f = 1–3 kHz. The acoustic-cavitation processes manifest themselves during the collapse phase, with high pressure gradient continuum deformation, with a multiple transformation of energy forms. Liquid whistles are widely used to create an acoustic field of high power, but their efficiency only reaches 6–12%. We propose a liquid whistle in the form of a vortex cavitator (analogue of the Ranque vortex tube) with a rotating body in which a reduction in the input power is predicted.

Objective: Verification of feasibility of using a rotating body in a vortex cavitator with a rotation co-directional to the operational pump impeller.

Method: The method for identifying the feasibility of using a rotating body is to exclude body from the prototype and directly connect vortex chamber outlet with the pump inlet, which ensures the most complete preservation of co-directional vortex component of the flux entering the pump impeller.

Results: The results of experimental studies confirmed the validity of the hypothesis to a greater extent, since we achieved an increase in pressure at the outlet of the pump and a decrease in power at the drive relative to the original design.

Conclusions: The feasibility of designing the vortex cavitator body with rotation capability has been established, which will provide a reduction in input power of at least 30% by a rotation of the body, co-directional with the impeller.

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Abstract

The existing effective domestic regional development framework requires analyses for increasingly wider areas (micro, meso and even macro regions) before operational – short-term – local developments to be prepared and implemented.

Such comprehensive complex studies or larger-term programmes may demonstrate the profitability of the given project and can complement it with combined utilization technologies; in the case of Himesháza several locally known renewable energy sources could facilitate geothermal heat, later electricity supply, e.g. local biomass (biogas-based) recovery technology (organic waste of the local pig farm) and, for example, the construction of a low-power “dwarf” hydroelectric power plant chain based on rich watercourses of the region (the “southern dwarves” in Hungary) and the connection of existing solar utility facilities to a modern “smart grid” system in the longer term.

Himesháza, located in southern Hungary in Baranya county, is developing; it has a detailed feasibility study of a thermal energy supply network and an energy supply development plan.

Based on the geothermal characteristics of Baranya county it would be reasonable to encourage the development of smaller-scale, decentralized heating systems for dynamic settlements. Several settlements in close proximity to Himesháza have already explored thermal wells. Power generation with a small scale, closed-loop system can be used in the project region for thermal water with an outflow temperature of 90 °C. The heating system may also be able to fulfill the needs of recreational, vacation-based or complex thermal spa facilities formerly planned in the region. Moreover, the system could also be capable of utilizing a larger spectrum of renewable energy through its combination with photovoltaic technology.

Due to the country's favorable agricultural characteristics, Hungary's biomass potential is higher than the European average. The utilization of organic waste from agricultural and farming sectors is highly recommended in Baranya county; biogas production seems to be the most suitable in the region of Himesháza too, broadening the utilization of renewable resources.

The realization of the current project could contribute to shifting the energy resource sector in a more modern, environmentally conscious direction.

The background for shorter-term plans and investment (carried out within the framework of operational programs) necessary for the optimal operation and maintenance of longer-term (25–50 years) energy development strategies is created by the analysis (at multiple scales) of complex regional characteristics and future potential, and the selection of optimal sites.

Open access
Csongrád megye talajainak szélcsatorna kísérletekre alapozott szélerózió veszélyeztetettség becslése
Authors: Máté Bartus, Károly Barta, József Szatmári and Andrea Farsang

Összefoglalás

A klímaváltozásnak köszönhetően a következő évtizedekben a talajok defláció veszélyezettségének mértéke emelkedni fog hazánkban (CSORBA et al. 2012). A kutatásunk során arra kerestünk választ, hogy a talajtani alaptulajdonságok miként befolyásolják a kritikus indítósebességet és jelenleg mennyire defláció veszélyeztetettek a Dél-Alföld talajai.

Mintaterületként a Szeged környéki talajokat választottuk. A vizsgálataink során megállapítottuk, hogy az összes vizsgált talajparaméter közül az agronómiai szerkezet, azon belül is a rögfrakció az, ami leginkább befolyásolja a kritikus indítósebességet. Ez felhívja a figyelmet az ember szerepére, aki megfelelő agrotechnikával képes lenne a széleróziós kockázat csökkentésére (BODOLAY 1966; SHAHABINEJAD et al. 2019). A szélcsatornás kritikus indítósebesség vizsgálatok eredményeit összevetettük az időjárási adatokkal, és ezek eredményeit kivetítettük Csongrád megye területére. Kutatásunk során meghatároztuk a széleróziós események jellemző éves előfordulását (homok: 16,8 esemény; homokos vályog és vályog 1,6 esemény; agyagos vályog: 0,4 esemény), ezen események átlagos hosszát (homok: 3,0 óra; homokos vályog és vályog 1,4 óra; agyagos vályog: 1,0 óra) és a deflációnak kitett területetek aránya Csongrád-megyében (homok: 8,4%; homokos vályog és vályog 29,1%; agyagos vályog: 20,0%).

Kutatásunkkal képet kaptunk arról, hogy a defláció mekkora területet érint és mennyire jelentős talajvédelmi probléma Csongrád megyében. Korábbi kutatásaink bizonyítják, hogy egy párperces széleróziós esemény is súlyos veszteséget okozhat a talajok tápanyagtartalmából (FARSANG et al. 2011; FARSANG 2016), mely csupán csak egy aspektusa a szélerózió negatív hatásainak.

Open access

Summary

In the present study, a design of experiment (DoE) approach was used to optimize chromatographic conditions for the development of a high-performance thin-layer chromatography (HPTLC) method for the simultaneous estimation of metformin hydrochloride (MET) and ursodeoxycholic acid (URSO) in pharmaceutical dosage form. The critical factors were identified using a Taguchi design, and after identification of critical factors, optimization was done using Box-Behnken design (BBD). BBD was used to optimize the compositional parameters and to evaluate the main effect, interaction effects, and quadratic effects of the mobile phase compositions, development distance, and saturation time on the retardation factor (R F) of both drugs. HPTLC separation was performed on aluminum plates pre-coated with silica gel 60 F254 as the stationary phase, using toluene–ethanol–acetone–formic acid (4.5:2:2.5:0.85, V/V) as the mobile phase at a wavelength of 234 nm and 700 nm for MET and URSO, respectively. A sharp and well-resolved peak was obtained for MET and URSO at R F values of 0.19 and 0.80 min, respectively. The calibration curve was in the range of 5000–40000 ng per spot and 1500–12000 ng per spot for MET and URSO, with r 2 = 0.984 and r 2 = 0.980, respectively. The method was validated for linearity, accuracy, precision, limit of detection, limit of quantification, and specificity. To provide a better visualization of the statistically significant factors derived from the statistical analysis, the perturbation plot and response surface plot for the effect of independent variables on the R F of MET and URSO were evaluated. Stability study was performed under different stress conditions such as acid and alkali hydrolysis, oxidation, and temperature. The developed method was able to resolve drugs and their degradation products formed under the afore-mentioned conditions.

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Determination of licochalcone A in rat plasma by UPLC–MS/MS and its pharmacokinetics
Authors: Qinghua Weng, Lianguo Chen, Luxin Ye, Xiaojie Lu, Zheng Yu, Congcong Wen, Yichuan Chen and Gang Huang

The aim of this study was to establish a rapid, sensitive, and selective ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method to quantify the concentrations of licochalcone A and applicate the technique to its pharmacokinetic study. Analytes were separated on an UPLC ethylene bridged hybrid (BEH) C18 column (2.1 mm × 50 mm, 1.7 μm). The mobile phase was consisted of acetontrile and 0.1% formic acid with a flow rate of 0.4 mL/min in a gradient elution mode. Multiple-reaction monitoring (MRM) was carried out in a negative mode for licochalcone A (m/z 337.2 → 119.7) and the internal standard (IS) (m/z 609.0 → 300.9). The linearity of licochalcone A was great from 0.53 to 530 ng/mL. The lower limit of quantification and the lower limit of detection were 0.53 ng/mL and 0.26 ng/mL, respectively. The intra-day precision was less than 14%, and the inter-day precision was no more than 11%. The accuracy was from 91.5% to 113.9%, the recovery was over 90.5%, and the matrix effect was between 84.5% and 89.7%. The results of stability were in an acceptable range. The bioavailability was only 3.3%, exhibiting poor absorption. The developed method was successfully applicable for determining the concentrations of licochalcone A and its pharmacokinetic study.

Open access

Metaldehyde is a molluscicide allowed for use in the control of slugs and snails in agriculture and horticulture in many countries. A simple, fast, and precise gas chromatography method was developed and single-laboratory validated for determination of metaldehyde in different formulations of plant protection products. The proposed method involves extraction of active substance from samples by sonication with acetone and analysis using gas chromatography–flame ionization detection (GC–FID). The suggested analytical procedure is accurate, precise, and repeatable. Moreover, it is environmentally friendly and useful for laboratories as it uses a no time- and no solvent-consuming reference chromatography technique for quality control of commercially available pesticide formulations. Advantages of the proposed method are consistent with the ideas of sustainable development, which are in accordance with the principles of Green Analytical Chemistry. Analysis of real samples of commercial pesticide formulations confirmed that the proposed method is fit for its purpose.

Open access