Retention Parameters Research Articles

Evaluation of pedotransfer functions for predicting soil hydraulic properties: A voyage from regional to field scales across Europe

Study regionEurope. A total of 660, 522, and 4940 soil samples belonging to GRIZZLY, HYPRES, and EU-HYDI databases, respectively, were used for parametric evaluation. Study focusThe soil water retention and hydraulic conductivity functions are crucial input information for land surface models. Determining these functions by using direct methods is hampered by excessive time and unaffordable costs required for field activities and laboratory analyses. Pedotransfer functions (PTFs) are widely-used indirect techniques enabling soil hydraulic properties to be predicted by using easily-retrievable soil information. In a parametric evaluation, the predictive capability of PTFs is examined by comparing measured and estimated soil water retention parameters and saturated hydraulic conductivity. Yet information about the performance of PTFs for specific modeling applications is mandatory to evaluate PTF effectiveness in greater depth. This approach is commonly defined as functional evaluation. New hydrological insights for the regionThe best performing four PTFs selected in the parametric evaluations are tested under two functional evaluations. The first encompasses a spatial interpolation with a geostatistical technique, whereas the second employs Hydrus-1D to simulate the water balance components along an experimental transect. Our results reinforce and integrate the insights of previous studies about the use of a PTF, and highlight the ability, or inability, of this technique to adequately reproduce the observed spatial variability of soil hydraulic properties and simulated water fluxes.

Recurrent Approximation of Retention Parameters of N-Substituted p-Toluenesulfonamides in Reversed-Phase High Performance Liquid Chromatography for Revealing the Formation of Their Hydrates

Recurrent Approximation of Retention Parameters of N-Substituted p-Toluenesulfonamides in Reversed-Phase High Performance Liquid Chromatography for Revealing the Formation of Their Hydrates

Global Flash Drought Monitoring Using Surface Soil Moisture

AbstractAbrupt onset and swift intensification characterize flash droughts. Global surface soil moisture (θRS) from NASA's Soil Moisture Active Passive (SMAP) satellite can facilitate a near‐real‐time assessment of emerging flash droughts at a 36‐km footprint. However, a robust flash drought monitoring using θRS must account for the (a) short observation record of SMAP, (b) nonlinear geophysical controls over θRS dynamics, and (c) emergent meteorological drivers of flash droughts. We propose a new method for near‐real‐time characterization of droughts using Soil Moisture Stress (SMS, drought stress) and Relative Rate of Drydown (RRD, drought stress intensification rate)—developed using SMAP θRS (March 2015–May 2021), footprint‐scale seasonal soil water retention parameters and land‐atmospheric coupling strength. SMS and RRD are nonlinearly combined to develop Flash Drought Stress Index (FDSI) to characterize emerging flash droughts (FDSI ≥ 0.71 for moderate to high RRD and SMS). Globally, FDSI shows a high correlation with concurrent meteorological anomalies. A mechanistic evaluation of flash droughts is presented for the Northern Great Plains, Central South Africa, and Eastern Australia using FDSI, SMS, and RRD. About 5.6% of the earth's landmass experienced flash droughts of varying intensity and duration during 2015–2021 (FDSI ≥ 0.71 for >30 consecutive days), majorly in global drylands. FDSI shows high skill in forecasting vegetation health with a lead of 0–2 weeks, with exceptions in irrigated croplands and mixed forests. With readily available parameters, low data latency, and no dependence on model simulations, we provide a robust tool for global near‐real‐time flash drought monitoring using SMAP.

Effects of surface roughness and mineralogy on the sorption of Cm(III) on crystalline rock

Crystalline rock is one of the host rocks considered for a future deep geological repository for highly active radiotoxic nuclear waste. The safety assessment requires reliable information on the retention behavior of minor actinides. In this work, we applied various spatially resolved techniques to investigate the sorption of Curium onto crystalline rock (granite, gneiss) thin sections from Eibenstock, Germany and Bukov, Czech Republic. We combined Raman-microscopy, calibrated autoradiography and µTRLFS (micro-focus time-resolved fluorescence spectroscopy) with vertical scanning interferometry to study in situ the impact of mineralogy and surface roughness on Cm(III) uptake and molecular speciation on the surface. Heterogeneous sorption of Cm(III) on the surface depends primarily on the mineralogy. However, for the same mineral class sorption uptake and strength of Cm(III) increases with growing surface roughness around surface holes or grain boundaries. When competitive sorption between multiple mineral phases occurs, surface roughness becomes the major retention parameter on low sorption uptake minerals. In high surface roughness areas primarily Cm(III) inner-sphere sorption complexation and surface incorporation are prominent and in selected sites formation of stable Cm(III) ternary complexes is observed. Our molecular findings confirm that predictive radionuclide modelling should implement surface roughness as a key parameter in simulations.

Modeling daily surface runoff, sediment and nutrient loss at watershed scale employing Arc-APEX model interfaced with GIS: a case study in Lesser Himalayan landscape

The present study was carried out to evaluate performance of Agricultural Policy Environmental eXtender (APEX) integrated with GIS as ArcAPEX model in simulating surface runoff, sediment and nutrients loss from a watershed located in lesser Himalayan region in Uttarakhand state, India. Daily surface runoff, sediment and nutrient loss data measured at watershed level for the year 2010–2011. Measurement at watershed revealed average daily sediment loss in range of 1.0–1.32 t ha−1 was measured with peak of 3.04 t ha−1 on daily time-step. The loss of total carbon (TC) and total nitrogen (TN) were estimated from 0.49 to 0.58 kg ha−1 and 0.16 to 01.7 kg ha−1, respectively from the watershed on daily basis for the rainfall considered for the modelling. A total of 40 rainy days surface runoff and sediment data were collected and of which half of the events data were used for calibration and remaining for validation. The calibration was done by changing the sensitive parameters. Analysis showed that SCS CN number was found most sensitive to runoff, followed by saturated hydraulic conductivity, available water-holding capacity, CN retention parameter and C factor whereas erosion control practice (P) factor was found to be most sensitive, followed by C factor, sediment routing coefficient, average upland slope and soil erodibility (K) factor for the sediment and nutrient loss. APEX model calibrated for the watershed and it predicted quite well for the surface runoff (r = 0.92, NSE = 0.50), sediment loss (r = 0.88, NSE = 0.61 and nutrients of total carbon (r = 0.78, NSE = 0.59) and fairly for total nitrogen (r = 0.77, NSE = 0.19). The calibration and validation results indicate that APEX model can be satisfactorily used for predicting runoff, sediment and nutrient (TC) loss at watershed scale on daily time-step. The landscape is prone landslips/ collapse of field terraces etc. occurring at high rainfall events was not accounted by the model that may be a reason for under prediction of sediment loss by the model. The study suggests to incorporate landslips/collapse of field terraces, etc., processes in future improved versions of APEX for improving sediment yield prediction in the Himalayan landscape.

Detection of organic hydrates in reversed phase high performance liquid chromatography using recurrent approximation of their retention times

Some organic compounds form hydrates in eluents under the conditions of reversed-phase high-performance liquid chromatography (RP HPLC). For some of them, variation of water to the organic solvent ratio in an eluent may influence the ratio of hydrated and non-hydrated forms of analytes, X + nH2O ⇄ X·nH2O, which complicates the relations of their chromatographic retention. To reveal the formation of such hydrates, the recurrent approximation of their retention parameters is recommended, t R(C + ΔC) = at R(C) + b (*), where ΔC = const is the concentration increment of an organic modifier in an eluent, and a and b are coefficients calculated by the least-squares method. If an analyte exists in a hydrated or non-hydrated form only, the correlation coefficients (R) of equation (*) exceed 0.999. If the reversible formation of hydrates takes place within the concentration range C min to C max, it leads to distortion of linear dependence (*) and to deviations of some data points from regression lines (R < 0.999). One of the structural factors responsible for the reversible formation of hydrates is the presence of polar sulfonamide group –SO2NRR' in a molecule. To confirm this, a series of N-substituted p-toluenesulfonamides were synthesized and characterized. However, the nonlinearity of recurrences (*) is observed only for acetonitrile-containing eluents.

Influence of Ascophyllum nodosum extract, homobrassinolide and triacontanol on fruit retention, yield and quality of mango

Aim: To evaluate the efficacy of foliar application of Ascophyllum nodosum extract, homobrassinolide, and triacontanol for improving fruit retention, yield, and quality in mango. Methodology: The experiment was laid out in a randomized block design with 10 treatments, comprising Ascophyllum nodosum extract (1000, 3000, and 5000 ppm), homobrassinolide (0.1, 0.3, and 0.5 ppm), triacontanol (1, 3, and 5 ppm), and water as control. Treatments were foliar sprayed at panicle initiation, pea, and marble stages of fruit growth. Observations were recorded on flowering, fruiting, yield, and fruit quality parameters. Results: All the treatments of Ascophyllum nodosum extract and triacontanol exhibited significant improvement in fruit retention, fruit weight, yield, and fruit quality parameters over control. However, 3000 and 5000 ppm Ascophyllum nodosum extract treatments outperformed all the treatments of triacontanol. Plants sprayed with 5000 ppm Ascophyllum nodosum extract recorded the maximum value for fruit retention (48.15, 36.74, 29.48, and 25.76% at 3, 6, 9, and 12 weeks after pea stage, respectively), number of fruits (133.25 per tree), fruit weight (188.84 g per fruit), and yield (25.16 kg per tree), whereas the lowest values were recorded under control. With respect to fruit quality, 3000 ppm ANE produced the fruits with the highest TSS (19.62 °B), whereas the highest TSS/acid ratio was recorded with 5000 ppm ANE (62.29) treatment. Interpretation: In mango, foliar application of Ascophyllum nodosum extract (3000-5000 ppm) thrice at panicle initiation, pea, and marble stages of fruit growth is effective for reducing fruit drop and enhancing quantum and quality of produce.

Reactive transport of strontium in two laboratory-scale columns: Experiments and modelling

To support the environmental monitoring of nuclear sites, reactive transport models used to predict the migration of contaminants such as strontium-90 (90Sr) in soils, sediments and aquifers are developed, continuously tested and improved. This study aims at assessing the adequacy of the multi-site ion exchanger model (MSIE) based on a component “additivity approach” and coupled to the advection-dispersion equation (ADE) to simulate Sr transport in a clayey sandstone and a Bt soil horizon. We have also compared the performance of the modelling approach with simulation results obtained by considering a Kd approach (constant Kd). Transport experiments were performed in centimetre- and decimetre-scale columns in order to test the model sensitivities to the mineral abundance and the specificities of their reactive parameters. Non-reactive transport experiments with conservative tracers allowed us to determine the transport parameters, such as porosity and dispersivity. In this paper, we have compared the Sr transport simulation results with Sr experimental breakthrough curves acquired at various flow velocities. The simulations results show that the Kd approach can reproduce experimental data in the case of the clayey sandstone when a certain amount of uncertainty is accepted, whereas the additivity approach better fits the Sr reactive transport in both columns (especially the maximum value) without it being necessary to adjust the parameters. These results advocate for more complex retention models than Kd to better understand and improve the robustness of Sr transport predictions. The clay content, the relative abundance of illite and smectite, and the clay mineral specificity, are all sensitive parameters when it comes to defining the reactive system involved in Sr transport simulation. The results highlight the influence of illite in the spreading of the Sr breakthrough curve, especially through its low-capacity and high-selectivity site. This implies having access to a robust and extensive set of retention parameters acquired on reference minerals. In this study, the results obtained for the clayey sandstone confirm the robustness of our selected parameters when clay minerals have similar reactivity levels as the reference minerals. This set of parameters appears more limited in the case of the Bt soil containing weathered or evolved minerals. The choice of modelling approach is therefore crucial for accurately modelling and predicting Sr transport behaviour in porous media, as is the representativeness of the minerals in the database.

Polynomial functions to predict flux-based field capacity from soil hydraulic parameters

We propose two new polynomials as pedotransfer function, PTF, to predict the flux-based Field Capacity water content, ΘFC. The inputs for the PTF are the bottom flux criterium, the profile depth, and the retention and conductivity parameters of the Van Genuchten – Mualem model, VGM. A first polynomial was developed including all VGM parameters and a second polynomial considers VGM parameter l equal to 0.5, the most commonly applied value. The polynomials were built using stepwise multiple linear regression and a generated dataset over a wide range of VGM model parameters. The “observed values” for the polynomial calibration were acquired from internal drainage simulations performed by the Richards equation-based model SWAP. The derived polynomials predicted the simulated ΘFC with high accuracy. The RMSD between observed and predicted ΘFC on tested datasets, for the complete version and the l = 0.5 polynomial version were, respectively, 0.01912 and 0.01362. The proposed polynomials may be combined with other PTFs providing the VGM parameters from texture and/or other basic data. Examples of predicted FC water content and pF are shown on texture triangles using the Rosetta PTF to predict VGM parameters from soil texture data. For stand-alone use, the polynomials allow predicting the flux-based ΘFC from VGM parameters without the need for numerical simulations.

Determination of six drugs used for treatment of common cold by micellar liquid chromatography.

The use of organic solvents as eluants in RP-HPLC has an important role to decrease retention time and improve peak shape; however, it has high environmental impacts. Their production and disposal represent economic and biohazard problems. So, alternatives had to be introduced and studied to minimize such pollution. Combination of sodium dodecyl sulfate (SDS) together with polyoxyethylene-23-lauryl ether (Brij-35) was studied as an alternative to the presence of organic solvents on the separation performance of six active pharmaceutical ingredients. Response surface methodology was applied to testthe impact of three independent variables; concentrations of SDS and Brij-35, as well as, pH of the mobile phase; on retention, peak symmetry, and resolution of the analytes using a rotatable central composite design. Significant variables were determined and the suggested models for predicting retention and resolution parameters were significant. Meanwhile, the common cold is the most abundant disease treated with over-the-counter (OTC) medications worldwide. In 2015, the USA recorded $9.56 billion total sales of OTC cold and cough medicaments alone, with average individual patient expenditure of $338. The worldwide sales and generics of common cold and cough products keep growing annually. The six active pharmaceutical molecules under study, namely, paracetamol, guaifenesin, pseudoephedrine, ibuprofen, chlorpheniramine, and dextromethorphan, are widely used in common cold products. The predicted optimum conditions were validated using mobile phase consisting of 93.6 mM SDS, 32.0 mM Brij-35, and 10.0 mM sodium dihydrogen phosphate, adjusted at pH 5.2, column temperature 35° C, and detection at 215-nm wavelength. The method was successfully applied to determine 12 different combination formulae of the analytes in their pharmaceutical products and was assessed for greenness on two novel metrics. A thorough comparison to previously reported methods was included and methods were assessed against greenness metrics Green Analytical Procedure Index and Analytical Greenness Metric to demonstrate superiority.

Transport of an Eco-friendly L70-c Bio-based Sucrose Ester Surfactant: Implication for Soil Remediation Purposes

Due to their biodegradability and low toxicity bio-based surfactants are very promising for use in remediation technologies, particularly for hydrocarbon contaminated soils. To enhance the application of surfactant-based technologies for remediation of organic contaminated sites, it is important to have a better understanding of the surfactant transport and retention mechanisms involved in this process, as they will impact the remediation efficiency. In this work, transport and retention mechanisms of an industrial bio-based nonionic sucrose ester surfactant were investigated through batch and column experiments, carried out on sandy porous media under saturated steady state flow conditions. Column transport experiments were conducted at surfactant concentrations ranged from 1 to 10 CMC (critical micellar concentration), for two distinct Darcy flow rates (0.35 and 0.70 cm.min-1). Surfactant transport and retention parameters were estimated by fitting a convection-diffusion transport model (implemented on HYDRUS-1D code) to the observed transport breakthrough curves, in order to provide an adequate description and understanding of the mechanisms involved in the transport and adsorption of these compounds through porous media. The results obtained from column experiments performed under high flow rate combined with high surfactant concentration provided the best conditions for high surfactant recovery in the effluent and low surfactant adsorption rate onto the sand. Numerical HYDRUS-1D simulations permitted to quantify surfactant transport behavior and provided attachment coefficients several order of magnitude greater than detachment coefficients, indicating that surfactant retention was an irreversible process.

The effect of dietary supplementation with silkworm pupae meal on gastrointestinal function, nitrogen retention and blood biochemical parameters in rabbits

BackgroundThe aim of this study was to determine the effect of dietary inclusion of silkworm pupae meal (SPM) on nutrient digestibility, nitrogen utilization, gastrointestinal physiology and blood biochemical parameters in rabbits. Thirty Termond White rabbits were divided into three groups: SBM – fed a diet containing 10% soybean meal (SBM), SPM5 – fed a diet containing 5% SBM and 5% SPM, and SPM10 – fed a diet containing 10% SPM.ResultsNutrient digestibility and nitrogen retention decreased with increasing SPM inclusion levels in rabbit diets. The dietary inclusion of SPM caused a significant increase in the stomach pH. Group SPM10 rabbits were characterized by the highest cecal tissue and digesta weights. The lowest cecal pH was noted in group SPM5. The relative weights of colonic tissue and digesta tended to increase with increasing levels of SPM. The total and intracellular activity of bacterial α-galactosidase decreased significantly in both SPM groups. The replacement of SBM with SPM led to a decrease in the activity of bacterial β-glucuronidase in the cecal digesta. The intracellular activity of bacterial α-arabinofuranosidase increased, and its release rate decreased in the cecum of rabbits in SPM groups. The extracellular activity of bacterial β-xylosidase in the cecal digesta tended to decrease in group SPM10. The highest extracellular and intracellular activity of bacterial β-cellobiosidase in the cecal digesta was noted in the SPM5 treatment. The lowest and the highest activity of bacterial N-acetyl-β-D-glucosaminidase (NAGase) was observed in groups SBM and SPM10. The SPM10 treatment contributed to a decrease in the cecal concentrations of butyric, iso-valeric and valeric acids. The lowest total concentration of putrefactive short-chain fatty acids (PSCFAs) was observed in group SPM10. The cecal concentration of propionic acid tended to increase in group SPM5, whereas the cecal concentration of iso-butyric acid tended to decrease in group SPM10. The colonic concentration of iso-valeric acid was lowest in group SPM5. SPM treatments resulted in a significant increase in plasma albumin concentration. Plasma urea concentration was significantly higher in group SPM10 than in SBM and SPM5.ConclusionsThe results of this study suggest that rabbit diets can be supplemented with SPM at up to 5%.

MesoSoil v2.0: An updated soil physical property database for the Oklahoma Mesonet

AbstractSoil moisture data from the Oklahoma Mesonet have been used in numerous fields within the Earth sciences, including agriculture, hydrology, and meteorology. Soil matric potentials measured by heat dissipation sensors at Oklahoma Mesonet stations have been converted to soil volumetric water content estimates using soil water retention curve parameters estimated by the Rosetta pedotransfer function. Recently, an improved version of Rosetta, Rosetta3, was released. Informed by this new pedotransfer function and soil sampling at additional locations, an improved version of the Oklahoma Mesonet soil physical property database, MesoSoil v2.0, has been created. This article presents this new soil database, compares soil water retention parameters estimated using Rosetta3 with those derived from the original Rosetta model, and describes the effects of changes in those parameters on estimated volumetric water content. Using the Rosetta3 model led to changes in the estimated water retention parameters, most notably decreases in the parameter α, which is related to the inverse of the air‐entry potential. These changes resulted in volumetric water content estimates that differed from those based on Rosetta1, with mean absolute differences averaging 0.02 cm3 cm–3 across all site‐years and the greatest differences occurring during wet periods. The mean volumetric water content estimated using the Rosetta3 parameters across more than 100 sites was not significantly different from that determined by soil sampling. The updated database is publicly available and may be found here: http://soilphysics.okstate.edu/data.

Evaluation of drug-likeness and ADME properties of sunscreens and preservatives using reversed-phase thin layer chromatographic retention data and calculated descriptors

RP-18 TLC chromatography was used to evaluate the pharmacokinetic properties (volume of distribution, VD; plasma protein binding, %PPB; the ability to cross the blood-brain barrier expressed as log PS and log BB) of several cosmetic raw materials – sunscreen and preservatives. The majority of these compounds are intended for topical use on skin and their drug-likeness and the ability to cross biological barriers are undesired. The retention parameters RM0, S, PC1 and RM75 % obtained for mobile phases containing six organic modifiers (methanol, acetonitrile, THF, acetone, dioxane, DMF) were used as the sole descriptors or combined with calculated physicochemical properties (PSA, MW, VM) of studied compounds.The chromatographic parameters considered in this study are, generally speaking, good predictors of the compounds’ pharmacokinetic properties VD, %PPB and log PS. RM75 % and the novel parameters derived from it (RM75 %/MW and RM75 %/VM) can be considered time- and cost-effective alternatives to the chromatographic parameters obtained by extrapolation or interpolation methods. In the case of some pharmacokinetic properties investigated in this study additional descriptors (PSA) have a significant influence on the quality of correlations.

Comparison of Static Thermal Gradient to Isothermal Conditions in Gas Chromatography Using a Stochastic Transport Model.

This paper compares static (i.e., temporally unchanging) thermal gradient gas chromatography (GC) to isothermal GC using a stochastic transport model to simulate peak characteristics for the separation of C12-C14 hydrocarbons resulting from variations in injection bandwidth. All comparisons are made using chromatographic conditions that give approximately equal analyte retention times so that the resolution and number of theoretical plates can be clearly compared between simulations. Simulations show that resolution can be significantly improved using a linear thermal gradient along the entire column length. This is mainly achieved by partially compensating for loss in resolution from the increase in mobile phase velocity, which approximates an ideal, basic separation. The slope of the linear thermal gradient required to maximize resolution is a function of the retention parameters, which are specific to each analyte pair; a single static, thermal gradient will not affect all analytes equally. A static, non-linear thermal gradient that creates constant analyte velocities at all column locations provides the largest observed gains in resolution. From the simulations performed in this study, optimized linear thermal gradient conditions are shown to improve the resolution by as much as 8.8% over comparative isothermal conditions, even with a perfect injection (i.e., zero initial bandwidth).

Determination of clemastine by the HPLC method in the blood

Topicality. Сlemastine fumarate (tavegil)-1-methyl-2 [2-α-methyl-p-chlorobenzhydryloxy)-ethyl]-pyrrolidine fumarate is the first generation H1-histamine receptor blocker. Сlemastine fumarate selectively inhibits histamine H1 receptors and reduces capillary permeability. The drug has a pronounced anti-allergic and antipruritic effect. Clemastine prevents the development of vasodilation and the smooth muscle contraction induced by histamine. Сlemastine fumarate has an isignificant anticholinergic activity, causes sedation. The drug is used to treat pruritus in psoriasis, multiple sclerosis and optic neuritis. Clemastine is characterized by the following side effects: increased fatigue, drowsiness, sedation, weakness, lethargy, impaired coordination of movements; nausea, vomiting, decreased blood pressure, palpitations, hemolytic anemia, skin rash, anaphylactic shock. In case of an overdose, the drug has a neurotoxic effect, which manifests itself in impaired consciousness with the development of generalized anticholinergic convulsive syndrome. The urgent task for monitoring the treatment effectiveness of the population with сlemastine fumarate and diagnosis of drug intoxication is the choice of highly sensitive and selective research methods of its analysis in pharmaceuticals and biological matrices during the treatment. Aim. To develop an algorithm for directed analysis of clemastine in biological extracts from the blood using a unified method of the HPLC research. Materials and methods. The extraction of clemastine was performed with chloroform at Ph 9.0. The extracts were purified from impurities by a combination of TLC and extraction with hexane. The TLC purification and identification of clemastine were carried out under optimal conditions: the system of organic solvents – methanol – 25 % solution of ammonium hydroxide (100 : 1.5) and chromatographic plates – Sorbfil PTLC-AF-A, Rf сlemastine = 0.60 ± 0.03. To detect clemastine, the most sensitive location reagents were used –UV light (λ = 254 nm) and Dragendorff’s reagent modified by Mounier. The chromatographic analysis was performed on a “Milichrome A-02” microcolumn liquid chromatograph (EkoNova, Closed Joint-Stock Company, Russia) under standardized HPLC conditions: the reversed-phase variant using a metal column with a non-polar absorbent Prontosil 120-5C 18 AQ, 5 μm; the mobile phase in the linear gradient mode – from eluent А (5 % acetonitrile and 95 % buffer solution – 0.2 М solution of lithium perchlorate in 0.005 М solution of perchloric acid) to eluent B (100 % acetonitrile) for 40 min. Regeneration of the column was conducted for 2 min with the mixture of solvents; the flow rate of the mobile phase was 100 μl/min, the injection volume – 4 μl. The multichannel detection of the substance was performed using a two-beam multi-wave UV spectrophotometer at 8 wavelengths of 210, 220, 230, 240, 250, 260, 280, and 300 nm; the optimal value of the column temperature – 37-40 °С and the pump pressure – 2.8-3.2 MPa. Results and discussion. Isolation of clemastine from the blood was performed according to the method developed, including the extraction with chloroform at pH 9.0; the extraction purification of extracts with hexane from impurities; the TLC purification and identification of clemastine. Using the unified HPLC method clemastine was identified by retention parameters and spectral ratios. For the quantitative determination, a calibration graph or the straight line equation corresponding to this graph were used. The results obtained indicated the reliability and reproducibility of the method. It was found that the relative uncertainty of the average result in the analysis of clemastine in the blood was ε = ± 4.63 %, the relative standard deviation of the average result was RSDx = 1.67 %. Conclusions. Clemastine was extracted with chloroform at pH 9.0 from the blood. Purification of extracts from co-extractive compounds was performed by combining TLC and extraction with hexane. It has been found that when isolating сlemastine from the blood according to the methods developed it is possible to determine 36.05-39.55 % of the substance (ε = ± 4.63 %, RSDx = 1.67 %). The method of TLC purification and identification of сlemastine in biogenic extracts was tested under the optimal conditions: the system of organic solvents – methanol – 25 % solution of ammonium hydroxide (100 : 1.5), the use of reagents – UV light, Dragendorff’s reagent modified by Mounier, Rf сlemastine = 0.60 ± 0.03 (Sorbfil PTLC-AF-A). The unified HPLC method for identification and quantification of сlemastine was tested in biogenic extracts from the blood according to the algorithm of the directed analysis developed. It has been found that сlemastine can be identified by the retention time – 25.997-26.011 min; the retention volume – 2599.7-2601.1 μl; spectral ratios – 0.741; 0.536; 0.096; 0.023; 0.027; 0.005; 0.003. The сlemastine content was determined by the equation S = 0.15 · 10-3 С + 0.14 · 10-3; the correlation coefficient was equal to 0.9998. Chromatographic methods can be recommended for implementation in practice of the Bureau of Forensic Medical Examination, poison control centers, clinical laboratories regarding the study of medicinal substances in biological objects.

RP-18 TLC retention data and calculated physico-chemical parameters as predictors of soil-water partition and bioconcentration of organic sunscreens

RP-18 TLC chromatography was used to evaluate the impact on the environment (mobility in soil expressed as soil-water partition coefficient, log Koc; bioconcentration factor in aquatic organisms, log BCF) of several cosmetic raw materials - sunscreens, preservatives and vitamins. The retention parameters RM0 (RM extrapolated to zero concentration of an organic modifier in a mobile phase), S (slope), PC1 (1st principal component) and RM75% (single TLC run parameter for mobile phases containing 75% (v/v) of an organic modifier) obtained for six organic modifiers (methanol, acetonitrile, THF, acetone, dioxane, DMF) were used as the sole descriptors or combined with calculated physico-chemical properties (PSA – polar surface area; MW – molecular weight; VM – molar volume) of studied compounds.The chromatographic parameters considered in this study are, generally speaking, good predictors of the compounds’ mobility in soil or the affinity for aquatic organisms. The parameters RM0, S and RM75% obtained for THF, dioxane and acetone may be used to investigate even very lipophilic compounds. RM75% is of a little bit limited use but it should be considered a time- and cost-effective alternative to the chromatographic parameters obtained by extrapolation or interpolation methods. In the case of some environmental parameters investigated in this study additional descriptors (PSA) have a significant influence on the quality of correlations.

Formation and Chromatographic Detection of Organic Compound Hydrates

The formation of hydrates of inorganic compounds is well known and is widely discussed in the contemporary literature. The reasons for the insufficiently detailed characterization of numerous well-known hydrates of organic compounds are analyzed, the main of which is their instability. The CAS numbers assigned to many of these hydrates confirm interest in these hydrates. We found that the reversible formation of the hydrates of various organic compounds can be a reason for anomalous dependences of their retention parameters (tR) on the concentration of an organic eluent modifier (c) in reversed-phase high-performance liquid chromatography. The recurrent approximation of the retention parameters tR(c + Δc) = atR(c) + b (*), where Δc = const is a constant step of c, is the most effective way to detect these anomalies. Deviations of dependences like (*) from linearity are observed with compounds in which variations in c and, consequently, in the water content of the eluent (1 – c) affect the equilibrium of the reaction $${\text{X}} + n{{{\text{H}}}_{{\text{2}}}}{\text{O }} \rightleftarrows {\text{X}} \cdot n{{{\text{H}}}_{{\text{2}}}}{\text{O}}.$$

The effects of Cephalaria syriaca flour on physical, rheological and textural properties of sunn pest (Eurygaster integriceps) damaged wheat dough and bread

The aim of this study was to investigate the effects of Cephalaria syriaca flour (CSF; 0.5, 1.0 and 1.5%) on the physical, textural and rheological characteristics of dough and bread obtained from sunn pest-damaged wheat (SPDW; 5, 10 and 15%). An increased CSF level significantly decreased the stickiness and volume loss values of dough and the firmness and chewiness values of bread for all SPDW levels. The dough stickiness and bread firmness values were considerably increased by the addition of SPDW at the 15% level (1.05 N and 29.76 N), whereas these values were reduced by the addition of 1.5% CSF (0.6439 N and 22.56 N). In general, the stress relaxation, gas retention and gluten extensibility parameters of dough; and the specific volume, colour, cohesiveness, springiness and resilience values of bread significantly increased depending on the increasing level of CSF. Especially, the 1.5% CSF level significantly improved the quality of the dough and breads. The results of the present study revealed that CSF addition to SPDW flour positively affected the stickiness, gas retention and stress relaxation of dough and the specific volume and instrumental textural properties of bread.

Assessment of Lipophilicity Descriptors of Selected NSAIDs Obtained at Different TLC Stationary Phases.

Lipophilicity study of selected NSAIDs, the group of the bioactive compounds usually used in humans and animals medicine, with the use of experimental and calculation methods was evaluated. LogP values are proposed and compared as descriptors of the lipophilicity of eleven compounds (from oxicams and coxibs). Obtained data were designated by thin-layer chromatography (TLC) in various chromatographic conditions, with stationary phases with different properties. The mobile phase systems were prepared by mixing the respective amounts of water and organic modifier, methanol and acetone, in the range of 30 to 80% (v/v) in 5% increments. Retention parameters (RF, RM and RM0) were calculated and statistically evaluated to establish correlations. All experimentally determined RM0 values were compared with partition coefficients obtained by computational methods using linear regression analysis. Moreover, in order to extract information about the lipophilicity of compounds from large retention datasets, two chemometric approaches, namely principal component analysis (PCA) and cluster analysis (CA) were carried out. Established models of lipophilicity may have the potential to predict the biological activity of a number of drugs. The presented knowledge may also be of use during drug discovery processes, broadening the knowledge of potential ways to modify the physicochemical properties of chemical compounds.