Extraction selectivity
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Byly vypracovány podmínky pro stanovení karbethopendecinium-bromidu smodří bromthymolovoua oranží methylovou (koncentrace léčiva a barviva, pH vodné fáze, doba extrakce chloroformem).V rozmezí koncentrací karbethopendecinium-bromidu 1.10-5 až 6.10-5 mol/l byla potvrzena lineárnízávislost absorbance iontového asociátu s barvivem na koncentraci. Uvedeným postupem, při pH 3a pH 10 byl stanoven obsah karbethopendecinium-bromidu v léčivých přípravcích (oční a nosníkapky), s použitím kalibrační křivky a porovnáním s jedním standardem. Výsledky byly reprodukovatelné,zjištěné odchylky od deklarovaného obsahu se pohybovaly v toleranci ± 10 %.
The paper elaborated the conditions for the determination of carbethopendecinium bromide withbromthymol blue and methyl orange (concentration of the drug and the colouring agent, pH of theaqueous phase, period of extraction with chloroform). Within a carbethopendecinium bromideconcentration range of 1.10-5 to 6.10-5 mol/l, the linear dependence of absorbance of the ion-associatewith the colouring agent on concentration was confirmed. At pH 3 and pH 10, the above-describedprocedure was used to determine the content of carbethopendecinium bromide in medicinal preparations(eye and nasal drops) using the calibration curve and comparison with one standard. Theresults were reproducible and the found deviations from the declared content ranged withina tolerance of ± 10 %.
... Buser -- 2 Proceedings of the Third III Consensus Conference: -- Implants in Post-Extraction Sites 3 ... ... Statements 6 -- 2.1.2 Proposed Clinical Approaches 7 -- 2.1.3 Conclusions 8 -- 2.2 Implants in Post-Extraction ... ... Update 11 -- 2.2.3 Healing Adjacent to Implants in Post-Extraction Sites 12 -- 2.2.4 Implant Survival ... ... 13 -- 2.2.5 Esthetic Outcomes I4 -- 3 Pre-Operative Assessment and Treatment Options for Post-Extraction ... ... Implants 17 -- 3.1 Factors Influencing the Treatment Outcomes of Implants in Post-Extraction Sites 18 ...
ITI treatment guide ; Vol. 3
xiii, 202 s. : il., tab. ; 29 cm
- MeSH
- extrakce zubů MeSH
- implantace zubů klasifikace metody MeSH
- stomatochirurgické výkony MeSH
- zubní implantáty jednotlivých zubů MeSH
- zubní implantáty MeSH
- Konspekt
- Stomatologie
- NLK Obory
- zubní lékařství
- NLK Publikační typ
- kolektivní monografie
Brassinosteroids (BRs) are a class of steroid plant hormones that participate with other plant hormones in the regulation of numerous developmental processes, including root and shoot growth, vascular differentiation, fertility, and seed germination. A characteristic feature of all plant hormones, including BRs, is that their concentration is extremely low in plant tissues and, therefore, the methods dealing with their determination belong to ultra-trace analysis, for which very sensitive analytical tools are needed. The analysis of natural BRs is essential when their functions and roles in plant growth and development are to be elucidated. Here, we describe a reliable protocol for high-throughput extraction and purification of BRs. The procedure consists of two solid-phase extraction steps and provides selective enrichment and efficient cleanup of these compounds from complex plant extracts. The protocol is designed for sensitive liquid chromatography-tandem mass spectrometry-based method for simultaneous detection of 22 naturally occurring BRs, including their biosynthetic precursors and most of their biologically active metabolites, without need for derivatization.
- MeSH
- Arabidopsis chemie MeSH
- Brassica napus chemie MeSH
- brassinosteroidy chemie izolace a purifikace MeSH
- chromatografie kapalinová MeSH
- chromatografie plynová MeSH
- extrakce na pevné fázi metody MeSH
- hmotnostní spektrometrie MeSH
- regulátory růstu rostlin chemie izolace a purifikace MeSH
- rostlinné extrakty chemie MeSH
- Publikační typ
- časopisecké články MeSH
Seven solid phase sorbent materials with reversed-phase, mixed-mode interactions (ion-exchange and reversed-phase), and molecularly imprinted polymers (MIP), namely Oasis HLB, Oasis MAX, Oasis MCX, Bond Elute Plexa, Bond Elute Plexa PAX, Bond Elute Plexa PCX, and SupelMIP sorbents, were investigated. The present study was focused on the retention and elution of pharmaceutically active substances based on several analyte-sorbent interaction properties. Basic drugs, such as β-blockers (i.e., atenolol, pindolol, acebutolol, metoprolol, labetalol, and propranolol) were selected as the model compounds for this study. These compounds are frequently encountered in anti-doping tests. The extraction efficiencies of the individual sorbents were compared based on the recovery of known amounts of the targeted analytes in a metered elution volume (500 μL) in three separate elution fractions. The elution efficiency of the total amount of the target analytes on various sorbents was not appreciably influenced by the volume of eluent required for complete elution. Based on the small matrix effects and clear baseline, SupelMIP was the most suitable sorbent for urine analysis. The relative analyte recoveries of the SPE-HPLC procedure proved satisfactory for the range from 94% to 105%, with an RSD ranging from 2% to 4%. The regression equations for all of the targeted compounds exhibited excellent linearity (r(2) > 0.9991) over the range of 10 to 1000 ng mL(-1). The limits of detection and quantification for the selected β-blocker compounds in urine were in the ranges of 0.6 to 2.0 ng mL(-1) and 2.0 to 6.7 ng mL(-1), respectively.
- MeSH
- adsorpce MeSH
- beta blokátory izolace a purifikace moč MeSH
- extrakce na pevné fázi přístrojové vybavení metody MeSH
- lidé MeSH
- molekulový imprinting MeSH
- polymery chemická syntéza chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
Monitoring the selectivity of supported liquid membranes (SLMs) is of paramount importance since the amount and type of compounds that are transferred across a SLM directly influence the transfer efficiency, reproducibility and accuracy. To apply a correct SLM in particular sample pretreatment, rapid determination of the transfer of analytes and matrix compounds across the SLM is necessary, which requires the use of an analytical method with universal detection technique. Capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D) has proven to be a useful tool for the determination of SLM selectivity. Background electrolyte solution consisting of 1M acetic acid (pH 2.4) was used for simultaneous separation and detection of three basic drugs (nortriptyline, haloperidol and loperamide) and major matrix components (inorganic cations, proteins, amino acids, etc.) after electromembrane extraction (EME) of standard solutions and complex samples. The CE-C(4)D method has evidenced for the first time that large proteins, such as human serum albumin, are efficiently retained on all examined SLMs and that transfer of other matrix components and the analytes is strongly SLM dependent. Excellent transfer of the analytes was achieved across SLMs impregnated with 2-nitrophenyl octyl ether (NPOE) or 1-ethyl-2-nitrobenzene, however, an increased co-extraction of interfering matrix components, which disabled quantitative determination of haloperidol with the current CE-C(4)D setup, was observed for the latter. After addition of a commonly used ion carrier (bis(2-ethylhexyl)phosphate) to NPOE, a wide range of matrix components were transferred across the SLM with no measurable transfer of the analytes. Best selectivity regarding transfer of the basic drugs and elimination of matrix components was obtained using SLM impregnated with NPOE. An optimized EME-CE-C(4)D method was used to determine the basic drugs in various samples and satisfactory analytical parameters were obtained.
- MeSH
- adsorpce MeSH
- aminokyseliny analýza izolace a purifikace MeSH
- elektroforéza kapilární přístrojové vybavení metody MeSH
- extrakce na pevné fázi přístrojové vybavení metody MeSH
- léčivé přípravky analýza izolace a purifikace MeSH
- lidé MeSH
- membrány umělé MeSH
- proteiny analýza izolace a purifikace MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Effects of organic solvent type, pH value, and composition of donor/acceptor solution on the efficacy of electromembrane extraction (EME) were examined. For the first time, a comprehensive quantitative study, based also on measurements of electric charge passed through the EME system, was carried out, which demonstrates that apart from the pH value, also the nature of counter-ions in donor and acceptor solution plays a significant role in the electrically induced transfer of charged analytes across supported liquid membranes (SLMs). The EME transfer of model analytes correlated well with electrophoretic mobilities of inorganic cations, which were added to acceptor solutions during their alkalization with alkali metal hydroxides, and were highest for counter-cations with highest mobilities. Up to a 53-fold improvement of extraction efficiency was achieved for EMEs using optimized composition of donor (alkalized with KOH to pH 7) and acceptor (10 mM CsOH, pH 12) solutions. Six chlorophenols (CPs) were selected as model analytes due to the wide range of pH values that are required for their ionization and due to their high environmental relevance; quantitative measurements were carried out by CE with UV detection. Extraction recoveries of the six CPs ranged between 14 and 25% for 5 min EMEs at 150 V and 750 rpm across SLMs impregnated with 1-ethyl-2-nitrobenzene. Calibration curves were strictly linear (r(2) ≥ 0.999) in 0.01-10 μg/mL range, repeatability values of peak areas were between 0.7 and 5.6% and LODs for standard solutions and environmental samples were better than 5 ng/mL.
- MeSH
- chemická frakcionace přístrojové vybavení metody MeSH
- chemické modely * MeSH
- chlorfenoly analýza chemie izolace a purifikace MeSH
- elektroforéza přístrojové vybavení metody MeSH
- limita detekce MeSH
- lineární modely MeSH
- membrány umělé * MeSH
- reprodukovatelnost výsledků MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Selectivity of electromembrane extractions (EMEs) was fine-tuned by modifications of supported liquid membrane (SLM) composition using additions of various 18-crown-6 ethers into 1-ethyl-2-nitrobenzene. Gradually increased transfer of K(+) , the cation that perfectly fits the cavity of 18-crown-6 ethers, was observed for EMEs across SLMs modified with increasing concentrations of 18-crown-6 ethers. A SLM containing 1% w/v of dibenzo-18-crown-6 in 1-ethyl-2-nitrobenzene exhibited excellent selectivity for EMEs of K(+) . The established host-guest interactions between crown ether cavities in the SLM and potassium ions in donor solution ensured their almost exhaustive transfer into acceptor solution (extraction recovery ∼92%) within 30 min of EME at 50 V. Other inorganic cations were not transferred across the SLM (Ca(2+) and Mg(2+) ) or were transferred negligibly (NH4 (+) , Na(+) ; extraction recovery < 2%) and had only subtle effect on EMEs of K(+) . The high selectivity of the tailor-made SLM holds a great promise for future applications in EMEs since the range of similar selective modifiers is very broad and may be applied in various fields of analytical chemistry.
Optimized acceptor solutions, which eliminate electrolytically induced variations in their pH values, have been shown to improve electromembrane extraction (EME) performance. Acceptor solutions containing 500 mM formic acid (pH 1.97) ensured stable EME process for three basic drugs extracted at 50 V across 1-ethyl-2-nitrobenzene and constant extraction recoveries (66-89%) were achieved for 40-80 min EMEs. Back-extraction of analytes into donor solutions has been eliminated by application of optimized acceptor solutions, moreover, saturation of acceptor solutions with analytes had no additional effect on their back-extraction; the presence of up to 300-fold excess of analytes in optimized acceptor solutions led to slightly reduced but stable enrichment of analytes over the entire extraction time. Stable EME performance has been also achieved for extractions into 100mM HCl, note however, that seriously compromised performance of subsequent capillary electrophoretic analyses has been observed due to high conductivities of resulting acceptor solutions. Electrolytically produced H(+) and OH(-) ions have mostly remained in corresponding operating solutions, have determined their final pH values and have not been subjects of EME transfers across selective phase interfaces as was experimentally verified by pH measurements of anolytes and catholytes at various EME times.
Different types of mathematical models were applied in the last decade to simulate kinetics of supercritical fluid extraction (SFE) of essential oils from aromatic plants. Compared to the extraction of fatty oils, modeling of extraction of essential oils is more complicated due to their potential fractionation, co-extraction of less soluble compounds, and stronger effect of flow pattern on extraction yield, which is connected with solute adsorption on plant matrix. Fitting the SFE models to experimental extraction curves alone usually does not enable reliable selection among the models. Major progress was made when detailed models for the extraction from glandular structures of plants were developed. As the type of glands is characteristic for plant families, the choice of models for SFE of essential oils is substantially facilitated. As the extracts from aromatic plants contain also cuticular waxes and other less soluble substances, and essential oils themselves are mixtures of substances of different solubility in supercritical carbon dioxide, modeling of extraction of mixtures and their fractionation in time deserves more attention.
Zosyntetizovali sa polyméry s odtlačkami molekúl na extrakciu 1-metyl-2-piperidínoetylesterov 2-metoxyfenylkarbámovej kyseliny, ktorá sa použila ako templát. Pri syntéze sa použili funkčné monoméry akrylamid a kyselina metakrylová. Pripravené polyméry sa testovali ako sorbenty na extrakciu tuhou fázou (MISPE). Študovala sa ich kapacita a selektivita k derivátom 1-metyl-2-piperidínoetylesterov alkoxyfenylkarbámových kyselín, ktoré sú lokálne anestetiká. Zároveň rovnakou metódou sa pripravili polyméry bez použitia templátu, čím sa mohli zistiť nešpecifické interakcie medzi sorbentom a skúmanými látkami. Polymér pripravený pomocou metakrylovej kyseliny sa použil na predkoncentráciu 1-metyl-2-piperidínoetylesteru 2-metoxyfenylkarbámovej kyseliny z ľudskej plazmy, do ktorej sa pridala uvedená látka (1 µg v 1 ml plazmy).
Molecularly imprinted polymers for 1-methyl-2-piperidinoethylester of 2-methoxyphenylcarbamic acid (template) have been synthesised. Acrylamide and methacrylic acids, respectively, were used as the functional monomers. Imprinted polymers were used as the sorbents for solid-phase extraction (MISPE). The capacity and selectivity of prepared imprinted polymers were investigated with the use of some derivatives of 1-methyl-2-piperidinethylesters of alkoxyphenylcarbamic acids. The non-imprinted (blank) polymers were prepared by the same way without a template to study the non-specific interactions. The molecularly imprinted polymer prepared from methacrylic acid was used to preconcentrate 1-methyl-2-piperidinoethylester of 2-methoxyphenylcarbamic acid and its analogues from spiked human plasma (1 µg in 1 ml of plasma).
