Solid-phase Extraction Sorbent Research Articles

Novel dummy molecularly imprinted polymer for simultaneous solid-phase extraction of stanozolol metabolites from urine.

Stanozolol, a synthetic derivative of testosterone, is one of the common doping drugs among athletes and bodybuilders. It is metabolized to a large extent and metabolites are detected in urine for a longer duration than the parent compound. In this study, a novel dummy molecularly imprinted polymer (DMIP) is developed as a sorbent for solid-phase extraction of stanozolol metabolites from spiked human urine samples. The optimized DMIP is composed of stanozolol as the dummy template, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker in a ratio of 1:10:80. The extracted analytes were quantitively determined using a newly developed and validated ultrahigh-performance liquid chromatography tandem mass spectrometry method, where the limits of detection and quantitation were 0.91 and 1.81ngmL-1, respectively, fulfilling the minimum required performance limit decided on by the World Anti-Doping Agency. The mean percentage extraction recoveries for 3'-hydroxystanozolol, 4β-hydroxystanozolol, and 16β-hydroxystanozolol are 97.80% ± 13.80, 83.16% ± 7.50, and 69.98% ± 2.02, respectively. As such, the developed DMISPE can serve as an efficient cost-effective tool for doping and regulatory agencies for simultaneous clean-up of the stanozolol metabolites prior to their quantification.

Application of a novel deep eutectic solvent modified carbon nanotube for pipette-tip micro solid phase extraction of 6-mercaptopurine

Background6-mercaptopurine (6-MP) is a chemotherapy drug mainly used to treat leukemia. It is a persistent organic pollutant and can remain in the environment for a long period of time. The presence of 6-MP in the environment poses a number of hazards and needs to be assessed to monitor its potential risk to human health and the environment. However, due to its trace amount in complicated matrices, a clean-up and preconcentration step before its determination is compulsory.ResultsAs a highly efficient adsorbent for the extrication of 6-mercaptopurine (6-MP), a novel carbon nanotube doped with camphor: decanoic acid deep eutectic solvent was synthesized and applied as a packing material for the pipette-tip micro solid phase extraction sorbent of 6-MP from tap, wastewater and seawater samples before its spectrophotometric determination. Characteristics and structure of this adsorbent was fully investigated. Factors affecting extraction, including type and volume of the eluent, ionic strength and pH of the sample solution, amount of adsorbent, and number of extraction and elution cycles were optimized using one-factor-at-a-time and response surface methodologies. The method was found to be linear in the range of 1 to 1000 µg/L with a limit of detection and quantification of 0.2 and 0.7 µg/L, respectively. Reproducibility as relative standard deviation was better than 4.6%.ConclusionApplication of deep eutectic solvent modified carbon nanotube indicated suitable microextraction results and good potential for rapid extraction of trace amounts of 6-MP from different aqueous samples. The amount of sample required for the analysis was less than 10 mL and only 1.5 mg of the adsorbent was used. The total analysis time, including extraction was less than 15 min and the adsorbent could be used for at least 10 times, without significantly losing its adsorption ability. Compared to using unmodified usual carbon nanotubes, deep eutectic solvent doped carbon nanotubes showed 19.8% higher extraction ability.

Retraction Note: Application of Polypropylene Amine Dendrimers (POPAM)-Grafted MWCNTs Hybrid Materials as a New Sorbent for Solid-Phase Extraction and Trace Determination of Gold(III) and Palladium(II) in Food and Environmental Samples

Retraction Note: Application of Polypropylene Amine Dendrimers (POPAM)-Grafted MWCNTs Hybrid Materials as a New Sorbent for Solid-Phase Extraction and Trace Determination of Gold(III) and Palladium(II) in Food and Environmental Samples

Development of an innovative analytical method for forensic detection of cocaine, antidepressants, and metabolites in postmortem blood using magnetic nanoparticles.

Cocaine and antidepressants rank high globally in substance consumption, emphasizing their impact on public health. The determination of these compounds and related substances in biological samples is crucial for forensic toxicology. This study focused on developing an innovative analytical method for the determination of cocaine, antidepressants, and their related metabolites in postmortem blood samples, using unmodified commercial Fe3O4 nanoparticles as a sorbent for dispersive magnetic solid-phase extraction (m-d-SPE), coupled with liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis. An aliquot of 100 µL of whole blood and 5 µL of the internal standard pool were added to 30mg of nanoparticles. The nanoparticles were separated from the sample using a neodymium magnet inserted into a 3D-printed microtube rack. The liquid was then discarded, followed by desorption with 300 µL of 1/1/1 acetonitrile/methanol/ethyl acetate. The sample was vortexed and separated, and 1.5 µL of the organic supernatant was injected into the LC-MS/MS. The method was acceptably validated and successfully applied to 263 postmortem blood samples. All samples evaluated in this study were positive for at least one substance. The most frequent analyte was benzoylecgonine, followed by cocaine and cocaethylene. The most common antidepressants encountered in the analyzed samples were citalopram and fluoxetine, followed by fluoxetine's metabolite norfluoxetine. This study describes the first report of this sorbent in postmortem blood analysis, demonstrating satisfactory results for linearity, precision, accuracy, and selectivity for all compounds. The method's applicability was confirmed, establishing it as an efficient and sustainable alternative to traditional techniques for forensic casework.

Covalent organic framework aerogel for high-performance solid-phase extraction of tetracycline antibiotics: Experiment and simulated calculation on adsorption behavior

Three-dimensional sponge-architecture covalent organic frameworks (COFs)-aerogel was successfully designed and synthesized via a freeze-drying template approach, and utilized as an efficient sorbent in solid-phase extraction (SPE). A method for selective enrichment of pharmaceutical contaminants including tetracycline, chlortetracycline, methacycline and oxytetracycline in the environment and food samples was proposed by combining with high performance liquid chromatography (HPLC). To understand the adsorption mechanism, selectivity test and molecular dynamics (MD) simulated calculation were both carried out. The experimental and in-silico results demonstrated that the COFs-aerogel possessed high selectivity for contaminants with H bond acceptors/donors and good efficiency with maximum adsorption capacity up to 294.1 mg/g. The SPE-based HPLC method worked well in the range of 8-1000 ng/mL, with the need of little dose of adsorbent and sample volume while no need of spectrometer, outgoing the reported adsorbents. Under the optimized conditions, the intra-day and inter-day relative standard deviations (RSD) of repeatability were within 2.78-6.29 % and 2.44-8.42 % (n=5). The results meet the current detection requirement for practical applications, and could be extended for further design of promising adsorbents.

Preparation of ionic porous polymers for extraction of four phenolic endocrine disrupting chemicals from fish and water samples

In this paper, series of ionic polymers were synthesized by crosslinking alkyl quaternary ammonium salts with 1,4-bis(chloromethyl)benzene. Among them, hyper-crosslinked polymer fabricated with dodecyl dimethyl benzyl ammonium chloride (HCP-DD) as monomer delivered superior adsorption performance for endocrine disrupting chemicals (EDCs). The adsorption mechanism mainly includes π-π stacking, hydrophobic and electrostatic interaction. With HCP-DD as solid phase extraction sorbent, a high performance liquid chromatography-diode array detection method was developed for the detection of four phenolic EDCs in water and fish samples. The detection limits of the method were 0.005–0.02 ng mL−1 for water samples and 3–30 ng g−1 for fish samples. The recoveries of EDCs in water samples and fish samples were 80–119% and 81.3–117% (relative standard deviations <4.4%), respectively. The study not only provides a route for preparation ionic porous polymers, but also highlights the applications of ionic polymers as efficient adsorbent to enrich organic pollutants.

The potential of polyaniline-coated stationary phase in hydrophilic interaction liquid chromatography-based solid-phase extraction for glycopeptide enrichment

Glycopeptide enrichment is a crucial step in glycoproteomic analysis, often achieved through solid-phase extraction (SPE) on polar stationary phases in hydrophilic interaction liquid chromatography (HILIC). This study explores the potential of polyaniline (PANI)-coated silica gel for enriching human immunoglobulin G (IgG). Experimental conditions were varied to assess their impact on glycopeptide enrichment efficiency, comparing PANI-cotton wool SPE with conventional cotton wool as SPE sorbents. Two formic acid concentrations (0.1% and 1%) in elution solvent were tested, revealing that higher concentrations led to earlier elution of studied glycopeptides, especially for sialylated glycopeptides. Substituting formic acid with acetic acid increased the interaction of neutral glycopeptides with the PANI-modified sorbent, while sialylated glycopeptides showed no significant change in enrichment efficiency. Acetonitrile concentration in the elution solvent (5%, 10%, and 20%) affected the enrichment efficiency with most glycopeptides eluting at the lowest acetonitrile concentration. The acetonitrile concentration in conditioning and washing solutions (65%, 75%, and 85%) played a crucial role; at 65% acetonitrile, glycopeptides were least retained on the stationary phase, and neutral glycopeptides were even detected in the flow-through fraction. This study shows the potential of in-house-prepared PANI-modified sorbents for SPE-HILIC glycopeptide enrichment, highlighting the crucial role of tuning experimental conditions in sample preparation to enhance enrichment efficiency and selectivity.

Rapid, efficient, and accurate determination of aflatoxins and capsaicinoids in vegetable oils by immunomagnetic sorbents coupled with UHPLC–MS/MS

AbstractA fast, simple, and sensitive analytic method was proposed for the simultaneous quantification of aflatoxins (AFTs) and capsaicinoids in vegetable oils by immunomagnetic sorbent coupled with ultra‐performance liquid chromatography coupled with tandem mass spectrometry. The immunomagnetic solid phase extraction (IMSPE) sorbents were synthesized with the monoclonal antibodies via cyanogen bromide magnetic sorbents, which could modify the surface magnetic sorbents under mild synthetic condition. The IMSPE procedure had the following aspects such as ease manipulation, easy disperse, quick isolation, eco‐friendly, and cost‐effective. The major conditions of IMSPE procedure were systemically studied, and the optimized pretreatment was accomplished in 15 min avoding complicated condition or sophisticated equipment. Excellent linearities were achieved by the correlation (R2) more than 0.9983. The limits of quantifications of all analytes ranged from 0.03 to 0.20 µg kg−1, and the recoveries were satisfactory ranging from 75.7% to 124.0% with the intra‐day and inter‐day precisions less than 10.1%. Additionally, the proposed method was used to analyze AFTs and capsaicinoids in retail oil samples. Overall, 25% of soybean and peanut oils and 12.5% of corn and blended oil were detected with AFTs, and no capsaicinoid was found. The content of AFTs was under the MRLs set by EU and China regulation for food quality and safety. The validated results indicated that this method could be utilized for a rapid, efficient, and accurate quantification of AFTs and capsaicinoids in complex lipid‐based matrix.

Molecularly imprinted polymers as solid-phase and dispersive solid-phase extraction sorbents in the extraction of antiretroviral drugs in water: adsorption, selectivity and reusability studies

AbstractThe antiretroviral drugs (ARVDs) have been reported to be among the emerging water pollutants as a results attention is being paid on their analysis. This work therefore explored for the first time the multi-template MIP for the selective removal of selected ARVDs (abacavir, efavirenz and nevirapine) in wastewater, river water and tap water. The adsorption studies of a multi-template MIP were conducted by determining the effect of an increase in ARVDs concentration in solution and the effect of an increase in contact time between the sorbent and the ARVDs. High adsorption efficiencies were observed for abacavir, efavirenz and nevirapine analytes within 5 min and the maximum adsorption efficiency was observed at 60 min ranging from 94.76 to 96.93%. Adsorption kinetics showed that pseudo-second rate order was the best fitting model, while adsorption isotherms indicated that the Freundlich isotherm (R2 = 0.94–0.98) best described the adsorption mechanism of ARVDs onto the MIPs. These results indicated that the electrostatic attractions influenced the multilayer coverage and chemisorption process. Selectivity studies conducted in the presence of competitors gave the recoveries between 92 and 98% for the target analytes, while they were 63–79% for competitors indicating good selectivity and strong affinity of the polymer towards the target analytes. Reusability studies showed that the MIP can be reused for up to 8 cycles with recoveries above 92% for all target ARVDs. The application of the MIP-DSPE method to wastewater, river and tap water samples gave concentrations of 28.75–178.02, 1.95–13.15 and 2.17–6.27 µg L−1, respectively. These results indicate the potential unplanned consumption of ARVDs upon drinking contaminated water which could result to their resistance by the human body. Therefore, their continuous monitoring as well as investigation of their removal strategies is of paramount importance.

Determination of atropine and scopolamine in honey using a miniaturized polymer-based solid-phase extraction protocol prior to the analysis by HPLC-MS/MS

Two homopolymers have been prepared employing methacrylic acid and 4-vynylpiridine as functional monomers (p-MAA, p-4-VP) through an easy and quick precipitation polymerization method for application as sorbents in solid-phase extraction (SPE) to determine atropine and scopolamine in honey. The optimized SPE conditions were as follows: 25 mg of p-MAA, 4 mL of sample loading volume (diluted honey 1:10 with water), 4 mL of elution solvent (methanol/water with 1 % formic acid, 80/20, v/v). The extracts were analyzed by HPLC-MS/MS. The cartridges were reusable for forty cycles demonstrating an environmentally friendly approach. The methodology was validated in terms of linearity, accuracy, precision, selectivity, matrix effect and sensibility, highlighting the absence of matrix effect. The miniaturized polymer-based SPE was successfully applied to fifteen honeys, showing concentrations up to 7.23 ng/g in the most contaminated honey. All quantified honey samples (5 in total) were of multifloral type.

Analysis of vitamin D and its metabolites in biological samples – Part II: Optimization of a sample preparation method for liver tissue

Extraction of vitamin D, including its hydroxylated and esterified metabolites, from soft tissues such as the liver is challenging due to the lipophilic character of matrix and analytes that are expected in very low concentration levels.In this study, we aimed at the optimization of two-step extraction using solid–liquid extraction as the first step, followed by solid-phase extraction. Various solvents, including ethanol, acetonitrile, methanol, acetone, heptane, and heptane with isopropanol, were investigated to isolate vitamin D compounds from liver tissue in the first step. Acetone was finally selected as the most suitable solvent for the solid–liquid extraction, with the highest recovery in the range of 67 – 98% for polar hydroxylated forms and 3 – 28% for lipophilic vitamin D and esters. Two solid phase extraction (SPE) based on the (i) “bind and elute strategy” and (ii) “removal strategy” using hydrophilic-lipophilic balanced SPE sorbent were optimized as a proceeding step for acetone extracts to increase the method selectivity. Finally, two optimized methods, combining solid–liquid extraction and individual SPE strategy, were examined in terms of sensitivity, recovery, matrix effect, accuracy, and precision.The limits of quantification were in the range of 1 – 10 ng/mL and 3 – 20 ng/mL analyzed by ultra-high performance supercritical fluid chromatography and ultra-high performance liquid chromatography hyphenated a with tandem mass spectrometer, respectively. The absolute recovery determined for the “bind and elute strategy” protocol was in the range of 3 – 24 %. Nevertheless, this method was free of matrix effects, which were determined to be in the 73 – 120 % range. On the contrary, the “removal strategy” approach provided higher recovery values for all compounds (47 – 123 %), but the results for nonpolar vitamin D and esters were strongly affected by signal suppression (matrix effects 3 – 51 %). Both methods fulfilled the criteria for accuracy and precision requested by the European Medicine Agency Guideline on Bioanalysis.“Removal strategy” SPE with decreased manual intervention and lower solvent consumption was finally applied to mouse liver tissue to determine vitamin D and its hydroxylated and esterified metabolites for the first time. The results, i.e., vitamin D esters detected in liver tissue, supported the notion that esters of vitamin D can be stored in lipophilic tissues to release vitamin D.

Covalent organic frameworks: spotlight on applications in the pharmaceutical arena.

Covalent organic frameworks (COFs) have much potential in the field of analytical separation research due to their distinctive characteristics, including easy modification, low densities, large specific surface areas and permanent porosity. This article provides a historical overview of the synthesis and broad perspectives on the applications of COFs. The use of COF-based membranes in gas separation, water treatment (desalination, heavy metals and dye removal), membrane filtration, photoconduction, sensing and fuel cells is also covered. However, these COFs also demonstrate great promise as solid-phase extraction sorbents and solid-phase microextraction coatings. In addition to various separation applications, this work aims to highlight important advancements in the synthesis of COFs for chiral and isomeric compounds.

Determination of Aminophylline in Human Serum Using Hydrogel Microspheres for Coupled Surface-Enhanced Raman Spectroscopy (SERS) and Solid-Phase Extraction.

Aminophylline (AMP) is a bronchodilator. The therapeutic and toxic doses are very close. Therefore, therapeutic drug monitoring (TDM) of AMP is essential in clinical practice. Microgels were synthesized by free radical precipitation polymerization. Silver@poly(N-isopropyl acrylamide) (Ag@PNIPAM) hybrid microgels were obtained by loading silver (Ag) nanoparticles into the three-dimensional network of the microgels by in situ reduction. The microgel is a three-dimensional reticular structure with tunable pore size, large specific surface area, and good biocompatibility, which can be used as a sorbent for solid-phase extraction (SPE) of target molecules in complex matrices and as a surface-enhanced Raman spectroscopy (SERS) substrate. We optimized the conditions affecting SERS enhancement, such as silver nitrate (AgNO3) concentration and SPE time, according to the SERS strategy of Ag@PNIPAM hybrid microgels to achieve label-free TDM for trace AMP in human serum. The results showed good linearity between the logarithmic concentration of AMP and its SERS intensity in the range of 1-1.1 × 102 µg/mL, with a correlation coefficient (R2) of 0.9947 and a low detection limit of 0.61 µg/mL. The assay accuracy was demonstrated by spiking experiments, with recoveries ranging from 93.0 to 101.8%. The method is rapid, sensitive, reproducible, requires simple sample pretreatment, and has good potential for use in clinical treatment drug monitoring.

Chiral HPLC-MS/MS determination of hyoscyamine enantiomers in baby herbal infusions after preconcentration with sulfonic HMS mesostructured silica synthesized by co-condensation

Tropane alkaloids are considered a major food safety issue in recent years, due to their worrying appearance in many foods, such as herbal infusions, usually due to cross-contamination with weeds during harvest. (−)-Hyoscyamine is synthesized by tropane alkaloids-producing plants and its ingestion can cause all types of disorders in humans. Its enantiomerization occurs easily over time, so the inactive (+)-hyoscyamine can be found in foods in variable proportions. Therefore, the goal of the current work was to develop a chiral high performance liquid chromatography tandem mass spectrometry method for the enantiomeric determination of (−)- and (+)-hyoscyamine. Chromatographic separation was optimized, and the best chiral resolution (Rs = 1.59) was achieved in 6.5 min with a Chiralpak® AY-3 polysaccharide-based stationary phase column using ethanol with 0.05 % diethylamine as mobile phase. For the preconcentration of the sample, two types of mesostructured silicas with sulfonic groups were synthesized, by grafting and co-condensation methods, and characterized. The materials were evaluated as sorbents for strong-cation exchange solid-phase extraction of hyoscyamine in baby herbal infusions. Based on the findings gathered, silica denoted as HMS-SO3−(co) was the best sorbent due to the high number of functional groups attached to silica (2.63 mmol/g) and its textural properties. Under optimal conditions, the preconcentration factor obtained was 167, using only 50 mg of the material, and a very low racemization of the (−)-hyoscyamine to the (+) enantiomer was found (<20 %). The method was validated with recoveries of 94–99 %, good linearity (R2 > 0.99), precision (RSD < 20 %), no matrix effect for both analytes and low method quantification limit (0.089 µg/L and 0.092 µg/L for (+)-hyoscyamine and (−)-hyoscyamine, respectively) to meet its applicability in monitoring real samples. Two types of herbal teas for babies (instant and teabags) were analyzed with the developed methodology. Two of the instantaneous infusions analysed were contaminated, one of them with 0.21 µg/L of (−)-hyoscyamine and 0.09 µg/L of (+)-hyoscyamine (ratio 70(−)/30(+)) and the other with 0.075 µg/L of (−)-hyoscyamine (the (+)- enantiomer was below the limit of quantification of the method). Taking these results into account, it is important to evaluate the content of hyoscyamine enantiomers in the infusions to avoid overestimation of (−)-hyoscyamine exposure.

Magnetic phytic acid-modified kapok fiber biochar as a novel sorbent for magnetic solid-phase extraction of antidepressants in biofluids

BackgroundTherapeutic drug monitoring (TDM) of antidepressants is essential for monitoring patient medication to avoid drug toxicity, complications, or nonadherence. Chromatographic techniques with high sensitivity and reproducibility are the main detection method for antidepressants. Effective pretreatment of biological sample processes is necessary prior to instrumental analysis. Magnetic solid-phase extraction (MSPE) has received much attention for its advantages of simple operation, rapidity, cost-effectiveness and low organic solvent consumption. Therefore, the development of a suitable and green magnetic sorbent for the detection of antidepressants in plasma and urine is apparently necessary. (88) ResultsA magnetic phytic acid-modified kapok fiber biochar sorbent (Fe3O4/PAKFBC) was successfully synthesized by pyrolytic impregnation and physical milling methods. Fe3O4/PAKFBC exhibited a large specific surface area (214 m2 g−1) and a rich pore structure (5–10 nm). The extraction equilibrium, using 10 mg Fe3O4/PAKFBC, can be completed in about 1 min. The density functional theory (DFT) results showed that the adsorption mechanism of Fe3O4/PAKFBC on the six antidepressants mainly included electrostatic interactions, van der Waals interactions, π-π interactions and weak hydrogen bonding. Examination using the greenness assessment tools showed that the developed method exhibited excellent greenness. By combining with liquid chromatography-ultraviolet (LC-UV), a quantitative method with good linearity (R2 > 0.993) and relative recoveries (92.4–107.7%) and negligible matrix effect (−11.5–6.0%) was developed. The Fe3O4/PAKFBC successfully detected six antidepressants in plasma and urine samples, requiring no pH adjustment with buffer salts. (142) SignificanceThe environmental sustainability of the proposed methods was affirmed by six greenness evaluation tools, all indicating exceptional eco-friendliness. The Fe3O4/PAKFBC demonstrated outstanding greenness in both its creation and analytical application, proving highly effective in real sample applications and showcasing potential for broader use. This study contributes to a deeper and broader understanding of the microscopic adsorption mechanism, which can help in the optimization and development of more green sorbents. (69).

Design, synthesis, and characterization of molecularly imprinted solid phase extraction for alpha Mangostin analysis in blood sample

AbstractLow levels of α‐mangostin (AM) in biological fluids require adequate sample preparation to be analyzed. Molecularly imprinted polymers can serve as sorbents in solid phase extraction, enabling concentration and extraction of α‐mangostin from complex matrices, such as biological fluids. To date, there are no molecular imprinted polymers for the analysis of α‐mangostin in biological fluids. In this study, AM molecular imprinted polymer (MIP) was designed using molecular modeling, molecular dynamic simulations, and prepared by bulk polymerization and suspension polymerization methods. The geometry optimization results showed that acrylamide (AAM) monomer forms the most stable complex with AM at the pre‐polymerization with the most negative Gibbs free energy (ΔG) of −6.91818 Kcal/mol. Radial distribution function (RDF) in molecular dynamics simulation of AM:AAM:ethylene glycol dimethacrylate (EGDMA) with mol ratio 1:4:20 shows the complex with the best composition through the formation of four stable hydrogen bonds. Based on the experimental results, molecularly imprinted polymers in suspension exhibit better characteristics, selectivity, and adsorption capacity than in bulk. The suspension polymerization method showed a high recovery (85.88% ± 2.5), which was higher than C18 SPE cartridge (24.19% ± 1.47). Hence, it can be concluded that the MIPs from MD simulations were accessible and could be used in practice, such as in the separation and detection of AM in blood serum.

ПРИМЕНЕНИЕ СОРБЕНТА ДЛЯ ТВЕРДОФАЗНОЙ ЭКСТРАКЦИИ НА ОСНОВЕ ГИПРОМЕЛЛОЗЫ ДЛЯ КОЛИЧЕСТВЕННОГО ОПРЕДЕЛЕНИЯ КИСЛОТЫ САЛИЦИЛОВОЙ В КОМБИНИРОВАННЫХ ЛЕКАРСТВЕННЫХ ПРЕПАРАТАХ

Introduction. In quality control of pharmaceutical formulations, there are methodological approaches based on the preliminary separation of sample components and approaches without preliminary separation. The use of solid-phase extraction (SPE) allows to separate analytes during sample preparation, with the separation selectivity determining the analysis selectivity as a whole. Currently, sorbents that provide selectivity in interaction with the analyte are of interest. Various derivatives of cellulose are used to obtain selective sorbents: ethylcellulose, hydroxypropylmethylcellulose (hypromellose), carboxymethylcellulose, etc. On the pharmaceutical market of the Russian Federation, there are pharmaceutical formulations with the active pharmaceutical substance salicylic acid. The use of selective SPE for analysis is a promising direction of research in drug quality control. Aim. Evaluation of the metrological characteristics of benzocaine quantitation by UV-spectrophotometry in certain pharmaceutical formulations using hypromellose sorbent for solid-phase extraction. Material and methods. The sorbent using a method developed by us was obtained. Salicylic acid (FS.2.1.0634, Russia State Pharmacopoeia XV ed.) to form active binding sites in sorbent structure was applied. The sorbent structure is polycyanoacrylate matrix with hypromellose fragments, the surface area is 255.50 m2/g, pore volume is 0.1433 cm3, pore diameter is 5.32 nm. The sorption capacity of hypromellose sorbent for benzocaine was 12.2 ± 0.8 μg/g. The SPE technique is proposed. SPE includes the stages: conditioning, sample addition and step-by-step elution with purified water and sodium hydroxide solution 0.1 mol/L. The spectrophotometer SF-56 was used to measure the absorbance at an analytical wavelength of 286 nm. To evaluate the selectivity (specificity) of sample preparation during chromatographic (SPE) separation of pharmaceutical formulations, absorption spectra of eluates in the wavelength range of 200-400 nm were scanned. The salicylic acid identification in the eluate was carried out based on absorption peaks at 228 and 298 nm.The salicylic acid calibration curve in the range of 1-20 μg/ml. To determination the metrological characteristics of salicylic acid quantitation method, 16 parallel determinations of samples of each pharmaceutical formulation were made. Statistical processing of the experimental results and determination of the metrological characteristics evaluation of analytical technique were carried out in accordance with general pharmacopoeial monograph (OFS.1.1.0013 "Statistical processing of results of physical, physicochemical, and chemical tests"). Results. When realizing the salicylic acid quantitation technique for measuring absorbance, it is advisable to use only the first portions of eluate (a solution of sodium hydroxide) in a volume of 5-10 ml were obtained. The relative error in determining the average content of salicylic acid in the analyzed preparations ranged from 1.18 to 1.44% for methods with solid-phase extraction (SPE) and 1.86-2.62% in its absence. It has been shown that there is a statistically significant difference in reproducibility for all preparations, as indicated by F-criteria values ranging from 7.81 to 13.5, exceeding their tabulated values. For the method without solid-phase extraction (SPE), there was an overestimation of the salicylic acid content in all cases, increasing the systematic error on average by 87.5%. Conclusion. The possibility of using a selective hypromellose sorbent for sample preparation for salicylic acid quantitation determination in pharmaceutical formulations has been showed. The use of sorbent for analysis provides to systematic error decrement of salicylic acid quantitation by an average of 87.5%.

APPLICATION OF SELECTIVE HYPROMELLOSE SORBENT FOR THE BENZOCAINE QUANTITATION IN PHARMACEUTICAL FORMULATIONS

Introduction. In quality control of pharmaceutical formulations, there are methodological approaches based on the preliminary separation of sample components and approaches without preliminary separation. The use of solid-phase extraction (SPE) allows to separate analytes during sample prepa-ration, with the separation selectivity determining the analysis selectivity as a whole. Currently, sorbents that provide selectivity in interaction with the analyte are of interest. Aim. Evaluation of the metrological characteristics of benzocaine quantitation by UV-spectrophotometry in certain pharmaceutical formulations using hypromellose sorbent for solid-phase extraction. Material and methods. The sorbent using a method developed by us was obtained. Benzocaine (FS.2.1.0634, Russia State Pharmacopoeia XV ed.) to form active binding sites in sorbent structure was applied. The sorbent structure is polycyanoacrylate matrix with hypromellose fragments, the sur-face area is 255.50 m2/g, pore volume is 0.1433 cm3, pore diameter is 5.32 nm. The sorption capacity of hypromellose sorbent for benzocaine was 12.2±0.8 μg/g. The SPE technique is proposed. SPE includes the stages: conditioning, sample addition and step-by-step elution with purified water and hydrochloric acid solution 0.1 mol/L. The spectrophotometer SF-56 was used to measure the absorbance at an analytical wavelength of 286 nm. To evaluate the selectivity (specificity) of sample preparation during chromatographic (SPE) separation of pharmaceutical formulations, absorption spectra of eluates in the wavelength range of 200400 nm were scanned. The benzocaine identification in the eluate was carried out based on absorption peaks at 220 and 286 nm. The benzocaine calibration curve in the range of 120 μg/ml. To determination the metrological characteristics of benzocaine quan-titation method, 11 parallel determinations of samples of each pharmaceutical formulation were made. Results. When realizing the benzocaine quantitation technique for measuring absorbance, it is advisable to use only the first portions of eluate (a solu-tion of hydrochloric acid) in a volume of 510 ml were obtained. The relative error of benzocaine average concentration in the pharmaceutical formula-tions ranged from 1.28 to 1.34% for technique that included the SPE stage, and from 1.86 to 2.02% for technique that did not include it. A comparison of the modifications of the spectrophotometric quantitation of benzocaine in pharmaceutical formulation using hypromellose sorbent and technique without the SPE did not reveal a statistically significant difference in reproducibility. For the modification technique without SPE, an increase of benzo-caine concentration and in determination relative error by an average of 48.0% were observed. Conclusion. The possibility of using a selective hypromellose sorbent for sample preparation for benzocaine quantitation determination in pharmaceu-tical formulations has been showed. The use of a sorbent for SPE at the sample preparation stage reduces the systematic error of benzocaine spectro-photometry quantitation for the analyzed pharmaceutical formulations by an average of 79.2%.

Selective sorption of hippuric acid and 4-methylhippuric acid by polyethylene glycol modified ZIF based molecular imprinted polymer

A novel solid phase extraction (SPE) adsorbent, polyethylene glycol (PEG) immobilized zirconium ion-modified zeolite-imidazole framework (ZIF) molecular-imprinted polymer (ZIF@PEG@Zr@MIPs), was developed for detecting hippuric acid (HA) and 4-methylhippuric acid (4-MHA) in human urine using HPLC-UV. Zirconium ions (Zr4+) anchored on the porous ZIF act as binding sites, facilitating coordination and electrostatic interaction with HA and 4-MHA carboxyl groups. Dopamine (DA) imprinting introduces additional sites, enabling π-π conjugation and hydrogen bonding with HA and 4-MHA, enhancing specific adsorption. The adsorbent, using HA as a template, demonstrated adsorption capacities of 37.98 mg g−1 for HA and 32.99 mg g−1 for 4-MHA. Imprinted factors (IF) were 2.68 for HA and 2.17 for 4-MHA, with a limit of detection (LOD) of 0.015 mg L−1 for HA and 0.011 mg L−1 for 4-MHA. The SPE-HPLC-UV method achieved 84.8–96.2% recovery and 0.3–2.2% relative standard deviation (RSD), illustrating its potential in health monitoring and environmental safety.

A novel removal of Ni2+ ions from water solutions using dispersive solid-phase extraction method with nano Fe3O4/chitosan-acrylamide hydrogel.

The effluent release containing heavy metals as Ni2+ ions has drastic risks to both the natural environment and human health. In this research, the nano Fe3O4/chitosan-acrylamide hydrogel was prepared as a novel nano sorbent for dispersive solid-phase extraction of Ni2+ ions and applied to the water sample solution. The pH, amount and type of elution solvent, the extraction time, etc. were optimized to improve the efficiency of the proposed method. Analytical parameters such as concentration factor and relative standard deviation (%) were achieved as 33.3 and 1.8%, respectively. The capacity in equilibrium sorption was calculated at 22.54 mg g-1. Furthermore, to estimate the adsorption mode, Freundlich, Langmuir, and Temkin models were fitted with experimental isotherm data. Besides, to check the basic process of the metal adsorption mechanism, pseudo-first-order, pseudo-second-order, and Roginsky-Zeldovich models were investigated and the results were fitted with the pseudo-second-order model. The value of change in entropy (⊿S) obtained is -65.24 (J(mol K)-1). Negative values of change in enthalpy, ⊿H in (kJ mol-1) is -24.45 (kJ mol-1) which indicates both physical and chemical adsorptions involved in the process of adsorption. Finally, the nano Fe3O4/chitosan-acrylamide hydrogel exhibited high performance to remove the Ni2+ ions from water sample solution.