Relative Standard Deviation Values Research Articles

A solid-liquid microextraction approach from a spot in an adsorbent layer of a chromatographic plate

A new approach to extracting substances from a spot on a chromatographic plate for subsequent liquid chromatography-mass spectrometry analysis is described. This method involves extraction in a solid phase (an adsorbent layer of a chromatographic plate) - a liquid system using a simple device. For a single extraction of six selected coccidiostats from the adsorbent layer on the chromatographic plate with silica gel, 50 µL of methanol was used for 5 min. The data from the extraction experiments and liquid chromatography-mass spectrometry measurements demonstrated a good correlation between the ratio of the peak areas of the coccidiostats to the internal standard and the concentration of the substances in the range of two orders of magnitude. The coefficients of determination for the mentioned correlations range from 0.962 to 0.999. Moreover, the repeatability and reproducibility, expressed as the percentage values of relative standard deviation, do not exceed 7.5 % for any of the coccidiostats.

Colorimetric probe for the determination of osmium through a novel optical sensor in environmental samples

A novel optical probe has been successfully developed for the selective detection of Os(VIII) ions. This osmium-sensing platform was intricately designed by incorporating 4-(thiazol-2-yldiazenyl)benzene-1,3-diol (TDBD) as the ionophore within a plasticized PVC membrane, and tributylphosphate (TBP) serving as the plasticizer. Upon exposure to Os(VIII) ions in a 0.5 M HClO4 acid milieu, the sensing membrane undergoes a distinctive chromatic transition, shifting from a yellow to a pink hue. The preparation of the sensor and the methodology for Os(VIII) determination were meticulously refined to achieve optimal performance. Under these carefully optimized experimental conditions, the proposed optode demonstrated an impressive linear detection range spanning from 2.5 × 10−9 to 2.5 × 10−5 M for Os(VIII), alongside remarkable detection and quantification limits of 7.24 × 10−10 and 2.4 × 10−9 M, respectively. The sensor consistently delivered highly reproducible results, as evidenced by relative standard deviation (RSD) values of 1.45% and 1.30% for Os(VIII) concentrations at 7.5 × 10−7 and 2.5 × 10−6 M, respectively, underscoring its precision and reliability. Furthermore, the sensor exhibited a swift response time of 3.0 min, further emphasizing its efficiency. The incorporation of PIMs into the sensor architecture led to a remarkable eight-fold enhancement in its response compared to counterparts lacking PIMs, signifying a significant performance improvement. In assessing potential interference, an investigation into the influence of other ions on Os(III) determination revealed that the prepared sensor displayed exceptional selectivity for Os(VIII) ions, with negligible responses observed in the presence of common ions. Collectively, these experimental findings underscore the sensor's efficacy as an invaluable tool for the precise analysis of osmium content in water samples, aligning it with the rigorous standards of international scientific research.

"UHPLC-Q-TOF/MS-chemometrics-network pharmacology" integrated strategy to discover quality markers of raw and stir-fried Fructus Tribuli and process optimization of stir-fried Fructus Tribuli.

Fructus Tribuli, the dried ripe fruit of Tribulus terrestris L., has various beneficial effects, including liver-calming and depression-relieving effects. Raw Fructus Tribuli (RFT) and stir-fried Fructus Tribuli (SFT) are included in the Chinese Pharmacopoeia 2020 edition (Ch. P 2020). However, owing to the lack of specific regulations on SFT-processing parameters in Ch. P 2020, it is difficult to ensure the quality of commercially available SFT. The present study aimed to screen the quality markers (Q-markers) of RFT and SFT and optimize the processing technology of SFT based on the identified Q-markers. First, the ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) technology as well as multiple statistical analysis along with network pharmacology was used to comprehensively identify the Q-markers of RFT and SFT. Then, based on single-factor experiments, the Box-Behnken design (BBD) response surface methodology (RSM) was used to optimize the processing technology of SFT and perform process validation. A total of 63 components were identified in RFT and SFT extracts. Terrestrosin D and Terrestrosin K were initially considered the Q-markers of RFT and SFT, respectively. The optimum processing technology conditions were 208°C, 14 min, and 60 r·min-1. Three batches of process validation were performed, and the mean composite score was 56.87, with a relative standard deviation (RSD) value of 1.13%. The content of steroidal saponin components in RFT was significantly different before and after stir-frying. Terrestrosin D and Terrestrosin K were validated as the Q-markers of RFT and SFT, respectively. The identification of Q-markers for RFT and SFT offered a clear index for optimizing the SFT-processing technology and provided a basis for the quality control of RFT and SFT decoction pieces.

Development and Validation of a New Reversed Phase HPLC Method for the Quantitation of Azithromycin and Rifampicin in a Capsule Formulation.

This research aimed to develop a new method for simultaneously estimating the presence of azithromycin (AZT) and rifampicin (RIF) in a capsule formulation using reverse-phase high-performance liquid chromatography. The developed method utilized a Gemini column with a 60:40% v/v acetonitrile and potassium dihydrogen phosphate mobile phase, a flow rate of 1mL/min, and an injection volume of 20μL. The detection wavelengths of 210 and 254nm for AZT and RIF, respectively, were used. Validation ensures specificity with a peak purity index > 0.99999 for AZT and >0.99995 for RIF, affirming unambiguous analyte detection. The system suitability test, within acceptable limits, validates method reliability. Linearity calibration curves (R2 = 0.998) cover a 25-150% target concentration range. Accuracy studies employing the standard addition method yield recovery values between 96.6 and 103.9% for both drugs, confirming method accuracy. Precision studies reveal % relative standard deviation values consistently below 2%, highlighting reproducibility. Robustness testing supports method reliability under varying conditions. Application to a pharmaceutical capsule formulation demonstrates the method's practicality, accurately quantifying AZT (98.30%) and RIF (99.37%). This study provides a validated analytical approach for simultaneous quantification in commercial pharmaceutical products containing both drugs, enhancing pharmaceutical quality control for critical antibiotics in complex formulations.

A smartphone sensing platform for the sensitive and selective detection of clothianidin based on MIP-functionalized lanthanide MOF.

Anovel molecularly imprinted nanomaterial (Eu (BTC)-MPS@MIP) was synthesized on the surface of silanized europium-based metal-organic frameworks (Eu (BTC)-MPS) using 1, 3, 5-benzotrioic acid (H3BTC) as a ligand. The resulting Eu (BTC)-MPS@MIP was applied to constructing a smartphone sensing platform for the sensitive and selective detection of clothianidin (CLT) in vegetables. The synthesized Eu (BTC)-MPS@MIP demonstrated the successful formation of a typical core-shell structure featuring a shell thickness of approximately 70 - 80nm. The developed sensing platform based on Eu (BTC)-MPS@MIP exhibited sensitivity in CLT detection with a detection limit of 4µg/L and a linear response in the range 0.01 - 10mg/L at excitation and emission wavelengths of 365nm and 617nm, respectively. The fluorescence sensing platform displayed excellent specificity for CLT detection, as evidenced by a high imprinting factor of 3.1. This specificity is primarily attributed to the recognition sites in the molecularly imprinted polymer (MIP) layer. When applied to spiked vegetable samples, the recovery of CLT ranged from 78.9 to 102.0%, with relative standard deviation (RSD) values falling between 2.2 and 6.2%. The quenching mechanism of Eu (BTC)-MPS@MIP toward CLT can be attributed to the inner filter effect (IFE), resulting from the optimal spectral overlap between the absorption spectrum of CLT and the excitation spectra of Eu (BTC)-MPS@MIP. The proposed method has the potential for extension to the detection of other pesticides by replacing the MIP recognition probes.

High-Performance Liquid Chromatography (HPLC) Method Validation for Identifying and Quantifying Rebamipide in Ethosomes.

Introduction The research aimed to develop a robust, high-performance liquid chromatography (HPLC) analytical method for the quantitative assessment of rebamipide encapsulated in ethosomes. Rebamipide, a quinolinone derivative, holds promise as a therapeutic agent for dry eye, but challenges such as low bioavailability and vision clouding post-installation have prompted innovative approaches. Encapsulation in ethosomes, lipid-based nanovesicles, offers a potential solution to enhance ocular bioavailability. Materials and methods The study focused on creating a specific, linear, accurate, precise, and robust HPLC method, addressing entrapment efficiency (%EE), drug content, and drug release of rebamipide in prepared ethosomes. Statistical validation followed International Conference of Harmonization (ICH) specifications. The method's parameters were evaluated within a concentration range of 4-24 µg/ml, with recovery rates indicating accuracy and low % relative standard deviation (RSD) values confirming precision. Limits of detection (LOD) and quantification (LOQ) for rebamipide were determined. Results After preparing the ethosome dosage form by film hydrating method for rebamipide, the rebamipide entrapment efficiency in ethosomes was established at 76% ± 7, while the drug content was found to be 93% ± 6. The drug release process demonstrated zero-order kineticsand five different models of kinetics were applied for a comprehensive analysis. The method exhibited excellent system suitability, specificity, and linearity. Recovery rates for rebamipide ranged from 90% to 100%, and repeatability was confirmed by low %RSD values. The LOD and LOQ for rebamipide were determined to be 1.04 μg/mL and 3.16 μg/mL, respectively. Conclusion The developed HPLC method proved suitable for the quantitative determination of rebamipide in ethosomes, offering rapid and accurate analysis. The results underscore the method's specificity, accuracy, and precision within the specified concentration range. Overall, the validated method contributes to the advancement of ocular drug delivery systems, providing a reliable analytical tool for pharmaceutical research.

Novel HPTLC method for simultaneous estimation from ternary mixture of chlorpheniramine maleate, dextromethorphan hydrobromide and phenylephrine hydrochloride in syrup formulations

A synergic antihistamine, cough suppressant, and decongestant combination of chlorpheniramine, dextromethorphan, and phenylephrine is used to treat acute respiratory infections caused by seasonal viruses. The effective qualitative and quantitative methods require the simultaneous measurement of a ternary combination in the pharmaceutical syrup dosage form. Therefore, a new, simple, fast and robust high performance thin layer chromatographic (HPTLC) method has been developed and validated for chlorpheniramine maleate (CPM), dextromethorphan hydrobromide (DEXO) and phenylephrine hydrochloride (PE). The chromatographic separation was carried out on precoated aluminium plates with silica gel 60 F254 as the stationary phase. Mobile phase used was chloroform: methanol: ammonia (2.5:7.5:0.3, v/v/v) for proper separation. The detection was carried out at 270nm wavelength in absorbance mode. Developed method was validated as per International Council for Harmonization (ICH) Q2 (R1) guideline. The linearity range is 400 to 1400ng/band for CPM, 3000 to 11500ng/band for DEXO and 1000 to 3500ng/band for PE with correlation coefficient ≥0.995. The consistent lower values of relative standard deviation (RSD, %) for precision and robustness study indicate the method reliability. The percent recovery ranged from 97.82 to 102.03% indicates the good accuracy of the method. The proposed method was complying for the analytical method validation parameters suggested by the ICH Q2 (R1) guideline. The method was found to be simple, rapid and reliable for the simultaneous estimation of CPM, DEXO and PE from its pharmaceutical syrup dosage form. The method was successfully applied to quantify these analytes from the several pharmaceutical syrup dosage form.

Quantitative Applications of ATR-FTIR Spectroscopy with Chemometrics for the Estimation of Amikacin in Amikacin Sulphate Injections

Background: Amikacin belongs to the class of aminoglycoside antibiotics used in the treatment of gram-negative bacterial infections. It is resistant to the aminoglycosides modifying enzymes, making it a clinically effective drug in multidrug-resistant infections. Methods: In this study, a simple Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy was used for the quantification of amikacin in amikacin sulphate injection. The infrared spectra were generated in the spectral range of 4000–667 cm-1. The calibration curve was computed through TQ Analyst Pro edition software, and the partial least square regression analysis found the linearity in the range of 10-60% w/w. Results: The best calibration results were obtained in the spectral region from 1040 to 1020 cm-1 with a correlation coefficient (r2) of 1.000. The residual mean standard error (RMSEC) value was 0.00235. The percent relative standard deviation (%RSD) values for intra-day and inter-day precision were less than 8.0. The percent relative error (%RE) values were calculated and found in between the range of 0.52 to 5.60. The percent recovery of the amikacin estimation was 113.09 ± 4.27(n=3). Conclusion: This validated method is considered a green method, which is suitable for the routine analysis of amikacin in amikacin sulphate injections.

Mesoporous silica nanoparticles decorated with C3N4 framework as a novel electrocatalyst for the design of a selective clonazepam sensor

In this study, a new chemical modifier based on copper nitrate hydroxide-containing mesoporous silica decorated with a C3N4 framework (MSN/C3N4/CNH) was developed to design a modified sensor for the determination of clonazepam (CZP). The resulting composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), simultaneous thermal analysis (STA), Brunauer-Emmett-Teller (BET) and Barrett Joyner–Halenda (BJH) analyses. The fabricated electrochemical sensor which was designed with a new modified glassy carbon electrode (GCE) for CZP analysis, exhibits outstanding electrocatalytic activities toward the reduction of CZP. The results showed that significant sensitivity compared to existing methods improved with an excellent detection limit of 2.50 nmol L−1 for the CZP detection, and the modified electrode has high activity toward the oxidation and reduction of CZP, with an oxidation peak around 0.32 V, and a lower reduction peak around −0.78 V; at pH = 7.0. The effect of experimental and instrumental factors on the electrochemical sensor response was examined, and the cyclic voltammetric results confirmed the 4H+/4e− process in the electrochemical studies. Moreover, in differential pulse voltammetry, the reduction peak current was proportional toward the CZP concentration from 0.82 to 76.90 μmol L−1, at optimum conditions. The modified electrode showed good reproducibility, and repeatability with relative standard deviation values of 2.7% and 1.2%, respectively. The proposed method can be applied as a simple, selective, and precise method to determine CZP drug in real samples, with satisfactory results.

Sea hedgehog-inspired surface-enhanced Raman scattering biosensor probe for ultrasensitive determination of Staphylococcus aureus in food supplements

Staphylococcus aureus contamination in food supplements poses substantial challenges to public health and large-scale production but the sensitive detection in a timely manner remains a bottleneck. Drawing inspiration from the sea hedgehog, gold nanostars (AuNSs) were leveraged to design an ultrasensitive surface-enhanced Raman scattering (SERS) biosensor for the determination of Staphylococcus aureus in food supplements. Besides the surface enhancement furnished by the AuNSs, Raman reporter molecules and specific aptamers sequentially self-assembled onto these AuNSs to construct the “three-in-one” SERS biosensor probe for label-based quantitation of Staphylococcus aureus. Following incubation with contaminated health product samples, the gold nanostars@Raman reporter-aptamer specifically recognize and assemble around Staphylococcus aureus cells, forming a distinctive sea hedgehog structure. This unique configuration results in an amplified Raman signal at 1338 cm−1 and an enhancement factor of up to 6.71 × 107. The entire quantitative detection process can be completed within 30 min, boasting an exceptional limit of detection as low as 1.0 CFU mL−1. The method exhibits a broad working range for the determination of Staphylococcus aureus, with concentrations spanning 2.15 CFU mL−1 to 2.15 × 105 CFU mL−1. Furthermore, it demonstrates outstanding precision, with relative standard deviation values consistently below 5.0%. As a showcase to validate the practicality of the SERS method, we conducted tests on determining Staphylococcus aureus in a herbal food supplement, i.e., Ginkgo Biloba extract (GBE); the results align closely with those obtained through the conventional lysogeny broth agar plate method, pointing to the potential applicability in real-world scenarios.

Developing a sensitive voltammetric platform constructed with dysprosium nanoparticles supported on gadolinium oxide–carbon nanotube for the determination of centrophenoxine

This study reports the development of a sensitive voltammetric method of analysis based upon the impact of dysprosium oxide (Dy2O3) on a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs) and gadolinium oxide (Gd2O3). The electrochemically active surface area of Dy2O3@Gd2O3-MWCNTs/GCE had the highest value of 0.495 cm2 of electrochemically active surface area compared to the other electrodes. The proposed platform (Dy2O3@Gd2O3-MWCNTs/GCE) was applied for the sensitive voltammetric determination of centrophenoxine. The novel platform exhibited improved the voltammetric behavior of centrophenoxine in respect to catalytic oxidation and value of the current response owing to high impact of Dy2O3 on synergistic effect between Gd2O3 and MWCNTs. A linear concentration range of 1.0 × 10−7 ∼ 1.7 × 10−5 M with a detection limit of 1.9 × 10−8 M was obtained by the proposed platform. Average recoveries of 98.5 % − 101.3 % with low relative standard deviation (RSD%) values in urine confirmed that Dy2O3@Gd2O3-MWCNTs/GCE produces reliable measurements for the determination of centrophenoxine.

Synthesis of the magnetic composite of Ni-MOF-I in aqueous medium and its application in magnetic dispersive micro solid phase extraction of plasticizers from pharmaceutical samples

For the first time, this research presents the synthesis procedure and analytical application of Ni-MOF-I magnetic composite. The synthesis method was green and done in an aqueous medium. The composite was employed as an adsorbent in a magnetic dispersive solid phase extraction process followed by dispersive liquid–liquid microextraction for the extraction and preconcentration of some plasticizers from pharmaceutical samples stored in plastic containers. The Ni-MOF-I magnetic composite was characterized by applying Fourier transform infrared spectrophotometry, vibrating sample magnetometry, scanning electron microscopy, energy-dispersive X-ray, X-ray diffraction, and nitrogen adsorption/desorption analyses. For operating the extraction procedure, initially, the plasticizers were adsorbed onto the adsorbent particles by vortexing. Then, the plasticizers were desorbed from the adsorbent surface using a mL volume of 2-proponal. Subsequently, the obtained eluate phase was mixed with a mixture of 1,2-dibromoethane and 1,1,2-trichloroethane and then injected into deionized water using a glass syringe. Afterward, centrifugation was done to isolate the extractant from the aqueous phase. Eventually, one microliter of the sedimented phase was injected into gas chromatography-flame ionization detection. Acceptable analytical results such as high enrichment factors (355–415) and extraction recoveries (71–83 %), low limits of quantification (0.76–1.08 μg L−1) and detection (0.23–0.33 μg L−1), wide linear ranges (1.08–300 μg L−1), and satisfactory relative standard deviation values of 4.0–6.3 % (intra-day precision, n = 5) and 4.9–7.4 % (inter-day precision, n = 5) were achieved. The suggested procedure was used as a productive analytical method based on the Ni-MOF-I magnetic composite for the extraction and determination of some plasticizers from different pharmaceutical samples filled in plastic containers. Elimination of centrifugation, using 2-propanol as a green desorption/disperser solvent, detection of di-(2-ethylhexyl) phthalate in boric acid alcohol drop, and applying µL-level of the extraction solvent are the advantages of this proposed method.

Bioinspired composite packed in blunt needles, integrated microextraction and determination of oxycodone and naloxone in saliva by substrate spray mass spectrometry

BackgroundOpioids are effective painkillers used for medical purposes. Their prolonged ingestion can provoke some side effects (including overdose or constipation) that are minimized by using opioid antagonists (e.g., naloxone). The rapid determination of opioids and their antagonists in biosamples is essential for an effective medical treatment. The direct combination of sample preparation and mass spectrometry (MS) fits well in this scenario. It can speed up the analysis achieving a good selectivity, which relies on the sample preparation and MS, and sensitivity levels. ResultsThis article presents a novel substrate-spray mass spectrometry interface based on a polydopamine-cotton (PDA-Cel) composite hosted inside the inner diameter of a 14-gauge blunt needle to determine oxycodone and naloxone in saliva samples. The needle is used as a microextraction device and a substrate for mass spectrometric analysis. The lack of sharpness of the 14-gauge (14G) blunt needles challenges the formation of the electrospray (ESI), and a commercial 10 μL pipette tip is proposed as a simple solution to this shortcoming. Under the optimum parameters, the proposed method was validated, obtaining limits of detection lower than 0.6 μg L−1, linear range up to 200 μg L−1, and linearity better than 0.9915. Relative standard deviation (RSD) and relative recoveries (RR) were studied at three different concentration levels (2, 40, and 200 μg L−1). RSD values were better than 20.7 %, and RR ranged from 90 to 114 %. Finally, a positive sample from a patient under medical treatment was analyzed. Significance and novelty14G blunt needles have been demonstrated as effective extraction devices due to their low price (<0.15 € per extraction unit), their better safety (avoiding finger pricking), and their higher hosting capacity (up to 8 mg of sorbent). The conductivity of stainless steel permits their use as electrospray emitters, making their direct combination to MS easier. The large variety of fibrous sorbents makes this approach versatile enough to be adapted to other analytical problems.

Gold-Deposited Graphene Nanosheets for Self-Cleaning Graphene Surface-Enhanced Raman Spectroscopy with Superior Charge-Transfer Contribution.

The interaction of graphene with metals initiates charge-transfer interaction-induced chemical enhancements, which critically depend on the doping effect from deposited metallic configurations. In this paper, we have explored the gold nanoparticle-decorated monolayer graphene nanosheets for the large graphene-induced Raman enhancement of adsorbed analytes, indicating the surface-enhanced Raman spectroscopy (SERS) capabilities of metal-doped graphene (G-SERS). Here, the systematically sputtered Au thickness optimization procedure revealed noticeable modifications in the graphene Raman spectra and photoluminescence (PL) background quenching, which indicated favorable charge transfer through n-type doping of chemical vapor deposition-grown graphene nanosheets. The highly consistent, individually distributed morphology of the gold nanoislands over graphene nanosheets depicted a reproducibly uniform G-SERS signal with excellent relative standard deviation values (<5%), resulting in the strongest Raman intensity enhancement factors of ∼108 (MB) (methylene blue) and 107 (DPA) (2,6-pyridinedicarboxylic acid) composed of the weakest PL background. The combined charge-transfer-induced chemical enhancement and electromagnetic enhancement from individual Au nanoislands result in a lowering of detectability down to 10-16 M (MB) and 10-11 M (DPA) concentrations with efficient time-dependent signal stability. Additionally, the GAu demonstrated its effective (∼94.4%) photocatalytic degradation capabilities by decomposing MB dye molecules from a concentration of 1 μM to 2.52 fM within 60 min. Therefore, the prominent charge-transfer contribution through controlled Au decoration over graphene nanosheets provides a potential strategy for fabricating superior SERS sensors and photocatalysts exhibiting adequate signal consistency, stability, and photodegradation efficiency through overcoming the limitations of the traditional sensing platforms.

Experimental and theoretical study on the facet‐dependent SERS activity of α‐Fe2O3 films

AbstractSemiconductors have attracted great attention for surface‐enhanced Raman scattering (SERS) applications due to their rich variety, adjustable band structure, good chemical stability, and biocompatibility. However, their intrinsic weak SERS activity limited the further development of semiconductor substrates. Here, the α‐Fe2O3 films with high {} and {} facet exposure ratios were fabricated through an electrodeposition method with the existence of NH4Cl and CH3COONa. The α‐Fe2O3{} and α‐Fe2O3{} films show excellent SERS properties with enhancement factor of 4.155×103 and 5.481×103, as well as the relatively low limit of detection down to 2 × 10−7 M for 4‐nitrobenzenethiol. Meanwhile, the lower relative standard deviation values (&lt;10%) confirm the well uniformity of as‐prepared substrates. Ultraviolet photoelectron spectroscopy analysis reveals that the α‐Fe2O3{} possesses the lower work function, which could guarantee the efficient interfacial charge transfer between substrates and probe molecules. Moreover, first principles calculations further indicates that the charge transfer efficiency on {} facet can be effectively improved, and thus significantly enhance the SERS activity of α‐Fe2O3. The current study provides a strategy for the fabrication and application of semiconductor‐based SERS substrates.

Voltammetric determination of bisphenol A using modified carbon paste electrode

ABSTRACT Designing effective and accurate methods to determine bisphenol A (BPA) residues is crucial for safeguarding food safety and preserving the environment. The main objective of the present work is to develop a simple and sensitive electrochemical sensor to detect BPA based on a modified carbon paste electrode (CPE). For this, CeO2 nanoparticles (CeO2 NPs) and ionic liquid (IL) were used to modify CPE. Cyclic voltammetry (CV) was utilised as the technique to investigate the electrochemical behaviour of BPA at the surface of various electrodes (unmodified CPE, CeO2 NPs/CPE, ILCPE, and CeO2 NPs/ILCPE). The obtained result showed that the CeO2 NPs/ILCPE exhibited better electrocatalytic performance to BPA oxidation than that observed at other CPEs. For quantification of BPA, differential pulse voltammetry (DPV) was utilised. Under the optimum detection conditions, the CeO2 NPs/ILCPE sensor showed good linearity in the detection of BPA within range 0.02–460.0 µM with a limit of detection (LOD) of 0.01 µM. Finally, the enhanced electrochemical response from CeO2 NPs/IL-modified CPE towards BPA has been used to evaluate the practical application of this sensor. The obtained results (recovery and relative standard deviation (RSD) values) confirmed the applicability of the modified CPE to detect BPA in real samples. Based on the findings, the CeO2 NPs/ILCPE sensor appears to be a suitable platform for BPA determination.

Ultra‐high‐performance liquid chromatography method development for the quantification of Molnupiravir and its process‐related impurities using Box‐Behnken experimental design

AbstractMolnupiravir, a promising antiviral agent, has gained significant attention for its potential in treating viral infections, particularly in the context of the coronavirus disease 2019 pandemic. This study aimed to develop and validate an ultra‐high‐performance liquid chromatography (UHPLC) method for the quantification of Molnupiravir and its associated impurities (Imp‐I, Imp‐II, Imp‐III, and Imp‐IV). The method involved a systematic investigation of critical method parameters and their optimization using Quality by Design principles. The percentage of organic modifiers, column temperature, and flow rate were systematically optimized using the Box‐Behnken design. The developed method was assessed for specificity, system suitability, accuracy, precision, linearity, and detection limits. The results demonstrate strong specificity, with the analysis remaining accurate even in the presence of impurities. The developed method exhibits excellent precision, with repeatability and intermediate precision showing relative standard deviation values ranging from 0.78% to 1.14% for impurities and 0.82% to 1.91% for Molnupiravir. Furthermore, the method displays exceptional linearity, covering a wide range of concentrations. The linear regression analysis yields high coefficients of determination (r2, 9993–0.9997), confirming the linearity. The developed UHPLC method is well‐suited for the accurate and reliable analysis of Molnupiravir and its impurities, making it a valuable tool for quality control and pharmaceutical research applications.

Construction and Application of an Electrochemical Sensor for Determination of D-Penicillamine Based on Modified Carbon Paste Electrode.

D-penicillamine (D-PA) is a sulfur-containing drug that has been used for various health conditions. However, like any medication, overdosing on D-PA can have adverse effects and may require additional treatment. Therefore, developing simple and sensitive methods for sensing D-PA can play a crucial role in improving its efficacy and reducing its side effects. Sensing technologies, such as electrochemical sensors, can enable accurate and real-time measurement of D-PA concentrations. In this work, we developed a novel electrochemical sensor for detecting D-PA by modifying a carbon paste electrode (CPE) with a multi-walled carbon nanotube-Co3O4 nanocomposite, benzoyl-ferrocene (BF), and ionic liquid (IL) (MWCNT-Co3O4/BF/ILCPE). Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CHA) were employed to explore the electrochemical response of D-PA on the developed sensor, the results of which verified a commendable electrochemical performance towards D-PA. Under optimized conditions, the developed sensor demonstrated a rapid response to D-PA with a linear dynamic range of 0.05 μM-100.0 μM, a low detection limit of 0.015 μM, and a considerable sensitivity of 0.179 μA μM-1. Also, the repeatability, stability, and reproducibility of the MWCNT-Co3O4/BF/ILCPE sensor were studied and showed good characteristics. In addition, the detection of D-PA in pharmaceutical and biological matrices yielded satisfactory recoveries and relative standard deviation (RSD) values.

Simultaneous identification and quantification of three water-soluble polymers (PVP, PNVCL and PEI) in wastewater samples by continuous-flow off-line pyrolysis GC/MS

In environmental analysis, the detection of water-soluble synthetic polymers (WSSP) presents considerable challenges. Thus, a precise and reproducible analytical method was developed using continuous-flow off-line pyrolysis with gas chromatography/mass spectrometry (GC/MS) to simultaneously identify multiple water-soluble polymers from a single environmental sample.WSSP are widely used in multiple industries as hydrogels due to their hydrophilic character and potential biocompatibility. This adaptability of hydrogels is reflected in their ability to provide customized formulations for specific needs, such as in the development of personal care products, medicine, and pharmaceuticals.Specifically, polyvinylpyrrolidone (PVP), poly(N-vinylcaprolactam) (PNVCL), and polyethyleneimine (PEI) were targeted for analysis in wastewater, employing unique pyrolysis products for identification. These polymers require careful assessment in wastewater to evaluate potential environmental risks associated with their release.PVP and PNVCL were identified through two pyrolysis products, while six pyrolysis products were utilized for the identification of PEI.The validated method demonstrated very good linearity and reproducibility, with correlation coefficients ranging from 0.94 to 0.99 and relative standard deviation (RSD) values between 3 % and 36 % for the targeted compounds. The limit of quantification (LOQ) for the three polymers ranged from 1 to 10 μg L-1. Moreover, the average recovery rates for these polymers, determined from artificial water samples, were approx. 85 %.Utilizing the validated method, water samples from seven wastewater treatment plants in Germany were successfully analyzed, confirming the presence of these polymers at elevated concentrations in the μg L-1 range. Notably, untreated influent waters exhibited higher polymer levels compared to treated influents and effluents, underscoring their significant contribution to overall polymer content.The developed analytical method provides an efficient tool for the simultaneous identification and quantification of PVP, PNVCL, and PEI in wastewater samples. The results highlighted the prevalent presence of PVP, PNVCL, and PEI in the tested wastewater samples, indicating their significant abundance.

Titanium carbide MXene/silver nanostars composite as SERS substrate for thiram pesticide detection

Two-dimensional transition metal carbonitrides, Ti3C2Tx MXene nanosheets, have drawn much attention due to their unique optical properties. These materials have huge potential to be employed as surface-enhanced Raman scattering (SERS) substrates. Herein, to combine the benefits of metal nanoparticles and MXene as SERS substrates, we prepared composite SERS films with different volume ratios composed of Ti3C2Tx MXene with silver nanostars (AgNs) as a promising SERS substrate for detection of pesticides. These SERS films were prepared via a drop-casting technique. The SERS activities of the MXene/AgNs composites were evaluated through detection of the thiram pesticide. MXene/AgNs exhibited the highest SERS intensity compared to MXene or AgNs substrate alone. Sampling from 20 different areas and samples of the substrate gave very consistent SERS signals. The MXene/AgNs substrate shows good stability for 1 month when stored in a small transparent container with silica gel. The MXene/AgNs SERS substrate exhibits excellent sensitivity able to detect thiram concentrations as low as 10−8 M which also having low a relative standard deviation (RSD) value for reproducibility and stability over a significant period.