Relative Standard Deviation Values Research Articles

High-Performance Liquid Chromatography with DAD Detection for the Determination of Cannabinoids in Commercial Veterinary CBD Oil

The study highlights the need for quality control in evaluating medicinal plant products, especially CBD oils, before market release. Due to varying regulatory requirements, product labeling can sometimes be misleading, especially regarding cannabinoid concentrations such as CBD and THC. This research focused on developing a validated high-performance liquid chromatography (HPLC) method for accurately identifying and quantifying key cannabinoids in Commercial Veterinary CBD Oil. The main compounds identified included Cannabidivarin (CBDV), Cannabidiolic Acid (CBD-A), Cannabigerolic Acid (CBG-A), Cannabigerol (CBG), Cannabidiol (CBD), Tetrahydrocannabivarin (THCV), Cannabinol (CBN), ∆9-Tetrahydrocannabinol (d9-THC) ∆8-Tetrahydrocannabinol (d8-THC), Cannabicyclol (CBL), Cannabichromene (CBC), and Tetrahydrocannabinolic Acid (THCA), determined in line with the International Conference on Harmonization’s (ICH) guidelines. The method was validated for linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). It was determined to be linear, with a correlation coefficient (R²) > 0.999. The LOD and LOQ values calculated from the calibration curve ranged from 0.05 to 0.13 and 0.50 to 0.61 µg/mL, respectively. The method also exhibited acceptable precision, with relative standard deviation values lower than or equal to 2%. The method’s accuracy was assessed through recovery percentages and fell within an acceptable range of 98–102 if the RSD was 2%. This study’s rigorous methodology and comprehensive findings significantly contribute to cannabinoid analysis. This validated protocol was used to analyze cannabinoids in 14 commercial veterinary CBD oil products from the Republic of North Macedonia. The performance parameters demonstrated that the method is reliable for quantitatively measuring cannabinoids in CBD oil. The analysis showed that the cannabinoid levels in the products were consistent with the manufacturers’ declared specifications, with no significant discrepancies in labeling.

Miniature lab-made electrochemical biosensor: A promising sensing kit for rapid detection of E. coli in water, urine and milk

A novel, rapid production methodology for laboratory-made carbon electrodes (LCE) employing cost-effective and readily available materials has developed in the present work. The LCE presents superior electrochemical characteristics compared to commercially available screen-printed carbon electrodes (SPCE). Furthermore, this research has demonstrated the performance of readily accessible, highly sensitive, and portable biosensors for on-site detection of E. coli in aqueous samples. Silver nanoparticles (AgNPs) were successfully electrodeposited onto the LCE (Ag-LCE) using the electrochemical method at optimised parameters. The E. coli-specific aptamer was conjugated with AgNPs, and uncoated Ag-LCE surfaces were blocked with a BSA (BSA-Apt-Ag-LCE). The developed BSA-Apt-Ag-LCE biosensor was characterised and validated for the successful detection of E. coli in aqueous samples using cyclic voltammetry (CV). A linear correlation was obtained for sensor response in the 3.4 × 101 to 3.4 × 106 CFU/ml bacterial concentration as ΔIpa = 5.71 log C + 2.91 with R2 = 0.987. BSA-Apt-Ag-LCE biosensors have a limit of detection of 34 CFU/ml and a response time of 15 min, indicating their prompt and practical on-site identification capabilities. The proficient detection of E. coli in diverse aqueous samples, substantiated by its consistent reproducibility as indicated by the relative standard deviation (RSD) value of a maximum of 1.71 %, is a compelling validation of the biosensor's efficacy and reliability. The proposed biosensor exhibited selectivity towards E. coli and was found stable even after being stored at 4 °C for four weeks.

Enhanced analysis of PAHs in tea using GC–MS/MS with hydrogen carrier gas

A green multiresidue method for PAH analysis was developed using hydrogen as the carrier gas, avoiding harmful solvents and integrating waste-reducing strategies such as µSPE. The use of hydrogen carrier gas in gas chromatography coupled with tandem mass spectrometry (GC–MS/MS) was explored for the enhanced detection of polycyclic aromatic hydrocarbons (PAHs) in black tea. The study demonstrated that hydrogen, as a carrier gas, offers better chromatographic properties than helium or nitrogen. This leads to improved separation of critical pairs using a short run time method. A fast extraction method using micro solid-phase extraction (µSPE) as a clean-up step was developed to analyze 24 PAHs. The extraction method was optimized using a 4 mL 1:1 mixture of ethyl acetate and acetone. The method was validated and demonstrated good recoveries, ranging from 73 % to 113 % for most PAHs, with lower recoveries (50–63 %) observed for high molecular weight PAHs. Reproducibility was also high, with relative standard deviation (RSD) values below 15 %. Linearity and matrix effects were also evaluated, yielding excellent results, with no PAH exhibiting strong matrix effects. Real sample analysis of black tea from various brands and origins revealed the presence of multiple PAHs with concentrations ranging 9.5–39.2 µg/Kg, some exceeding the maximum residue levels set by the European Union. These findings highlight the need for efficient methodologies to monitor PAHs in food products.

Ultrasensitive electrochemical detection of miDNA-21 in human serum based on synergistic signal amplification by conducting polymers and bimetallic nanoparticles

MicroRNA-21 (miRNA-21) is a class of small non-coding RNAs that play a crucial role in the regulation of post-transcriptional gene expression. By leveraging the principle of base complementary pairing, the detection of miRNA-21 can be achieved through its analogue, MicroDNA-21 (miDNA-21), which possesses an identical sequence. Utilizing screen-printed carbon electrodes (SPCE), a conducting polymer (polypyrrole, Ppy), and metal nanocomposites (gold-platinum nanoparticles, Au@Pt NPs) were sequentially electrodeposited to create an electrochemical biosensor for the detection of miDNA-21. This biosensor employed ferrocyanide/ferricyanide (Fe(CN)63−/4−) as the electrochemical signaling probe, and its structure was elucidated via field emission scanning electron microscopy (FESEM) and Energy Dispersive Spectrometer (EDS). Quantitative detection was facilitated through differential pulse voltammetry (DPV), yielding a concentration range and linear fitting equation of 10.00–7.00 × 10.00−14 mol/L: ΔI = 0.5143 lgc + 9.191, R2 = 0.9986. The limit of detection (LOD) was determined to be 2.90 × 10−15 mol/L, with a sensitivity of 9.42 μA/μmol/L·cm2. Subsequent performance assessments confirmed the sensor’s excellent selectivity, reproducibility, and stability. Evaluation using the standard addition method, with normal human serum as the matrix, yielded recoveries ranging from 98.97 % to 102.70 %, and relative standard deviation (RSD) values below 1.00 %. These results demonstrate the method’s viability for practical application in detecting miRNA in human serum.

Combination of quadruple isotope dilution strategy and dispersive solid phase extraction method for accurate quantification of selected steroid hormones.

Steroid hormones are essential for the regulation of various vital body functions. Therefore, the determination of steroid hormones in biological fluids is a significant issue to find out the mechanism of steroid hormones related to disorders. In this study, Fe3O4/reduced graphene oxide (Fe3O4/rGO) nanocomposite based dispersive solid phase extraction (DSPE) was coupled with liquid chromatography - quadruple isotope dilution - triple quadrupole mass spectrometry (LC-ID4-MS/MS) for the accurate and precise determination of aldosterone, testosterone, 17-hydroxyprogesterone and estrone in serum samples. There is no study in literature about the combination of DSPE and LC-ID4-MS/MS methods for the extraction and determination of selected steroid hormones. Significant improvements in accuracy and precision for the proposed method was achieved by the combination of DSPE and LC-ID4-MS/MS. The percent recovery results were calculated between 100.0 and 103.4% with low percent relative standard deviation values (≤2.0%). The obtained recovery results proved the application of the developed method with high accuracy and precision for the determination of steroid hormones in serum samples. Hence, the developed method is superior to the current analytical methods for the determination of selected steroid hormones in terms of sensitivity, accuracy and precision.

Development of a 3D printed chemiluminescence smartphone detector for high performance liquid chromatography

A novel chemiluminescence detector for high-performance liquid chromatography (HPLC) was designed that incorporates a smartphone as photodetector, signal processor, and data storage unit. All detector components, including flow cell, flow cell holder, mixers, and housing, were fabricated by 3D printing and integration of the smartphone and 3D printed components provides a portable, low-cost, and user-friendly device. The detector was applied in the determination of carbamazepine using HPLC through a chemiluminescence reaction with tris(2,2′-bipyridyl)ruthenium(II) and cerium sulfate. Design and fabrication of the flow cell using two fabrication methods—3D printing and laser cutting—along with the integration of a mixer and the optimization of smartphone parameters were investigated. To expand the applicability of the detector for other analytes and different chemiluminescence reactions, detection of three piperazine derivatives by reaction with tris(2,2′-bipyridyl)ruthenium(II) and four phenethylamine compounds via reaction with acidic potassium permanganate reagent was studied. The linear dynamic range, limit of detection, and limit of quantification of the detector for the determination of carbamazepine were measured as 3.0–30.0 mg/L, 1.0 mg/L, and 3.0 mg/L, respectively, using the Samsung S20 smartphone device. Intraday and interday precision was evaluated for carbamazepine, with relative standard deviation (RSD) values for intraday precision ranging from 1.7 % to 6.2 % (n = 3) and interday precision RSD values ranging from 3.2 % to 4.8 % (n = 9).

Dendritic copper nanostructures for ultrasensitive detection of rhodamine 6G and Congo red

Surface-Enhanced Raman Scattering (SERS) is a fast-responding and non-destructive ultra-sensitive detection technique that can replace traditional chromatographic and spectroscopic analysis techniques. In this experiment, dendritic copper nanostructures were prepared by the solid-state ionics method and the vacuum hot evaporation process with an applied current of I=9μA. Using them as a SERS substrate, Raman detection was performed on the dye molecules Rhodamine 6G (R6G) and Congo Red (CR) to determine SERS enhancement performance. It is found that the growth of the prepared copper nanostructures has a top-end dominant phenomenon. The fractal dimension of the copper nanostructure was calculated using fractal theory, and it was revealed to be 1.560. Scanning electron microscopy (SEM) results showed that a large number of 60-80 nm regularly arranged copper nanoparticles were attached to the surface of the dendritic copper nanostructure. This is beneficial to increase the surface roughness of the substrate and improve the detection level of dye molecules. Subsequently, copper nanostructures can sensitively detect R6G and CR solutions as low as 1×10-13 mol/L and 1×10-7 mol/L, reaching single-molecule levels. The Raman mapping experiment showed that the mean relative standard deviation (RSD) values of R6G and CR were 12.3% and 12.9%, indicating high uniformity and reproducibility of the structure. This structure effectively achieves the fusion of uniformity, repeatability, and sensitivity, and shows broad application prospects in food detection.

Application of liquid chromatography-mass spectrometry for the determination of semaglutide in human serum in clinical pharmacokinetic studies

Introduction. Semaglutide preparations are an important therapeutic option for patients suffering from type 2 diabetes mellitus and obesity due to their high efficacy and the expected increase in the prevalence of these diseases. Consequently, there is a growing need for the development of domestic analogs of semaglutide requiring bioequivalence studies. This study proposes the use of high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) as an alternative to the widely used immunoassay for the quantitative determination of semaglutide in human serum.Aim. To develop and validate a method for the quantitative determination of semaglutide in human serum using HPLC-MS/MS.Materials and methods. Serum sample preparation was based on protein precipitation using an acetonitrile-methanol mixture. Liraglutide was selected as the internal standard. The mobile phase consisted of 0.3% formic acid in water and acetonitrile. The stationary phase was represented by a Phenomenex Kinetex C18 chromatographic column 100×3.0 mm, 5 μm, 100 Å. Ionization of semaglutide and liraglutide was performed in positive electrospray mode. Detection was carried out in multiple reaction monitoring mode (MRM).Results. The method demonstrated high accuracy and precision, with relative error and relative standard deviation values of less than 15% across all quality control levels. The confirmed analytical ranges of the method were 0.50–200.00 ng/mL and 1.00–800.00 ng/mL. Over 3.400 volunteer samples were analyzed as part of the studies. Compared to the ELISA method, the proposed method provides higher selectivity and reproducibility of measurements.Conclusions. The method has been developed that provides reproducible quantitative determination of semaglutide in human blood serum. The method was validated in accordance with EAEU requirements and was successfully applied in bioequivalence studies of semaglutide GP40331 (GEROPHARM LLC, Russia). The method is suitable for conducting pharmacokinetic studies of other semaglutide preparations.

Fast Molecular Recognition of Docosahexaenoic Acid Ethyl Ester in the Liver and Meat of Stingray Using a Miniplatform Based on a 3D Stochastic Microsensor

Docosahexaenoic acid ethyl ester has an important role in the prevention of the neuropsychiatric and neurodegenerative diseases. Its extraction from fish such as the stingray as anoil creates a pharmaceutical formulation. Therefore it is essential to develop fast molecular recognition methods able to perform both qualitative and quantitative determination of docosahexaenoic in stingray meat and liver. A miniplatform incorporating a 3D stochastic microsensor was designed and validated for the molecular recognition of docosahexaenoic acid ethyl ester. The design of the microsensor was based on the modification of a graphene decorated with nitrogen and boron paste (NB-graphene paste) with 10−3mol L−1 alpha-cyclodextrin. A wide linear concentration range (5.0 × 10−14 − 5.0 × 10−7 g mL−1) and a low limit of quantitation (5.0 × 10−14 g mL−1) were obtained. High recovery values were determined when the miniplatform was used for the assay of docosahexaenoic acid ethyl ester from stingray liver and meat with recoveries higher than 99.20%. The relative standard deviation values were less than 0.05 (N = 10).

Development of a rapid magnetic relaxation switching aptasensor for detection of saxitoxin using Fe3+/silver nanoparticles reaction system

Saxitoxin (STX) is a highly toxic marine bio-toxin, which has attracted great attention in the field of environmental and food safety. It is of crucial importance to develop efficient, sensitive and cost-effective methods for detecting STX. Here, we designed a magnetic relaxation switching (MRS) aptasensor for detection of STX based on FeCl3-regulated the aptamer-functionalized silver nanoparticles-coated magnetic nanoparticles (MNP@Ag NPs). In the light of the sensing effect of transverse relaxation time (T2) for optimizing, the etched time, the concentration of MNP@Ag NPs, the concentration of aptamers and incubation time were 15 min, 4 mg mL−1, 0.4 μM and 90 min, respectively. The MRS aptasensor showed good linearity amidst the sensing range of 0.2 μM to 1.0 μM and the limit of detection (LOD, S/N = 3) of 0.18 μM. Additionally, the MRS aptasensor demonstrated excellent sensitivity, reproducibility, and stability in clams and mantis shrimps. The recovery of STX ranged from 82.6 % to 101.5 % with low relative standard deviation (RSD) values, suggesting its effectiveness for detecting STX across a wide array of seafood samples.

Validation of chromatographic methods, TLC and HPLC, to quantify known radiochemical impurities and the radiochemical purity the radiopharmaceutical [177Lu]Lu-PSMA I&T

The Energy and Nuclear Research Institute (IPEN) is studying the production of the radiopharmaceutical [177Lu]Lu-PSMA I&T, in accordance with the good manufacturing practices recommended by the National Health Surveillance Agency (ANVISA), to be used in the therapy of prostate cancer. This work aims to validate chromatographic methods, Thin-Layer Chromatographic (TLC) and high-performance liquid chromatography (HPLC), to determine the radiochemical purity (RCP) of the product. The entire validation process of this work was based on ANVISA's RDC 166, 2017 and the Guide 10, version 1, 2017, guided the statistical treatments adopted. With the selectivity study we can observe that the presence of impurities or excess excipients in the sample does not interfere with the quantification of the product. The proposed methods were linear with linear correlation coefficients (r) above 0.99. The precision and repeatability presented relative standard deviation values lower than specified (RSD <5 %). The small controlled variations in the method suggested for the robustness test also did not affect the radiochemical purity of the product. In view of the results and in accordance with the criteria established by the National Health Surveillance Agency (ANVISA), the two chromatographic methods were validated in accordance with RDC 166, 2017, proving to be selective, precise, linear and robust. The validation of TLC and HPLC methods enables their application in the batch release routine of the new radiopharmaceutical at Radiopharmacy Center of IPEN.

Portable Miniature Mass Spectrometry for Enhanced On-Site Detection of Analytes in Complex Samples by Integrating Solid-Phase Microextraction and Nano-Electrospray Ionization.

On-site mass spectrometry (MS) analysis plays a crucial role in timely understanding chemical compositions of field samples but presents a challenge to miniaturization, portability, and sensitivity. In this work, a portable MS approach was developed by integrating biocompatible solid-phase microextraction (SPME) and a nano-electrospray ionization (nESI) emitter into a kit to couple miniature MS (mMS). The SPME fiber was used for on-site extractive sampling of analytes from complex liquid samples and living organisms and was then inserted into an nESI emitter for on-site MS analysis via the facile kit. The limit of detection was found to be at the pg/mL level for various compounds tested. Acceptable relative standard deviation (RSD) values (5.5-7.6%, n = 6) were obtained for direct measurement of analytes in complex matrixes; acceptable linear responses (0.1-50 ng/mL) and matrix effects (76.0-82.6%) were also found. Enhanced detection of compounds of interest in various real samples, such as food samples, human fluids, environmental water, and living organisms, was unambiguously demonstrated. Our experimental data showed that SPME-nESI-mMS is a promising tool for on-site analysis of various complex samples in significant applications including but not limited to food safety, environmental monitoring, forensic investigation, and bioanalysis.

Novel and simple electrochemical sensing platform based on polypyrrole nanotubes/ZIF-67 nanocomposite/screen printed graphite electrode for sensitive determination of metronidazole

Here, a simple, fast, and sensitive voltammetric sensor based on screen printed graphite electrode (SPGE) modified with polypyrrole nanotubes/zeolitic imidazolate framework-67 (PPy NTs/ZIF-67) nanocomposite is introduced for the metronidazole (MNZ) determination. The PPy NTs/ZIF-67 nanocomposite was synthesized and characterized by using X-ray diffraction (XRD) spectroscopy, field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS) techniques. The developed sensor based on PPy NTs-ZIF-67 nanocomposite modified SPGE shows an obvious reduction peak at −650 mV for MNZ, mainly due to the synergistic effects of the ZIF-67 and PPy NTs. Differential pulse voltammetry (DPV) was found to be the most suitable method for MNZ detection, showing a linear dynamic range of 0.01–500.0 µM and a low limit of detection (LOD) of 0.004 µM. In investigating the practicability, the PPy NTs/ZIF-67/SPGE sensor demonstrated efficient practicability with satisfactory recoveries (97.1 % to 103.5 %) and low relative standard deviation (RSD) values of 1.8–3.6 % for MNZ determination in MNZ tablets and urine samples.

Smartphone-based electrochemical sensing of propyl gallate in food samples by employing NiFe-Oxide decorated flexible laser-induced graphene electrode

Flexible graphene electronics utilizing laser-induced graphene (LIG) technology offer an efficient, cost-effective, and mask-free approach to produce graphene in a single step. LIG can be directly patterned on polyimide films, impacting their surface properties, chemical composition, and electrical conductivity. However, the electrochemical performance of standalone LIG is limited. To address this, the study enhances LIG by synthesizing nickel-iron Prussian blue analogues through co-precipitation and calcination, forming porous NiFe-Oxide, which is subsequently deposited onto the LIG surface via a facile physical deposition method. The porous NiFe-Oxide@LIG electrode material demonstrates excellent electrochemical sensing capabilities due to its high conductivity, improved surface area, enhanced active sites, and superior electrocatalytic performance for detecting the antioxidant propyl gallate (PG). This porous NiFe-Oxide@LIG electrode material features a linear detection range (0.5–5 μM), low detection limit (0.01 μM), high sensitivity (17.12 μAμM−1cm−2), and strong selectivity for PG. Additionally, it offers high reproducibility and repeatability, evidenced by the low relative standard deviation values of 2.61 % and 1.96 %, respectively. The practicality of the proposed sensor was validated using food samples, integrated into a smartphone-based sensing device, achieving satisfactory recovery rates above 79.2 %. This smartphone-based sensor enables effective onsite food quality and safety monitoring.

Fluorescence Sensing of Cu2+ Ion and Some Organic Pollutants by Using Katiragum Dialdehyde‐α‐Amino Acid Schiff Bases in Aqueous Medium

AbstractEfficient and selective fluorescence sensors based on katiragum dialdehyde‐ amino acid Schiff's base is developed for fluorometric sensing to detect vanillin, Cu2+ ions and 4‐nitrophenol (4NP) in their aqueous solution. Two Schiff bases namely katiragum dialdehyde‐ arginine (KGDR) and katiragum dialdehyde‐ tryptophan (KGDT) are developed in the author's laboratory between which KGDR can detect vanillin with a detection limit of 60.29 nM whereas KGDT can detect both Cu2+ ion and 4NP with a detection limit of 72.6 nM and 97.83 nM respectively. KGDR and KGDT show significant quantum yields of 0.47 % and 0.25 % compared to a standard known substance fluorescein (0.97 %). The detection limit of vanillin, Cu2+ ions and 4NP are lower than other reported sensors. The developed Schiff base KGDR and KGDT show excellent recovery percentage and relative standard deviation (RSD) values in real sample analysis.

Applicability of QbD-assisted Analytical Method for Simultaneous Detection of Tetrahydrocurcumin and Folic Acid in Developed Nanostructured Lipid Carriers

Aims: Applicability of QbD-assisted analytical method for simultaneous detection of tetrahydrocurcumin and folic acid in developed nanostructured. Background: Diabetic foot ulcer (DFU) is a multifactorial disorder that involves chronic inflammation, oxidative stress and neuropathy. Current treatment therapies involving the use of growth factors and skin substitutes being costly, are out of reach for the majority of patients. The present research explored the usefulness of (5929IN008, application number 202211045937), a combination of tetrahydrocurcumin and folic acid-loaded nanostructured lipidic carriers. Objectives: To develop and validate a QbD-assisted method for simultaneous analysis of tetrahydrocurcumin (THC) and folic acid (FA). Applicability of the above method to determine total drug content (TDC) and entrapment efficiency (EE) of nanostructured lipid carriers (NLCs) loaded THC and FA. Methods: A high-performance liquid chromatographic (HPLC) method was developed, optimized and validated using Box-Behnken design for improved method performance. Chromatographic separation was conducted on a Supelco 250 x 4.6 mm (5 μm) column with optimized mobile phase composition containing tetrahydrofuran: citric acid buffer pH 3.5 (50:50) at a flow rate of 0.4 mL.min-1 and diode array detection between 210 and 360 nm. Results: The method developed in a concentration range of 1 to 100 μg.mL-1 was found to be linear (R2 0.999, p≤0.001), accurate (99.10-101.70%) and precise with high recovery values in intra and inter-day results. The system adaptability and robustness evaluation revealed that the percent recovery ranged from 96.90 to 102.80%, and the percent relative standard deviation (%RSD) values were less than 2%. Moreover, the method was further applied for the determination of TDC (86±6% and 96±8%) and drug EE (81±21% and 73±13%) for THC and FA, respectively. Conclusion: The investigation indicated the applicability of the developed and validated method for the estimation of THC and FA in the developed nanostructured lipidic carriers.

Electrochemical Determination of Cysteine Using a 2-(2,5-Dihydroxy-Phenyl)-Naphtho[1,2-d] Oxazole-5-Sulfonic Acid (DHPNOS) and Cerium Oxide Nanoparticle (CeO2NP) Composite Carbon Paste Electrode (CPE)

An electrochemical sensor for the electrocatalytic oxidation of cysteine was designed based upon a 2-(2,5-dihydroxy-phenyl)-naphtho[1,2-d] oxazole-5-sulfonic acid (DHPNOS) and cerium oxide nanoparticle (CN) modified carbon paste electrode (CPE). An investigation of the redox properties of this modified electrode indicates a reduction in oxidative overvoltage and an intense increase in the analytical current. The pH, modifier, and nanoparticles were optimized to 7, 4% weight percent, and 5% weight percent, respectively. The apparent charge transfer rate constant (ks) and transfer coefficient for electron transfer between modifier and electrode were 2.776 s−1 and 0.47, respectively. Using differential pulse voltammetry, a linear range from 1 to40 µM with a detection limit of 0.33 µM was observed in phosphate buffer (pH 7.0). This work introduces a simple approach for selective determination of L-cysteine in the presence of uric acid. Also, based on chronoamperometry, the diffusion coefficient was determined to be 2.61 × 10−5 cm2 s−1. The effect of interferences on L-cysteine peak current were studied. The repeatability and reproducibility of the designed sensor were also measured with relative standard deviation values of 1.00% and 4.45%, respectively. The constructed sensor was employed for the determination of L-cysteine in acetylcysteine tablets.

Green Voltammetric Detection of Ophthalmic Drug Nepafenac Using Pencil Graphite Electrode as a Responsive Disposable Electrochemical Sensor

AbstractIn this study, the electrochemical properties of nepafenac, used after eye surgery operations, were investigated on a disposable pencil graphite electrode. Cyclic and square wave voltammetry techniques were used to investigate the electrochemical properties of nepafenac. Two peaks at potentials of approximately +0.33 V and +1.03 V in the anodic direction and two peaks at potentials of approximately +0.29 V and +0.08 V in the cathodic direction were observed on the surface of the disposable pencil electrode in acetate (pH 4.8) medium with the cyclic voltammetry technique. The analytical performance of the developed voltammetric technique had good linearity in the concentration range of 0.30 µM to 3.5 µM at pH 4.8. The LOD value of this voltammetric method in acetate (pH 4.8) medium was calculated as 0.035 µM (8.90 ng mL−1). For reproducibility, the relative standard deviation (RSD) values for Ia and IIa anodic peak current/potential were found to be 1.45%/0.43% and 1.28%/0.25%, respectively. The voltammetric method was successfully applied to urine and pharmaceutical preparations and the results were compared with the spectrophotometric method.

Development of a green microextraction procedure for determining polyaromatic hydrocarbons in electronic equipment plastics

The global proliferation of electronic devices, driven by technological advancements, has led to the release of organic pollutants from the plastic components of these devices, particularly in indoor environments. Among these pollutants, polycyclic aromatic hydrocarbons (PAHs), which are emitted into the air from plastic components, play a critical role in the field of indoor environment pollution. Consequently, effectively monitoring the PAH content in plastics used in electronic equipment is crucial for preventing indoor contamination.In this study we aimed to develop a fast, inexpensive, easy, and environmentally friendly analysis method for determining PAH content in plastic equipment. A dispersive liquid liquid microextraction (DLLME) combined with solidified organic drop (SFO) microextraction technique was developed.Considering the eleven number of parameters that can affect the signal in the DLLME-SFO method, Plackett Burmann's design was applied to select the most three impactful parameters for 18 PAH species. A Box-Behnken experimental design was also applied to optimize the identified parameters. The optimal conditions for the most influential parameters such as solvent type, pH, and the sample weight were identified as 1-dodecanol, 12 and 0.24 g, respectively.The proposed method was validated under these optimized conditions, yielding low detection limits ranging from 0.004 to 0.11 ng mL−1. The calibration curves were linear with correlation coefficients above 0.98 and relative standard deviation (RSD) values ranging from 2.4% to 20%. This method was successfully applied to analyze PAH content in the plastic components of electronic devices. The extraction technique developed in this study is a newly developed technique and has not been previously used to analyze organic pollutants that may be present in electronic equipment plastic.

Large scale screening and quantification of micropollutants in fish from the coastal waters of Cochin, India: Analytical method development and health risk assessment

Urban estuarine and coastal water receive several micropollutants through industrial and agricultural influxes. The bioaccumulation of these micropollutants in fish and their entry into the coastal population's food chain raises significant food safety concerns. Hence, a comprehensive analytical method was developed for ultra-trace level quantification of 345 micropollutants in fish. The optimized sample preparation method could extract compounds suitable for both GC–MS/MS and LC-MS/MS analysis simultaneously. The target list of contaminants included 278 agricultural pesticides and also 102 endocrine disruptors covering polyaromatic hydrocarbons, polychlorinated biphenyls, organochlorines, and endocrine-disrupting pesticides. The GC–MS/MS with large volume injection (LVI) technique, and LC-MS/MS operating in MRM mode, achieved an LOQ of <2.00 ng/g for most of the analytes. The extraction strategy involved tri-phase partitioning between water, acidified acetonitrile, and hexane, followed by salting out. Dispersive solid phase cleanup (dSPE) with C18, Z-Sep+, CaCl2, and MgSO4 was able to reduce the matrix influence, and the method achieved satisfactory recovery in the range of 70.0–120.0 % for all the target analytes. The repeatability and reproducibility relative standard deviation values of the measured analytes were <20.0 %, and the Horwitz ratio values were well below 2. The method was used to accurately measure the target micropollutants in fish from the Cochin estuary, the highly urbanized portion of the Vembanad Lake, and an important Ramsar site. At least one or more of the 41 different micropollutants were identified and quantified in about 90.7 % of the 108 samples analyzed. The importance of large-scale screening and trace-level quantification methods in environmental monitoring and risk assessment is underscored by the results. The risk assessment showed a moderate risk of exposure to the nearby coastal population through the food chain.