RSD Values Research Articles

Fast screening of Milk for Deoxynivalenol

A 2D platform was designed and validated for fast screening of milk for deoxynivalenol. The qualitative and quantitative assay of deoxynivalenol in the milk samples was done using a 2D stochastic sensor based on single walled carbon nanotubes modified with [N-(pyridine-4-yl-methyl)]octadec-9-enamide. The working concentration range was between 10−15 and 10−6 g mL−1, with a sensitivity of 5.48 × 105 s−1g−1mL, and a limit of determination of 1 fg mL−1. Recovery values higher than 99.00 % with RSD values lower than 1.00 % were recorded for the determination of deoxynivalenol in cow's and in the vegetarian (coconut milk, soy milk, almond milk) milk.

The portable stochastic sensor as a screening tool for simultaneous determination of HER-1 and CA 125 - a key factor in the rapid recognition of gastric cancer.

The significance of HER-1 and CA 125 lies in their ability to guide cancer diagnosis, treatment, and monitoring, improving personalized care and enhancing prognostic accuracy. The utilization of HER-1 and CA 125 as screening biomarkers for the anticipation of early-stage cancer and monitoring cancer progression is expanding due to the invasive and costly nature of present techniques.In this study, a novel stochastic sensor was developed forthe simultaneous determination of HER-1 and CA 125 in whole blood, saliva, and gastric tumor tissue samples usinga fast, easy, inexpensive, and portable method.The stochastic sensor was prepared by electropolymerization of cysteine on the surface of the Au-TiO2@rGO/SPCE sensor. The Au-TiO2@rGO nanocomposite was synthesized using a simple chemical reduction process. The proposed sensor showed wide linear concentration ranges and very low limits of quantification (LOQ). The concentration ranges were from 3.9 × 10-14 to 3.9 × 10-8µgmL-1, with a LOQ of 3.9 × 10-14µgmL-1 for HER-1. For CA 125, the concentration ranges were from 8.3 × 10-14 to 8.3 × 10-10 U mL-1, with a LOQ of 8.3 × 10-14 U mL-1. Both biomarkers exhibit precise discrimination in different biological samples, with recoveries above 96.78% and RSD values below 0.04%. With a confidence level of 99%, the Student t-test revealed that there is no statistically significant difference between the outcomes obtained by using the poly-Cys/Au-TiO2@rGO/SPCE sensor for screening examinations of biological samples. This was determined because the results were not significantly different from one another.

Validation of a global method for the simultaneous analysis of polar and non-polar pesticides by online extraction and LC-MS/MS

BackgroundMulti-residue methods for pesticide analysis in food are available for many compounds, but polar pesticides are not generally included due to their specific properties, which include high polarity and low molecular weight. Single residue methods are therefore needed for sample preparation, while chromatographic separation often requires derivatization, ion paring, or dedicated methods suitable for polar compounds, mostly ion chromatography and hydrophilic interaction liquid chromatography (HILIC). These challenges affect the important pesticide glyphosate and the related compounds aminomethylphosphonic acid (AMPA) and glufosinate. There are only a few methods including these compounds in large-scale analysis, mostly complex methods based on multidimensional chromatography. ResultsA new method, for the global online extraction and analysis of pesticides in beer was developed and validated. The method exploited an online trapping device, with reversed-phase (RP) and anion exchange properties, that can trap small molecules from liquid samples. The ion exchange mechanism was used to retain the very polar pesticides glyphosate, AMPA, and glufosinate. The hydrophobic properties of the trapping column were also exploited to trap pesticides suitable for multi-residue investigations. The chromatographic separation was optimized by comparison of HILIC and RP C30, which could separate pesticides, including the polar ones, with modulation by the trapping column after proper selection of the mobile phase composition and basic modifier. The validation for beer provided recoveries in the range 71–112 %, with <15 % RSD, and LOD and LOQ values of 0.02–1 and 0.3–3 μg L−1, respectively. The result was competitive with previous methods on polar pesticide analysis in beer. SignificanceThe method was validated for 15 pesticides, over the log Kow range from −4.4 to 4.5, using a methodology with single and fast chromatographic separation under conditions compatible with multi-residue analysis by RP-LC-MS/MS. In the case of beer, for which the method was validated, the sample preparation was also performed online, after simple degassing, and sample dilution.

Investigation of green synchronous spectrofluorimetric approach for facile sensitive estimation of two co-administered anti-cancer drugs; curcumin and doxorubicin in their laboratory-prepared mixtures, human plasma, and urine

Recently, phytochemicals play an important role in cancer management. Curcumin (CUR), a natural phytochemical, has been co-administered with widespread chemotherapeutic agents such as doxorubicin (DOX) due to its excellent antitumor activity and the ability to lower the adverse reactions and drug resistance cells associated with DOX use. The present study aims to determine DOX and CUR utilizing a label-free, selective, sensitive, and precise synchronous spectrofluorimetric method. The obvious overlap between the emission spectra of DOX and CUR prevents simultaneous estimation of both analytes by conventional spectrofluorimetry. To solve such a problem, synchronous spectrofluorimetric measurements were recorded at Δλ = 20 nm, utilizing ethanol as a diluting solvent. Curcumin was recorded at 442.5 nm, whereas DOX was estimated at 571.5 nm, each at the zero-crossing point of the other one. The developed method exhibited linearity over a concentration range of 0.04–0.40 μg/mL for CUR and 0.05–0.50 μg/mL for DOX, respectively. The values of limit of detection (LOD) were 0.009 and 0.012 µg/mL, while the values of limit of quantitation (LOQ) were 0.028 and 0.037 µg/mL for CUR and DOX, respectively. The adopted approach was carefully validated according to the guidelines of ICH Q2R1. The method was utilized to estimate CUR and DOX in laboratory-prepared mixtures and human biological matrices. It showed a high percentage of recoveries with minimal RSD values. Additionally, three different tools were utilized to evaluate the greenness of the proposed approach.

Full green assay of rosuvastatin utilizing sulphophtalein dyes: application to tablet analysis

The aim of the work was to develop a «green» and extraction-free spectrophotometric procedure for the assay of rosuvastatin in tablets. The present work describes three new spectrophotometric procedures (A, B and C) that can be utilized for routine quality control of rosuvastatin in laboratories. Materials and methods. Analytical instrumentation: Shimadzu UV-1800 double beam UV-vis spectrophotometer (Japan) with attached UV-Probe ver. 2.62 software, RAD WAG AS 200/C precise analytical balance (Poland). Rosuvastatin calcium (purity ≥98 % (HPLC)) was bought from Sigma-Aldrich Chemicals Co. (St. Louis, MO, USA). Rosuvastatin 10 mg tablets were acquired from a nearby drugstore. All solvents used in this study, including methanol, ethanol, chloroform, acetonitrile and ethyl acetate, were produced by Honeywell and had a purity of 99.9 %. BCG, BCP and BTB were acquired from Sigma-Aldrich Chemicals Co. (USA, St. Louis). All chemicals utilized in the experiment were of analytical purity. Results and discussion. New simple «green» and extraction-free spectrophotometric procedures for assay of rosuvastatin in tablets involve the formation of ion-pair complexes with sulphophtalein dyes (BCG (Method A), BCP (Method B), BTB (Method C)) have been developed. The absorbances of the coloured reaction products were registered at 405 nm (Method A) and 400 nm (Methods B, C). The concentration was linearly proportional to absorbance values in the range of 2.51-20.08 μg/mL (method A), 2.50-24.90 μg/mL (method B) and 2.51-12.56 μg/mL (method C). Estimation of LOD and LOQ parameters were obtained as 0.67 μg/mL and 2.23 μg/mL (Method A), 0.39 μg/mL and 1.32 μg/mL (Method B), 0.30 μg/mL and 1.01 μg/mL (Method C). The stoichiometric ratio of the reactive components of rosuvastatin - BCG, BCP, and BTB corresponded 1: 1. The %RSD values of intra-day and inter-day were obtained less than &lt; 1.5 %, which showed excellent repeatability and RE % data was ≤ 3 %. The effect on the environment of the proposed spectrophotometric procedures and their compliance with the GAC principles were endorsed by the output of AGREE, GAPI, and AES metrics tools. The values of these three «green» metrics show that the proposed spectrophotometric procedures had a low environmental impact compared with the reported ones. Conclusions. The developed fast, simple and cost-effective methods A, B, and C can be used for routine analysis of rosuvastatin in tablets

ANALYSIS OF METANIL YELLOW IN PACKAGED JAMU BY UV-VIS SPECTROPHOTOMETRIC METHOD

Introduction. Metanil yellow is a synthetic coloring material used for textile products, wood paint, painting paint, and fur. Despite its use having been banned in the Regulation of the Minister of Health of Indonesia No. 239/MENKES/PER/V/1985, metanil yellow is still commonly found in the local community. In Indonesia, this coloring material is often misused to color various types of food, including herbs, crackers, noodles, tofu, and yellow snacks. The purpose of this research is to validate the analytical method for determining metanil yellow levels in herbal medicine of jamu using the UV-Vis spectrophotometric method. Method. In this research, the determination of metanil yellow levels was carried out by instrument analysis using the UV-Vis Sectrophotometric method. Result &amp; Analysis. In the linearity validation parameter, the regression equation y = 0.0548x-0.01398 is obtained with an r² value of 0.9999, the LOD parameter is 0.11686 ppm, LOQ is 0.5620 ppm, the precision parameter RSD value obtained is 0.87% which meets the requirements of ≤ 4%. Furthermore, the results on the determination of metanil yellow levels in each sample A obtained a percentage of 0.00006755% ± 3.9260; sample B obtained a percentage of 0.000110% ± 10.5309; and sample C obtained a percentage of 0.0001023% ± 9.2998. Discussion. Given the very low concentration, it is possible that the yellow color in the herbal medicine samples is not completely caused by metanil yellow, but it might also be influenced by other natural ingredients with yellow pigments.

1-Benzhydryl-piperazine: Isolation, structure determination, and in silico studies for a novel potential narcotic agent detected in sports supplements

Adulteration of sports supplements poses significant health risks, necessitating stringent regulatory oversight. This study investigates deceptive practices by manufacturers, including concealment of formulations and manipulation of label information, impacting a wide demographic beyond elite athletes. Cinnarizine (CIN), and its degradation product, 1-benzhydryl-piperazine (BHP), which has amphetamine-like effects, are detected for the first time in 8 out of 41 sports supplements. An HPTLC method was developed to quantify CIN, and validated with specificity, linearity, the limit of detection (LOD), the limit of quantification (LOQ), accuracy, and precision studies. The linear range was between 50–800 ng spot−1. LOD and LOQ were 15 and 50 ng spot−1, respectively. The average recovery was calculated as 88.32 %, and %RSD values were less than 4 %. CIN’s degradation products were detected using GC-MS. CIN's decomposition into BHP also was confirmed via NMR analysis. Molecular docking studies revealed BHP's superior binding affinity and stability compared to 1-benzyl-piperazine (BZP), a prohibited narcotic agent, for dopamine and serotonin receptors, indicating potent psychoactive effects. Molecular dynamics simulations further elucidated interaction patterns, highlighting BHP's robust binding and potential for abuse, necessitating regulatory scrutiny and potential reevaluation of its legal status. It is also the first in silico study to compare BHP with BZP in terms of receptor interactions, which makes it pioneering. This study emphasizes the critical need for regulatory vigilance in the sports supplement industry to ensure consumer safety. Methodologies developed here for detecting adulterants provide foundational tools for future research aimed at enhancing public health protections against adulterated supplements. Regulatory collaboration and enhanced quality controls are essential to mitigate risks associated with deceptive practices and ensure the well-being of consumers.

A photoelectrochemical sensor based on polydopamine membrane-coated CdS@C core-shell heterostructure for curcumin detection

Curcumin has been widely employed in various fields, but excessive intake may cause tissue necrosis and pose a serious threat to people’s lives and health. Hence, it is crucial to rapidly and precisely detect the content of curcumin. In present research, CdS@C heterostructure materials were successfully prepared through a one-pot solvothermal reaction strategy, utilizing glucose as the carbon source. Simultaneously, polydopamine thin films (ePDA) were successfully deposited on the surface of CdS@C-modified electrodes by the cyclic voltammetry (CV) method. A photoelectrochemical sensor based on the polydopamine membrane-coated CdS@C core–shell heterostructure (ePDA/CdS@C) was designed for curcumin detection. Furthermore, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible spectrophotometers (UV-vi) techniques were applied to characterize the structure and morphology of the synthesized photoelectric materials. The ePDA coating enhances the stability of the CdS@C material, and the CdS@C core-shell heterostructure accelerates electron transfer. Consequently, the ePDA/CdS@C material generates an outstanding and steady photocurrent response. Under ideal conditions, the novel sensor exhibits a satisfactory linear response to curcumin detection within the concentration range of 0.025–370 μM, with a detection limit as low as 0.0165 μM. Additionally, the ePDA/CdS@C-based photoelectrochemical aptasensor displays remarkable reproducibility, stability, and selectivity. This innovative sensing platform accurately detects curcumin in human serum and urine samples, with an excellent recovery range (99.47 %–103.60 %) and relatively low RSD values (1.49 %–3.56 %). In conclusion, this work offers a novel approach for curcumin detection.

2D/1D VSe2/MWCNT hybrid-based electrochemical sensor for carbendazim quantification of environmental, food, and biological samples.

Forthe first time the sensitive determination of carbendatim (CRB) is reportedutilizing a well-designed sensing architecture based on vanadium diselenide-multiwalled carbon nanotube (VSMC). FTIR, XRD, FESEM, EDS, and EIS were employed to evaluate the sensor's structural integrity, and the results demonstrated the successful integration of nanomaterials, resulting in a robust and sensitive electrochemical sensor. Cyclic voltammetry (CV) and chronoamperometric (CA) investigations showed that the sensor best performed at pH 8.0 (BRB) with an excellent detection limit of 9.80nM with a wide linear range of 0.1 to 10.0µM. A more thermodynamically viable oxidation of CRB was observed at the VSMC/GCE, with a shift of 200mV in peak potential towards the less positive side compared with the unmodified GCE. In addition, the sensor demonstrated facile heterogeneous electron transfer, favorable anti-fouling traits in the presence of a wide range of interferents, good stability, and reproducible analytical performance. Finally, the developed sensor was validated for real-time quantification of CRB from spiked water, food, and bio-samples, which depicted acceptable recoveries (98.6 to 101.5%) with RSD values between 0.35 and 2.23%. Further, to derive the possible sensing mechanism, the valence orbitals projected density of states (PDOS) for C, H, and N atoms of an isolated CRB molecule, VSe2 + CNT and VSe2 + CNT + CRB were calculated using density functional theory (DFT) calculations. The dominant charge transfer from the valence 2p-orbitals of the C and N atoms of CRB to CNT is responsible for the electrochemical sensing of CRB molecules.

Ultrasensitive detection of water pollutant PFOA based on AuNPs decorated NiOScZ screen-printed electrode

This study focuses on the development of a highly sensitive and on-site detection method for the water pollutant perfluorooctanoic acid (PFOA). The method utilizes gold nanoparticles (AuNPs) decorated on a screen-printed electrode and nickel oxide-scandium zirconium (NiOScZ). The newly developed electrode demonstrates outstanding analytical performances in a wide linear range between 0.001 nM and 100 nM, a remarkable detection limit of 0.3 pM, and a high sensitivity of 3.76 μA/nM cm2. The method's applicability for detecting PFOA in water samples was verified by achieving spiked recovery results ranging from 96.5 % to 105.6 %, with RSD (%) values below 5 %.

Self-assembled magnetic particles on hard magnetic materials substrate for simple and rapid SERS detection of organic dye

In this paper, a detection strategy based on Surface-enhanced Raman Scattering (SERS) was proposed to quickly and simply separate target molecules from samples. Fe3O4@SiO2@Ag (FSA) magnetic particles modified with flower-like silver nanosheets were employed for efficient enrichment of target molecules, followed by their self-assembly onto the NdFeB substrate surface in fluid medium. The SERS sensitivity was indirectly adjusted by changing the reaction time to control the morphology of flower-like silver nanosheets on the surface of magnetic particles. SERS experiment showed that the substrate prepared by this detection strategy had high sensitivity, Rhodamine 6G (R6G) could be detected at the concentration of 10−8M and Methylene Blue (MB) could be detected at the concentration of 10−7M, the calculated enhancement factor was 1.34 × 105. In addition, the uniformity of the substrate was evaluated by SERS mapping using 10-6 M R6G, the RSD value of 8.89% was obtained. This detection strategy provides a new idea for simple and rapid SERS detection of organic dye.

Simultaneous determination of Rosuvastatin calcium and Bempedoic acid in fixed-dose combination pharmaceutical dosage forms using RP-HPLC method

A precise, simple, and, accurate method for simultaneous estimation of Rosuvastatin calcium and Bempedoic acid was developed by Reversed phase High-Performance Liquid Chromatographic (RP-HPLC). The validation of the developed method is done as per ICH guidelines. The method was developed on Waters HPLC using a Kromasil 100-5-C18 (4.6 × 250 mm) column with a detection wavelength of 220 nm. The mobile phase consists of 0.1 % OPA in water: Acetonitrile (50:50 v/v). The retention time for Rosuvastatin calcium and Bempedoic acid was found as 5.4 and 10.7 min respectively. The linearity range was established between 10.0–100.0 µg/ml for Rosuvastatin calcium and 45.0–450.0 µg/ml for Bempedoic acid. The correlation coefficients (r2 values) for Rosuvastatin calcium and Bempedoic Acid were 0.9985 and 0.9988 respectively, indicating a strong concentration–response relationship. The method was found to be specific as there was no interference with the peak of Rosuvastatin calcium and Bempedoic acid in presence of excipients. The % Recovery of the method was found to be 98.64 %, 99.35 %, and 98.27 % for Rosuvastatin calcium and 99.11 %, 99.16 %, and 99.46 % for Bempedoic Acid. Therefore, the method has good trueness. Repeatability analysis of 6 samples revealed %RSD values of 0.92 % and 1.41 % for Rosuvastatin calcium and Bempedoic Acid respectively. The method is precise as the mean %RSD for Intraday studies of Rosuvastatin calcium and Bempedoic acid was 0.6064 % and 0.5289 % respectively while the Interday studies were 0.8763 % and 0.4955 % respectively. The LOD and LOQ for Rosuvastatin calcium are 0.054 µg/ml and 0.163 µg/ml and for Bempedoic acid are 0.127 µg/ml and 0.387 µg/ml respectively. Also, the method is robust as there was no significant change in result upon changing the method parameter. The developed method is environment friendly and is suitable for the quality control analysis of Rosuvastatin calcium and Bempedoic acid either alone or in combination.

ZnS/MXene/CdS heterostructure modified electrode for ultrasensitive miRNA-21 assay with signal amplified photoelectrochemical strategy

The early-stage detection of microRNA (miRNA) holds significant value for clinical diagnosis of tumor. In this study, a highly sensitive miRNA detection platform is developed using a photoelectrochemical sensing system based on layer-by-layer (LBL) assembled ZnS/MXene/CdS (ZMC) heterostructure electrode. By incorporating ultrathin and highly conductive MXene, the ZMC electrode exhibits robust photocurrent signals upon exposure to light. The electrode is further modified HS-H1 DNA via disulfide bonds.With the help of auxiliary H2 DNA, a target miRNA-21 triggered catalytic hairpin assembly (CHA) amplification reaction is realized on the electrode surface through complementary base pairing. Then, manganese porphyrin (MnPP) is introduced to the formed double-stranded DNA after CHA reaction to catalyze the conversion of 4-chloro-1-naphthol (4-CN) to benzo-4-chloro-hexanedione (4-CD) precipitate in the presence of hydrogen peroxide, which leads to a significant decrease in photocurrent signals. As a result, the sensor demonstrates a reliable linear correlation in miRNA-21 detection with detection limits as low as 0.36 fM. The recoveries of miRNA-21 in human serum samples ranged from 98.27 % to 101.35 % with RSD values below 3.67 % suggest the reliability and practicality of this method. Therefore it shows great potential for the construction and application of highly sensitive photoelectrochemical biosensors in clinical sample detection.

Urine Glucose Detection Via Gold Nanoparticle Formation Using 3D-Connector Microfluidic Paper Based Analytical Devices

A metabolic disorders that have experienced a significant increase in the world are diabetes mellitus. Diabetes is caused by two main factors: the first is damage to pancreatic beta cells, which prevents insulin from being produced, and the second is impaired insulin secretion and function. Chronic diabetes, if not treated properly, can lead to acute complications including eye, kidney, lung, nerve, and even death. Diabetes can be diagnosed through blood and urine. In general, glucose detection is carried out using invasive methods that use blood samples, which can cause pain and discomfort for users. Current research is developing non-invasive glucose detection using urine samples. This research aims to develop non-invasive glucose detection technology using 3D-connector μPADs (Microfluidic Paper Based Analytical Devices) which have the advantages of being safe, easy, and simple. The three-dimensional connector on the device functions as a connector to facilitate the coordination of fluid flow in the sample zone and detection zone. The glucose detection method uses gold (III) chloride as a gold nanoparticle (AuNPs) precursor, an aqueous extract of Acalypha indica Linn as a stabilizing agent, sodium hydroxide (NaOH) as a catalyst, and glucose in artificial urine as a sample. Method validation results using imageJ software indicated linearity with a coefficient of determination value (R2) of 0.9714, precision with a %RSD value (Relative Standard Deviation) of 2.69, and an accuracy level ranging from 92.22-99.23%.

Fast On-Site Electroanalysis of Eicosapentaenoic Acid Ethyl Ester in the Liver and Meat of Stingray Using a Stochastic Miniplatform Based on a 3D Stochastic Microsensor

Eicosapentaenoic acid ethyl ester has an important role in metabolism and it is also an important antithrombotic agent. Its concentration in the liver and meat of the stingray is essential when one would like to use the extracts containing the eicosapentaenoic acid ethyl ester from stingray as biopharmaceutical products. A miniplatform having as detection tool a 3D stochastic microsensor was designed and used for the assay of eicosapentaenoic acid ethyl ester from stingray liver and meat. Natural monocrystalline diamond paste was modified with a solution of heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin to obtain the modified diamond paste used in the 3D stochastic microsensor. A wide working concentration range (5.0 × 10−15 – 5.0 × 10−8) and a very low limit of quantitation (5.0 × 10−15) were attained. The proposed miniplatform was successfully used for the assay of eicosapentaenoic acid ethyl ester from stingray liver and meat with recoveries higher than 99.90%, and % RSD values lower than 0.05 (N = 10).

Factorial design-aided derivatization-free fluorimetric ultrasensitive assay of vonoprazan with application in uniformity of dosage units and plasma samples analysis: Comprehensive and comparative greenness and whiteness assessment

This study presents a novel derivatization-free spectrofluorimetric method for the quantification of vonoprazan (VPZ) that is characterized by its high sensitivity, environmental friendliness, and cost-effectiveness. Notably, this method eliminates the requirement for pre-derivatization, extraction procedures, large amounts of organic solvents, and/or expensive instrumentation, which distinguishes it from previous approaches. The approach employed in this study relies on the formation of an association complex between VPZand the xanthene dye acid red 87 (AR87) under acidic conditions. The stability of the VPZ-AR87 complex was determined to be remarkably high, with a complex formation constant (Kf) value exceeding 2 x 106 M−1. The fluorimetric measurements rely on the quantitative and selective quenchingof the dye’s native fluorescence emission at 545 nm. The experimental parameters were optimized utilizing a quality-by-design 23 full factorial design. This strategy yielded a highly favorable linearity range of 10.0 to 400.0 ng/mL, with a correlation coefficient (r) of 0.9997. The presented methodology exhibited a high level of sensitivity, as evidenced by its ability to detect concentrations as low as 1.2 ng/mL. This sensitivity enabled its successful application for the estimation of VPZ in human plasma samples with high %recoveries (98.21–101.67) and low %RSD values (<1.52). Furthermore, content uniformity testing of low-dose VPZ tablets was performed according to United States Pharmacopeia guidelines. Greenness and whiteness metrics analysis showed a significant advantage of the proposed method over previously reported fluorimetric methods. Validation of the developed approach was carried out in accordance with ICHQ2 (R1) guidelines.

RP-HPLC Method Development and Validation for Simultaneous Determination of Sofosbuvir and Ledipasvir: A Pharmaceutical Application Study

The objective of the present work was to develop a simple, precise, accurate, reproducible, and specific reversed-phase high performance liquid chromatographic method for the simultaneous determination of sofosbuvir and ledipasvir in pharmaceutical dosage form. The HPLC system (Shimadzu, LC-2030) consisted of Hypersil ODS - C18 (250 mm, 4.6 mm, 5 μm- Thermo Scientific) was used for the isocratic elution using mobile phase composed of sodium phosphate buffer (pH 3.5) and acetonitrile in the ratio of 40:60% (v/v). Both sofosbuvir and ledipasvir were detected at 260 nm with a flow rate of 1 mL/min. The mean retention time of sofosbuvir was 3.094, whereas ledipasvir was 6.22 minutes. A linear relationship was found in the concentration ranged from 0.54 to 162 μg/mL for sofosbuvir (r2 = 0.9993) and 0.14 to 42 μg/mL for ledipasvir (r2 = 0.9994). The RSD values for recovery test were found 0.99% for sofosbuvir and 0.22% for ledipasvir. The lower limit of detection (LOD) were 0.054 mcg/mL and 0.012 mcg/mL, and the limit of quantification (LOQ) were 0.135 mcg/mL and 0.030 mcg/mL for sofosbuvir and ledipasvir, respectively. The method was successfully applied to the assay and in-vitro dissolution studies of sofosbuvir and ledipasvir in tablet dosage form and all the results were found within the acceptance limits.

NiFe2O4 nanoparticles grafted sulfonated melamine for rapid magnetic dispersive µ-solid phase extraction of pesticides in apple and pear samples: Greenness evaluation

In this research, a facile and rapid magnetic dispersive µ-solid-phase extraction technique based on novel and high-performance sulfonated melamine-modified NiFe2O4 nanoparticles was developed forsimultaneous extraction and separation of fifteen pesticides followed by gas chromatography-mass spectrometry. The characterization of the synthesized nano-adsorbent was carried out using scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and Fourier-transform infrared spectroscopy (FT-IR) techniques. The substantial factors including pH, the amount of nano-sorbent, ionic strength, sample volume, and desorption conditions (i.e. desorption solvent type and volume, and desorption time) on the extraction efficiencies of the interest pesticides from apple and pear samples were explored using the matrixed match method. Under the optimum conditions, the linear range of 0.2-500µg kg−1, LODs, and LOQs in the range of 0.065–0.077µg kg−1 and 0.22–0.26µg kg−1 for apple and 0.065–0.085µg kg−1 and 0.22–0.29µg kg−1 for pear were acquired. The intra-day and inter-day precisions were evaluated at three spiked concentration levels (10, 50, and 100 μg kg−1 of each analyte) on the same day and five distinct days, respectively. The RSD (%) values were ≤ 3.6 % for intra-day (n = 6) and ≤ 4.3 % for inter-day (5 days and n = 3) precisions. High relative recoveries of 92.5–98.9 % revealed high potential of the presented method for analysis of pesticides in complex matrixes. Moreover, Analytical Greenness metric approach was applied and consequently confirmed the greenness of the method which accompanied with the green analytical aspects.

Method Development and Validation of an Aerosol Sampling Technique for the Analysis of Nicotine in Electronic Cigarette Aerosols.

Because of the increasing popularity of e-cigarettes, monitoring the e-cigarette market has become important for national health authorities to guarantee safety and quality. In the EU, the Tobacco Products Directive requires emission studies for e-cigarette products. The absence of industry guidelines for studying these emissions and the lack of proper validation in the literature led us to develop and validate a method using the total error approach for the determination of nicotine in e-cigarette aerosols. A commercial vaping device was used to generate aerosols, which were then collected on Cambridge filter pads and measured for nicotine concentration by UHPLC-DAD after extraction. The method was successfully validated by generating accuracy profiles, which show that the β-expectation tolerance intervals remained below the acceptance limits of ±20%. Within-run repeatability and intermediate precision were considered acceptable since the highest RSD value obtained was below 5%. The method was applied to 15 commercial e-liquids. A complete validation of a method for the analysis of e-cigarette emissions is presented, including several parameters that impact the accuracy and reproducibility. Similar systematic approaches for method development and validation could be used for other e-cigarette emission analysis methods to ensure the reliability of the measurements.

Natural deep eutectic solvent for the simultaneous derivatization and microextraction of isoniazid from human plasma

BackgroundPersonalized medicine is a rapidly revolving field that offers new opportunities for tailoring disease treatment to individual patients. The main idea behind this approach is to carefully select safe and effective medications and treatment plant based on each patient's unique pharmacokinetic profile. Isoniazid is a first-line anti-tuberculosis drug that has interindividual variability in its metabolic processing, leading to significant differences in plasma concentrations among patients receiving equivalent doses. This variability necessitates the creation of individualized treatment regimens as part of personalized medicine to achieve more effective therapy. ResultsIn this work, a deep eutectic solvent-based liquid-liquid microextraction approach for the separation and determination of isoniazid in human plasma by high-performance liquid chromatography with UV–Vis detection was developed for the first time. A new natural deep eutectic solvent based on thymol as a hydrogen bond donor and 4-methoxybenzaldehyde as a hydrogen bond acceptor was proposed as the extraction solvent. The developed microextraction procedure assumed two simultaneous processes during the mixing of the sample and extraction solvent: the derivatization of the polar analyte in the presence of 4-methoxybenzaldehyde (component of the natural deep eutectic solvent) with the formation of a hydrophobic Schiff base (1); mass transfer of the Schiff base from the sample phase to the extraction solvent phase (2). Under optimal conditions, the limits of detection and quantification were 20 and 60 μg L−1, respectively. The RSD value was <10 %, the extraction recovery was 95 %. SignificanceIn this work, the possibility of isoniazid derivatization in the natural deep eutectic solvent phase with the formation of the Schiff base was presented for the first time. The approach provided the separation and preconcentration of polar isoniazid without the use of expensive derivatization agents and solid-phase extraction cartridges. The formation of the Schiff base was confirmed by mass spectrometry.