Standard Calibration Curve Research Articles

Development and Validation of RP-HPLC Method for Roflumilast Nano Particles in Rat Plasma for Pharmacokinetic Study Analysis

Aim: The aim of this study is to develop a sensitive, specific, rapid, and precise reverse- phase high-performance liquid chromatography (RP-HPLC) method and validate it to determine the Roflumilast in rat plasma. Background: This study was aimed at developing a simple HPLC method for the detection of Roflumilast in rat plasma after ingestion of nanoparticles into the rat. A bioanalytical method was developed and validated. Methodology: The drug sample (Roflumilast) was eluted isocratically using a mobile phase of Ammonium acetate buffer (pH = 7.0), acetonitrile, and methanol (20:40:40, v/v/v) made up the mobile phase on a Phenomenex C-18 (150mm x 4.68mm pore size 5-micron analytical column. The drug was quantitatively determined at a UV wavelength of 254 nm using a standard calibration curve spanning the range of 1.5, 3.0, 4.5, 6.0, 7.5μg/mL-1 Results: The results showed that the limits of quantitation (LOQ) and detection (LOD) were 0.18 μg/ml and 0.54μg/ml, respectively. For both the intra-day and inter-day analysis, relative standard deviation (% RSD) was less than 2%, and the drug’s percentage accuracy was between 96% and 98%. Conclusion: As per the established protocols, the developed method was quantitatively assessed for its intended use in terms of specificity, linearity, accuracy, precision, robustness, and sensitivity analysis. Roflumilast-loaded nanoparticles were effectively used to determine the drug entrapment efficiency using the currently validated RP-HPLC method. Besides, highly efficient drug extraction from plasma was attained, and mobile phase composition was suitable to the pharmacokinetic study of Roflumilast-loaded nanoparticles in rats. other: NA

Can fragment ion intensity be used for fatty acid sn-position determination of food phospholipids?

Fatty acid (FA) regio-position is critical information for the structures of both triglycerides and phospholipids in food products. Although lipase/phospholipase hydrolysis combined with TLC separation and GC analysis can be used to determine the overall sn-2 FA composition of triglycerides/phospholipids in food samples, it is much more challenging to pinpoint FA regio-position at the molecular species level. Currently, the most widely used method to obtain such information is based on the relative intensity of fragment ions generated in tandem mass spectrometry. The reliability of this approach was verified in this study using regio-pure phospholipid standards and by cross-validation with the Paternò–Büchi photochemical reaction. We have demonstrated that for food materials with widespread regioisomers, a standard calibration curve from regio-pure standards is needed to determine the proportion of each isomer, whereas fragment ion intensity can only be used to reveal the sn-position of FA in phospholipid molecules devoid of regioisomers.

A Novel PCR-Free Ultrasensitive GQD-Based Label-Free Electrochemical DNA Sensor for Sensitive and Rapid Detection of Francisella tularensis.

Biological warfare agents are infectious microorganisms or toxins capable of harming or killing humans. Francisella tularensis is a potential bioterrorism agent that is highly infectious, even at very low doses. Biosensors for biological warfare agents are simple yet reliable point-of-care analytical tools. Developing highly sensitive, reliable, and cost-effective label-free DNA biosensors poses significant challenges, particularly when utilizing traditional techniques such as fluorescence, electrochemical methods, and others. These challenges arise primarily due to the need for labeling, enzymes, or complex modifications, which can complicate the design and implementation of biosensors. In this study, we fabricated Graphene Quantum dot (GQD)-functionalized biosensors for highly sensitive label-free DNA detection. GQDs were immobilized on the surface of screen-printed gold electrodes via mercaptoacetic acid with a thiol group. The single-stranded DNA (ssDNA) probe was also immobilized on GQDs through strong π-π interactions. The ssDNA probe can hybridize with the ssDNA target and form double-stranded DNA, leading to a decrease in the effect of GQD but a positive shift associated with the increase in DNA concentration. The specificity of the developed system was observed with different microorganism target DNAs and up to three-base mismatches in the target DNA, effectively distinguishing the target DNA. The response time for the target DNA molecule is approximately 1010 s (17 min). Experimental steps were monitored using UV/Vis spectroscopy, Atomic Force Microscopy (AFM), and electrochemical techniques to confirm the successful fabrication of the biosensor. The detection limit can reach 0.1 nM, which is two-five orders of magnitude lower than previously reported methods. The biosensor also exhibits a good linear range from 105 to 0.01 nM and has good specificity. The biosensor's detection limit (LOD) was evaluated as 0.1 nM from the standard calibration curve, with a correlation coefficient of R2 = 0.9712, showing a good linear range and specificity. Here, we demonstrate a cost-effective, GQD-based SPGE/F. tularensis DNA test suitable for portable electrochemical devices. This application provides good perspectives for point-of-care portable electrochemical devices that integrate sample processing and detection into a single cartridge without requiring a PCR before detection. Based on these results, it can be concluded that this is the first enzyme-free electrochemical DNA biosensor developed for the rapid and sensitive detection of F. tularensis, leveraging the nanoenzyme and catalytic properties of GQDs.

Determination and Residue Survey of Novel Nicotinic AcetylcholineReceptor Modulator Pesticides in Brown Rice by LC-MS/MS

Nicotinic acetylcholine receptors (nAChRs) are neurotransmitter receptors found in the nervous system of many organisms, including humans. Neonicotinoid pesticides act as nAChRs modulators that affect neurotransmission. Due to toxicity effects, their use has been restricted. However, a new class of modulators (nAChRMs) have been developed, but analytical methods for the detection of residues of these new pesticides in agricultural crops have not been established. Therefore, this study aimed to develop and validate an accurate determination method for novel nAChRMs, such as sulfoxaflor, flupyradifurone, flupyrimin, and triflumezopyrim in brown rice using liquid chromatography with tandem mass spectrometry (LC-MS/MS). The method was applied to commercially available brown rice samples from Tokyo, Japan. Target analytes were extracted with acetonitrile, cleaned with GC/PSA, and then cleaned again with MonoSpin PBA. In accordance with the method validation guidelines for residual pesticides in foods, the performance characteristics were evaluated, with trueness ranging from 86.3% to 98.2%, repeatability of less than 6.5% relative standard deviation (RSD), and within-laboratory reproducibility of less than 6.5% RSD. These results indicate that the developed method can be applied to residue surveillance of target analytes using solvent standard calibration curves. By applying the developed method to 53 brown rice samples commercially available in Tokyo, sulfoxaflor residues were found in two samples at concentrations of 3.7 and 21.9 ng/g. This is the first report of the detection of sulfoxaflor residues in domestic agricultural products.

Preparation and flavor characteristics of plant-based meat flavoring by mixed fermentation of multiple strains

In this study, plant-based meat flavoring was prepared by mixed fermentation and thermal reaction. Based on the changes of amino acid nitrogen, reducing sugar, and total acid during the fermentation process and combined with sensory evaluation, the optimal fermentation conditions were determined as 4 % total inoculation amount of Monascus purpureus, Actinomucor elegans, and Bacillus subtilis with an inoculation ratio of 1:1:1, and 36 h of fermentation time. The odor characterization of meat flavoring was identified by solid-phase microextraction–gas chromatography–mass spectrometry (SPME–GC–MS), aroma extract dilution analysis (AEDA), quantitative measurements, odor activity value (OAV) and aroma recombination and omission experiments. 64 volatile compounds and 28 odorants were identified. The compounds with FD ≥ 27 were precisely quantified by five-point standard calibration curve and OAVs were calculated, and those with OAV ≥ 1 were subjected to aroma recombination and omission experiments. Finally, furfuryl mercaptan, difurfuryl disulfide, 4-methyl-5-ethylthiazole, 1-octanal, and 2-acetylthiophene were determined to be the key aroma-active compounds. These compounds have been recognized as key aroma-active compounds or detected in other meats or meat flavorings. In this study, we prepared plant-based meat flavoring through mixed fermentation, and provide new ideas for the development of plant-based thermal reaction meat flavoring process.

An Optimized Liquid Chromatography-Mass Spectrometry Method for Ganglioside Analysis in Cell Lines.

Gangliosides are glycosphingolipids composed of a sialylated glycan head group and a ceramide backbone. These anionic lipids form lipid rafts and play crucial roles in regulating various proteins involved in signal transduction, adhesion, and cell-cell recognition. Neuroblastoma, a pediatric cancer of the sympathetic nervous system, is treated with intensive chemotherapy, radiation, and an antibody targeting the GD2 ganglioside. Gangliosides are critical in neuroblastoma development and serve as therapeutic targets, making it essential to establish a reliable, rapid, and cost-effective method for profiling gangliosides, particularly one capable of isomeric separation of intact species. In this study, liquid chromatography-mass spectrometry (LC-MS) was optimized using standard gangliosides, followed by the optimization of sphingolipid extraction methods from cell lines by comparing Folch and absolute methanol extraction techniques. Percent recovery and the number of identified sphingolipids were used to evaluate the analytical merits of these methods. A standard gangliosides calibration curve demonstrated excellent linearity (R2 = 0.9961-0.9975). The ZIC-HILIC column provided the best separation of ganglioside GD1 isomers with a 25 min runtime. GD1a elutes before GD1b on the ZIC-HILIC column. Absolute methanol yielded better percent recovery (96 ± 7) and identified 121 different sphingolipids, the highest number between the two extraction methods. The optimized method was applied to profile gangliosides in neuroblastoma (COG-N-683), pancreatic cancer (PSN1), breast cancer (MDA-MB-231BR), and brain tumor (CRL-1620) cell lines. The ganglioside profile of the neuroblastoma cell line COG-N-683 showed an inverse relationship between GD1 and GD2. Ceramide, Hex1Cer, GM1, and GM3 were highly abundant in CRL-1620, PSN1, and MDA-MB-231BR, respectively. These results suggest that our method provides a sensitive, reliable, and high-throughput workflow for ganglioside profiling across different cell types.

B-174 Quantification of vitamin C in serum as a biomarker using the Laser Diode Thermal Desorption technique “LDTD”/Mass Spectrometry (Luxon)

Abstract Background Ascorbic acid (AA) or vitamin C, is a crucial substance that is involved in numerous physiological processes in living beings, including collagen production and antioxidant activity. When ascorbic acid is exposed to moisture, air, heat, light and oxygen, it oxidizes and turns into dehydroascorbic acid (DHAA). Our objective is to describe the sample preparation procedure and total quantification of AA and DHAA in human serum sample based on LDTD-MS/MS, and demonstrate its efficiency in quantification, combined with analysis selectivity and rapidity. Methods The Luxon is a sample introduction and ionization source that used a fiber-coupled laser diode to thermally desorb neutral molecules and charge them using a corona needle so they can be analyzed by mass spectrometry. Due to the instability of ascorbic acid, plasma samples were enriched and stabilized with an acidic solution. Sample preparation utilized a phosphate-containing buffer to minimize interferents and help volatize the analyte, followed by a precipitation step using acetonitrile to further clean the extract. Stable isotope-labeled internal standard (13C6 ascorbic acid) and homemade calibration curve and water quality controls were used for quantification. The analysis was performed using a Sciex 6500+ Triple Quad in APCI (Atmospheric Pressure Chemical Ionization) negative mode. Calibration curves ranging from 1 to 100 μg/mL and QCs were prepared in ascorbic acid-depleted serum (kept at room temperature/exposed to light for 4 days). The peak area against the internal standard (IS) ratio was used to normalize the signal. The calibration curves were plotted using the peak area ratio and the nominal concentration of standards. The following parameters were assessed for quantitative analysis: linearity, precision, accuracy, carryover and parallelism. A linear regression model with 1/X2 weighting was used to obtain the calibration curve equation and determine the correlation coefficient (r2). Parallelism was assessed by comparing the correlation coefficient of calibration curves prepared in water to six curves prepared with biological matrixes. Intra and inter assay precision and accuracy were determined by measuring QC samples ranging from low to high concentration in five replicates for 3 consecutive days. Results Calibration curves (n=3) showed excellent linearity. The calibration curve resulted in a linear response throughout the concentration range, the correlation coefficient was 0.99. For each quality control concentrations CVs were <10% complying with desirable specifications for imprecision and accuracy. Intra-assay CVs were 3.0-8.89% and inter-assay CVs were 7.64-9.79% for precision which reflects the agreement between repeated measurements. The results for accuracy showed similar results, intra-assay CVs were 3.83-9.20% and inter-assay CVs were 5.0-9.7%. Conclusions The new LDTD-MS/MS method described here has been validated as an effective technique to reliably and rapidly quantify ascorbic acid. Simple sample preparation, rapid acid stabilization combined with high yield allow analysis without degradation responses.

Exploring the synergistic effect in polyherbal chewable antacid tablets: formulation and evaluation study

Abstract Polyherbal chewable tablets of Phyllanthus emblica and Glycyrrhiza glabra were developed with the objective to formulate an effective, safe and convenient dosage form for acid-related disorders. A standard calibration curve was constructed for Polyherbal extracts through UV-Spectrophotometry, achieving an absorbance maximum at 275 nm. Compatibility between the drug and excipients was examined through FTIR studies. Various pre-compression parameters, like bulk density, tapped density, compressibility index, Hausner’s ratio and angle of repose, were assessed for the powder blend. The tablets were evaluated for post-compression parameters, such as thickness, hardness, friability, and weight variation and disintegration time. The drug release study was conducted in vitro. The acid-neutralizing capacity of the formulated batches was compared with marketed formulations. The calibration curve showed a high correlation coefficient (r2=0.9972), suggesting accuracy and reliability. FTIR analysis confirmed the compatibility between the drug and excipients. Pre-compression studies revealed an acceptable range for all parameters, indicating good flow properties. For instance, Carr’s Index for all batches varied from 14.31% to 24.41%, and the angle of repose ranged from 33.7 to 35.21 degrees. Post-compression parameters were within the standard limits with hardness between 4.9 to 6.1 kg/cm2 and friability less than 1% for all batches. In vitro drug release showed a gradual increase over time with PF9 achieving 98.63% release at 60 min. The acid-neutralization capacity was highest for the combined extract at 27.83±0.34 mEq/g and PF9 batch at 28.12±0.43 mEq/g, demonstrating their effectiveness in neutralizing acid. The study successfully formulated a Polyherbal chewable tablet with optimized pre and post-compression parameters. The tablet exhibited promising in vitro drug release and an efficient acid-neutralizing capacity. It holds potential as an effective treatment option for acid-related disorders.

Addressing stability issues of vildagliptin: Method optimization and validation for accurate analysis in human plasma.

This research paper introduces novel strategies to address the stability issues arising with vildagliptin, marking the first attempt to tackle this challenge comprehensively. The study incorporates malic acid into the human plasma, a crucial step in stabilizing vildagliptin and preventing its degradation. Additionally, optimization of the elution process on a C18 Asentis Express column, fine-tuned with a combination of acetonitrile and ammonium trifluoroacetate 5mM, ensures optimal chromatographic conditions. For detection and quantification, electrospray ionization (ESI) is employed, monitoring multiple reactions for vildagliptin (304.2 → 154.2) and vildagliptin D7 (311.1 → 161.2). Meticulous validation of the method demonstrates high accuracy (97.30%-104.15%) and precision [(0.32%-3.09% coefficient of variance (CV)] for vildagliptin calibration curve standards (CC STD), establishing its sensitivity and reliability in measuring vildagliptin levels. This refined methodology offers numerous advantages, including the elimination of stability concerns, reduced human plasma sample volume (100 μL), exceptional reproducibility, shortened run time (~2.2min), and a wide concentration range (1.00 to 851.81 ng/mL). These attributes make it exceptionally well-suited for diverse research applications, spanning from extensive sampling in therapeutic drug monitoring units to bioequivalence and bioavailability studies, as well as pharmacokinetic investigations of vildagliptin.

Kinetics of Tofu Pulp as Copper Metal Adsorbent on the Waste of the Silver Craft Industry

Liquid waste originating from the silver crafts industry is heavy metal waste that is dangerous for the surrounding environment, one of which is copper (Cu). Copper is a heavy metal that can have toxic effects on human health. Based on these problems, processing is needed to reduce the pollutants produced. One of the technologies used is adsorption using a natural adsorbent that is efficient and easy to obtain, namely tofu dregs. Adsorption using tofu dregs is because tofu contains protein. This protein has the ability to absorb amino acids which form two charged ions (zwitter ions). Toxic metals can be bound to proteins as metallothionein. This research aims to determine the efficiency of using tofu dregs as an absorbent for copper metal (Cu) and to determine the effect of contact time and adsorption isotherms on copper metal adsorption. 1 gram of tofu dregs was used with 25 ml of waste and then contacted with a magnetic plate stirrer at varying times of 30, 60, 90, 120 and 150 minutes. The concentrations of all copper metals were analyzed using an Atomic Absorption Spectrophotometer. Next, each copper metal content was calculated using a copper metal standard calibration curve. Identification using an Infrared Spectrophotometer showed that the tofu dregs waste in this study contained the functional groups -OH, N-H (stretching), C-H (aliphatic), C=O, -OH (bending vibration), and C-O. From the research it was found that the copper metal content in the sample was 19.5979 ppm. The optimum contact time for copper metal adsorption is 120 minutes, which results in an optimum adsorption efficiency for copper metal, namely 54.88%. The isotherm equation that corresponds to the adsorption of copper metal using tofu dregs waste is the Freundlich isotherm with a Kf value of 0.072 L/g and a 1/n value of 2.366. This shows that the adsorption of copper metal occurs in a multilayer layer on the surface of the tofu dregs adsorbent, which illustrates the occurrence of physical adsorption. Tofu dregs waste is an effective adsorbent for reducing copper metal levels in silver craft waste.

A new method for quantification of tomatine-enriched extracts.

Green tomato extracts, an agro-food industry waste, are rich in the glycoalkaloid tomatine, which presents activity against several diseases. High-performance liquid chromatography (HPLC) with ultraviolet (UV) detection is one of the most used techniques for quantification of bioactive compounds. The aim of this study was to optimize and validate a selective HPLC method with diode array detector (DAD) for the quantitative analysis of tomatine extracted from green tomatoes by subcritical water. Chromatographic runs were performed on a InertSustain Phenyl (250 mm × 4.6 mm, 5 μm) analytical column, at a wavelength of 205 nm. A concentration range of 50-580 μg mL-1 was used. The validation process was performed considering the linearity, precision, trueness, limit of detection (LOD) and limit of quantitation (LOQ) of the method. The selected mobile phase composed of acetonitrile and a solution of 20 mmol L-1 potassium dihydrogen phosphate (KH2PO4) pH 3, resulted in suitable retention times and a standard calibration curve with adequate linearity (R2 = 0.9999). The method trueness was evaluated by the recovery assay, obtaining a mean recovery of 105% and the precisions were 1.4% and 0.9% (percentage relative standard deviation, RSD%) for the tomatine standard and extract samples, respectively. The inter-day variability was 2.7-9.0% (RSD%) for the standards and 6.9% (RSD%) for extract. The LOD and the LOQ of the method were determined at 8.0 and 24.1 μg mL-1, respectively. The herein described method was successfully used for the quantification of tomatine in a tomato-derived extract. Furthermore, the method constitutes a simple and rapid analytical approach able to be used as a routine protocol. © 2024 Society of Chemical Industry.

Compositional analysis and quantitative evaluation of organic emissions from asphalt materials: Improvements and refinements

The organic emissions resulting from the use and application of asphalt materials can pose significant risks to plant, animal life and human health, consequently, it is crucial to conduct compositional analysis and quantitative evaluation of organic emissions from asphalt materials. In this study, the qualitative and quantitative analysis method of organic emissions from asphalt materials was developed based on headspace gas chromatography-mass spectrometry (HS-GC-MS), selected ion monitoring (SIM) mode, internal standard method and calibration curve. The spiked recovery and surrogate standard recovery were employed to validate the method. The results show the excellent accuracy, precision, and reliability of the HS-GC-MS quantitative analysis method. And the results provide confirmation that total volatile organic compounds (TVOCs), polycyclic aromatic hydrocarbons (PAHs), and n-alkanes can indeed be identified as typical organic emissions originating from asphalt materials. Furthermore, the study successfully identifies benzothiazole, cyclohexyl disulfide, and N-(1,3-dimethylbutyl)-N′-phenyl-1,4-phenylenediamine as characteristic emissions in crumb rubber-modified asphalt (CRMA). The inclusion of the styrene-butadiene-styrene (SBS) modifier results in a significant reduction in n-alkane emissions by 41.11%, PAHs emissions by 25.22%, and TVOCs emissions by 47.21% in comparison to the base asphalt, demonstrating the effective inhibitory effect of the SBS modifier on organic emissions. When compared to the base asphalt, the addition of crumb rubber results in increased emissions of n-alkanes by 12.68% and PAHs by 50.60%, as well as the introduction of the emissions associated with CRMA characteristic compounds, indicating that the emission issue of CRMA is particularly prominent.

Determination of tetrodotoxin in human plasma and urine using online MCX SPE column cleanup coupled with liquid chromatography-tandem mass spectrometry

An efficient technique for quantitative analysis of tetrodotoxin (TTX) in human plasma and urine has been developed, which combines liquid chromatography-tandem mass spectrometry (LC-MS/MS) with online MCX solid phase extraction (SPE) cleanup. Sample preparation, including extraction with acetonitrile containing 0.5 % acetate acid, centrifugation, and filtration, was followed by online SPE cleanup. The whole run-time was less than 15 min, including online cleanup, chromatographic separation, and re-equilibration of the online SPE − LC-MS/MS system. The parameters of sample extraction, purification, separation, and detection were optimized. The matrix-matched internal standard calibration standard curves with linear regression coefficients larger than 0.9990 were established for quantification. The LOD and LOQ for this approach were determined to be 0.1 ng/mL and 0.3 ng/mL, respectively. The recoveries for varied concentrations of TTX in human plasma and urine were 84.9–104.2 % and 89.2–109.6 %, respectively. The matrix effects of TTX in human plasma and urine matrices were 85.5 % and 74.3 %, respectively, and both the inter- and intra-day precision values were less than 9.5 %. This analytical method was successfully employed for detecting TTX in biological samples from a poisoned patient who accidentally ingested the nassarius glans.

Generation of monoclonal antibody against 6-Keto PGF1α and development of ELISA for its quantification in culture medium

Prostacyclin or prostaglandin I2 (PGI2), a metabolite of arachidonic cyclooxygenase pathway, has been demonstrated as an effector of adipocyte differentiation. However, due to its instability in biological fluid, it is difficult to evaluate the role of PGI2 in regulating adipocyte differentiation in different stages in culture. Therefore, this study aimed to establish a simple and rapid method for the production of monoclonal antibody against 6-Keto PGF1α, a stable PGI2 metabolite, and its quantification to determine the role of PGI2 in culture medium. Eight-week-old female BALB/c mice were immunized with the hapten of 6-Keto PGF1α and BSA for several weeks until a higher antibody titer (absorbance value > 0.9 at 1000-times dilution) against 6-Keto PGF1α was found. Then, fusion of antibody-producing spleen lymphocytes with SP-2 myeloma cells and thymocytes was performed and cultured in HAT-medium supplemented with hypoxanthine, aminopterin, and thymine. Specific antibody-producing cells (M2-A4-B8-D10) against 6-Keto PGF1α were identified and separated. A standard ELISA calibration curve was developed with 100% reactivity for 6-Keto-PGF 1 α ranging from 0.26 pg to 6.44 ng corresponding to 90% and 10% of the maximum binding capacity for the immobilized antigen respectively. This method can easily be applied to monitor PGI2 regulation in different stages of cultured adipocytes to reveal the regulatory roles of PGI2 in maintaining homeostasis and adipocyte differentiation.

A green micelle-enhanced first derivative synchronous fluorescence approach for determination of donepezil HCl and trazodone HCl in their pure state, pharmaceutical dosage form and spiked human plasma.

The study's objective is to establish an eco-friendly, sensitive and economical quantitative methodology for the concurrent analysis of donepezil HCl (DPZ) and trazodone HCl (TRZ) in raw materials, tablets and human plasma. The first derivative synchronous fluorescence spectroscopic (FDSFS) technique was applied at constant wavelength difference (∆λ = 120) for assessment of DPZ and TRZ at each other's zero-crossing point at 279 nm and 297 nm, respectively. The submitted technique was validated in accordance with ICH Q2 R1 guidelines and the linearity of the standard calibration curve was observed over the concentration range of 10-500 ng/ml for DPZ and 20-1,000 ng/ml for TRZ. The detection limits (LOD) were found to be 2.65 and 5.4ng/ml, and the limits of quantitation (LOQ) were 8.05 and 16.3ng/ml for DPZ and TRZ, respectively. This technique was used further to quantify the studied medications in their laboratory-prepared mixtures, commercial tablets and spiked plasma samples. The results obtained were not significantly different from those acquired from the comparison methods, indicating the high accuracy and precision of the proposed method. Furthermore, the ecological friendliness of the suggested method was evaluated and proven to be excellent using Green Analytical Procedure Index (GAPI) and Analytical GREEnness (AGREE) evaluation tools.

Spectroscopic In-Vitro Drug-Drug Interaction Studies of Amoxicillin and Paracetamol Solid Dosage Forms

Potential drug-drug interactions (DDIs) are a public health concern in clinical therapy and drug development because of their contribution to actual adverse drug reactions (ADRs) or events. The study aimed to quantify the in-vitro drug-drug interaction of amoxicillin (AMX) and paracetamol (PCM) formulations which are commonly co-administered. Determinations were carried out by spectroscopic methods – zero-order and derivative spectroscopy. The data were analyzed using Microsoft Excel, 2016. The UV-Spectra of AMX and PCM showed two distinctive peaks at 240 nm and 260 nm were observed for AMX, while for PCM at 290nm and 340 nm, with maxima at 240 nm and 340 nm for AMX and PCM respectively. Absorption measurements were taken at the maximum wavelength of 290 nm and 240 nm for PCM and AMX respectively. The content of both drugs and potential DDIs of AMX and PCM were assayed by zero- and 3rd-derivative spectroscopy. The calibration curves for AMX and PCM standards showed good linearity at concentrations, with corresponding correlation coefficients (R) being 0.999 and 0.998. The intercept and slope for AMX were -0.0148 and 0.0732 respectively, while for PCM values were 0.0071 and 0.148. The content of PCM and AMX in the formulations was 98.40 ± 0.44% and 96.04 ± 0.29% respectively. The joint-drug-dissolution studies for AMX and PCM interaction (DDI) were obtained with the 3rd-order derivative spectroscopy at 210 nm (zero-crossing for PCM) and 290 nm (zero-line crossing for AMX) respectively - which showed overlapping spectra for their zero-order derivative spectra. No significant difference was observed in the in-vitro drug release profiles for AMX and PCM, while comparative profiles were observed to have a very strong correlation between individual-release and joint-release profiles.

LC-MS/MS-BASED QUANTITATIVE PROFILING OF PAPAIN ENZYME IN CARICA PAPAYA L.: METHOD DEVELOPMENT AND VALIDATION

Objective: To develop and validate a sensitive Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) method for quantifying the Papain enzyme in Carica papaya L. plant extracts. Methods: As an internal standard (IS), Papain was procured. A gradient-based LC-MS/MS method was developed using the Quasar C18, 150 mm × 2.1 mm, 3 µm column; the drug separation was accomplished using a gradient elution mode with a mobile phase consisting of 0.2% formic acid in water (A) and a 98:2% ratio of formic acid in acetonitrile (B). The mobile phase was injected with a volume of 10 µl at a flow rate of 0.5 ml/min. Results: Matrix-matched calibration adhering to SANCO guidelines was employed for accurate quantification, covering a concentration range of 1 to 2000 ng/ml. The method's selectivity and linearity were confirmed with an R2 correlation value of 0.990. Limits of detection (LOD) and quantification (LOQ) were determined as 170.5 ng/ml and 516.8 ng/ml, respectively. The developed LC-MS/MS method demonstrated robust analytical performance, providing a solid basis for quantifying Papain enzyme levels in Carica papaya L. plant extracts. The matrix-matched calibration approach, with a well-defined standard calibration curve, showcased the method's selectivity and linearity. The LOD and LOQ values further underscored the method's sensitivity. Conclusion: This study successfully establishes and validates a gradient-based LC-MS/MS method for accurate quantification of Papain enzyme levels in Carica papaya L. plant extracts. The demonstrated precision, accuracy, and sensitivity support the reliability of this analytical approach, offering a valuable tool for future investigations into the biological effects of Papain.

Determination of chromium in foodstuffs by using novel adsorbent in vortex assisted-dispersive solid phase micro-extraction method: An application of multivariate techniques

A new graft copolymer composed of polystyrene and polylinoleic acid (PLinas) with the sodium salt of iminodiacetate (Ida) was synthesized and used as an adsorbent. The vortex-assisted dispersive solid-phase micro-extraction (VA-dSPµE) method was used for the extraction and pre-concentration of chromium. Multivariate methodologies, such as factorial design and 3D surface plots, were applied for screening and optimizing effective extraction parameters. The influence of diverse analytical parameters, such as pH, sample volume, and interfering ions, on the extraction of chromium was studied. The calibration standard curve exhibited a linear range from 0.01 to 0.50 μg L−1. The relative standard deviation and limit of detection were found to be 1.65 % and 0.003 μg L−1, respectively. Extraction recoveries were found in the range of 96 to 99 % by using certified reference materials (CRMs). The adsorbent capacity of PLinas-Ida was found to be 112 mg g−1. The VA-dSPµE method demonstrated its effectiveness in the pre-concentration and determination of chromium within samples of foodstuffs by graphite furnace-atomic absorption spectrometry (GF-AAS).

Interlaboratory evaluation of LC-MS-based biomarker assays.

Validation of biomarker assays is crucial for effective drug development and clinical applications. Interlaboratory reproducibility is vital for reliable comparison and combination of data from different centers. This review summarizes interlaboratory studies of quantitative LC-MS-based biomarker assays using reference standards for calibration curves. The following points are discussed: trends in reports, reference and internal standards, evaluation of analytical validation parameters, study sample analysis and normalization of biomarker assay data. Full evaluation of these parameters in interlaboratory studies is limited, necessitating further research. Some reports suggest methods to address variations in biomarker assay data among laboratories, facilitating organized studies and data combination. Method validation across laboratories is crucial for reducing interlaboratory differences and reflecting target biomarker responses.

Rapid measurement of trace periodate concentration with bromide ion–catalyzed periodate for oxidation colorization of DPD

In the study, the Br−–DPD method for the determination of IO4− concentration was established. The method facilitated the DPD indicator reaction by adding Br− and DPD at pH 5.5 (50 mM phosphate buffer) to complete the measurement of the IO4− concentration. DPD+ could be detected by UV–visible spectrophotometer at 510 nm and 551 nm. The experimental results showed a strong linear relationship between the absorbance of DPD+ and the concentrations of IO4−. The slopes of the calibration standard curves for absorption wavelengths at 510 nm and 551 nm are 1.92 × 104 M−1 cm−1 (R2 > 0.999) and 2.06 × 104 M−1 cm−1 (R2 > 0.999). The stoichiometric coefficient of the Br−–DPD method for IO4− and DPD was 1:2, and pH in the range 3.0–7.0 had no significant different on the calibration curve of the Br−–DPD method. The absorbance in experimental water remained stable within 600 s. The Br−–DPD method accurately measured trace concentration of IO4− in ultrapure water at the range of 0.05 μM–10 μM. In addition, metal ions (Fe3+, Cu2+ and Co2+) and common anions (SO42−, NO3− and Cl−) showed little interference on the Br−–DPD method. The results suggested that the Br−–DPD method is a precise and versatile approach for measuring IO4− concentration.