Detection Wavelength Research Articles

A novel LC-TQ-MS/MS method for quantifying mefenamic acid-NDSRI (N-nitroso drug substance-related impurity) in mefenamic acid tablet and pediatric suspension dosage forms: a comparative study with a cost-effective white, green, and blue UPLC method.

The current research presents novel LC-TQ-MS/MS and cost-effective UPLC methods intended for the accurate quantification of mefenamic acid-N-nitroso drug substance-related impurity-NDSRI (N-MFA) in mefenamic acid (MFA) tablet and pediatric suspension dosage forms. The acceptable intake of N-MFA is derived from the TD50 (Median Toxic Dose-50%) value of N-nitroso diphenylamine. The analytical separation was achieved for the UPLC method using an XBridge BEH Shield RP18 Column (150 × 3.0 mm, 3.5 μm), employing 0.1% formic acid and acetonitrile as mobile phases in a gradient mode. A flow rate of 0.7 mL min-1 was set for the pump, and the detection wavelength was 230 nm. LC-TQ-MS-MS analysis was accomplished utilizing a Xevo TQ-XS mass spectrometer with electrospray ionization in the positive mode. N-MFA quantification was carried out using multiple reaction monitoring (MRM) as the mass transition: m/z 271.13 → 241.14. The proposed methods were successfully validated following ICH guidelines and are capable of quantifying at 0.01 ng mL-1 at an MFA concentration of 1 mg mL-1 for the LC-MS/MS method and at 0.036 μg mL-1 at an MFA concentration of 10 mg mL-1 for UPLC. The validated methods exhibited excellent linearity over the concentration ranges of 0.01 to 125 ppm for LC-MS/MS and 0.036 μg mL-1 to 1.250 μg mL-1 (3.6 to 125 ppm) for UPLC, with a Pearson correlation coefficient of 0.999. The method's trueness, in terms of accuracy recoveries, ranged from 90.43% to 101.34% for LC-MS/MS and 92.12% to 101.21% for UPLC. The applicability of these methods was successfully verified through the analysis of commercial samples of MFA formulations. Additionally, the sustainability and eco-friendliness of the method were assessed using whiteness and greenness metrics, including RGB12 (Red-Gree-Blue) tools, GAPI (Green Analytical Procedure Index), analytical eco-scale, AGREE (Analytical GREEnness), AGREEprep (Analytical GREEnnesspreparation), and BAGI (Blue Applicability Grade Index). Both methods can be used to determine N-MFA content in mefenamic acid formulation dosage based on the availability of instruments LC-TQ-MS/MS and UPLC in R&D (Research and Development) and quality control laboratories.

Development and comprehensive greenness assessment of HPLC method for quality control of β-sitosterol in pharmaceutical ointments with trio-color coded evaluation

A simple, rapid, and reproducible high-performance liquid chromatography (HPLC) method has been developed and validated for the determination of β-sitosterol in the pharmaceutical dosage form of moist exposed burn ointment (MEBO). This method involved an effective sample procedure for extraction of β-sitosterol from MEBO using an alkali saponification agent composed of 0.8 N ethanolic NaOH and diethyl ether. The chromatographic separation was achieved on a C18 column (50 × 3.0 mm, 2.5 μm), using a mobile phase composed of methanol and acetonitrile (70:30 v/v) pumped in an isocratic mode at a flow rate of 0.7 mL/min. The column temperature was maintained at 40 °C, the injection volume was 10 µL, and the detection wavelength was 203 nm. Employing these conditions, the retention time was found to be 2.10 min. The developed method was validated for its specificity, linearity, accuracy, precision, the limit of detection, the limit of quantification, robustness, and solution stability based on International Council for Harmonisation (ICH) guidelines Q2 (R1). Our proposed method demonstrated superior performance compared to other reported methods. It exhibited a linearity range of 30 to 500 µg/mL and improved detectability with a limit of detection (LOD) of 4.65 µg/mL, highlighting its high sensitivity. Additionally, the separation was achieved in a remarkably short analysis time of just 2.1 min, which not only enhanced throughput but also significantly minimized waste and solvent consumption, thereby making it a more sustainable and effective alternative for β-sitosterol extraction. Moreover, in the light of green and white analytical chemistry, a comprehensive ecological and sustainable tri-color coded assessment protocol was established. The proposed method has been successfully applied to quantify β-sitosterol in commercial products (MEBO®, Avomeb® and BISTROl®) demonstrating its suitability for routine quality control analysis of β-sitosterol in pharmaceutical ointment dosage forms.

Novel ecofriendly spectrophotometric methods for the determination of six dihydropyridines calcium channel blockers through derivatization with sulfophtalein dye: application to tablet analysis

Novel, «green» and simple visible spectrophotometric procedures for the determination of six dihydropyridines CCBs (amlodipine besylate (AML), lacidipine (LAC), levamlodipine besylate (LAML), nifedipine (NIF), nimodipine (NIM) and nitrendipine (NIT)) through derivatization with the sulfophthalein dye bromophenol blue (BPB) have been developed. The optimal parameters for CCBs spectrophotometric analysis via complex formation using BPB were as follows: detection wavelength—596 nm, reaction time—5 min, ratio of reacting components—1:1, operating temperature—25 ± 2 °C. The concentration was linearly proportional to absorbance values in the range of 3.40—17.00 μg/mL (AML), 1.14—9.11 μg/mL (LAC), 1.14—9.08 μg/mL (LAML), 4.16—12.40 μg/mL (NIF), 0.84—5.86 μg/mL (NIM), 6.52—19.60 μg/mL (NIT). The developed methods are colorimetric and therefore does not require a UV instrument to quantify these drugs. The proposed approach was more efficient in terms of time reliability, sensitivity and «greenness» than other recorded spectrophotometric methods and can be easily implemented for routine pharmaceutical analysis.

A bionic palladium metal-organic framework based on a fluorescence sensing enhancement mechanism for sensitive detection of phorate.

We have developed a biomimetic fluorescent nanoprobe (Pd-MOF) that can accurately identify phorate at a fixed wavelength for rapid, sensitive and selective detection. Pd-MOF was a nanoparticle (260.00 ± 27.83 nm) based on the linkage of Pd metal and a TCPP organic framework. It could detect phorate according to the fluorescence principles similar to that of the bioluminescence of Chrysaora pacifica (substance interaction and chromophore fluorescence enhancement). When phorate molecules enter the pores of Pd-MOF and interact with each other, the energy transfer process is stimulated, and the fluorescence signal is significantly enhanced, thereby improving the detection sensitivity. According to shift of the white line in the XANES energy spectrum and the DFT results, phorate increased the energy gap of Pd-MOF from 0.025 eV to 0.046 eV, enhanced the stability of the system, and thus achieved fluorescence enhancement. The sensitivity of Pd-MOF was due to its much smaller energy gap (<80 times) than other metal MOFs and thus it was easier to get excited. The linear detection range for the phorate of the nanoprobe in the water system was 0.01-100 ppb, and the detection limit was 0.0017 ppb. The response time of the Pd-MOF nanoprobe to phorate was 45 seconds. The detection of phorate in tap water, pear and cabbage samples showed that the recovery rates were in the range of 87.69-106.12%, and the relative standard deviation (RSD) was less than 11.16%, which verified the possibility of Pd-MOF nanoprobe in practical application. The sensitive and specific recognition of phorate by Pd-MOF nanoprobe and the development of a phorate test strip (Pd-MOF@paper) confirmed its potential application in pesticide residue detection.

Bandgap-Tunable Aluminum Gallium Oxide Deep-UV Photodetector Prepared by RF Sputter and Thermal Interdiffusion Alloying Method

Gallium oxide (Ga2O3) has gained considerable attention due to its wide bandgap, the availability of native substrates, and its excellent properties for solar-blind photodetectors, transparent electronics, and next-generation power devices. However, the expensive Ga2O3 native substrates have restricted its widespread adoption. To reduce costs and further the development of β-Ga2O3-based devices, there is a need for bandgap-tunable oxide films with high crystal quality for deep-ultraviolet (DUV) photodetectors and high-breakdown-field power devices. This study introduces a Thermal Interdiffusion Alloying method to address these requirements. It focuses on developing deep ultraviolet (DUV) photodetectors using β-Ga2O3 thin films on sapphire substrates by promoting the diffusion of aluminum (Al) atoms from the substrate into the film, resulting in the formation of aluminum gallium oxide (β-(AlxGa1−x)2O3). The aluminum content is controlled by adjusting the process temperature, allowing for tunable detection wavelengths and enhanced DUV sensing capabilities. Radio frequency (RF) sputtering optimizes the film’s quality by adjusting the sputtering power and the argon/oxygen (Ar/O2) flow ratio. Material analysis indicates that this method expands the optical bandgap and shifts the response wavelength to 210 nm, significantly boosting the performance of the fabricated photodetectors. This research presents considerable potential for advancing DUV photodetectors across various disinfection applications.

Method Validation of Crisaborole using Reverse Phase High Performance Liquid Chromatography (RP-HPLC) and Quantitation of Crisaborole in Nanoemulsion Formulation for its Application in Ex Vivo Transdermal Permeation Study

Crisaborole is a boron containing phosphodiesterase 4 (PDE4) inhibitor which in this study was formulated in nanoemulsion form to treat atopic dermatitis. The study aims to develop and validate a selective analytical method for determining crisaborole in nanoemulsion formulations, facilitating its application in ex vivo transdermal permeation studies for the treatment of atopic dermatitis. Crisaborole was eluted using gradient elution method in reverse phase (C18) chromatography. The mobile phases were comprised of phosphate buffer (pH3) and acetonitrile, which increasing acetonitrile volume from 30 to 95 percent within 15 min with constant flow rate of 0.65 ml/min. Column temperature was set at 40 ºC and detection wavelength was at 252 nm. The method produced linear responses (R2=0.99) in concentrations ranges from 1.56-100 μg/ml (n=7). The developed method was sensitive with limit of detection (LOD) and limit of quantitation (LOQ) values of 1.84 μg/ml and 5.58 μg/ml; respectively. Crisaborole was stable in various working conditions which were within the acceptance value provided by guidelines (±15%). In ex vivo studies, the concentration of crisaborole was plotted in cumulative permeated graph and this quantitative method was proven to provide a selective and sensitive measurement for detection of crisaborole.

Systematic analysis of New Technologies and trends of infrared photodetectors

Infrared detection has always been regarded as an important technology with significant applications in military, industrial, and daily life. Infrared photodetectors (IRPDs) have experienced the development process from thermal IRPDs to photonic IRPDs, until now, the latter can be widely used in focal plane array (FPA). For a long time, IRPD technology based on HgCdTe and InSb materials has dominated the market, but there are still limitations in operating temperature and detectable wavelength region. Since the 21st century, people have been committed to researching new types of IRPDs. Type-II superlattice system technology is considered an alternative solution to the long wave region, and its performance can be improved by adding unipolar potential barriers, which only allow one type of carriers to pass normally. Quantum well and quantum dot are new IRPD technologies based on quantum theory. The former is based on developed GaAs growth technology and can reduce production costs; The latter utilizes the binding mechanism of quantum dots to increase the operating temperature, but whether it can be applied to large-scale devices remains to be researched. All these technologies will contribute to the development and application of the third generation of IRPD.

Development and validation of RP-HPLC method for simultaneous estimation of lidocaine and nifedipine in pure and combined dosage form

The simultaneous estimation of Lidocaine and Nifedipine using reversed-phase high-performance liquid chromatography (RP-HPLC) is essential for analysing both the bulk drug and its topical dosage form. The objective of this study was to develop a novel HPLC method for the simultaneous estimation of Lidocaine and Nifedipine. The method aimed to provide accurate and precise results for both the bulk drug and topical dosage form. The HPLC method employed a C18 column measuring (150 mm × 4.6 mm × 5 µm). A mobile phase consisting of a mixture of methanol and water in a ratio of 80:20 v/v was used. The flow rate was set at 1.0 ml/min, and the detection wavelength was set at λ-max 236 nm. The retention time for Lidocaine was determined to be 2.560 min, while for Nifedipine it was found to be 5.470 min. The developed HPLC method demonstrated good linearity for both Lidocaine and Nifedipine, as evidenced by the obtained correlation coefficients (R2) of 0.9890 and 0.9986, respectively. The accuracy studies yielded results within the acceptable range of 98.11% - 105%. Additionally, the precision of the method was established with % RSD values of less than 2% for routine analysis of lidocaine and nifedipine. This method provides a reliable and effective approach for the simultaneous estimation of lidocaine and nifedipine, contributing to the quality control and safety assessment of pharmaceutical formulations containing these compounds.

Determination of Amino Acids of Novel Food in Food by HPLC Coupled with Pre-Column Derivatization

A method for simultaneous determination of Theanine and γ-aminobutyric acid (GABA), as the novel food of amino acids, which was established using pre-column derivatization and high-performance liquid chromatography (HPLC). 4-Dimethylaminoazobe nzene-4′-sulfonyl chloride (DABS-Cl) is employed as the derivatization reagent with chromophore linked to Theanine and GABA, which lacks chromophore for DAD analysis in its pristine structure. After the detection wavelength was confirmed, the chromatographic and derivatization conditions were also optimized, including the chromatographic column, mobile phases and their gradient, derivatization temperature and time, the additive amount of buffer solution and derivatization reagent. Methodological verification showed that the derivant of Theanine (DABS-Theanine) and derivant of GABA (DABS-GABA) have good linearity in the range of 1–100 μg/mL, with correlation coefficients of 0.9996 and 0.9995, respectively. The recoveries for both amino acids were between 93.95% and 103.90%, with RSDs ranging from 0.99% to 3.93%. The limit of detection (LOD) was 0.6 mg/kg for Theanine and 0.2 mg/kg for GABA. The limit of quantification (LOQ) was 1.7 mg/kg for Theanine and 0.6 mg/kg for GABA. Furthermore, five commercial products containing Theanine or GABA in two matrices (candy and beverage) were analyzed by the proposed method for validation. The average contents of Theanine and GABA were in the range of 307.49–1312.13 mg/kg and 22.98–6744.55 mg/kg, respectively. The developed method features easy sample pretreatment, a simple derivatization system, good separation specificity, good repeatability, accuracy and reliability, and can meet the large-scale determination Theanine and GABA in various food substrates.

Quantitative Analysis of Caffeine in Roasted Coffee: A Comparison of Brewing Methods

Coffee is one of the most widely consumed beverages in the world due to its sensory and health benefits. The caffeine content, a bioactive compound of coffee, depends on many factors, including the brewing method, which is the subject of ongoing scientific research. In addition, various methods are used in studies to determine the caffeine content. However, it is worth noting that there is considerable variation in the individual analytical parameters within these methods. The aim of this study was to update the data on the effects of different brewing methods on the caffeine content of the brew and to present the current state of knowledge on techniques for the determination of this compound. A literature review was conducted, taking into account the latest studies in this field. The results showed that the caffeine content (mg/100 mL) of the brew prepared with the Cold Brew method was 48.50–179.95, Espresso—50.40–965.60, French Press—52.00–123.90, AeroPress—56.35–120.92, and Moka—128.00–539.90. These methods were characterized by different brewing parameters (time, water temperature and pressure, ratio of coffee to water), which differentiated the caffeine content. In addition, some methods were characterized by a wide range of caffeine content, suggesting that even minor variations in brewing method parameters may affect the content of this ingredient. High-performance liquid chromatography (HPLC) was the predominant method used. The detector wavelengths, along with other parameters of the HPLC method, such as gradient profiles and column temperatures, can affect the precision and accuracy of the analysis, and these differences can modify analyte retention and detection, leading to discrepancies in results. These results point to the need for studies that consider various brewing methods and a wide range of coffee types, including roast and origin, to accurately determine the effects of these factors on caffeine content determined by one precise method.

Wavelength optimization of fine optical surface defect detection based on FDTD

Due to the similar order of magnitude of the defect size and the detection wavelength, when detecting micro-/nano-scale defects on the surface of a fine optical component, the intense modulation of the optical field poses challenges in correlating imaging widths of defects with actual widths. A dark-field scattering imaging (DFSI) model, based on the finite difference time domain (FDTD) method, is established to study the imaging for triangular and circular section defects and investigate the influence of wavelength on defect width detection. Simulated results indicate that a shorter wavelength of the light source in a DFSI detection system leads to a larger mapping range between the imaging width and the actual defect width, which makes calibration less difficult. A DFSI detection system for micro-/nano-scale surface defects on optical components is built to test defects with rectangular cross-sections on a calibration board. The defect widths estimated from the experimental and simulated results are in good agreement, with a root-mean-square error (RMSE) of 0.11 µm.

Qualitative and quantitative analysis of chemical components of Dracocephalum moldavica based on UPLC-Q-TOF-MS/MS and UPLC

Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS/MS) was used to rapidly identify the chemical components in Dracocephalum moldavica, and UPLC was employed to determine the content of its main components. MS analysis was performed using an electrospray ionization(ESI) source and data were collected in the negative ion mode. By comparing the retention time and mass spectra of reference compounds, and using a self-built compound database and the PubChem database, 68 compounds were identified from D. moldavica, including 36 flavonoids, 22 phenylpropanoids, 4 phenols, and 6 other compounds. On this basis, a UPLC quantitative method was established to simultaneously determine 8 main components, i.e., luteolin-7-O-glucuronide, apigenin-7-O-glucuronide, rosmarinic acid, diosmetin-7-O-glucuronide, tilianin, acacetin-7-O-glucuronide, acacetin-7-O-(6″-O-malonyl)-glucoside, and acacetin. A Waters ACQUITY BEH C_(18) column(2.1 mm × 100 mm, 1.7 μm) was used, with acetonitrile and a water solution containing 0.1% formic acid and 0.1% phosphoric acid as the mobile phase for gradient elution. The detection wavelength was set at 330 nm, with a flow rate of 0.4 mL·min~(-1), and the column temperature was maintained at 35 ℃. The 8 components demonstrated good linearity(r≥0.999 9) over a wide mass concentration range(50 or 100 times). The average recovery rate ranged from 97.5% to 105.1%, and the relative standard deviations(RSDs) were 0.90% to 3.4%(n= 6), indicating that the method was simple, accurate, and reliable. In 17 batches of D. moldavica samples, the content of these 8 components ranged from 0.405 to 2.10, 0.063 to 0.342, 0.446 to 2.43, 0.415 to 1.47, 1.57 to 4.34, 0.173 to 0.386, 1.00 to 5.40, and 0.069 to 0.207 mg·g~(-1), respectively. These results indicate significant differences in the internal quality of the samples, highlighting the need for strict quality control to ensure their pharmacodynamic efficacy. This study provides a scientific basis for the rapid discovery of pharmacodynamic substances, comprehensive quality control, and the formulation or revision of quality standards for D. moldavica.

Reliable wavelength detection method of sapphire fiber Bragg gratings using added multimode fiber

Sapphire fiber Bragg gratings (SFBGs) are promising high-temperature sensors, which can be applied to measure temperature and strain in extreme environments. However, the multimode operation of SFBGs is susceptible to disturbance, leading to unreliable wavelength detection. Here, we propose by using added multimode fibers (AMMF) and tracing the longwave edge of reflection envelope to enhance the stability of wavelength detection for SFBG. The near-field profiles of transmission modes are investigated in sapphire fiber with different lengths of AMMF. It is found that the mode-field distribution of sapphire fiber can be improved by using AMMF with a length of 1000 m, which results in a reduction of relative standard deviation (RSD) from 57 % to 10 %. Then, the signal-to-noise ratio (SNR) in the reflection spectrum of SFBG is improved to 16 dB by polishing inclined end faces of sapphire fiber using the removal mechanism of hard-brittle materials. Furthermore, we detect the wavelengths of both the longwave edge and peak on the reflection envelope, which reveals lower fluctuations (i.e., SD = 0.02 nm) of the longwave edge, since lower-order modes are more stable during transmission. The effect of external disturbances (i.e., torsion and vibration) on demodulation of SFBG is also evaluated, with a maximum fluctuation of 0.06 nm (SD = 0.01 nm). A temperature experiment is carried out with the assembly and polynomial fitting curves with high fitness are obtained. Thus, our proposed methods enhance the reliability of wavelength detection in the reflection spectrum of SFBG, which is beneficial to improving the sensing performance of SFBG-based sensors.

Determination of the Content of Hairy Vetch Isoflavone Glucoside in Qianliekang Tablets

Objective: To determine the content of maohui isoflavone glycoside based on its composition in Qianliekang tablets. Methods: High-Performance Liquid Chromatography (HPLC) was employed for the determination, with a detection wavelength set at 260 nm; column temperature maintained at 25°C; and mobile phase consisting of acetonitrile-0.1% formic acid solution (14:86). The flow rate was standardized to 1.0 ml/minute. Results: A good linear relationship between sample content and peak area was observed within the range of 0.051 μg to 0.816 μg for maohui isoflavone glycoside, with a relative standard deviation (RSD) of repeatability reaching 1.47%. The average recovery rate was found to be 98.21%, with an RSD of 2.31%. Conclusion: This method demonstrates excellent stability, high accuracy, precision, and reproducibility, making it suitable for quality control of Qianliekang tablets.

Development of an HPLC Method for Simultaneous Quantitation of Hyperin, Quercetin and Kaempferol in the Semen cuscutae

In this study, a method for the simultaneous quantification of hyperin, quercetin, and kaempferol in samples of Semen cuscutae was developed using high-performance liquid chromatography (HPLC). The chosen chromatographic conditions were a mobile phase of methanol – 0.1% formic acid in water, running in gradient mode, with a flow rate of 0.9 ml/min, and detection wavelengths of 354, 365, and 369 nm for hyperin, kaempferol, and quercetin, respectively. The results of the quantitative analysis of 5 samples of Semen cuscutae purchased from Phu Tho province showed hyperin content ranging from 0.950 to 1.218 mg/g; quercetin from 0.077 to 0.118 mg/g; and kaempferol from 1.051 to 1.190 mg/g based on the dry weight of the medicinal material. This research may be suitable for the quality control of Semen cuscutae in the market.

(Invited) Heterogeneous Integration of IR Detectors with CMOS and Thin Film Transistors

Colloidal quantum dots (CQDs) show promising performance in IR detection because of their many unique advantages, including high material quality, flexibility in operation wavelength, easy fabrication process and suitability for heterogeneous integration with CMOS. Our presentation will cover three areas about colloidal quantum dot detectors: (a) the physical model of CQDs, (b) integration of CQDs with electronics, and (c) strategies of overcoming the limit of dark current for uncooled IR detection. For (a), we will present a physical model considering the unique transport properties of ligand connected quantum dot detectors. The model shows how the CQD detectors perform differently than conventional p-i-n detectors and why those popular parameters derived from Shockley’s diode model such as reverse saturation current and ideality factor cannot model the CQD detectors. For (b), we will show how CQD detectors can be integrated with IGZO thin film transistors on glass substrate, GaN LEDs for wavelength converters, and Si CMOS in a back-end-of-line process. For (c), we will discuss designs of colloidal quantum dot detectors for longer IR wavelengths with minimal effects of dark current to support uncooled operation.

On-chip cascaded micro-ring filters for demodulation of multiplexed FBG accelerometers.

Fiber Bragg grating (FBG) accelerometers are extensively utilized across various industries. For a high-performance FBG accelerometer interrogator, achieving low cost, wide range, multi-channel capability, high precision, and high-speed demodulation is critical. This paper proposes a chip-level wavelength demodulation method for FBG accelerometers utilizing a cascaded micro-ring resonator (MRR) array. Capable of demodulating multiple accelerometers within a 27.8 nm bandwidth at a speed of up to 1.6 kHz, the system's performance is evaluated in terms of minimum detectable wavelength shift and noise level. We compare our system with a commercial FBG interrogator, and the results underscore the effectiveness and feasibility of our FBG accelerometer demodulation method, offering potential implications for various applications.

A sustainable HPTLC approach for green assessment of Tyrosine to phenylalanine ratio in chronic kidney disease

The kidney is considered the main site for the net release of Tyrosine (Tyr) to the circulation through hydroxylation of Phenylalanine (Phe) using phenylalanine hydroxylase enzyme. In chronic kidney disease (CKD) patients the enzyme activity is impaired, therefore the serum concentration ratio of Tyr/Phe is reduced compared to healthy individuals. This motivates us to develop a cost effective, green, simple, sensitive, and selective HPTLC method to measure the levels of Tyr and Phe in serum samples. The analysis was carried out using acetonitrile: ethanol: 25% ammonia solution: ethyl acetate (6.5: 1.5: 1: 0.5) as a mobile phase. Rf values were 0.55 ± 0.05 for Phe and 0.39 ± 0.05 for Tyr. Densitometry scanning was performed using UV detector and dual wavelengths of 210 and 225 nm were obtained. A linear correlation was observed between the levels of Phe and Tyr, ranging from 50 to 700 ng band− 1 and 50 to 600 ng band− 1, respectively, under the optimum conditions. The method selectivity, linearity, precision, accuracy, and robustness were all confirmed in accordance with ICH recommendations. Calculations of the separation and resolution factors, number of theoretical plates, and height equivalent to theoretical plates prove to the chromatographic system accuracy and high separation efficiency. The developed method exhibits an acceptable eco-scale when measuring the method greenness using AGREE and GAPI softwares. It was applied for the determination of Phe and Tyr concentrations in human serum samples.

OPTIMIZATION OF ROBUST HPLC APPROACH FOR ASSESSING PROCESS RELATED IMPURITIES OF LEMBOREXANT AND ELUCIDATION OF STRESS-INDUCED DEGRADATION PRODUCTS THROUGH LCMS/MS

This study primarily aimed to establish an uncomplicated yet highly responsive HPLC technique to effectively separate and quantify process-related impurities of Lemborexant. Additionally, it aimed to explore the forced degradation behavior of lemborexant through systematic assessments by utilizing LCMS. The chromatographic separation of drug substance, process related impurities and its degradation products (DPs) was achieved on Kinetex C18 (150×4.6 mm, 5 μm) column at that was maintained at 350C temperature using 10 mM ammonium formate buffer pH 4.2, acetonitrile and methanol in 65:25:10 (v/v) isocratic elution at 0.7 mL/min. Detection wavelength was selected as 265 nm. In the proposed conditions, lemborexant is identified at 4.06 and 6.19, 9.33 min and 1.60 min respectively for impurity 1, 2 and 3 min with acceptable system suitability and specificity. The method produces LOD at 0.009 for impurities with calibration range of 40–280 µg/mL for lemborexant and 0.04 - 0.28 µg/mL for impurities. The remaining validation parameters were observed to fall within acceptable ranges for both lemborexant and its impurities. The compound underwent exposure to various stress conditions (acid, base, peroxide, thermal, and UV light) as outlined in accordance with ICH Q1A (R2) guidelines. The degradation products formed during the stress study were detected and characterized using LCMS/MS in ESI positive mode. This involved a thorough comparison of collision-induced dissociation mass spectrometry data between the degradation products and lemborexant. Consequently, potential structures for five degradation compounds were proposed. The outcomes of supplementary validation investigations were equally satisfactory, confirming their appropriateness for the regular quantification of lemborexant and its related impurities in both bulk drug and pharmaceutical formulations. Furthermore, these findings have the potential to shed light on the mechanism of stress-induced degradation in lemborexant

Development and Validation of Rapid and Cost-Effective RP-HPLC/UV Method for Determination of Cetirizine/Levocetirizine in Blood Plasma of Smokers and Non Smokers: a Two Cohort Comparative Study.

In this research study, a simple, rapid, sensitive, and cost-effective Reverse Phase High Performance Liquid Chromatography method was developed and validated for determination of Cetirizine and Levocetirizine in human plasma. The drugs were separated on an ACE Generix100-5 C18 RP (250 × 4.6mm, 5μm) column, using Acetonitrile and Distilled water pH7 (59:41v/v) as mobile phase with a flow rate of 1.5mL/min, retention time of 3.39 ± 0.02min, detection wavelength of 230nm, and column oven temperature at 26°C. The drug was extracted from human plasma using Methanol, the percent recovery was 97%. The LOD and LOQ for Cetirizine and Levocetirizine were 0.5ng and 1ng. The method was linear over the concentration range of 0.5-1000ng /mL for Cetirizine and Levocetirizine. The method was applied for analysis of drugs in plasma following oral administration of Cetirizine (10mg) and Levocetirizine (5mg) in smokers and nonsmokers of Pashtun ethnicity belonging from different districts of Khyber Pakhtunkhwa, Pakistan. The difference between Cetirizine plasma levels in smokers and non-smokers was significant with p -value 0.0279.