Photodiode Array Research Articles

Miniaturized green capillary electrophoresis system for the simultaneous analysis of Linagliptin and cefiximein in plasma

A novel combination therapy, consisting of the antidiabetic drug linagliptin (LIN) and the third-generation cephalosporin antibiotic cefixime (CEF), has recently been introduced to combat infections in diabetic patients. However, there is no published method for their in-vivo simultaneous determination in clinical biological specimens to support their pharmacokinetics and therapeutic monitoring. This study focuses on the development of a miniaturized capillary electrophoresis system-assisted with photodiode array detection (CE-PDA) for the simultaneous determination of LIN and CEF in clinical settings for analysis of plasma samples containing LIN and CEF. The conditions of electrophoretic separation of LIN, CEF, and Ibuprofen (as an internal standard), and the analysis procedures were successfully established. The linear range of the CE-PDA method was determined to be 0.5–100 µg mL−1 for LIN and 1–100 µg mL−1 for CEF. The CE-PDA approach exhibited high sensitivity, with limits of quantitation of 0.9 µg mL−1 for LIN and 1.2 µg mL−1 for CEF. In addition, the CE-PDA system was validated, and subsequently applied to real plasma samples withdrawn from rats received concurrent administration of LIN and CEF. The plasma protein was precipitated by acetonitrile. The miniaturized features of the system and its environmental impact were confirmed using three different metric tools. Additionally, the proposed CE-PDA system proved to be time-saving and cost-effective, making it highly suitable for therapeutic drug monitoring of LIN and CEF in clinical settings.

The Development of One New Normal Phase Liquid Chromatography Method and Thermodynamic Investigation of Olodaterol Hydrochloride Enantiomer.

In order to improve and replace the enantiomer method outlined in the olodaterol hydrochloride draft monograph (From the European Pharmacopoeia forum), one new, simple, and fast enantioselective normal phase high-performance liquid chromatography chiral method was developed on polysaccharide-based Chiral MX (2) (4.6 × 250 mm, 5 μm) column. n-Hexane, ethanol, and diethylamine in the ratio of 40:60:0.1 (V/V/V) were selected as mobile phase at a flow rate of 0.8 mL/min, and the detection was performed on a photodiode array detector at 225 nm with 5 μL injection volume. The column temperature was set at 40°C for better peak shape and sensitivity. The analysis time can be shortened to 15 min, whereas the resolution between enantiomer and olodaterol was found to be even more than 10.0, which was far better than that obtained with the reported method in this draft monograph. The developed chiral method was validated in accordance with ICH Q2 (R1), including specificity, LOD&LOQ, precision, linearity, accuracy, and robustness. Thereby, the proposed method was demonstrated to be suitable for the determination of enantiomer inolodaterol hydrochloride bulk drug and drug product. Besides, the thermodynamic parameters were evaluated on the basis of Van't Hoff plots that was used to explain correlative chiral recognition mechanisms with the chiral stationary phase.

Anti-distortion bioinspired camera with an inhomogeneous photo-pixel array

The bioinspired camera, comprising a single lens and a curved image sensor—a photodiode array on a curved surface—, was born of flexible electronics. Its economical build lends itself well to space-constrained machine vision applications. The curved sensor, much akin to the retina, helps image focusing, but the curvature also creates a problem of image distortion, which can undermine machine vision tasks such as object recognition. Here we report an anti-distortion single-lens camera, where 4096 silicon photodiodes arrayed on a curved surface in a nonuniform pattern assimilated to the distorting optics are the key to anti-distortion engineering. That is, the photo-pixel distribution pattern itself is warped in the same manner as images are warped, which correctively reverses distortion. Acquired images feature no appreciable distortion across a 120° horizontal view, as confirmed by their neural-network recognition accuracies. This distortion correction via photo-pixel array reconfiguration is a form of in-sensor computing.

Chemical composition of Ecstasy tablets seized in Poland between 2005 and 2020.

The most commonly associated substance found in Ecstasy tablets is MDMA (3,4-methylenedioxymethamphetamine). In our study, we showed how the composition of psychoactive ingredients in Ecstasy tablets seized on the drug market in Poland has changed in the years 2005-2020. The study material consisted of nearly 20,000 single Ecstasy tablets seized by representatives of law enforcement (the police, prosecutors) from 2005 to 2020 and analysed by the Institute of Forensic Research, Krakow, Poland. The analysis of the tablets was carried out by gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography with diode array detection (HPLC-DAD) and ultra-high-performance liquid chromatography with photodiode array detection (UHPLC-PDA). Currently, new types of MDMA tablets are introduced onto the market, available in various colours and shapes. Our study showed that tablets sold on the street as Ecstasy have variable purity and sometimes contain little or no MDMA. The mean content of MDMA in one tablet seized in 2005-2011 decreased from 90 to 50mg. In 2013, Ecstasy tablets with a very high MDMA content (average 195mg per tablet) appeared on the market, but in the next 2years, the MDMA content decreased again. From 2016, the average MDMA content began to rise again, ranging from 60 to 280mg. Tablets sold as Ecstasy also contained completely different psychoactive substances, including new psychoactive substances (NPS) (found in almost 20% of all examined tablets sold as Ecstasy) belonging to different chemical groups or their dangerous combinations (i.e. phenylethylamines, piperazines, tryptamines, cathinones, arylalkylamines, arylcyclohexylamines and piperidines). Such a large variety of psychoactive substances in Ecstasy tablets is associated with a high risk for users unaware of their composition.

Development and validation of a HPLC method for the determination of chemical and radiochemical purity of O-(2-[18F]fluoroethyl-l-tyrosine ([18F]FET)), a PET radiotracer for the imaging of brain tumor

A novel HPLC method was developed and validated to determine radiochemical identity, radiochemical purity and chemical purity for the analysis of O-(2-[18F]fluoroethyl-l-tyrosine ([18F]FET). In this method, an analytical Phenomenex Gemini C18 column was used with an isocratic eluent of 7 % ethanol and 93 % 50 mM potassium phosphate buffer (pH = 6.9). The flow rate was 1.0 mL/min and the injection volume was 10 μL. A photo-diode array detector set at 220 nm was used for UV mass detection and a single channel, high sensitivity radiation detector was used. The method validation assays including specificity, linearity, precision, accuracy, and robustness were evaluated. Results show that the method was suitable for qualitative and quantitative determination of radiochemical and chemical purity of [18F]FET. This system has been routinely used for the analysis of more than 120 batches of [18F]FET with radiochemical yield 23.7 ± 6 % (no decay corrected) and molar activity 593 ± 284 GBq/μmole in our facility to support human use.

Linear Photodiode Arrays For Time-Domain FLEET Velocimetry In Hypersonic Flows

Linear photodiode arrays are applied to Femtosecond Laser Electronic Excitation Tagging (FLEET) to determine the stream-wise velocity of flow at Mach 8 in the Sandia Hypersonic Wind Tunnel (HWT). Incident light emitted by nitrogen gas upon FLEET excitation is collected by intensifying optics that amplify and transmit the light to the photodiode elements as the gas advects downstream. Two photodiode array configurations are considered: one aligned with the flow direction and one that is perpendicular to it. Conventional FLEET using a CMOS image sensor is also performed for quantitative comparison. The configurations are tested for purely free-stream cases as well as the wake of a seven-degree half-angle cone model at various Reynolds number. The influence of the bi-exponential decay of the FLEET line and the transfer function imposed by the intensifying optics are identified as key considerations on the time-domain method accuracy. Overcoming these effects leads to promising application spaces due to the compact nature of photodiodes and low data overhead.

High‐Performance Liquid Chromatography–Based Standardization of Stigmasterol in Moringa oleifera: Method Development and Validation Through Design of Experiment Approach

ABSTRACTThe primary objective of this investigation was to develop and validate a robust reversed‐phase high‐performance liquid chromatography (RP‐HPLC) method for quantifying stigmasterol in both Moringa oleifera powder and tablets. The analysis was conducted using a Box–Behnken design. Stigmasterol separation was achieved with a Phenomenex Luna C‐18 column (4.6 × 150 mm2, 5 µm) and a mobile phase consisting of methanol and 0.1% formic acid in an 80:20% v/v ratio. The separation was performed at a flow rate of 1 mL/min, and stigmasterol was detected at a wavelength of 210 nm using a photodiode array detector. Method validation followed the guidelines set forth by the International Council for Harmonisation (ICH) Q2 (R1). This rigorous validation process evaluated critical parameters, including linearity, accuracy, system suitability, precision, and robustness. The results for each parameter were well within the acceptable range, confirming the reliability and efficacy of the established RP‐HPLC method. The findings of this study highlight the potential of the RP‐HPLC method as a dependable tool for the routine analysis of stigmasterol in herbal formulations.

A High‐Speed Image Sensor Based on Large‐Area MoTe2/Si Photodiode Arrays

AbstractThe market demand for optoelectronic devices is increasing, leading to a need for low‐cost, high‐performance image sensors that can operate effectively in challenging environments such as darkness and fog. The emerging 2D transition metal dichalcogenides (TMDs) have garnered significant interest due to their exceptional optoelectronic properties and compatibility with silicon (Si) complementary metal oxide semiconductor (CMOS) technology. However, the large‐scale synthesis of TMD films and uniform preparation of photodiode arrays remain challenging. This paper reports a synthesis method for heteroepitaxial growth of 2H‐ molybdeum diyelluride (MoTe2) semiconducting films on 3D wafer‐level Si substrates. Using this method, arrays of 2H‐MoTe2/Si heterojunction photodiodes are prepared that demonstrate excellent uniformity and 100% device yield. The photodiodes exhibit satisfactory optoelectronic properties, including a small dark current maintained within a range of 1–3 nA and a maximum responsivity of 521.1 mAW−1 under near‐infrared light at 800 nm, with rise and fall times of less than 4 ms. To demonstrate the image‐sensing capabilities of the photodiode array under visible and near‐infrared (NIR) light illumination, a complete imaging system is designed.The MoTe2/Si photodiode arrays examined in this study offer a practical solution for integrating Si‐based readout circuits and photodetector arrays on a single chip.

Routine oxygen heterocyclic compounds analysis of fragrances using an eco-friendly liquid chromatography coupled to tandem mass spectrometry method

ABSTRACT Coumarin and furocoumarins characterization in cosmetics plays an important role in protecting consumer health. The analytical technique mostly employed for the analysis of these molecules is certainly liquid chromatography coupled to photodiode array or mass spectrometer detectors. The aim of this article was to investigate on the oxygen heterocyclic compounds content in fifty hydro alcoholic fragrances using a fast, sensitive and eco-friendly liquid chromatography coupled to a triple quadrupole mass spectrometer detector analytical method without any sample pre-treatment. To the best of the author’s knowledge, this is the first research article on the quantification of thirty-six oxygen heterocyclic compounds in hydro alcoholic fragrances in less than 4 min and with the use of water/ethanol as mobile phase. Thanks to the good performance of the analytical method used, this can be proposed among the routine methods for the quality control of cosmetics and finished products.

Characterization of Functional Ingredients Extracted with Ethanol Solvents from Ponkan (Citrus reticulata) By-Products Using the Microwave Vacuum Drying Method Combined with Ultrasound-Assisted Extraction.

For this study, microwave vacuum drying (MVD) was combined with ultrasound-assisted extraction to compare the effects of different ethanol volumes on ponkan extract and to evaluate the total phenolic content (TPC), total flavonoid content (TFC), and total ascorbic acid content (TAAC). High-performance liquid chromatography with photodiode array detection (HPLC-PDA) was used to analyze the flavanone contents and antioxidant activity of ponkan (Citrus reticulata) peels. The experimental results showed that the TPC and TFC increase with ethanol volume. Ethanol extraction (75%) showed significant advantages by increasing the TPC to 17.48 mg GAE/g (DW) and the TFC to 2.96 mg QE/g (DW) of ponkan extract and also exhibited the highest antioxidant activity. The TAAC improved along with increased water content. Water extraction showed the highest content (13.07 mg VitC/100 g, DW). The hesperidin content analyzed by HPLC-PDA was 102.95-622.57 mg/100 g (DW), which was the highest among the flavanones. Then, the ethanol insoluble residue extracts were taken from the pectin with four different solvents, evaluating TPC, TFC, and antioxidant activity. The TPC, TFC, and antioxidant capacity of pectin are significantly lower than those of the peels. Combining MVD and 75% ethanol with ultrasound-assisted extraction in the pre-treatment process can effectively eliminate polyphenols, flavonoids, and other compounds, thus enabling the extraction of high-methoxyl pectin. The total dietary fiber (TDF) content of MVD ponkan by-products was 25.83%. Ponkan by-products have the potential for the future development of functional foods and supplements.

Design and simulation of sun position sensors for space applications: A comparative study.

Sun position sensors are used in space applications as part of the attitude determination and control system. The aim of this work is to describe the design process of single and dual axis sun position sensors based on a photodiode array detector and a window to limit and direct the light that reaches the detector. The design process involves choosing the sensor architecture, modeling its output, and then evaluating the model through simulation. Six architectures, with different configurations and geometries for both the detector and window, were modeled and compared. To evaluate the model and performance of the sensor, a program was developed, and simulations were made varying the window height and size as well as the photodiode size. From the simulations performed, we concluded that for each design, the key factors that influence the sensitivity and field of view performance are the window height and window or photodiode size, depending on the sensor configuration. From the comparison across architectures, the detector configuration, as well as the window geometry, influences the sensitivity and linearity of the response for similar conditions of operation. The two-quadrant detector configuration offers a better sensitivity than the triangular photodiode configuration. For a better linearity of the output, a square window is preferred. This comparative study is part of the development of new products for space applications by the National Atomic Energy Commission and contributes to the Argentinian National Space Plan.

Development and Validation of a Systematized Liquid Chromatographic Method for Estimation of Roflumilast in Tablets and in Presence of its Degradation Products

Background: Roflumilast (ROF) is an antiasthmatic drug used frequently for treating chronic obstructive pulmonary disease (COPD). The various reported methods developed with a non-systematised traditional workframe for routine estimation of ROF in formulations indicated the demand for developing a systematised new method. Objective: In the present study, an attempt was made to develop a new validated liquid chromatographic method with federal flexibilities and stability-indicating potential. Method: A time-efficient, rapid, and systematised quality by design (QbD) approach was developed to avail regulatory flexibilities with assured performance. Defining the analytical target profile (ATP) and associated critical analytical attributes (CAAs) helped control the method’s performance. Methanol proportion, flow rate, pH, and detection wavelength were the four identified critical method variables (CMVs) that were further studied for robustness investigation. Moreover, the control strategies for CMVs were defined as per method intent. Chromatography constituted methanol: water (pH 3.5 maintained by orthophosphoric acid) (90:10% v/v) as the mobile phase, flowing at 1.2 ml/min on a ShimPack GWS C18 column. The photodiode array (PDA) detector provided the best results at 250 nm. Results: ROF was eluted at a retention time of 3.1 min with acceptable system suitability values. Validation studies postulated method acceptability and suitability. Results for parameters viz. linearity (0.5–160 µg/ml), accuracy (> 98%), and precision (< 1%) advocated method reliability. ROF was susceptible to applied acidic and alkaline stress, requiring adequate preventive measures during formulation development. Conclusion: Overall, this method worked well for figuring out ROF even when there were product additives and possible degradation products present, showing that it can be used on a regular basis.

Characterization of low-molecular-weight fucoidan prepared by photocatalysis degradation and its regulation effect on metabolomics of LPS-stimulated macrophages

Fucoidan (ANP) from Ascophyllum nodosum demonstrates significant anti-inflammatory activity. Because lower-molecular-weight polysaccharides usually process even better bioactivities, in the present study, the photocatalytic degradation method with TiO2 and H2O2 was used to prepare low-molecular-weight derivatives (D-ANP-1.5 and D-ANP-3.5) with molecular weight of 5.0 kDa and 2.3 kDa, respectively. The characteristics of D-ANP-1.5 and D-ANP-3.5 were identified by chemical composition analysis, high-performance gel permeation chromatography, high-performance liquid chromatography photo-diode array mass, and Fourier transform-infrared spectrum, and compared with that of original fucoidan. The sulfate group retention rates of D-ANP-1.5 and D-ANP-3.5 were over 90.0% and the fucose and total sugar contents increased. However, the uronic acid and protein contents were decreased and the functional groups were not changed during degradation. Subsequently, 7 oligosaccharides in D-ANP-3.5 were identified by high-performance liquid chromatography-electrospray ionization detector mass and 6 of them were sulfated. Moreover, D-ANP-3.5 (2.3 kDa) supplement showed stronger inhibition effect of nitric oxide production than D-ANP-1.5 and undegraded ANP in LPS-stimulated RAW 264.7 cells. In addition, metabolic profiles results indicated that arginine biosynthesis, phenylalanine, tyrosine, and tryptophan biosynthesis, the TCA cycle, purine metabolism, and glutathione metabolism, along with influencing metabolic biomarkers such as betaine, arginine, NAD+, ATP, and pyroglutamic acid, were involved in the effects of D-ANP-3.5. The superior regulation effect on metabolomics in LPS-stimulated RAW 264.7 cells of D-ANP-3.5 could be attributed to its relatively low molecular weight and high fucose content. The present study advance understanding of the mechanism for the anti-inflammation of D-ANP-3.5.

Development of a Stability-Indicating Purity Method for Ubrogepant Through Stress Degradation Analysis, Extraction, and Characterization of Unidentified Degradation Products Using Flash Chromatography, NMR, IR, and LC–MS

Abstract Background Ubrogepant is a prescription medication used to prevent migraine headaches. It is currently available in tablet form. Objective The goal of this work is to investigate the drug degradation profile of ubrogepant, as well as to isolate and characterize undiscovered ubrogepant degradation products by utilizing LC–MS, NMR, and IR spectroscopic analytical techniques and, furthermore, to develop a high-resolution, sensitive, stability-indicating analytical approach for detecting and quantifying ubrogepant degradation products in its pharmaceutical formulation. Methods To identify and quantify the degradation products of ubrogepant in pharmaceutical products, a novel gradient reverse-phase HPLC (RP-HPLC) technique with a photo diode array (PDA) detector was developed by utilizing a C18 stationary phase column. The eluent comprised a mixture of acetonitrile and water with 0.1% (v/v) ortho-phosphoric acid. To establish the intrinsic stability of the ubrogepant pharmaceutical product, it was stress-tested under various degradation conditions, including water, alkaline, acid hydrolysis, photolytic, oxidative, and thermal. Flash chromatography was used to isolate the two major degradants, and the structures were determined using NMR (1H, 13C, distortionless enhancement by polarisation transfer-DEPT-135), IR, and LC–MS methods. Results The ubrogepant medication was relatively more degradable in alkaline and acidic conditions, and two unique degradation products were discovered. Based on spectroscopic and chromatographic evidence, it was conclusively demonstrated that these unique compounds were ubrogepant hydrolysis products. All degradation products were separated with a resolution greater than 2.0. The peak purity data showed that the ubrogepant peak in all of the stress samples examined was pure. Under all stress environments, ubrogepant achieved a minimum mass balance of 95%. The validated approach developed was sensitive enough to quantify ubrogepant degradation products at 0.03% of the ubrogepant test concentration. Conclusion The proposed method was found to be stability-indicating since it fits all of the regulatory authorities' typical requirements. This method is highly efficient for detecting and quantifying impurities in ubrogepant drug substances and drug products in QC laboratories. Highlights Two new degradation products of ubrogepant were successfully extracted and characterized using NMR, IR, and LC–MS spectroscopic methods. The proposed HPLC method can accurately quantify the degradation products of ubrogepant in pharmaceutical products and is sensitive enough to detect degradation products of ubrogepant as low as 0.17 µg/mL.

Rapid identification and quantitation of 34 synthetic colorants in 125 beverages and candies by ultraperformance liquid chromatography with photodiode array detection

Ultraperformance liquid chromatography with photodiode array detection was used to simultaneously quantify 34 permitted and prohibited synthetic colorants in beverages and candies. Solvent extraction was employed to extract colorants from food samples, proving to be simpler, more rapid and cost-effective, and less labor-intensive than other pretreatment techniques. Additionally, a single-laboratory study was conducted to validate the above method. The results of this validation, which was performed using blank beverage and candy samples, demonstrated satisfactory linearity and detection/quantitation limits. According to the FDA guidelines for the validation of chemical methods, the method exhibited a recovery of 85.4–108 % and repeatability of 0.427–6.73 % for intra- and interday tests. The established method enabled the simultaneous analysis of 34 permitted and prohibited colorants within a short timeframe of 13 min, and its applicability was confirmed by analyzing 93 types of beverages and 32 types of candies available on the market to ensure that the colorant content in all products was within permissible limits. Thus, the developed method was concluded to be particularly suitable for the rapid, accurate, and convenient monitoring of colorant content in commercial products.

Archaeometric characterization of a textile fragment recovered from a Byzantine Period tomb in Nysa ad Maeandrum in the light of archaeological and anthropological evaluations

Nysa ad Maeandrum (also known as the ancient city of Nysa) is an ancient city located in Western Anatolia of today’s Türkiye. It was determined during the excavations that an uninterrupted life continued in the ancient city of Nysa from the Hellenistic Period (330 BCE-30 CE) to the Byzantine Period (330–1453). The aim of this study is the anthropological evaluation of the skeleton in tomb chamber-11 (T-11) found during the excavations in 2023 and the characterization of the well-preserved textile fragment on the coin unearthed from the individual’s skull. In this study, the textile sample underwent analysis using a polarized optical microscope (OM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and high-performance liquid chromatography with photodiode array detection (HPLC-PDA). As a result of the analysis, it is thought that the textile fragment has a tabby weave and the fiber is a cellulosic bast fiber, which is most likely flax fiber. In the dyestuff analysis, alizarin and ellagic acid dyestuffs were detected, and it was determined that the textile fragment was dyed by using the madder plant (Rubia tinctorum L.), which we frequently encounter in Anatolia, and a plant containing tannins. In addition, according to anthropological studies, it is thought that the individual in T-11 belongs to a female between the ages of 30–40 and was engaged in weaving based on the marks on her teeth.

Pharmacokinetic profile of phenytoin in dried blood spot with high-performance liquid chromatography-photodiode array.

Phenytoin is a first-line antiepileptic drug with narrow therapeutic range and follows non-linear pharmacokinetics. Pharmacokinetics of phenytoin have been studied in plasma matrix before, however, there were several disadvantages. This study aimed to obtain partial validation data of the analytical method and the pharmacokinetic profile of phenytoin in Dried Blood Spot (DBS) of six healthy subjects. DBS has the advantage of only requiring small sample volumes and could be transported more efficiently. Phenytoin along with carbamazepine as the chosen internal standard was analyzed with a reversed-phase high performance-liquid chromatography system and a photodiode array detector at 205nm. The results of partial validation, which evaluated the linearity, within-run accuracy, and precision, were within the criteria acceptance range. The pharmacokinetic profile showed that average AUC0-t was 83.81 ± 37.32μg.h/mL and AUC0-∞ was 83.65 ± 38.89μg.h/mL with an average ratio of 93%. Previous study quantifying phenytoin in the plasma matrix found the average AUC0-t was 39.41 ± 8.57µg.h/mL and AUC0-∞ was 42.94 ± 9.55µg.h/mL. Despite the difference between parameters of phenytoin analyzed in DBS and plasma matrices, the pharmacokinetic profiles obtained from both matrices were similar indicated by comparable concentration-time curves, thus, proving that DBS matrix can be used interchangeably with the plasma matrix as a more comfortable and effective alternative to phenytoin quantification in blood.

Development of a Validated RP-HPLC Method Using Full Factorial Design for the Analysis of Ramipril

The primary objective of this study is to develop and optimize a simple, novel, reproducible, and efficient RP-HPLC method using quality by design (QbD) approach for the routine analysis of ramipril. The chromatographic separation was carried out by C18 column with an isocratic elution of a mobile phase of 65:35 (%v/v) acetonitrile: water at a flow rate of 0.9 mL/min. The detection was done at a wavelength of 210 nm using a photo-diode array plus (PDA+) detector. A 32 full-factorial design was employed for the development of analytical method using Design Expert® software in which the mobile phase composition and flow rate were taken as independent variables and the retention time (RT), tailing factor (TF) and theoretical plate count (TP) were chosen as responses of the study. Statistically significant models were obtained for the development of the method (p<0.05). The empirical responses perfectly fitted to that of predicted, with an error within the tolerance of ± 2%. This indicates that the model efficiently identified the optimum levels of independent variables, i.e. the composition of mobile phase and its flow rate, to get the desirable responses. The validation of the developed method followed the ICH Q2 (R1) guidelines, demonstrating that the method is robust and well-suited for the routine analysis of ramipril in active pharmaceutical ingredients and in drug products. Dhaka Univ. J. Pharm. Sci. 23(1): 93-102, 2024 (June)

Transfer of Caffeine and Its Major Metabolites to Chicken Eggs.

This study aimed to determine whether the eggs of laying hens fed caffeine contain this compound and its primary metabolites (theophylline, theobromine, and paraxanthine). Laying hens were distributed into four experimental groups fed rations containing 0 (control), 150, 300, or 450 μg/g of caffeine. For residual analysis, six eggs per group were collected after 4, 8, and 12 weeks. The concentrations of caffeine, theophylline, theobromine, and paraxanthine were determined in the white and yolk of each egg by a high-performance liquid chromatography with photodiode array detector (HPLC-PDA) method. All four compounds were detected in the white and yolk of eggs produced by hens fed caffeine, but their levels in the egg white were approximately twice those in the yolk. The major metabolite found in eggs was theophylline (57.5% of caffeine metabolites in the egg white and 58.5% in the yolk), followed by theobromine (39.9% in the egg white and 41.5% in the yolk), and paraxanthine (2.64% in the egg white and non-detected in the yolk). In summary, caffeine and its metabolites, theophylline, theobromine, and paraxanthine, are transferred to the chicken eggs.

Development and validation of quantitative procedure of clotrimazole and eugenol in gel product using high-performance liquid chromatography

Vulvovaginitis is a prevalent gynaecological ailment worldwide, often attributed to bacteria, Candida fungi, or Trichomonas. The synergistic action of antifungal agents and essential oils can enhance the efficacy against pathogenic microorganisms. In this study, a simultaneous quantitative method for determining clotrimazole and eugenol in a laboratory-compounded gel product was developed using high-performance liquid chromatography with a photodiode array detector (HPLC-PDA). The HPLC-PDA system utilised in this study was the Shimadzu LC-20AD, with a HiQ Sil RP C18 HS column (250 x 4.6 mm, 5 μm), and a mobile phase consisting of methanol-water in an 80:20 (v/v) ratio, employing isocratic elution at a flow rate of 1.0 ml/min. The injection volume was set at 20 μl, and detection was performed at a wavelength of 229.0 nm. The analytical procedure was validated in accordance with ASEAN guidelines for the validation of analytical procedures, successfully meeting the criteria for specificity, accuracy, system suitability, repeatability, intermediate precision, and linearity within the concentration range of 2.25 to 36.00 ppm for eugenol and 12.00 to 200.00 ppm for clotrimazole. Subsequently, this validated procedure was applied to quantify the clotrimazole and eugenol content in bulk materials and three different lots of gel products. The results for clotrimazole and eugenol content in both the raw materials and the gel product lots fell within an acceptable range, with deviations of less than ±10% compared to the labelled content.