LOD Values Research Articles

A major QTL simultaneously increases the number of spikelets per spike and thousand-kernel weight in a wheat line.

A novel and stably expressed QTL QSNS.sicau-SSY-7A for spikelet number per spike in wheat without negative effects on thousand-kernel weight was identified and validated in different genetic backgrounds. Spikelet number per spike (SNS) is an important determinant of yield in wheat. In the present study, we combined bulked segregant analysis (BSA) and the wheat 660K single-nucleotide polymorphism (SNP) array to rapidly identify genomic regions associated with SNS from a recombinant inbred line (RIL) population derived from a cross between the wheat lines S849-8 and SY95-71. A genetic map was constructed using Kompetitive Allele Specific PCR markers in the SNP-enriched region on the long arm of chromosome 7A. A major and stably expressed QTL, QSNS.sicau-SSY-7A, was detected in multiple environments. It was located in a 1.6cM interval on chromosome arm 7AL flanked by the markers AX-109983514 and AX-109820548. This QTL explained 6.86-15.72% of the phenotypic variance, with LOD values ranging from 3.66 to 8.66. Several genes associated with plant growth and development were identified in the interval where QSNS.sicau-SSY-7A was located on the 'Chinese Spring' wheat and wild emmer reference genomes. Furthermore, the effects of QSNS.sicau-SSY-7A and WHEAT ORTHOLOG OFAPO1(WAPO1) on SNS were analyzed. Interestingly, QSNS.sicau-SSY-7A significantly increased SNS without negative effects on thousand-kernel weight, anthesis date and plant height, demonstrating its great potential for breeding aimed at improving grain yield. Taken together, these results indicate that QSNS.sicau-SSY-7A is a promising locus for yield improvement, and its linkage markers are helpful for fine mapping and molecular breeding.

Repurposing of waste ammonium sulfate as S,N-doped carbon quantum dots: A sensitive and selective fluorescent probe for the determination of tetracycline

BackgroundCurrently, many types of pharmaceuticals are used to treat disease and bacterial infections. Tetracycline (TC) is a widely applied human and veterinary medicine. However, the widespread usage and lack of awareness in the management of TC lead to its unavoidable discharge into the environment. The consequences include the proliferation of resistant strains of bacteria and adverse impacts on nontarget organisms and microbial ecosystems, which means that TC is an emerging substance of concern and that it is crucial to develop determination platforms with cost-effective and fast-response features. MethodsCarbon quantum dots (CQDs) have received tremendous attention owing to their great performance in fluorescent probing. In the present work, ammonium sulfate-doped carbon quantum dots (S,NCQDs) are fabricated through a facile hydrothermal synthesis pathway. Significant FindingsThe results illustrate that the S,NCQDs exhibit sensitive determination ability toward tetracycline via a static quenching mechanism and possess several superior features, including a rapid response, good sensitivity and stability, broad linear detection range (1–100 μM), and low LOD value (0.1203 μM), when applied in the determination of TC. Additionally, the application of S,NCQDs valorizes ammonium sulfate waste from semiconductor manufactory waste and has great potential in fluorescence sensing.

HPLC/UV approach method for the first simultaneous estimation of molnupiravir and ertapenem as a binary mixture in human plasma and dosage form as a regimen for COVID-19 treatments

COVID-19 is a serious virus that can have a lot of effects, one of which is a secondary bacterial infection that can be more life-threatening and even lethal than the initial viral infection. Hence a fast and sensitive HPLC/UV method was developed and validated for the first estimation of a binary mixture of molnupiravir (MOL) and ertapenem (ERT) as a co-administrated medicine for the management of COVID-19 in pharmaceutical dosage forms, and human plasma samples. The drug combination was separated within 5 min via RP-ODS column using isocratic elution with a mobile phase of 0.05 M phosphate buffer (pH 3.5): acetonitrile with a 76: 24% ratio v/v. The presented method provided a linear response ranging from 0.03 to 17.0 and 0.05–20 µg mL−1 with LOD values of 0.009 and 0.008 µg mL−1 for MOL and ERT respectively. The good separation and high sensitivity of the HPLC method provide the determination of the cited drugs in human plasma without matrix interference with a percent of recovery ranging from 94.97 ± 2.05 to 98.44 ± 1.92. Based on the results, this method could be utilized to monitor cited drugs in quality control and therapeutic laboratories.

Molecular half-subtractor and memory device based on a new Schiff-based colorimetric sensor for anions detection and computational studies

A new multi-analyte chromogenic sensor (L) for rapid detection of CN– and HSO4− was synthesized by reacting azo dye with furfurylamine (1: 1). The sensing ability of the L was investigated towards different anions by visual test, and UV–Vis spectroscopy in CH3CN: H2O (4: 1, v/v) media. The Job’s plot and HRMS data confirmed that the CN– and HSO4− ions bind with L in 2: 1, and 1: 1 stoichiometric ratio, respectively. The binding constants (Ka) and LOD values for CN–, and HSO4− were determined 4.45 × 10+4 M−1; 1.71 µM, and 3.67 × 10+5 M−1; 0.22 µM, respectively. Furthermore, DFT calculations supported the binding framework between L and the said anions. In addition, L was used to successfully detect CN– in peach kernel samples in aqueous media and as a colorimetric test strip for HSO4−. The UV–Vis absorption bands offer the possibility for fabrication of complex logic circuits such as complementary IMP/INH logic circuits, half subtractor and ‘set- reset’ flip flop memory elements.

The performance of hypochlorous acid modified Ag nanoparticle-based assay in the determination of total antioxidant capacity of Boswellia Serrata and Aronia

In this study, the SNPAC method was developed by using hypochlorous (ClO−) at pH 9.3. Polyvinylpyrrolidone (PVP) was used as a stabilizer. The existence of HOCl enables to formation stronger and more stable yellow emission which gives sensitivity. As a result, lower LOD and LOQ values were achieved by the AgNP–HOCl method. The obtaining lower values was attributed to the reoxidation of silver atoms with ClO− ions in the presence of PVP. The newly modified method was applied to the total antioxidant capacity (TAC) measurement of Boswellia Serrata, Aronia Melanocarpa tea, and juice. The results were compared with the results obtained by application of CUPRAC (Cupric ion Reducing Antioxidant Capacity) and FRAP (Ferric Reducing Antioxidant Power) assays. The TAC values of Boswellia Serrata, Aronia Melanocarpa tea, and juice were found as 6.18, 137.98, and 12.08 mmol TEAC/kg, respectively.

A novel thiazole-based covalent organic framework as turn-off fluorescent sensor for detection of aniline and triethylamine in liquid and vapor phase

Due to the diverse chemical structures and varying basicity of amines, the development of rapid, portable, and reversible methods for the selective recognition of trace organic amines in the environment remains a challenge. Herein, a novel recyclable and selective turn-off fluorescent sensor for organic amines detection based on covalent organic framework (COF) was developed. As-synthesized COF, TAPB-BTDD exhibits good crystallinity, high chemical stability and strong fluorescence, which can selectively recognize triethylamine (TEA) and aniline in both liquid and vapor phase. The COF material demonstrates impressively low LOD values for aniline and triethylamine in solution, estimated to be 27 nM and 170 nM, respectively. Moreover, when detecting aniline and triethylamine vapors, the calculated LOD values are 20.1 ppb and 106.4 ppb, respectively. In addition, TAPB-BTDD showed basically unchanged emission intensities and rapid response to the amines after ten recycling tests, suggesting that the COF has high stable recycle repeatability. The combination of experimental analysis and density functional theory (DFT) calculations demonstrates that the unique fluorescence-quenching response of TAPB-BTDA can be attributed to the photoinduced electron transfer (PET) between the amines and the COF. This COF-based sensor offers a promising solution for the accurate and reliable detection of organic amines in various environmental settings.

Design, development and in vitro quantification of novel electrosprayed everolimus-loaded Soluplus®/Polyvinyl alcohol nanoparticles via stability-indicating HPLC method in cancer therapy

Everolimus (RAD001) a mammalian target of rapamycin has been hampered by poor solubility, affecting its dissolution rate, a relationship that extends to low bioavailability. Nanoparticles (NP) based on Soluplus (SOL®) and Polyvinyl alcohol (PVA) was fabricated by electrospraying (ES) for the delivery of RAD001 to improve anti-tumour efficacy. Electrospraying with established experimental conditions produced PVA-SOL®-RAD001 NP with 71 nm mean diameter, smaller particle size distribution and >90 % encapsulation efficiency. Various polymer-drug concentrations exposed to various freeze–thaw (F/T) cycles were studied for NP optimisation and to enhance its mechanical properties. The optimised NP formulation demonstrated complete encapsulation as well as a sustained and pH dependent drug release profile for in vitro release test. In addition, to specifically study the degradation profile of RAD001 and to quantify RAD001 in the fabricated NP, a new HPLC method was developed and validated. The purpose and novelty of the HPLC method was also to ensure that RAD001 can be detected at low amounts where other conventional characterisation methods are unable to detect. The developed HPLC method was accurate, precise, robust and sensitive with LOD and LOQ values of 4.149 and 12.575 μg/mL. In conclusion, the novel developed HPLC system can be applied for the quantification of different chemotherapeutic agents and the novel electrosprayed hydrogel NP is a potential drug delivery system to increase solubility and bioavailability of RAD001 in cancer therapy.

Easy-to-prepare graphene-based inkjet-printed electrodes for diclofenac electrochemical sensing

Inkjet-printed electrodes (IPEs) from flexible Kapton® as substrate and easy to prepare graphene oxide (GO)-based inks (K/GO) were prepared using a standard desktop printer. Subsequently, they were submitted to a post-processing thermal treatment (K/GO_TR400) and assessed as disposable working electrodes (WEs) for diclofenac (DCF) indirect electrochemical detection at pH 7.0 (close to physiological pH value). DCF monitoring is attracting much interest, due to its classification as contaminant of emerging concern in water sources. The performance of the printed active sensor material was compared to that of thermally reduced (at 400 °C) graphene oxide (TRGO-400, in a powder form), which has been successfully used as glassy carbon electrode (GCE) modifier for the detection of DCF. This electrode worked linearly within the concentration range between 5 and 25 μM with an LOD value of 2.25 μM. Moreover, the morphology and chemical composition of the obtained IPEs were characterized by means of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) and compared with GCE/TRGO-400. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements using a miniaturized 3-electrode cell of the post-processed IPEs showed a promising electrochemical performance for DCF sensing. Thus, this study demonstrated the effective partial recovery of the valuable properties of graphene on the IPEs after the thermal treatment and the successful production of flexible and disposable electrodes for target analyte detection. Therefore, this is a promising alternative to conventional modified GCEs, as it offers a facile approach for the fabrication of cutting edge graphene-based electrodes and widens the available portfolio of electrochemical sensors towards detection of water contaminants of emerging concern.

Preparation of a composite sensor based on a fluorescent and magnetic molecular imprint polymer for metronidazole extraction–detection

We developed a metronidazole (MNZ)-selective sensor, combining magnetic and fluorescent molecularly imprinted polymers (MFMIP) with a non-imprinted reference composite (MFNIP). Using isothermal titration calorimetry (ITC), we optimized the MNZ-to-APTES ratio during polymerization, obtaining a specific MNZ-APTES bonded complex (Kb= 2.575 × 103 L/mol, ΔH° = −1.079 kJ mol−1, TΔS° = 18.389 kJ mol−1, and ΔG° = −19.468 kJ mol−1). The MFMIP composite, incorporating Fe3O4@TEOS magnetite nanoparticles and CdTe@TGA quantum dots, exhibited cavity-specific interactions with MNZ, as confirmed by surface plasmon resonance (SPR) studies. Compared to MFNIP, the MFMIP sensor demonstrated superior selectivity in water samples (5–60 μM, with LOD and LOQ values of 1.28 and 5.00 μM), and even in the presence of interferents. In addition, the use of CdTe quantum dots enabled real-time analysis via Stern–Volmer quenching mechanisms without complex sample preparation. In conclusion, our MFMIP sensor offers sensitive and selective MNZ detection. It presents practical advantages, including real-time analysis and ease of handling, making it a promising extraction–determination system for trace concentrations of MNZ.

THE DEVELOPMENT AND VALIDATION OF HPLC AND HPTLC-DENSITOMETRY METHODS FOR THE DETERMINATION OF 1, 4-NAPHTHOQUINONE CONTENT IN ELEUTHERINE BULBOSA EXTRACT

Objective: The aim of this research was to develop and validate identification and Quantitation methods for 1,4-naphthoquinone in the extract of Eleutherine bulbosa. Methods: High-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography with densitometric detection (HPTLC-densitometry) were employed as analytical techniques. HPTLC-densitometry was performed at a wavelength of 249 nm, while UHPLC was conducted at a wavelength of 254 nm. Both methods were utilized to analyze 1,4-naphthoquinone in 96% ethanol extract of E. bulbosa as a Quantitation parameter in the standardization of the formulation. HPTLC separation was carried out on a 20 cm × 20 cm HPTLC glass plate coated with silica gel 60 F254 using a mobile phase of chloroform: methanol (8:2, v/v). For HPLC analysis, a C18 column with an isocratic method was employed using a mobile phase of 95% methanol in pump A and 0.5% chloroform in pump B. The calibration curve of peak area against concentration showed linearity within the range of 2500-15000 ppm/spot−1 and 3–21 μg/ml for HPTLC and HPLC, respectively. Both methods were validated for accuracy, precision, linearity, selectivity, LOD, and LOQ. Results: The results showed that both methods exhibited linearity that met the standards, as they produced correlation coefficients (r) greater than 0.9900. Furthermore, both methods demonstrated good accuracy, with consecutive recovery values of 99.53% and 101.89%. On the other hand, the methods fulfilled the precision requirements, with respective values of 0.7159% and 2.884% (in compliance with the requirement of<5%). Additionally, to meet the LOD and LOQ requirements in HPTLC, the LOD value obtained was 163 ppm, and the LOQ value was 495 ppm. In HPLC, the retention time of the standard 1,4-naphthoquinone and the analyte compound in the extract of E. bulbosa were the same, at 3.507 min. The selectivity test on HPTLC indicated that the 1,4-naphthoquinone compound was at an RF value of 0.81, which was also detected in the extract of E. bulbosa at the same RF value. Conclusion: In conclusion, our findings demonstrate that HPLC and HPTLC methods for the determination of 1,4-naphthoquinone content have met the standards for linearity, accuracy, precision, selectivity, LOD, and LOQ. Therefore, these methods can be recommended for the quality control of raw materials of E. bulbosa extract.

Phenolphthalein based molecule as a lighting–up fluorescent chemoprobe for the nanomolar recognition of Al3+: DFT study and its applications in test kits, food and water samples

Phenolphthalein–based compound (PHAB) was synthesized, well–characterized and studied as a lighting–up fluorescent chemosensor for Al3+. Fluorescence studies were performed at 25 °C in H2O/CH3CN (20/80, v/v) media. Free PHAB was non–fluorescent; but, it depicted a strong fluorescence toward Al3+ at 468 nm over potential competitive cations. The mechanism of C = N isomerisation and blocking PET enhanced its emission with a remarkable color alteration from colorless to blue. The LOD value was found at nano–molar level (51.5 nM), indicating high sensitivity toward Al3+. The validation study also confirmed the sensing performance of PHAB based on different analytical parameters. Job's plot, 1H NMR titration and MALDI TOF–MS studies authenticated the stoichiometry between PHAB and Al3+ (1:2). The binding of PHAB with Al3+ was further verified by the theoretical study. Furthermore, the fluorescence sensing performance of PHAB makes it perfect for practical applications in drinkable water and food samples with satisfactory recovery values (91.42%–108.8%), as well as in simple test–kit applications.

Machine learning-driven multi-level composite SERS platform for trace detection of chlorogenic acid as pharmacodynamic substance in honeysuckle

We reported a multi-level composite SERS platform which could provide a new method for accurate and quantitative trace detection for pharmacodynamic substance in traditional Chinese medicine (TCM). Using natural dragonfly wings as the template, Ag NPs were deposited on V-Ti nano-columns through controllable magnetron sputtering technology. Ag30@V-Ti20@D.W possessed a uniform nanostructure and exhibited High-performance SERS signal sensing capability. The detection limit (LOD) of R6G was 1 × 10−10 M. Through machine learning, we accurately classified and recognized R6G at different concentrations. The multi-level composite structure provided a wide range of “hot spots” areas and ensured good reproducibility with a relative standard deviation (RSD) value of 7.13%. When quantitatively detected chlorogenic acid, an active ingredient in honeysuckle, LOD value of 1 × 10−6 g/l was obtained. In the future, the combination of SERS spectroscopy technology and machine learning will provide theoretical and experimental support for the development of new strategies for detecting Other pharmacodynamic substances in TCM.

Modification of nickel slag nanomaterials as a smart modifier of carbon paste electrodes in voltammetry-based lead pollutant detection

Modification of nickel slag (NS) into a smart modifier carbon paste electrode (CPE) and its application test on lead (Pb) detection by voltammetry has been successfully investigated. The modification stage begins with the preparation of NS through the crushing process. The NS powder was put into the Hydrothermal Autoclave Reactor, heated at 180 °C for 2 h, calcined at 600 °C, and incorporated into the carbon paste electrode (NS/CPE) through mass variation. SEM and XRD characterization results illustrate that NS has a morphology composed of solid particles of varying sizes. Modification at 600 °C causes changes in morphology and an average diameter of 27.77 nm. Testing of the electrochemical behavior of NS/CPE on the Fe(CN)63−/Fe(CN)64− solution system described superior behavior marked by Ipa and Ipc values of 1.13x10−5 and −1.36x10−5 A/cm2, respectively. This value is generated from the NS/CPE application with a mass composition (w/w) of 2:5. Another superior behavior was demonstrated by the detection of reversible Pb (II) with Epa and Epc values of −0.10 V and −0.24, respectively. NS/CPE has good sensitivity with LOD and LOQ values of 0.889 μM and 2.96 μM, respectively. In addition, repeatability and reproducibility tests show that NS/CPE has good precision with a %RSD of 4.02% and 5.15%. The results of this work illustrate the potential for NS to be studied further as a new modifier material in the further development of voltammetry-based Pb (II) detection systems in the future.

Dual-emission Sm(III)-macrocycle as the lab-on-a-molecule chemosensor for nitroaromatic antibiotic analogues

Highly selective and discriminative detection of analogous nitroaromatic antibiotics necessitates the development of high-efficient sensing matrixes and detection modes, where multi-emission materials combined with statistical analysis methods can provide a feasible pathway to construct the lab-on-a-molecule chemosensor for antibiotic detection. Herein, a dual-emission macrocyclic samarium complex Sm-2j3 is synthesized by template method, and it provides three fluorescence channels (436, 596 and 643 nm) along with two imine bond sensing sites. As a result, Sm-2j3 allows high-throughput identification of ten analogous antibiotics by PCA and HCA methods, even in real water sample. And it also exhibits sensitive quantitation of NFT and NFZ, which have LOD values as low as 0.67 μΜ and 0.70 μΜ. Further experiments show that Sm-2j3 still can clearly distinguish a range of two-component antibiotic mixtures in different proportions. Our proposed Sm-2j3 provides a distinctive reference for effective detection of various antibiotics and is expected to widen applications on luminescent lanthanide materials, being potentially useful in multianalyte detection.

Validated green high performance liquid chromatographic and capillary electrophoretic methods for estimation of dinitolmide in presence of its acid-degradation product

This study describes two new, green, fast, specific and highly sensitive stability-indicating techniques for determination of Dinitolmide (DM) in presence of its acid induced degradation product without prior separation; Acid degradation was carried out by hydrolysis with 0.1 N HCl; and the acidic degradation pathway was established by IR, and MS techniques. The first is a HPLC-Diode Array detector was performed by isocratic mode on BDS Hypersil C18 column (150 mm × 4.6 mm × 5 μm particle size) at ambient temperature with a mobile phase consisting of 5 mM sodium acetate buffer (pH 5.5): acetonitrile (40:60, v/v), flow rate of 1 mL/min and detection at 210 nm. DM and its acid degradant were eluted at 4.3 and 2.8 min, respectively offering quick analysis. Linearity of the calibration curves confirm good correlation in range of 1–15 μg/mL with recovery % of 100.02 ± 0.460. The LOD and LOQ were 0.243 and 0.737, respectively. The second method is CE -Diode Array detector was carried out at 25 °C using borate buffer (30 mM, pH 9) as background electrolyte solution and detection at 225 nm. The migration times were 2.26 and 2.97 min for DM and its acid degradant, respectively. The linearity range was 5–50 μg/mL with recovery % of 99.55 ± 0.910, LOD and LOQ were 1.010 and 3.050, respectively. The small LOD and LOQ values for both methods confirm high sensitivity of the methods The developed methods were validated according to the ICH guidelines demonstrating good accuracy and precision. The results were statistically compared with those obtained by a reported method in terms of accuracy, precision, and no significant difference was found. Both methods were successfully applied for estimating DM and its acid degradant in pure and pharmaceutical dosage forms. In addition, the methods were assessed for their greenness profile and CE was greener owing to using safer solvents and less energy consumption.

Analytical method validation of cinnamaldehyde content in cinnamon (Cinnamomum burmannii) extract using high-performance liquid chromatography

The use of herbal medicinal plants has been found widely in the community as traditional medicine. One example is the Cinnamon plant (Cinnamomum burmannii) which contains cinnamaldehyde as the main compound. Cinnamaldehyde is known to have a major role in lowering blood sugar levels. Determination of the content of bioactive compounds in extracts is beneficial in determining the safety, quality, and efficacy of the plants used. So it is necessary to do a quantitative analysis test on the cinnamaldehyde compound in cinnamon plants by determining its levels using the HPLC method. It is necessary to validate the method analysis based on parameters including selectivity, linearity, accuracy, precision, detection limit, and quantitation limit. The mobile phases in this method were acetonitrile mobile and 0.04�etic acid solution (60:40), The stationary phase was octadecylsilane (C-18), The flow rate was adjusted at 1.0 mL/min with column temperature adjusted at 29°C, injection volume 20 μl, and using a Photodiode array detector at a wavelength of 280 nm. The results showed that the resolution value obtained was 3.401; the correlation coefficient value obtained is 0.9941; The percent recovery obtained between 98.74% - 101.95%; percent RSD obtained between 0.92% - 2.68%; and the LOD and LOQ values were 0.069 ppm and 0.23 ppm. The HPLC method met the validation requirement and can conclude to be valid.

Kıbrıs’ın Kuzeyinde Üretilen Süt Örneklerinde Aflatoksin M1 Düzeyleri

Aflatoxin M1 (AFM1) is the hydroxylated metabolite of aflatoxin B1 (AFB1), which is formed in the liver by cytochrome P450 enzymes and can be secreted into the urine, feces, and milk of mammals. AFM1 is a carcinogenic, cytotoxic, teratogenic, mutagenic and genotoxic agent that poses a significant health risk to both humans and animals. This study was conducted to determine the presence of AFM1 in both raw and ultra-high temperature (UHT) cow’s milk samples produced in the northern part of Cyprus, and to determine whether it poses a risk to public health. In this survey, a total of 20 UHT cow’s milk samples from 2 different milk brands produced in the northern part of Cyprus, and 22 raw cow’s milk samples collected from the different dairies were analyzed for the presence of AFM1 by high performance liquid chromatography (HPLC) with fluorescence detector after immunoaffinity cleanup. AFM1 could not be detected in any of the analyzed raw and UHT cow milk samples. The LOD and LOQ values of the HPLC-FLD method were 1.038 μg/kg and 3.145 μg/kg, respectively. The mean recovery and repeatability values of the method were 95.6% and 4.9%, respectively. Although the presence of AFM1 in milk samples produced in the northern part of Cyprus poses no major risk to public health, more milk samples and animal feed must be monitored on a regular basis to decrease potential consumer exposure.

EXTRACTION, IDENTIFICATION AND ESTIMATION OF CAFFEINE IN GREEN AND BLACK TEA SAMPLES BY A SIMPLE UV-VISIBLE SPECTROSCOPIC METHOD

Caffeine is a widely consumed psychoactive compound present in coffee, tea, soft drinks, energy drinks, and chocolates. It is a diuretic and a central nervous system (CNS) stimulant. Apart from stimulating the CNS, it exerts beneficial effects in combination with other substances like L-theanine and catechins. Caffeine was extracted from green tea and black tea samples using various solvents. The maximum yield of caffeine was obtained from dichloromethane extracts. The extracted caffeine was identified by TLC and FTIR. A simple UV spectroscopic method was developed and validated for the estimation of caffeine in green tea and black tea. The wavelength maximum of caffeine was obtained at 272 nm in distilled water. The Beer-Lambert law was obeyed in the concentration range of 0.5 to 35 µg mL-1 for caffeine. The linearity, accuracy, precision, robustness, and ruggedness, limit of detection and limit of quantification of this method are within the limits of ICH guidelines. This method was found to be precise as % RSD was less than two. The LOD and LOQ values were 0.03 µg mL-1 and 0.091 µg mL-1,respectively. The percentage purity of caffeine from green tea and black tea samples was found to be 98.32% and 99.42 %. Thus, the proposed method was found to be rapid, specific, precise and accurate for the routine analysis of caffeine in green and black tea samples.

Analytical Method Development and Validation for Estimation of Spironolactone and Hydrochlorothiazide in Bulk and Tablet Dosage form by High Performance Liquid Chromatography

Analytical Method Development and Validation for Spironolactone and Hydrochlorothiazide in bulk and Combined Dosage Form by RP-HPLC. New method was established for simultaneous estimation of Spironolactone and Hydrochlorothiazideby RP-HPLC method. The chromatographic conditions were successfully developed for the separation of Spironolactone and Hydrochlorothiazideby using Inertsil C18 (4.6mm ×250mm, 5µm particle size), flow rate was 1.0ml/min, mobile phase ratio was (55:45% v/v) Methanol: Phosphate buffer pH 4.8 (pH was adjusted with ortho phosphoricacid), detection wavelength was 282nm. The instrument used was WATERS Alliance 2695 separation module, Software: Empower 2, 996 PDA detector. The retention times were found to be 1.688mins and 3.282mins. The %purity of Spironolactone and Hydrochlorothiazidewas found to be 99.86%. The system suitability parameters for Spironolactone and Hydrochlorothiazidesuch as theoretical plates and tailing factor were found to be 7586, 1.69 and 6235 and 1.58, the resolution were found to be 10.85. The analytical method was validated according to ICH guidelines (ICH, Q2 (R1)). The linearity study ofSpironolactone and Hydrochlorothiazidewas found in concentration range of 100µg-500µg and 30µg - 70µg and correlation coefficient (r2) was found to be 0.999 and 0.999, % recovery was found to be 100.112% and 100.16%, %RSD for repeatability was 0.1702 and 0.043 respectively. The precision study was precise, robust, and repeatable. The LOD value was found to be 2.1µg/ml and 1.28µg/ml, and LOQ value was 6.3µg/ml and 3.84µg/ml for Spironolactone and Hydrochlorothiaziderespectively. Hence the suggested RP-HPLC method can be used for routine analysis of Spironolactone and Hydrochlorothiazide in API and Pharmaceutical dosage form.

Simultaneous Determination of Luliconazole and Salicylic Acid by Simultaneous Equation Method and Absorbance Ratio Method

The simultaneous determination of Luliconazole and Salicylic Acid in pharmaceutical formulations holds significant importance for ensuring therapeutic efficacy and patient safety. This research focuses on developing an accurate and efficient method using UV-Visible spectrophotometry, specifically the Simultaneous Equation Method (SEM) and Absorbance Ratio Method (ARM), to quantify these active ingredients in topical creams. The study begins with the preparation of stock solutions and selection of the analytical wavelength, with 298 nm chosen in reference to the isobestic point at 230 nm. Cream samples containing 10 mg Luliconazole and 30 mg Salicylic Acid are prepared, sonicated, and filtered for analysis. The UV method is validated in accordance with ICH guidelines, encompassing linearity, precision, LOD, LOQ, specificity, robustness, and accuracy. Calibration curves show excellent linearity within the concentration range of 5-30 µg/ml for both compounds. Intra-day and inter-day precision studies exhibit low % RSD values, indicating the reliability and reproducibility of the method. LOD and LOQ values demonstrate the sensitivity of the method, enabling detection and quantification at trace levels. Specificity is confirmed through overlay spectra and comparisons of analyte responses. Robustness is assessed by varying temperature and concentration, demonstrating the method's resilience to minor changes. Accuracy is evaluated through the standard addition method, yielding recoveries within acceptable limits. The proposed UV method is successfully applied to the analysis of Luliconazole and Salicylic Acid in commercial cream samples, with assay results confirming its accuracy and suitability for routine quality control.