Silica Plates Research Articles

Chromatographic assay of recently approved co-formulation of Vonoprazan fumarate with low dose Aspirin: AGREE, Complex MoGAPI, and RGB 12-model assessments

Two simple, valid and green chromatographic based techniques are developed in the present work for first time to simultaneously analyze the recently approved combination of Aspirin (ASP) with the novel gastro-protective agent Vonoprazan (VON). First method is an HPLC-DAD “diode array detection”, where separation was successful using C18 (250 × 4.6 mm) column with isocratic elution of phosphate buffer-pH 6.8 and acetonitrile in ratio of 63:37 with detection at 230 nm. Second method is an HPTLC method on HPTLC silica plates using ethyl acetate: ethanol (75%): ammonia (5:5:0.05 v/v) mobile phase followed by densitometric scanning at 230 nm. The methods were applied successfully for analysis of VON and ASP mixture in laboratory-prepared tablets and the methods were validated in regards to linearity, precision, accuracy and selectivity. The proposed methods are assessed for their greenness and whiteness as well using the “Analytical GREEnness Metric Approach”, “Complementary Modified Green Analytical Procedure Index” and the new algorithm “RGB 12 model” (Red-Green-Blue) and proved the greenness and the sustainability of the methods in the routine assay of the newly marketed formulation.

An integrated paradigm between green analytical chemistry and quality-by-design for robust analysis of alcaftadine and ketorolac tromethamine in aqueous humor via sustainable chromatographic methods

The field of pharmaceutical industry has witnessed the launch of a new co-formulated eye drop, composed of alcaftadine and ketorolac tromethamine, for alleviating allergic conjunctivitis. Such new formulation evokes the need for a sensitive, robust and fast analytical method capable of their quantification in their dosage form, in aqueous humor for pharmaco-kinetics studies as well as in presence of plausible degradation products. In this work, two validated stability-indicating chromatographic methods were developed for alcaftadine and ketorolac assaying with good adherence to values of green analytical chemistry. Drugs stabilities were tested under various stress conditions where drugs showed liability for oxidative degradation only. For the first chromatographic method, an integrated merger between analytical quality-by-design and green analytical chemistry was implemented via a UPLC method coupled with photo-diode array detector. A short C18 analytical column of 100 mm was utilized with mobile phase of ethanol: aqueous solution pH 4.0 containing 0.1% triethylamine (40: 60, by volume). Second method was thin layer chromatographic one using HPTLC silica plates as a stationary phase and a developing system of dichloromethane: ethanol (5:4, by volume). Both methods achieved to selectively quantify the studied drugs with high accuracy and precision without any interference from degradation products or related excipients in eye drops. The methods were also successfully exploited for ALF and KTC assaying in rabbit aqueous humor, with no need for prior extraction procedures, for further pharmacokinetic studies. Finally, usage of green solvents gives us the advantage of applying various evaluation tools to conclude method greenness.

Independent concentration extraction as a novel green approach resolving overlapped UV–Vis binary spectra and HPTLC-densitometric methods for concurrent determination of levocloperastine and chlorpheniramine

BackgroundThe proposed research study introduces independent concentration extraction (ICE) as a novel UV–Vis spectrophotometric approach. The approach can be used for extracting the concentration of two analytes with severely overlapped spectra from their binary mixtures. ICE is based on spectral extraction platform involving simple smart successive methods that can directly extract the original zero order spectra of the analytes at their characteristic (λmax). Chlorpheniramine maleate (CPM) and Levocloperastine fendizoate (LCF) are two commonly co-formulated drugs in cough preparations. The combined mixture was used to confirm the validity of the developed ICE tool. Another less green HPTLC was developed for the first time to separate both drugs and help also in confirming the proposed tool.MethodsFor the simultaneous determination of CPM and LCF, two ecologically friendly techniques were employed. The first approach encompasses the use of the ICE spectrophotometric method that could be successively applied for extracting the concentration of two analytes with severely overlapped unresolved spectra in their binary mixtures. Other complementary methods aiming at original spectral extraction; including spectrum subtraction (SS) and unity subtraction (US) were also successfully employed to resolve the zero order spectra of the combined drugs with all their characteristic features and peaks. The second technique used, a high-performance TLC-densitometric one, was performed on silica plates with silica plates F254 and a mobile phase with a ratio of 3:3:3:1 by volume of toluene, ethanol, acetone, and ammonia as a developing system at 230 nm.ResultsThe presented extraction approach was executed without any optimization steps or sample pretreatment for the simultaneous determination of CPM and LCF. The method was found to be valid for their determination within concentration range of 3.0–30.0 μg mL−1 for both drugs. For HPTLC method, the resulting Rf values of CPM and LCF were 0.37 and 0.78, within concentration ranges of 0.3–4.0 μg/spot and 0.8–10.0 μg/spot, respectively. Greenness assessment of both developed methodologies showed that the HPTLC method is less green than the spectrophotometric method, yet with comparable sustainability when it comes to the used technique.ConclusionThe procedures were found to be selective, accurate, and precise for analysis of the studied binary mixture. Furthermore, the environmental impact of the introduced methods was assessed using novel greenness metrics, namely AGREE and Green Analytical Procedure Index (GAPI) to prove their ecological safety. In addition, white analytical chemistry (WAC) evaluation metric was employed to ensure the synergy and coherence of analytical, practical, and ecological attributes.

Microstructuring of fused silica by laser-induced microplasma using a pyrographite target for phase optical elements fabrication

In this paper, we purpose to use laser-induced microplasma occurred from a pyrographite target by laser ablation for microstruturing of fused silica plate to fabricate phase optical elements. Laser parameters for erosive plasma torch formation and subsequent etching of fused silica were determined based on preliminary experimental studies and estimated energy calculations. The influence of the overlap coefficients in the focal spot on the reproducibility of etching depths results and the deviation accuracy of etching depths with the found laser parameters was experimentally studied. The best results in terms of accuracy (no more than 0.1 μm) in deviations of etching depths are achieved with the overlap coefficient of 0.5. Moreover, the paper presents estimated calculations of the speed and efficiency of ablation, as well as the coefficient of energy conversion from laser radiation to the ablation energy of fused silica, which was ∼ 0.25. Based on achieved results an attempt was made to fabricate the 6-sector SPP for the wavelength of 355 nm.

Four-Fold, Cross-Phase Modulation Driven UV Pulse Compression in a Thin Bulk Medium

Generation of high energy few-fs pulses in the ultraviolet (UV) still represents challenges due to compression and phase control difficulties in this spectral range. Presented here is a pulse compression approach utilizing cross-phase modulation within a thin solid-state medium induced by a strong, spatially and temporally controllable near-infrared (NIR) pulse acting on a weaker, 400 nm UV pulse. Through this method, four-fold compression is attained within a single fused silica plate, resulting in a 13 fs UV pulse with preserved beam quality. With some further technical adjustments, this method’s applicability could be extended to deep or even vacuum UV, where direct compression is difficult.

Spatial shaping of low- and high-order harmonics generated using vortex beams

We demonstrate the generation of the low- and high-order harmonic vortex beams from a single spiral phase plate illuminated by different laser wavelengths. The second harmonic (532 nm) originates from the application of the wavefront-structured 1064 nm femtosecond pulses with fractional orbital angular momentum (OAM) during propagation through a lithium triborate crystal, while the third harmonic (500 nm) originates from the application of the wavefront-structured near-IR (1500 nm) femtosecond pulses with integer OAM during propagation through a 150 μm thick fused silica plate. The topological charges (TCs) of the second and third harmonics are measured and compared. The increase in TC and the peculiarities in OAM variations during modification of the polarisation of the incident radiation are analysed and discussed. The two-colour-pump-driven second-harmonic vortex radiation interacted with an Ar gas jet to generate vortex harmonics up to the 14th order with double-lobe complex spatial profiles in the extreme ultraviolet region.

HPTLC Stability Indicating Analytical Method of Andrographolide and 5-fluorouracil with Network Pharmacology Analysis against Cancer.

Herbal drugs when used in combination with chemotherapeutic drugs can reduce the side effects and increase the efficacy by acting on multiple targets. Andrographolide (AG), a diterpene lactone isolated from Andrographis paniculata Nees, is a bioactive compound with anticancer potential, and 5-fluorouracil (FU), a pyrimidine analogue, is used in the treatment of cancer. Both drugs are used to formulate combination nanoformulation to increase absorption, thereby increasing their oral bioavailability. The study aimed to develop and validate stability indicating simultaneous HPTLC method for quantification of FU and AG in combination nanoformulation along with in silico docking and network pharmacology analysis to understand the interaction between the drugs and cancer targets. Chromatographic separation was performed using mobile phase chloroform: methanol: formic acid (9: 0.5: 0.5, v/v/v) on HPTLC silica plates 60 F254 as a stationary phase using UV-Vis detector and HPTLC scanner at 254 nm. Further, in silico docking analysis was performed to predict the binding affinity of AG and FU with different proteins and network pharmacology to find out the exact biomolecular relationship of AG and FU in alleviating cancer. The data from the calibration curve showed a good linear regression relationship with r² = 0.9981 (FU) and r² = 0.9977 (AG) in the concentration range of 0.1-2.0 μg/mL. The developed method was validated according to the ICH guidelines. Stability studies showed changes in peak patterns and areas. Bioinformatic and network pharmacology analyses of AG and FU with target proteins and genes associated with cancer play a multimechanistic role in alleviating cancer. The developed method has been concluded to be robust, simple, precise, reproducible, accurate, and stability indicating for simultaneous quantification of AG and FU, and the molecular interaction studies have further indicated that the combination nanoformulation of AG and FU could be effective against cancer.

Nonequilibrium Casimir–Polder Force between Nanoparticles and Graphene-Coated Silica Plate: Combined Effect of the Chemical Potential and Mass Gap

The Casimir–Polder force between spherical nanoparticles and a graphene-coated silica plate is investigated in situations out of thermal equilibrium, i.e., with broken time-reversal symmetry. The response of the graphene coating to the electromagnetic field is described on the basis of first principles of quantum electrodynamics at nonzero temperature using the formalism of the polarization tensor in the framework of the Dirac model. The nonequilibrium Casimir–Polder force is calculated as a function of the mass-gap parameter, the chemical potential of graphene, and the temperature of the graphene-coated plate, which can be both higher or lower than that of the environment. It is shown that the force value increases with the increasing chemical potential, and this increase is more pronounced when the temperature of a graphene-coated plate is lower than that of the environment. The nonequilibrium force also increases with increasing temperature of the graphene-coated plate. This increase is larger when the plate is hotter than the environment. The effect is revealed that the combined impact of the chemical potential, μ, and mass gap, Δ, of the graphene coating depends on the relationship between Δ and 2μ. If 2μ>Δ, the magnitude of the nonequilibrium force between nanoparticles and a cooled graphene-coated plate becomes much larger than for a graphene coating with μ=0. The physical reasons explaining this effect are elucidated. Possible applications of the obtained results are discussed.

Efficient dual-stage all-solid-state post-compression for 100 W level ultrafast lasers

Abstract We demonstrate efficient and economical all-solid-state post-compression based on dual-stage periodically placed thin fused silica plates driven by a more than 100 W ytterbium-doped yttrium aluminum garnet Innoslab amplifier seeded by a fiber frontend. Not only is a more than eight-fold pulse compression with 94% transmission achieved, but also the pulse quality and spatial mode are improved, which can be attributed to the compensation for the residual high-order dispersion and the spatial mode self-cleaning effect during the nonlinear process. It enables a high-power ultrafast laser source with 64 fs pulse duration, 96 W average power at 175 kHz repetition rates and good spatiotemporal quality. These results highlight that this all-solid-state post-compression can overcome the bandwidth limitation of Yb-based lasers with exceptional efficiency and mitigate the spatiotemporal degradation originating from the Innoslab amplifier and fiber frontend, which provides an efficient and economical complement for the Innoslab laser system and facilitates this robust and compact combination as a promising scheme for high-quality higher-power few-cycle laser generation.

Nonlinear pulse compression technique based on in multi-pass plano-cancave cavity

<sec>Ultrafast femtosecond laser system with hundreds of microjoules of energy, operating at a repetition frequency of several kilohertz, has very important applications in many fields such as medicine, mid-infrared laser generation, industrial processing, and vibrational spectroscopy. The chirped pulse amplification technique provides a feasible path to obtain light sources with those parameters. However, the use of chirped pulse amplification increases the technical complexity and cost of the laser system. Recently, the proposal of a multi-pass cell (MPC) nonlinear pulse compression technique has enabled us to obtain high power ultrafast femtosecond pulses with reduced technical complexity and cost. The device requires only two concave mirrors and a nonlinear medium in between. In the past seven years, the multi-pass cell nonlinear pulse compression technique has made great progress, making it possible to obtain ultrashort pulses with average power of more than a few kW and peak power of tens to hundreds of TW.</sec><sec>In this work, we achieve nonlinear pulse compression of a 100-W picosecond laser by using an improved nonlinear pulse compression scheme that combines a hybrid of a plano-cancave multi-pass cell and multi-thin-plate. Using fused silica plates in plano-cancave cavity, the spectral bandwidth (FWHM) of input picosecond laser is broadened from 0.24 nm to 4.8 nm due to self-phase modulation effect, the pulse is compressed to 483 fs by dispersion compensation using grating pairs, which corresponds to a compression factor of 22, and the final output power of 44.2 W is obtained. Compared with traditional MPC, the plano-cancave cavity scheme we developed is a very promising solution for nonlinear compression due to its compactness, more stability and large compression ratio.</sec>

Efficiency of Phenazine Compound Produced by Rhizospheric Pseudomonas fluorescens against Few Pathogenic Bacteria Isolated from Ear Infections

The most typical bacterial infection in children of pediatric age is acute otitis media. Because resistance to these microorganisms grows, management expenses for each pathogen must be specifically adapted to that pathogen. Pseudomonas fluorescens isolated from the rhizosphere rice soil revealed a higher level of antibacterial activity against ear infection pathogenic bacteria than other species of Pseudomonas. Phenazine was extracted P. fluorescens by using organic solvents such as benzene with 3.76 μg/ml then characterized with thin layer chromatography and gave a band with a retardation factor (RF) of 0.64 based on the compound’s mobility on the silica plate. In comparison to the antibacterial activity of crude phenazine, the purified phenazine revealed the highest activity against Staphylococcus aureus at 32 mm, and the lowest activity was recorded on bacteria P. aeruginosa with an 18 mm diameter of inhibition. This leads to the encouragement of the use of phenazine compound for the treatment of the increased ear infections due to multi-resistance by causing pathogens.

Quantification of Aflatoxin B1 by thin layer chromatography in present peanut samples contaminated by Aspergillus flavus commercialized in Brazil

The quantification of aflatoxin B1 was performed in (CCD) samples of peanut grains positive in culture media for Aspergillus flavus fungi from the city of São José dos Campos - SP; Brazil, comparing the results with the reference values of aflatoxin B1 allowed by ANVISA legislation. According to previous research, we obtained 4 positive samples in culture medium for Aspergillus flavus fungi, where these samples for this study were ground and then performed the following 4 steps of (Extraction, Extract Purification, Liquid Extraction and Thin Layer Chromatography) - Eluted with 5 ml of chloroform, polar substance capable of diluting the aflatoxin B1 being polar substances, after that they were revealed the silica plates in UV light - 366 nm where it was determined the values of Rf (Retention Factor) give each sample, then the results were applied in the formula of quantification of aflatoxin B1. We obtained positive results for 1 sample of the 4 with presence of A. flavus in the culture medium of peanut grains, but only in sample 11 we obtained the presence of aflatoxin B1 in high quantity with about 25.5 µg/kg, It concludes that the contaminated sample is above the ANVISA reference values, causing great pathological and neoplastic impact to the health of human beings, affirming that still there was limitrophic presence of aflatoxin B1 in sample 10, causing serious pathological and neoplastic problems, attributing that this present study and research stimulates and gives the basis of stimuli for unedited creation of anti-aflatoxin B1 serums.

Comparing plasma and skin imprint metabolic profiles in COVID-19 diagnosis and severity assessment.

As SARS-CoV-2 continues to produce new variants, the demand for diagnostics and a better understanding of COVID-19 remain key topics in healthcare. Skin manifestations have been widely reported in cases of COVID-19, but the mechanisms and markers of these symptoms are poorly described. In this cross-sectional study, 101 patients (64 COVID-19 positive patients and 37 controls) were enrolled between April and June 2020, during the first wave of COVID-19, in São Paulo, Brazil. Enrolled patients had skin imprints sampled non-invasively using silica plates; plasma samples were also collected. Samples were used for untargeted lipidomics/metabolomics through high-resolution mass spectrometry. We identified 558 molecular ions, with lipids comprising most of them. We found 245 plasma ions that were significant for COVID-19 diagnosis, compared to 61 from the skin imprints. Plasma samples outperformed skin imprints in distinguishing patients with COVID-19 from controls, with F1-scores of 91.9% and 84.3%, respectively. Skin imprints were excellent for assessing disease severity, exhibiting an F1-score of 93.5% when discriminating between patient hospitalization and home care statuses. Specifically, oleamide and linoleamide were the most discriminative biomarkers for identifying hospitalized patients through skin imprinting, and palmitic amides and N-acylethanolamine 18:0 were also identified as significant biomarkers. These observations underscore the importance of primary fatty acid amides and N-acylethanolamines in immunomodulatory processes and metabolic disorders. These findings confirm the potential utility of skin imprinting as a valuable non-invasive sampling method for COVID-19 screening; a method that may also be applied in the evaluation of other medical conditions. KEY MESSAGES: Skin imprints complement plasma in disease metabolomics. The annotated markers have a role in immunomodulation and metabolic diseases. Skin imprints outperformed plasma samples at assessing disease severity. Skin imprints have potential as non-invasive sampling strategy for COVID-19.

Analisis mutu fisik, mikrobiologi, dan kandungan metabolit sekunder serbuk instan jamu kunyit asam

The lifestyle “back to nature” is growing and in demand by the public. Herbal turmeric tamarind is a herbal product often consumed by the public to reduce pain during menstruation (dysmenorrhea). This study aimed to verify the secondary metabolites in the instant herbal turmeric tamarind powder developed by the research team using the thin-layer chromatography method. TLC was identified by extracting instant powder of tamarind turmeric herbs using ethanol, methanol, distilled water, chloroform, ethyl acetate, and n-hexane solvents. The stationary phase used is a 60 GF ₂₅₄ silica plate and the detection of compounds by UV₂₅₄, UV₃₆₆, and chemical reagents. Identification results were analyzed descriptively by looking at the stains on the plates, calculating the Rf value of each compound, and carrying out a comparative analysis of the literature with reference standards. The results showed that the processed tamarind herbal turmeric instant powder sample of the research team positively contained alkaloids, flavonoids, tannins, steroids, and curcumin characterized by the presence of colored spots, and the resulting Rf values ​​were the same or close to those of the sample and the standard for each compound.

Nanomolar “Turn-On” Hg2+ detection by a fluorescein based fluorescent probe: DFT calculations, bioimaging and on-site assay kit studies

Sensitive yet rapid methodologies for efficient recognition of toxic heavy metals, like Hg2+, would avert the poisonous impacts of these elements on the environment and human health. Herein, we present a highly selective fluoresceine-based fluorogenic probe FP for Hg2+ recognition with quick response, an impressive LOD of 67.1 nM, high sensitivity, and a linear emission increment relationship with Hg2+ concentration (0–20.0 μM). FP could specifically recognize Hg2+ and it exhibited a 250-fold emission enhancement at 515 nm to Hg2+, but no response to other common cations. The mechanism for FP-Hg2+ was completely examined through FTIR, 1H NMR, TOF-MS, and density functional theory (DFT) calculations. To examine naked-eye recognition of Hg2+, the FP-coated silica plates, and cotton swabs were productively manufactured for the sensing of Hg2+. Besides, FP was able to recognize Hg2+ in biological systems with excellent efficiency. Overall, ultra-fast recognition property of FP for Hg2+, high sensitivity, and selectivity of FP against Hg2+ could be conveniently utilized to prevent the toxicity of Hg2+.

Chromatographic reversed HPLC and TLC-densitometry methods for simultaneous determination of serdexmethylphenidate and dexmethylphenidate in presence of their degradation products—with computational assessment

Two Chromatographic methods have been established and optimized for simultaneous determination of serdexmethylphenidate (SER.DMP) and dexmethylphenidate (DMP) in the presence of their degradation products. The first method is a reversed phase high performance liquid chromatography with diode array detection (HPLC–DAD). Isocratic separation was carried out on Waters X-bridge Shield RP18 column (150×3.9×5 μm particle size) using a mixture of 5 mM phosphate buffer (pH 5.5): acetonitrile (40:60, v/v) as a mobile phase, flow rate 1 mL/min and detection at 220 nm. The second method is a thin-layer chromatography (TLC)—densitometry method using methanol: chloroform (70:30, v/v) as a mobile phase and UV scanning at 220 nm. In HPLC method, the linearity range of SER.DMP was (2.5–25 μg/mL); with LOD (0.051 μg/mL) and LOQ (0.165 μg/mL) while for DMP was (2.5–25 μg/mL); with LOD and LOQ of (0.098 μg/mL) and (0.186 μg/mL), respectively. For TLC method the sensitivity range of SER.DMP was (5–25 μg/mL), LOD was (0.184 μg/spot), while LOQ was (0.202 μg/ spot) whereas for DMP the sensitivity range was (5–25 μg/mL) with LOD of (0.115 μg/ spot) and LOQ of (0.237 μg/ spot), respectively. SER.DMP was found to be equally labile to acidic and alkaline hydrolysis, whereas DMP was sensitive to acidic hydrolysis only. Both drugs were successfully determined in presence of acidic and basic degradants by the two developed methods (stability indicating assay method). Chromatographic separation of the degradation products was carried out on TLC aluminum silica plates 60 F254, as a stationary phase, using methanol: dichloroethane: acetonitrile (60:20:20 v/v), as a mobile phase. The degradation pathway was confirmed using TLC, IR, 1H-NMR and mass spectroscopy; moreover, the separation power was correlated to the computational results by applying molecular dynamic simulation. The developed methods were validated according to the International Conference on Harmonization (ICH) guidelines demonstrating good accuracy and precision. They were successfully applied for quantitation of SER.DMP and DMP in pure and capsule forms. The results were statistically compared with those obtained by the reported method in terms of accuracy, precision and robustness, and no significant difference was found.

Genome analysis of Parmales, the sister group of diatoms, reveals the evolutionary specialization of diatoms from phago-mixotrophs to photoautotrophs

The order Parmales (class Bolidophyceae) is a minor group of pico-sized eukaryotic marine phytoplankton that contains species with cells surrounded by silica plates. Previous studies revealed that Parmales is a member of ochrophytes and sister to diatoms (phylum Bacillariophyta), the most successful phytoplankton group in the modern ocean. Therefore, parmalean genomes can serve as a reference to elucidate both the evolutionary events that differentiated these two lineages and the genomic basis for the ecological success of diatoms vs. the more cryptic lifestyle of parmaleans. Here, we compare the genomes of eight parmaleans and five diatoms to explore their physiological and evolutionary differences. Parmaleans are predicted to be phago-mixotrophs. By contrast, diatoms have lost genes related to phagocytosis, indicating the ecological specialization from phago-mixotrophy to photoautotrophy in their early evolution. Furthermore, diatoms show significant enrichment in gene sets involved in nutrient uptake and metabolism, including iron and silica, in comparison with parmaleans. Overall, our results suggest a strong evolutionary link between the loss of phago-mixotrophy and specialization to a silicified photoautotrophic life stage early in diatom evolution after diverging from the Parmales lineage.

Ionization wave propagation and cathode sheath formation due to surface dielectric-barrier discharge sustained in pulsed mode

This work deals with the experimental study of a surface dielectric-barrier discharge, as a part of the ongoing interest in the control of plasma induced electro-fluid dynamic effects (e.g. plasma actuators). The discharge is generated using a plasma reactor consisting of a fused silica plate which is sandwiched between two printed circuit boards where the electrodes are developed. The reactor is driven by narrow high voltage square pulses of asymmetric rising (25 ns) and falling (2.5 μs) parts, while the discharge evolution is considered in a temporarily and spatially resolved manner over these pulses. That is, conventional electrical and optical emission analyzes are combined with high resolution optical emission spectroscopy and ns-resolved imaging, unveiling main characteristics of the discharge with a special focus on its propagation along the dielectric-barrier surface. The voltage rising part leads to cathode-directed ionization waves, which propagate with a speed up to 105 m s−1. The voltage falling part leads to cathode sheath formation on the driven electrode. Τhe polarization of the dielectric barrier appears critical for the discharge dynamics.

A near-infrared ratiometric fluorescent probe for hydrazine and its application for gaseous sensing and cell imaging

Hydrazine (N2H4) is a widely used raw material in the chemical industry, but at the same time hydrazine has extremely high toxicity. Therefore, the development of efficient detection methods is crucial for monitoring hydrazine in the environment and evaluating the biological toxicity of hydrazine. This study reports a near-infrared ratiometric fluorescent probe (DCPBCl2-Hz) for the detection of hydrazine by coupling a chlorine-substituted D-π-A fluorophore (DCPBCl2) to the recognition group acetyl. Due to the halogen effect of chlorine substitution, the fluorophore has an elevated fluorescence efficiency and a lowered pKa value and is suitable for physiological pH conditions. Hydrazine can specifically react with the acetyl group of the fluorescent probe to release the fluorophore DCPBCl2, so the fluorescence emission of the probe system significantly shifted from 490 nm to 660 nm. The fluorescent probe has many advantages, such as good selectivity, high sensitivity, large Stokes shift, and wide applicable pH range. The probe-loaded silica plates can realize convenient sensing gaseous hydrazine with content down to 1 ppm (mg/m3). Subsequently, DCPBCl2-Hz was successfully applied to detect hydrazine in soils. In addition, the probe can also penetrate living cells and allow the visualization of intracellular hydrazine. It can be anticipated that probe DCPBCl2-Hz will be a useful tool for sensing hydrazine in biological and environmental applications.

Development of a thin‐layer chromatographic method for detection of lipstatin produced by Streptomyces toxytricini

AbstractLipstatin or its saturated analog (orlistat), being the irreversible inhibitor of intestinal lipase, is widely used for the treatment of obesity. The bacterium Streptomyces toxytricini is the main source for the production of lipstatin/orlistat. There are continuous attempts to increase the production of lipstatin in S. toxytricini. For optimization of best conditions/strains for lipstatin production, there are requirements for a fast, simple, and reliable method to detect/estimate lipstatin. At present, highly sophisticated methods such as high‐performance liquid chromatography, mass spectrometry, and so forth are available for the detection and estimation of lipstatin/orlistat. These methods are very costly, time‐consuming, and require state of the art facility. Here we report a simple, fast, cost‐effective method based on thin‐layer chromatography for the detection of lipstatin in S. toxytricini. The optimized mobile phase was acetone: ethanol in a ratio of 3:7. Development of thin‐layer chromatography was done by ρ‐anisaldehyde staining that showed the pink color to the silica plate and greenish‐blue color to the lipstatin/orlistat drug. Conclusively, here we mention a simple and reproducible method of detection of orlistat and lipstatin samples extracted from S. toxytricini.