Thin-layer Chromatography Plates Research Articles

Aggregation-induced emission enhancement (AIEE) active bispyrene-based fluorescent probe: “turn-off” fluorescence for the detection of nitroaromatics

The detection of nitroaromatic explosives in real samples is essential for environmental monitoring because of their strongly powerful nature and wide applications in industries. Aggregation-induced emission enhancement (AIEE) active fluorescent probe has been widely employed to detect nitroaromatic explosives. Hereby, a simple V-shaped bispyrene-based fluorescent probe (called py-o) with AIEE properties was designed and synthesized, which was fully charactered by 1D NMR, ESI, FTIR, and 2D NOESY spectra. The py-o displayed bright blue-green fluorescence excimer emission at 480 nm in DMF/H2O (v/v 1:1). It is observed that the fluorescence excimer emission of py-o at 480 nm was quenched by PA in solution with a quenching constant of 5.45 × 104 M–1, and the limit of detection was approximately 0.139 μM. The details of the sensing mechanism were explained using 1H NMR titrations, Job’s plot and Bensi-Hildebrand methods, which revealed a 1:1 binding ratio via the π-π interactions between PA and py-o. Meanwhile, it exhibited outstanding anti-interference ability in the detection of PA when interfering analytes were added under the same conditions. Furthermore, low-cost thin-layer chromatography (TLC) plates coated with py-o were developed as fluorescent tools for naked-eye detection of PA in the solid state. Therefore, this work provides a new method for constructing an AIEE fluorescent probe for the detection of nitroaromatic explosives to utilize in environmental monitoring.

Extraction, Isolation and Neuropharmacological Potential of Peristrophe bicalyculata (R.) Nees

Because of their widespread availability, low cost, low risk, and lack of side effects, medicinal herbs play a crucial role in traditional medicine all throughout the world. For medicinal purposes, Peristrophe bicalyculata (R.) is being used today. Nees as a nerve system tonic. Plant roots have antibacterial, anti-inflammatory, immunostimulating, and aphrodisiac properties. This plant root may provide health advantages, making it suitable for nutraceutical and functional food compositions. This research examined P. bicalyculata (R.) neuropharmacological effects on memory enhancement to treat cognition-related illnesses and learning and memory disorders. In phytochemical investigation, P. bicalyculata (R.) Nees ethanolic extract has higher phytoconstituents. Spectrophotometric and thin layer chromatography (TLC) plate bioassay detection showed that P. bicalyculata (R.) Nees ethanolic extract inhibits acetylcholinesterase activity. TLC and high-performance thin layer chromatography (HPTLC) were performed on P. bicalyculata (R.) Nees ethanolic extract. TLC and HPTLC spots are well resolved, indicating active ingredients in the extract. Total phenolic, flavonoid, and ascorbic content of P. bicalyculata (R.) Nees ethanolic extract was measured. Ex-vivo tests like lipid peroxidation testing reveal the extract is antioxidant. In conclusion, the ethanolic extract of P. bicalyculata (R.) Nees has memory-enhancing, antidepressant, and neuroprotective properties due to its anticholinesterase potential, effect on neurotransmitters like dopamine and serotonin, and antioxidant profile. More research is needed on its safety, effectiveness, and mechanism of action for therapeutic use.

Desitometric Development and Validation for Simultaneous Determination of Antiretroviral Drugs Lamivudine, Zidovudine and Nevirapine in Fixed-Dose Combination Tablets

A cutting-edge high-performance thin layer chromatography (HPTLC) approach designed for simultaneous measurement of tablets containing drugs like lamivudine, nevirapine, and zidovudine. Chromatograms were performed employing chloroform and methanol (8:2 v/v) on pre-coated silica gel aluminum thin-layer chromatography (TLC) plates. The data was quantified using the optical density absorbance mode at 271 nm. The Rf values for lamivudine, zidovudine, and nevirapine were 0.140, 0.523, and 0.678, respectively. Linearity was found for lamivudine, zidovudine and nevirapine at concentrations of 150 to 900 ng band-1, 300 to 1800 and 200 to 1200 ng band-1, respectively. Lamivudine had a lower limit of detection (LLoD) of 27.36 ng band-1 and a lower limit of quantitation (LLoQ) of 82.91 ng band-1, whereas zidovudine had LoQs of 64.13 ng band-1 and 194.34 ng band-1. For nevirapine, the values were 35.52 and 107.64 ng band-1, respectively. Lamivudine had a lower LoD of 27.36 ng band-1 and a lower LoQ of 82.91 ng band-1, whereas zidovudine had LoQs of 64.13 and 194.34 ng band-1. For nevirapine, the values were 35.52 and 107.64 ng band-1, respectively. The recovery, specificity, and accuracy of this device have been demonstrated. This new formulation evaluated market tablet formulations of the above drugs (Duovir, Cipla Ltd.). The developed method demonstrated the ability to simultaneously identify these drugs from quantitative data without interference.

Amino acid profile and potential biomass conversion of Vitellaria paradoxa fruit pulp

Vitellaria species is one of Africa's most important fruit crops with enormous human benefiting nutrients including amino acids. This study characterised Vitellaria paradoxa shea nut pulp from 5 regional zones of Ghana based on its acidity, pH and among the few for its qualitative and quantitative amino acids profile. Thin Layer Chromatography (TLC) techniques, using cellulose TLC plates were used to profile and quantify the amino acids. Fifteen essential amino acids were detected in the Vitellaria paradoxa shea nut pulp. Alanine, arginine, glutamic acid, glutamine and histidine were common in the Vitellaria paradoxa shea nut pulp. The most concentrated (41.02 g/100 g) of the 7 essential amino acids in the shea nut pulp was arginine and the least was glycine, 2.12 g/100 g. All seven 7 essential amino acids, except leucine and valine, were significantly different (P < 0.05) across the 5 shea regional zones of Ghana. The most acidic pulp, with 18.63% acidity, was from the Upper West Region. The quality and quantitative of amino acids in Vitellaria paradoxa shea nut pulp differed significantly from one region to the other. The shea nut pulp is a good source of essential amino acids and can be used fruit juice production and provide the required N for an effective fermentation to proceed. This has remarkable economic implication and significant environmental effects. Some health benefits of eating shea nut fruits consequential of its nutritional effects due to its amino acids composition have been noted to include its ability to help improve mood, boost exercise performance, prevent muscle loss and promote weight loss. Moreover, the amino acids profile of shea nut pulp may provide researchers with useful applications of the Vitellaria paradoxa shea nut pulp in the various industries.

Antifungal and antioxidant properties of medicinal plants used against fungal infections

Background: Antioxidants present in plant extracts prevent free radicals from causing chronic diseases in humans.Aim: The study investigated 12 medicinal plants (Kleinia longiflora DC., Berchemia discolor [Klotzsch] Hemsl., Persea americana Mill., Sansevieria hyacinthoides [L.] Druce, Dichrostachys cinerea [L.] Wright Arn, Withania somnifera Dunal [Ashgandh], Momordica balsamina L., Lonchocarpus capassa, Pappea capensis, ‘Rhus lancea L. fil’ with ‘Searsia lancea (L.F.) F.A. Barkley’ Peltophorum africanum, Maytenus heterophylla [Eckl. Zeyh.] Robson) for antioxidant activity using the qualitative and quantitative 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay.Setting: The plant species were selected from the ethnomedicinal plant database of over 300 medicinal plants used for therapeutic purposes in Limpopo province.Methods: The plant materials were extracted with solvents of various polarities such as acetone, dichloromethane (DCM), methanol, hexane, and water. The qualitative and quantitative DPPH methods were used to determine the antioxidant activities of plant extracts.Results: The yellow bands revealed the presence of antioxidant compounds against the purple background on the Thin Layer Chromatography (TLC) plates. Methanol, hexane, and water extracts of L. capassa were the most active radical scavengers in the DPPH assay among the six medicinal plants screened. Plant extracts of P. africanum showed strong antioxidant activity by inhibiting DPPH, compared with the standard ascorbic acid.Conclusion: The findings indicate that some extracts can be used as an easily accessible source of natural antioxidants.Contribution: The findings revealed that the plant species investigated displayed noteworthy antioxidant activity, which provides scientific evidence for their utilisation by traditional health practitioners to treat fungal infections.

Contaminant Spot Check and Removal Assay (ContamSPOT) for Mass Spectrometry Analysis.

Mass spectrometry (MS) analysis is often challenged by contaminations from detergents, salts, and polymers that compromise data quality and can damage the chromatography and MS instruments. However, researchers often discover contamination issues only after they acquire the data. There is no existing contaminant assay that is sensitive enough to detect trace amounts of contaminants from a few microliters of samples prior to MS analysis. To address this crucial need in the field, we developed a sensitive, rapid, and cost-effective contaminant spot check and removal assay (ContamSPOT) to detect and quantify trace amounts of contaminants, such as detergents, salts, and other chemicals commonly used in the MS sample preparation workflow. Only 1 μL of the sample was used prior to MS injection to quantify contaminants by ContamSPOT colorimetric or fluorometric assay on a thin layer chromatography (TLC) plate. We also optimized contaminant removal methods to salvage samples with minimal loss when ContamSPOT showed a positive result. ContamSPOT was then successfully applied to evaluate commonly used bottom-up proteomic methods regarding the effectiveness of removing detergent, peptide recovery, reproducibility, and proteome coverage. We expect ContamSPOT to be widely adopted by MS laboratories as a last-step quality checkpoint prior to MS injection. We provided a practical decision tree and a step-by-step protocol with a troubleshooting guide to facilitate the use of ContamSPOT by other researchers. ContamSPOT can also provide a unique readout of sample cleanliness for developing new MS-based sample preparation methods in the future.

Facile fluorescence detection of malachite green in fish using molecularly imprinted polymers doped CdTe quantum dots based system

Malachite green (MG) possesses high toxicity, therefore, the detection of MG in fish tissues is of vital importance. A novel core–shell MIPs doped CdTe quantum dots coated silica nanoparticles (CdTe-MIP/SiO2 NPs) were synthesized via a simple one-pot strategy. The materials were characterized carefully. The resulting CdTe-MIP/SiO2 NPs were coated on the thin layer chromatography plate, and coupled with miniaturized fluorimeter for fluorescence detection of MG in fish samples. The resulting CdTe-MIP/SiO2 NPs based system possessed good linearity (0.01 ∼ 20 μmol/L), high recoveries (98.36 %∼101.45 %) and low detection limit (3.7 nmol/L) for MG. Furthermore, CdTe-MIP/SiO2 NPs based system were employed to measure fish samples spiked with MG, meanwhile, HPLC was utilized to evaluate the accuracy and reliability. And the paired t-test was conducted to evaluate differences between fluorescence method and HPLC, P > 0.05 means no significant difference was observed, the results demonstrated that both fluorescence method and HPLC are suitable for MG analysis.

Antiinflammatory Lupeol and Antidiabetic Compound Coexist in Ethyl Acetate and n-Hexane Extracts from Stem Bark of Anogeissus leiocarpus (African Birch Tree): The Therapeutic Advantages

Objectives: Anogeissus leiocarpus stem bark is endowed with numerous antidiabetic properties, such as its prognostic value, treatment of organic damages, dyslipidaemia and enhancement of haematopoiesis. In addition to its antioxidant activity on oxidative stress, it accelerated wound healing and has a wide range of safety value. From the purification of its compounds to the points of crystallization it became necessary to analyse the structures for an insight into its mechanisms of actions.&#x0D; Design: Ethanolic extracts were partitioned with ethyl acetate, onto column chromatography packed with silica gel (70-230 mesh) mixed with 95% n-hexane and 5% ethyl acetate; concentrated fractions were loaded onto silica gel-coated thin layer chromatographic plate. Different compounds were observed under UV-light fluorescence and sprayed with sulfuric acid. Similar fractions were pooled, purified to crystals for Nuclear Magnetic Resonance structural analysis.&#x0D; Results: Nuclear Magnetic Resonance revealed fraction A is Lupeol, a pentacyclic triterpene anti-inflammatory compound.&#x0D; Conclusion: Lupeol in the crude ethanolic extract is significant in inflammatory pain of diabetes.&#x0D; Keywords: Lupeol, Anti-inflammatory, Anogeissus leiocarpus, Purified extract, inflammatory pain, Diabetes mellitus.

Speciation of inorganic arsenic by μ-thin-layer chromatography coupled with laser ablation inductively coupled plasma mass spectrometry based on an ion imprinted polymer.

An efficient strategy utilizing μ-thin layer chromatography coupled with laser ablation inductively coupled plasma mass spectrometry (μ-TLC-LA-ICP-MS) based on an IIP (ion imprinted polymer) was developed for the speciation of inorganic arsenic [As(III) and As(V)]. The characterization of the fabricated IIP was performed applying Fourier-transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). To prepare the thin layer chromatography plate, CaSO4 (as a binder) was incorporated with the IIP. Then, the surface of the TLC plate was swept by LA, which volatilized the species of arsenic from the thin layer chromatography plate which thereafter were introduced into the ICP-MS system. Various effective parameters on isolation efficiency, such as the IIP/CaSO4 mass ratio, mobile phase composition, and pH, were examined. Under optimized conditions, the developed method demonstrated a detection limit of 0.3 μg L-1 with a wide linear dynamic range of 0.2-100 μg L-1, and a relative standard deviation of 3.8. The performance of the developed method was investigated for the isolation of As(III) and As(V) in wastewater (Mouteh, Aghdareh, and Zarmehr mines) and human blood plasma real samples.

Optimizing solid-state fermentation for metabolite enrichment by Aspergillus tamarii on rice bran and wheat

Globalization has led to an increase in the global population and drug resistance, necessitating the development of novel pharmaceuticals. Fungi represent a promising source for new drugs, producing a diverse array of secondary metabolites, some of which are integral to clinically essential drugs. This study aimed to determine the optimal conditions for enhancing metabolite production by the Indonesian fungal strain Aspergillus tamarii (IPBCC 880066) when cultivated on solid media, specifically rice bran and wheat. The optimal fermentation conditions, including moisture content, growth temperature, and incubation duration, were determined based on the number of spots observed on thin-layer chromatography plates. Results indicated that the optimum conditions for metabolite production were a 40% moisture content, a growth temperature of 25°C, and a 14-day incubation period. Subsequent UPLC-MS/MS analysis identified 22 metabolites produced by A. tamarii on rice bran and 20 metabolites on wheat. Notably, two compounds, N-(2-hydroxypropyl)-2-methylacrylamide and N6-[(benzyloxy)carbonyl]-L-lysine, were detected in both rice bran and wheat fermented by A. tamarii. Some of the identified metabolites have the potential to be applied in the pharmaceutical industry. In conclusion, our study emphasizes A. tamarii’s efficacy in diverse metabolite production under optimized conditions, providing valuable insights for maximizing fungal metabolite production in potential pharmaceutical applications.

A rapid optimization method for Sepbox system separation using HPTLC: an application of Cerbera manghas L. separation.

The rapid isolation of natural products and efficient drug screening are pivotal in expediting drug development. Techniques ranging from traditional open column chromatography to medium-pressure liquid chromatography (MPLC), and the latest Sepbox technology, have been developed to accelerate separation processes and streamline drug development timelines. The Sepbox system combines two-dimensional high-performance liquid chromatography (2D-HPLC) and solid-phase extraction (SPE) technologies, coupled with UV and evaporative light scattering detection (ELSD) systems, offering various column options to cater to diverse sample requirements. Furthermore, the Sepbox system automates and expedites sample fractionation into numerous fractions, facilitating subsequent high-throughput screening and analysis. Despite previous emphasis on 2D-HPLC development, optimizing separation conditions with the Sepbox system poses challenges due to the requirement for substantial sample and solvent quantities, limiting its practicality compared to conventional methods. Hence, this study employed eight standard compounds to explore the correlation between retention factor (Rf) values obtained from high-performance thin-layer chromatography (HPTLC) plates and retention times on the Sepbox main column. Mass spectrometry was utilized to confirm the retention times of the standard compounds. The findings yielded a conversion equation between HPTLC Rf values and Sepbox main column retention times, thereby enhancing the separation efficiency of Sepbox 2D-2000 system. Finally, the efficacy of this method was validated using Cerbera manghas leaf crude extracts and its purified compounds, demonstrating the rapid optimization of suitable elution conditions for the Sepbox 2D-2000 system using HPTLC.

Investigation of Metabolites Isolated from Sphingomonas Egypticus DM, A Rhizosphere of Datura Metel

Using naturally occurring bioactive compounds has been crucial in progressing contemporary medical practices. The rhizosphere, which refers to the narrow region of soil surrounding plant roots, serves as a highly dynamic environment for soil bacteria owing to the substantial quantity of organic compounds released into the soil by plant roots. This paper outlines the fermentation and subsequent processing of rhizosphere Sphingomonas egypticus DM. The culture media of Sphingomonas was cultivated and subsequently subjected to propagation. The ethyl acetate extract was then obtained and subjected to fractionation and purification utilizing various chromatographic techniques. This process led to the isolation of a compound under investigation that exhibited a distinct spot on thin-layer chromatography (TLC) plates, with a calculated retention factor (Rf = 0.56) using a mobile phase composed of methylene chloride and methanol (9:1). Upon spraying with anisaldehyde/sulphuric reagent and subsequent heating for a brief period, the compound displayed a violet colour. This compound was investigated in vitro to assess its antimicrobial and minimum inhibitory concentration (MIC) capabilities. The results demonstrated a significant inhibitory effect against phytopathogenic fungi, specifically Rhizoctonia solani (21.3 mm) and Alternaria alternate (18.3 mm). Additionally, a moderate inhibitory effect was observed against Pseudomonas aeruginosa (12.7 mm), whereas a somewhat less inhibitory effect was shown against Streptococcus mutans (9.3 mm). The study also demonstrated that (MIC) against Fusarium oxysporum was seen at a concentration of 125 µg/mL compared to various conventional antibiotics. Finally, the strain underwent PCR screening to detect PKS and lipopeptide 4'-phosphopantetheinyl transferase sfp genes. The PCR amplification assay demonstrated the presence of genes encoding the KS domain and Surfactin. Furthermore, the sequences of Sphingomonas egypticus DM have been officially recorded in the NCBI GenBank database and can be accessed using the accession codes OR469907 and OR499756.

TLC-fingerprinting and chemometrics for identification of Curcuma xanthorrhiza from different geographical origins in Indonesia

Abstract. Kartini K, Sabatini SS, Haridsa NM, Jayani NIE, Setiawan F, Hadiyat MA. 2023. TLC-fingerprinting and chemometrics for identification of Curcuma xanthorrhiza from different geographical origins in Indonesia. Biodiversitas 24: 6557-6566. Geographical origin is an important parameter that influences the quality of herbal medicine. The fingerprint of herbal plants is expressed as chemical compounds contributing to said quality. Curcuma xanthorrhiza, popular as java turmeric, is extensively used in Indonesian traditional medicine. This study aimed to validate and develop a Thin Layer Chromatography (TLC) fingerprint of C. xanthorrhiza, followed by chemometric techniques to classify C. xanthorrhiza rhizomes from 15 regions in Indonesia. Under selected TLC conditions (i.e., stationary phase: TLC plate Silica gel 60 GF254, mobile phase: dichloromethane, chloroform, and ethanol (10: 10: 1), detection: vanillin-sulfuric acid reagent), C. xanthorrhiza produced five zones of the compound. Extracts were stable both on the TLC plate and in the extract solution during chromatography and within 60 minutes after derivatization. In terms of precision, the chromatogram meets the requirement of intraday precision. Chemometric analysis with Principal Component Analysis (PCA) and Cluster Analysis (CA) showed that the samples of C. xanthorrhiza from 15 regions in Indonesia were grouped into five clusters based on the similarity of the chemical compounds, namely cluster 1 (Tawangmangu, Bangkalan, Kediri, and Surabaya); cluster 2 (Batu, Sragen, Tulungagung, Pasuruan, Blitar, and Lombok Tengah); cluster 3 (Ngawi); cluster 4 (Gresik); and cluster 5 (Bojonegoro, Banyuwangi, and Palangkaraya). The TLC fingerprinting with chemometrics on C. xanthorrhiza rhizome is useful for quality control based on geographic origin and authenticity identification.

Evaluation of Stability and TLC Fingerprinting of the Artemether Component in Artemether-Lumefantrine Combination Suspension Formulations Available in Nigeria Pharmaceutical Market

Aim: Artemether is the main component of the artemisinin-based combination therapy (ACT), used in the management of malaria infection caused by Plasmodium falciparum. Hence, its stability and conformation to pharmacopeia standards are necessary for use. The study aimed to review the first-order derivative spectrophotometric method for simultaneous estimation of artemether and its derivatives in pure and combined formulations, and their stability profiles, then develop a simple, precise, and fast technique for their rapid physicochemical analysis.&#x0D; Methodology: Thin-layer chromatographic (TLC) Fingerprinting principles were used in the analysis. Artemether and its derivatives were spotted on the TLC chromatograms after adding 25 mL of the suspension to a mixture of 100 mL of distilled water and 4 mL of NaOH, extracting the mixture with 60 mL of dichloromethane (DCM), drying, and sonicating the residue with 20 mL of the solvent. It was centrifuged, and the clear supernatant was spotted on the TLC plates.&#x0D; Results: The color test results revealed the presence of the artemether compound in the reference standard as well as the six brands of suspensions (A, B, C, D, E, and F) utilized in the study. Artemether melting point was obtained between 86 - 89 °C; within the International Pharmacopeia specified range. The chromatograms of Artemether and derivatives showed Rf values of 0.25 (impurity A), 0.3 (artenimol impurity B), 0.35 (impurity C), 0.4 (α-artemether: impurity D), and 0.55 (artemether).&#x0D; Conclusion: The devised method can be applied to the routine quality control analysis of artemether-lumefantrine suspension in addition to existing analytical techniques.

Quantitative monitoring ofloxacin in beef by TLC-SERS combined with machine learning analysis

Ofloxacin is one kind of quinolone antibiotic drugs, the abuse of ofloxacin in livestock and aquaculture may bring bacterial resistance and healthy problem of people. The illegally feeding cattle with ofloxacin will help it keep health, but the sedimentation of ofloxacin could bring problem in food safety. The accurate, simple and instant monitoring ofloxacin from beef by portable sensor was of vital issue in food quality. A simple and reliable method was proposed for instant and quantitative detecting ofloxacin in beef, in which the thin-layer chromatography (TLC) -surface-enhanced Raman scattering (SERS) spectroscopy was in tandem with machine learning analysis base one principal component analysis-back propagation neural network (PCA-BPNN). The TLC plate was composed with diatomite, that was function as the stationary phase to separate ofloxacin from beef. The real beef juice was directly casted onto the diatomite plate for separating and detecting. The directly monitor ofloxacin from beef was achieved and the sensitivity down to 0.01 ppm. The PCA-BPNN was used as reliable model for quantitative predict the concentration of ofloxacin, that shown superior accuracy compared with the traditional model. The results verify that the diatomite plate TLC-SERS combined with machine-learning analysis is an effective, simple and accurate technique for detecting and quantifying antibiotic drug in meat stuff to improve the food safety.

A new universal detection system for high-performance thin-layer chromatography plates using chemiluminescence

High-performance thin-layer chromatography (HPTLC) is a cost-effective method for the separation of small molecules, such as active pharmaceutically ingredients. The method can be used without sophisticated equipment. For example, the detection and quantification of colored compounds on an HPTLC plate can be performed with a CCD camera. For noncolored compounds, a new dipping solution for the generation of chemiluminescence on an HPTLC plates is presented. In combination with a charge-coupled diode (CCD) camera, this can be used as a universal detection system. The efficiency of this new staining reagent is demonstrated by the detection of trimethoprim and sulfamethoxazole from a fixed-dose combination in a ratio of 1:5.

Facile chemical hydrophobization of thin-layer plates by vapor deposition of methyltrimethoxysilane for reversed-phase chromatography

Reversed-phase chromatography is based on a polar mobile phase and an apolar stationary phase. This separation mode is regularly used in planar (thin-layer) chromatography, and the necessary plates are commercially available. We investigated the preparation of hydrophobic plates for thin-layer chromatography by chemical vapor sorption of methyltrimethoxysilane directly onto a normal-phase plate. For this, a commercial normal-phase plate is simply exposed to the vapors of the reagent in a closed vessel. The obtained plates were characterized by infrared spectroscopy and dynamic water vapor sorption, which reported an extensive conversion of free hydroxyl groups by the reagent. The obtained plates were hydrophobic with a water contact angle close to 135°. The extent of hydrophobization precluded the use of pure water as an eluent while mixtures with organic solvents were perfectly adequate. The plates’ chromatographic performance was compared with that of C18 and paraffin-coated plates. For this, a set of parabens was separated with mixtures of acetone and water. The height of a theoretical plate was similar for the hydrophobized and the C18 plates (50–90 µm) and larger for the paraffin-coated ones. In contrast to the C18 plate, the hydrophobized and the paraffin-coated plates showed some selectivity for the analyte pair n-butylparaben and iso-butylparaben, which indicates a separation mechanism with the potential for regioselectivity.

Phytochemical Compounds and Antimicrobial Activity of Extracts of Bamboo Against Staphylococcus aureus and Escherichia coli

Plants contain bioactive compounds which can be used to develop novel antibiotics. There is need to search for new antimicrobial compounds to address the problem of microbial resistance against antibiotics. Little research has been done on phytochemical and antimicrobial activity of Bambusa vulgaris. The study was designed to screen phytochemical compounds present in the roots and leaves extracts and to test antimicrobial activity of the extracts of Bambusa vulgaris against Staphylococcus aureus and Escherichia coli. Plants were collected from Maseno University Botanic Garden. Roots and leaves were dried separately, ground into fine powder and extracted using Soxhlet method. Phytochemicals: flavonoids, saponins, terpenoids, tannins, alkaloids and glycosides were tested. Thin layer chromatography plate was coated with silica gel. n-Hexane and Ethyl acetate were used as solvents in the ratio 2:3 respectively. Plant extracts were prepared; 25%, 50%, 75%, and100% (stock extract) and Positive control (Amoxicillin). The bacteria were inoculated into the nutrient agar. Antimicrobial activity of acetone extracts of leaves and roots were carried out by disc diffusion method. Diameter of inhibition zones was measured using a ruler. The leaves extracts were found to contain saponins, flavonoids, glycosides tannins and terpernoids. The root extracts contained saponins, glycosides and tannins. TLC revealed that there were 7 spots in the leaves and 4 spots in roots extract. Increase in concentration of the leaves and roots extracts of Bambusa vulgaris significantly inhibited the growth of Staphylococcus aureus and Escherichia coli. Leaves extracts showed a higher inhibition activity compared to roots. The growth inhibition may be attributed to the presence of the various phytocompounds. The study has shown that Bambusa vulgaris leaf methanol extract has antimicrobial activity against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria and hence can be used as source of bioactive agents to control these pathogens.

Development of a thin layer chromatography-based method to detect sorbitol presence in milk and its applicability in formalin preserved milk samples.

Sorbitol has been the new and emerging adulterant in dairy industry. The main aim of the study was to develop a method to detect sorbitol in milk, which is not affected by other sugars, polyols and formalin. Hence, a thin layer chromatographic (TLC) method was standardized to detect the sorbitol in milk. In the study 90s duration for the impregnation of Silica gel 60F TLC plates with Cu- ions was found suitable to resolve sorbitol as a distinct spot. The standardized conditions were (1) developing solvent system consisting of n-propanol: ethyl acetate: water (7:1:2), (2) 0.5% of potassium permanganate in 0.1M NaOH as color developing reagent. (3) Drying temperature (65°C/ 10min.) after spraying the color developing reagent. The limit of detection was 0.2% of added sorbitol in milk. The standardized method could also detect the sorbitol in the presence of sucrose, glucose and polyols like mannitol and maltitol. In both cow and buffalo milk samples the standardized methodology performed well in detection of sorbitol. The method also performed well in sorbitol spiked formalin preserved milk samples. This method can be an alternative to the other methods involving costly equipment in detecting adulteration of milk with sorbitol.

Analysis of polyisoprene oligomers via in situ silver nanoparticle formation on thin-layer chromatography plate using matrix-assisted laser-induced desorption/ionization mass spectrometry.

The direct mass spectrometry (MS) detection of polyisoprene (PI) oligomers on a thin-layer chromatography (TLC) plate using matrix-assisted laser-induced desorption/ionization (MALDI) with silver trifluoroacetate as the cationization reagent was investigated. The spots of PI oligomers and silver trifluoroacetate on the TLC plate resulted in brown materials after UV laser irradiation. It was suggested that silver trifluoroacetate yielded Ag nanoparticles as brown materials after heating via laser irradiation. The nanoparticles behaved as an inorganic matrix and a source of Ag+ adduct in the analysis of PI oligomers. The use of organic matrices together with silver trifluoroacetate reduced the signal intensity of PI oligomers on MALDI-MS on a TLC plate. The separation of PI oligomers (polymerization degree, n = 5-11) by TLC resulted in a single elliptical spot without a clear separation after the chromatographic procedure. However, in MS imaging, differences in migration lengths based on degrees of polymerization were clearly observed and the degrees of polymerization were identified without comparison with standards.