Titration Method Research Articles

Tannin gradation of living pine (Pinus merkusii) and mahogany (Swietenia mahagoni) bark

ABSTRACT This study aims to assess the tannin gradation extracted from the bark of pine and mahogany tree. Tannin content was analyzed using the permanganometric titration method and was identified using gas chromatography-mass spectrometry. The results show that pine and mahogany bark consist of three and four layers, respectively. The secondary phloem of pine locates in the deepest layer, while its periderm locates in the first and second outermost layers. The secondary phloem of mahogany locates in the first and second innermost layers, while its periderm locates in the first and second outermost layers. It is found that higher in vertical position of bark on the tree, the smaller in amount of tannin could be extracted, both on pine and mahogany tree. However, the outer layer of both pine and mahogany barks provides lower tannin content. It could be suggested from this study that tannin from pine bark should be extracted from the layer near the cambium, meanwhile tannin from mahogany bark should be extracted from the middle layer of the bark. Thus, large amounts of tannin from living tree bark could be obtained without damaging the tree's physiology or inhibiting tree growth.

A novel mucoadhesive paliperidone-nanoemulsion developed using the ultrasonication method in the treatment of schizophrenia.

Aim: To develop paliperidone mucoadhesive-nanoemulsion (PLP-NE) to enhance brain bioavailability. To evaluate comparative effects of PLP-NE and CS-PLP-NE in the treatment of schizophrenia, followed by a toxicity study of opt-NE. Material and methods: Oil: oleic acid, surfactant: Tween-80, and co-surfactant: Labrasol were chosen based on the solubility and maximum nanoemulsion area. The ultrasonication technique was applied with the aqueous micro titration method for the development of PLP-NE. The optimization of the method for the excellent PLP-NE was performed using a central composite design based on a five-factor and four-level. Oil (% v/v), S mix (v/v%), ultrasonication intensity in percentage, ultrasonication time in minutes, and temperature (°C) were optimized and used to the independent variables. Results: The parameters i.e., oil (5%), S mix (10%), ultrasonication time (5.0 min), ultrasonication intensity (25%), and temperature (38 °C) were optimized and used as independent and dependent variables for the development of novel PLP-NE. Based on experimental data, the dependent variables, i.e., globule size (53.90 ± 4.01 nm), % transmittance (92.56% ± 1.06%), PDI (0.218 ± 0.007), and zeta potential (-11.60 ± 0.031 mV), were determined. The smooth near about spherical shaped of PLP-NE globules with, refractive index i.e., 1.62 ± 0.021, viscosity: 39 ± 6 cp with the pH: 7.40 ± 0.089, and content of drug (97.98 ± 0.39%) for optimized-PLP-NE. The optimized PLP-NE with oleic acid, Tween-80, and Labrasol was used to improve brain bioavailability with good permeation via the intranasal route. CS-PLP-NE yielded good mucoadhesive property results compared to paliperidone-nanoemulsion, and PLP-S containing a 0.751 minutes retention time with their deuterated-IS (0.806 min) and m/z of 427.2/207.2 with IS (m/z: 431.2/211.2) for PLP and PLP-IS. A calibration curve was plotted with a linear range of 1-2000 ng mL-1 with inter- and intraday accuracy (97.03-99.31%) and precision (1.69-50.05%). The results of AUC(0-24) and C max for PLP were found to be highly significant (p < 0.001) as an improvement of brain bioavailability in rats via intranasal delivery of CS-PLP-NE. Furthermore, the locomotion test, social interaction, and forced swimming test (forced swimming, climbing, and immobility) of a mucoadhesive CS-PLP-NE (intranasally) provided highly significant results with the improvement of behavioral analysis when compared to the PLP-NE and PLP-S studies. Conclusion: CS-PLP-NE (i.n.) showed highly significant results, i.e., p < 0.001 for the improvement of bioavailability of the brain in the treatment of schizophrenia. Optimized-mucoadhesive-CS-based-PLP-NE is safe and shows no toxicity.

Sulfonated graphitic carbon catalyst derived from coffee waste: A sustainable valorization approach for highly efficient production of 5-hydroxymethylfurfural (5-HMF) from fructose

According to recent research, a sulfonated 2D graphitic carbon catalyst for the dehydration of fructose to the platform chemical 5-Hydroxymethylfurfural (5-HMF) can be made from used ground coffee. By carbonizing and activating at different temperatures, sulfonated graphitic carbon (SC) catalysts with varied chemical compositions and textural characteristics were obtained. The physical and chemical characteristics of the SC catalysts were assessed using XRD, Raman, SEM-EDX, HR-TEM, BET analysis, and XPS. Due to its microporous structure, SC-900 exhibited a high specific area and demonstrated selective and efficient production of 5-HMF from fructose. All in all, the surface acidity of catalysts was measured by NH3-TPD, and acid-base titration methods. The SC-900 catalyst, designed through carbonization at 900 ℃, achieved a fructose conversion rate of 100 % and a 5-HMF yield of 97.91 % without generating any by-products. This indicates the catalyst essentially produces 5-HMF under the specified optimal conditions (140 ℃, 90 min) observed in this study. To determine the origins of the highly efficient and highly selective conversion of fructose to 5-HMF, the performance of the SC catalysts was systematically investigated vi-a-vis their physical and chemical properties. The development of microporous SC catalysts and their application as catalysts not only enhances the value of waste coffee but also provides an environmentally friendly approach for converting carbohydrates into 5-HMF.

An isocratic HPLC-UV analytical procedure for assessment of glutathione and its related substances

Reduced glutathione (GSH) is an endogenous tripeptide antioxidant which plays a crucial role in a variety of physiological and pathological activities. Although GSH is not present in any FDA-approved drug product, GSH dietary supplement products and compounded GSH drugs are available to patients in the US. Several incidents of toxicity have occurred in recent years due to endotoxin or otherwise contaminated GSH in compounded drugs. Efficient and sensitive analytical methods are needed for assessing and ensuring the quality of GSH substance and associated drug or dietary supplement products. Impurities A (L-cysteinylglycine), B (cysteine), C (oxidized L-glutathione) and D (γ-L-glutamyl-L-cysteine) are the main related impurities for GSH drug substance which have been detected and quantified by capillary electrophoresis and qNMR analytical procedures. However, there are no reported HPLC methods for detecting or quantifying the three main related impurities A, B and D even though numerous HPLC analytical methods have been reported for analyzing GSH and impurity C. In this report, an isocratic HPLC-UV analytical procedure was developed and validated for separating and identifying GSH and related impurities A-D as well as a newly identified degradant, L-pyroglutamic acid (pGlu), within 10 minutes with resolution (RS) more than 3. The LOD and LOQ were determined to be 0.02 % w/w and 0.05 % w/w, respectively, for impurities A-D and pGlu. Importantly, the optimized HPLC analytical procedure for GSH assay does not have interference from impurities A, B and D, providing highly specific results compared to the commonly used iodine titration method. The newly validated analytical procedure was applied to assess different commercial GSH bulk substance samples. The results suggest that the analytical procedure described in this work is suitable for quality assessment of GSH samples.

Oxygen Measurement in Cuprate Superconductors Using the Dissolved Oxygen/Chlorine Method

We have developed a dissolved oxygen (DO) method with differential equation (DE) correction. We measured the oxygen content in La-based and Y-based superconductors, and succeeded in measuring the oxygen content simply in one-third of the time required by the iodometric titration method. However, there was a problem with Bi-based superconductors where the measured oxygen content was smaller compared to the iodometric titration method. We hypothesized that not only O2 but also Cl2 gas is generated when dissolving Bi-based superconductors and developed a dissolved oxygen/chlorine (DO/Cl) method with DE correction. This method uses only a dissolved oxygen sensor and a dissolved chlorine sensor to measure the dissolved oxygen and dissolved chlorine content in Bi2Sr2−xLaxCuOy, allowing for the calculation of copper valence and oxygen content. The results from the DO/Cl method with DE correction show that the measured copper valence and oxygen content differ very little from those obtained using the iodometric titration method, with discrepancies within 0.016 and 0.008, respectively. Additionally, this method reduces the measurement time by one-third compared to the iodometric titration method. The results demonstrate that the DO/Cl method with DE correction can effectively measure the copper valence and oxygen content in cuprate superconductors, and using hydrochloric acid as the experimental solution is superior to sulfuric acid and nitric acid.

Thermodynamic and surface active investigations of aqueous solution of sodium dodecylbenzene sulfonate in presence of builders: sequestration of Ca2+ ions and interaction with H2O2

Abstract The current investigation examines the micellization process of sodium dodecylbenzene sulfonate in aqueous media with builders at temperatures ranging from 298.15 K to 313.15 K. Using conductometry and tensiometry analyses, the study examines changes in micellar properties in different surfactant solutions, focusing primarily on CMC. Additionally, the variation of CMC with temperature was used to determine the thermodynamic parameters of micellization such as ∆ G m ° , Δ H m ° , ${{\increment}G}_{\mathrm{m}}^{{}^{\circ}},{\Delta }{H}_{\mathrm{m}}^{{}^{\circ}}\text{,}$ and ∆ S m ° ${{\increment}S}_{\mathrm{m}}^{{}^{\circ}}$ . This approach provides valuable insights into the behavior of the surfactant and the different intermolecular interactions involved in the system. The different surface active parameters π CMC, A min, and Γ max were elucidated using tensiometry via the Wilhelmy plate technique. Moreover, the capacity of the builder to sequester calcium ions was studied using a well-established titration method, offering valuable insights into their effectiveness. Their efficiency under oxidative conditions, particularly in preventing the interaction between copper ions and hydrogen peroxide, was evaluated. This article provides a comprehensive analysis of different builders when used with the anionic surfactant, sodium dodecylbenzene sulfonate. Their combination provides improved efficiency in protecting metals from corrosion, extracting heavy metals from polluted soils, and in personal care products such as shampoos and soaps.

Genomic Insights into and In Vitro Evaluation of Antimicrobial Combination Therapies for Carbapenem-Resistant Acinetobacter baumannii.

Background and Objectives: Acinetobacter baumannii (A. baumannii), particularly carbapenem-resistant A. baumannii (CRAB), represents a grave concern in healthcare settings and is associated with high mortality. This study aimed to conduct molecular, mutational, and phylogenetic analyses of specific genes in CRAB and evaluate the synergistic effects of selected antimicrobial combinations. Materials and Methods: Phenotypic characterization was performed on six CRAB strains by using the Modified Hodge Test (MHT) and IMP-EDTA Double-Disc Synergy Test (IMP-EDTA DDST). Carbapenemase- and metallo-beta-lactamase-encoding genes were amplified by using Polymerase Chain Reaction. Phylogenetic analysis using the MEGA 11 tool was used to determine the evolutionary relatedness of these genes. Mutational analysis was performed by using I-Mutant, MUPro, and PHD-SNP bioinformatics tools to predict mutations in the carbapenemase-encoding genes. Microdilution checkerboard titration assessed the synergistic effects of antimicrobial combinations (azithromycin-meropenem, rifampicin-meropenem, meropenem-colistin, and azithromycin-colistin) on these CRAB isolates. Results: The phenotypic characterization of six CRAB isolates revealed positive results for MHT and IMP-EDTA DDST. The molecular characterization revealed that carbapenemase- and MBL-encoding genes were present in all isolates with varying frequencies, including blaOXA-51 (100%) and blaIMP (0%). The sequence analysis revealed high evolutionary relatedness to sequences in the NCBI database. The mutational analysis identified 16 mutations, of which 1 mutation (P116L) in the blaOXA-58 gene predicted a change in the protein product, potentially contributing to carbapenem resistance. The checkerboard titration method did not reveal any synergism among the tested antimicrobial combinations against CRAB. Conclusion: This study's findings underscore the significant challenges posed by CRAB isolates harboring multiple resistant genes in treatment. This highlights the urgent need for novel antimicrobial agents, a crucial step towards reducing mortality rates not only in Pakistan but also globally.

Portable fiber-optic sensor for simple, fast, cost-effective, and environmentally friendly quantification of total acidity in real-world applications

In this work, an innovative fiber-optic sensor for measuring total acidity (TA: expressed as the % w/v of acetic acid) in beverages was developed. For this purpose, we relied on the kinetic principles of heterogeneous solid-phase reactions (slow reactions due to diffusion processes) to develop a novel pH-sensitive fluorescent membrane calibration method for the quantification of TA. In the proposed calibration method, a linear relationship between TA and the protonation rate of a pH-sensitive fluorescent membrane with a pKa ≥ 9 (Paper-FM) is established. Paper-FM was synthesized by the covalent immobilization of the pH-probe Nile Blue on a porous paper membrane. In addition, a 3D-printed interface was designed to implement Paper-FM into a 0.5 mm diameter optical fiber. The fiber-optic sensor developed in this work was tested by analyzing 21 vinegar samples of different origins, and the results were successfully validated with a reference titration method. The results presented in this work show that our fiber-optic sensor allows a direct, simple, and fast (15 s response time) quantification of TA in vinegar samples. In addition, it is environmentally friendly, because, unlike titration methods, it does not generate toxic waste, is reversible, and is extremely stable (a 0.9 mm diameter circle of Paper-FM allows at least 50 consecutive measurements).

Comparing the Two Methods of Ion Chromatography and Titration in Evaluating the Concentration of Sulfuric Acid Mist and Vapor in the General Air of the Electrolysis Unit of the Copper Production Industry

Comparing the Two Methods of Ion Chromatography and Titration in Evaluating the Concentration of Sulfuric Acid Mist and Vapor in the General Air of the Electrolysis Unit of the Copper Production Industry

Determination of insoluble (INSOL) calcium content in Cheddar, Feta, Juustoleipa, and Mozzarella cheeses using acid-base buffering curves

The amount of colloidal calcium phosphate (CCP) complex associated with caseins (INSOL Ca) determines the body, texture, flavor and breakdown of cheese constituents during aging. The continuous pH decline during cheese making because of lactic acid fermentation results in solubilization of insoluble (INSOL) calcium. Measuring INSOL Ca in such a dynamic and wide range pH system (6.6 to 5.3) is challenging. The purpose of this study was to test utility of acid-base auto-titration method in differentiating INSOL Ca content in cheeses with a wide range of pH (i.e., Juustoleipa 6.6, Mozzarella 5.6, Cheddar 5.3, Feta 4.8) and also to understand the relationship between pH, protein content, and INSOL Ca. A positive relationship was obtained for pH (R2 = 0.62) and protein content (R2 = 0.85) with INSOL Ca, suggesting concomitant release of CCP content at lower pH values and association of higher amount of CCP with higher protein content. Despite having a pH slightly closer to Mozzarella (pH 5.56), Cheddar cheese (pH 5.25) had more INSOL Ca (0.67%) owing to the highest amount of protein (26%) and low moisture content (33%). Feta had the lowest amount of INSOL Ca (0.15%) owing to a low pH (4.79), higher moisture content (55%), and low protein content (14%). Juustoleipa had the highest percentage of INSOL Ca out of total calcium (88%) due to higher pH (6.62) and more intact casein. It was evident that the acid-base titration method was able to differentiate INSOL Ca between different types of cheeses with varying pH and protein content. Findings of this work will help tracking the proportion of INSOL Ca at various stages of cheese making and understanding kinetics of INSOL Ca solubilization and its role in causing pH variation in the early stage of cheese ripening.

SPATIO-TEMPORAL EVALUATION OF FERORO STREAM WATER QUALITY, CHIKUN LOCAL GOVERNMENT AREA OF KADUNA STATE, NIGERIA

Aquatic environment is faced with pollution problems most of which are anthropogenic in nature. Feroro stream water was evaluated for its quality and suitability for the growth of organisms. The temporal and spatial qualities of the water was observed to be deteriorating. Water sampling was done once monthly for twenty-four months from five stations along the stream. The water samples were put into 2-litre sterilized plastic bottles. Some physical and chemical parameters were determined using HANNA meter, Dissolved oxygen meter, titration and colorimeter methods. All the parameters tested ranged within Federal Ministry of Environment standard limits. Turbidity and Total Hardness are above the standard limits. There was significant difference temporally P&lt;0.05. Electrical Conductivity was significant different in all the stations P&lt;0.05, lowest at Station 1(137.55µS/cm) and high at Station 5 (235.21µS/cm). Across the wet and dry seasons, the parameters significantly varied except in Temperature (25.79±0.12 and 25.57±0.26) and Total Hardness (119.68±6.13 and 109.50±3.38) P&lt;0.05.

An Overview of Pollution Level in Vlora Port

This study reports the concentrations of organic pollutants, nutrients, and some physicochemical parameters in water samples from Vlora Port. Organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAH) and BTEX (Benzene, Toluene, o-, m- and p-Xyelenes, Ethylbenzene) were analyzed organic pollutants. The levels of NO3-, NO2-, NH4-, N-total, PO4-, and P-total were determined. Temperature, PH, Conductivity, Turbidity, TDS, TSS DO, BOD and COD were physical-chemical parameters determined in the water samples. Vlora Port is located in the southern part of Albania in Vlora Bay, near Vlora City in the Adriatic Sea. Elevated activities in port areas (terrestrial and marine areas) are the main causes of water pollution. Urban pollution, agriculture, and water currents can influence marine water pollution in this area. To evaluate pollution levels at the port of Vlora, water samples (12 stations) were analyzed over a two-year period (2022 – 2023). Water samples were collected during two seasons: March and July of each year Analyses of organic compounds were performed using a gas chromatograph (Varian 450 GC) equipped with ECD and FID detectors. Nutrients were analyzed using the UV-VIS technique. Titration, automatic, semi-automatic, and gravimetric methods were used to determine the physicochemical parameters. Organic pollutants were detected in all the water samples. Nutrient concentrations and physicochemical values classified the marine water of Vlora’s port as moderately good. Levels of organic pollutants, nutrients, and physicochemical parameters in water samples from Vlora’s port were higher/comparable with those reported in previous studies of the Adriatic Sea (Albania coastline).

A quantitative analysis of vitamin C in fruits, khat (Catha edulis), and pharmaceutical tablets using potassium iodate titration

Vitamin C, or ascorbic acid, is an essential antioxidant in various resources, such as pharmaceutical tablets, fruits, and vegetables. The human body cannot synthesize it by itself. This research aims to measure the vitamin C content in 29 commonly assessable compressed tablets, effervescent tablets, fruits, and khat (Catha edulis) leaves that are found in the Yemeni local markets. This study used a redox titration method with potassium iodate. These results reveal confirmed European and American standards and no significant difference between the measured vitamin C content in the commercial tablet (p &lt;0.05) and the amount stated on the product label, as well as the highest amount of vitamin C content in fruits in guava (111.21 mg/100 g), while the lowest amount of vitamin C is in apple (8.72 mg/100 g).

Definition of halal analysis of formulation of kombucha drink from simplicia of malay apple fruit (Syzygium malaccense)

The wealth of biodiversity and the abundance of native Indonesian germplasm resources have not been optimally utilized domestically. Malay apple, which belongs to the myrtaceae family, has various health benefits. However, its utilization is still limited, thus requiring ideas to increase public interest in this fruit. Therefore, innovation is carried out by transforming malay apple into kombucha fermentation beverages as a step to optimize its utilization. The research aimed to measure the total alcohol content, total acid, and total sugar in the formulation of kombucha beverages derived from malay apple fruit juice, with the goal of developing it into a functional beverage. The research process involved testing alcohol content using gas chromatography, measuring total acid by alkalimetric titration method, and measuring total sugar content by anthrone method. The research results showed that the malay apple kombucha sample the level of alcohol content was 0.0213%, the total acid was 1.38% (&lt;2 g/L), and the total sugar was 0.807 µg. The kombucha malay apple which category halal kombucha.

Optimization of malic anhydrate concentration in manufacturing PP-g-MA compatibilizer on test percent of grafting degree

The difference in polarity means that two or more materials cannot react, a connecting material such as a compatibilizer is needed to react between polar and non-polar materials. This research aims to determine the effect of maleic anhydride (MA) concentration on the process of grafting MA onto polypropylene (PP) chains with the help of benzoyl peroxide (BPO) as an initiator. The method used to mix these two materials uses the blending method using an internal mixer instrument and testing the percent degree of grafting using the titration method with three repetitions of the test.The research results showed that the highest percent grafting degree occurred at a concentration of 86% PP, 11% MA, and 3% BPO, with a value of 10.28%. The Spectroscopy Fourier Transform Infrared (FTIR) analysis of Polypropylene grafted maleic anhydride (PP-g-MA) showed the presence of new peaks at wavenumbers 1707cm-1 and 1162 cm-1.Increasing the concentration of maleic anhydride had no effect on increasing the percent degree of grafting.

The Determination of Minerals in Soil, Water, Fodder, and Serum and their Effects on Reproductive Efficiency of Nili Ravi Buffaloes

Introduction: Minerals play an essential role in the reproductive performance of dairy animals, especially in buffaloes. The present study aimed to evaluate the mineral concentrations in different types of samples, including soil used for fodder cultivation, canal water used for fodder irrigation, drinking water for buffaloes, fodder used for buffalo feeding, and serum of buffaloes and their effects on the reproductive efficiency of buffaloes. Materials and methods: The current study was carried out for three months and samples were analyzed twice at the beginning and the end of the study. The concentrations of calcium, magnesium, and inorganic phosphorus in the soil were checked through the versinate method. The concentration of calcium, magnesium, and inorganic phosphorus in water was checked through the titration method and the concentration of calcium, magnesium, and inorganic phosphorus contents in fodder was checked through the wet digestion method. The minerals of blood serum (n = 80) were analyzed through commercial kits. Results: In canal water, calcium concentration was higher for irrigation compared to buffalo drinking water. Similarly, on the upper surface of the soil compared to its low surface, the level of calcium was high. Calcium values of serum were higher in cyclic buffaloes compared to buffalo heifers. In comparison to all groups, the levels of inorganic phosphorus were found to be lower in non-cyclic buffaloes. Similarly, the calcium-to-phosphorus ratio was found to be lower in non-cyclic buffaloes and heifers compared to repeat breeders and cyclic buffaloes. At the beginning of the study, cyclic buffaloes had higher magnesium levels than all other groups, except for non-cyclic buffaloes. By the end of the study, magnesium concentrations were higher in non-cyclic buffaloes and heifers compared to repeat breeders and cyclic buffaloes. Conclusion: The mineral deficiencies in water and soil can affect the fodder content in the feed of buffaloes.

The Effect of Different Temperatures on Addition of Powdered Lactobacillus plantarum Dad-13 on Peanut Chocolate Jam Towards Total Lactic Acid Bacteria (LAB), Sublethal Injury, pH, and Total Acids

Lactobacillus plantarum Dad-13 is an indigenous probiotic that was isolated from Dadih. Peanut chocolate jam has the potential to be developed into a probiotic food product. However, peanut chocolate jam involves a heating process which can affect the number of probiotics and their metabolic processes. This research aims to determine the optimal temperature of L. plantarum Dad-13 probiotic powder in addition to peanut chocolate jam products. The different temperatures of probiotic powder L. plantarum Dad-13 addition at 30 oC, 40 oC, 50 oC, and 60 oC were used to measure total lactic acid bacteria (LAB), sublethal injury, pH value, and total acids. Total lactic acid bacteria and sublethal injury were measured by Total Plate Count (TPC), pH value was measured by pH meter and total acids were analyzed using the titration method. Results show significant differences (p&lt;0,05) on total lactic acid bacteria (LAB) and sublethal injury. Total lactic acid bacteria (LAB) resulting in a value of 8.04±0.02 to 7.67±0.05 and sublethal injury 0.04±0.01 to 0.26±0.03. Meanwhile, no significant differences (p&gt;0,05) in pH value (7.20±0.16 to 7.30±0.15) and total acids (0.09±0.01 to 0.08±0.01). The best temperature of L. plantarum Dad-13 probiotic powder addition on peanut chocolate jam was at 30–40 oC because it showed the highest amount of total lactic acid bacteria (LAB) and the least sublethal injury.

Spatial distribution of sediment dissolved organic matter in oligotrophic lakes and its binding characteristics with Pb(II) and Cu(II).

Dissolved organic matter (DOM), the most active component in interstitial waters, determines the stability of heavy metals and secondary release in sediments. However, little is known about the composition and metal-binding patterns of DOM in interstitial water from oligotrophic lakes affected by different anthropogenic perturbations. Here, 18 interstitial water samples were prepared from sediments in agricultural, residential, tourist, and forest regions in an oligotrophic lake (Shengzhong Lake in Sichuan Province, China) watershed. Interstitial water quality and DOM composition, properties, and Cu(II)- and Pb(II)-binding characteristics were measured via physicochemical analysis, UV-vis spectroscopic, fluorescence excitation-emission matrix-parallel factor analysis (EEM-PARAFAC), and fluorescence titration methods. The DOM, which was produced mainly by microbial activities, had low molecular weights, humification degrees, and aromaticity. Based on EEM-PARAFAC results, the DOM was generally composed of tryptophan- (57.7%), terrestrial humic- (18.7%), microbial humic- (15.6%), and tyrosine-like (8.0%) substances. The DOM in the metal complexes was primarily composed of tryptophan-like substances, which accounted for ~42.6% of the DOM-Cu(II) complexes and ~72.0% of the DOM-Pb(II) complexes; however, microbial humic-like substances primarily contributed to the stability of DOM-Cu(II) (logKCu = 3.7-4.6) and DOM-Pb(II) (logKPb = 4.3-4.8). Water quality parameters did not significantly affect the stability of DOM-metal complexes. We demonstrated that the metal-binding patterns of DOM in interstitial water from oligotrophic lakes are highly dependent on microbial DOM composition and are affected by anthropogenic perturbations to a lesser extent.

Development and Optimization of Dipyridamole- and Roflumilast-Loaded Nanoemulsion and Nanoemulgel for Enhanced Skin Permeation: Formulation, Characterization, and In Vitro Assessment.

This study explores developing and optimizing a nanoemulsion (NE) system loaded with dipyridamole and roflumilast, aiming to improve skin penetration and retention. The NE formulation was further transformed into a nanoemulgel to enhance its application as a topical treatment for psoriasis. Solubility studies were conducted to select the oil, surfactant, and co-surfactant. Phase diagrams were constructed using the aqueous phase titration method. All the formulations were in nanoscale, and Formula (F2) (which contains oleic acid oil as the oil phase, a mixture of Surfactant Tween 80 and co-surfactant (ethanol) at a ratio of 1:2 in addition to distilled water as an aqueous phase in a ratio of 1:5:4, respectively) was the selected formula depending on the particle size, PDI, and zeta potential. Formula (F2) has the best ratio because it gives the smallest nanoemulsion globule size (particle size average of 167.1 nm), the best homogenicity (lowest PDI of 0.195), and the highest stability (higher zeta potential of -32.22). The selected formula was converted into a nanoemulgel by the addition of 0.5% (w/w) xanthan gum (average particle size of 172.7 nm) and the best homogenicity (lowest PDI of 0.121%) and highest stability (higher zeta potential of -28.31). In conclusion, the selected formula has accepted physical and chemical properties, which enhanced skin penetration.

Water-soluble polymeric probe with tryptophan pendants for formaldehyde sensing

Formaldehyde (FA) is a grade-I carcinogen and the most reactive aldehyde in the carbonyl family, posing substantial health hazards. Herein, a water-soluble polymeric probe with side-chain tryptophan pendants is proposed that relies on an FA-induced Pictet-Spengler reaction for FA sensing in an aqueous medium. The polymeric probe shows cyan fluorescence in an aqueous medium after the interaction with FA due to the formation of a β-carboline derivative, confirmed by high-resolution mass spectrum analysis of the product from the model reaction between tryptophan methyl ester and FA. The copolymer’s sensitivity to FA in aqueous solutions at the nanomolar level is estimated using the fluorescence titration method, where ∼20-fold enhancement in fluorescence intensity is observed within 2 min when 200 µM FA is added to the aqueous solution of the copolymer. The probe can selectively detect FA using colorimetric and fluorometric methods with a detection limit as low as 25 nM. The FA-sensing mechanism is studied from the model reaction of tryptophan methyl ester (TME) with FA, and density functional theory (DFT).