Optimization of Fermentation Process of Pomegranate Peel and Schisandra Chinensis and the Biological Activities of Fermentation Broth: Antioxidant Activity and Protective Effect Against H2O2-induced Oxidative Damage in HaCaT Cells

In this study, the lactobacillus fermentation process of pomegranate (Punica granatum L.) peel and Schisandra chinensis (Turcz.) Baill (PP&SC) was optimized by using the response surface method (RSM) coupled with a Box-Behnken design. The optimum fermentation condition with the maximal yield of ellagic acid (99.49 ± 0.47 mg/g) was as follows: 1:1 (w:w) ratio of pomegranate peel to Schisandra chinensis, 1% (v:v) of strains with a 1:1 (v:v) ratio of Lactobacillus Plantarum to Streptococcus Thermophilus, a 37 °C fermentation temperature, 33 h of fermentation time, 1:20 (g:mL) of a solid–liquid ratio and 3 g/100 mL of a glucose dosage. Under these conditions, the achieved fermentation broth (FB) showed stronger free radical scavenging abilities than the water extract (WE) against the ABTS⁺, DPPH, OH⁻ and O₂⁻ radicals. The cytotoxicity and the protective effect of FB on the intracellular ROS level in HaCaT cells were further detected by the Cell Counting Kit-8 (CCK-8) assay. The results showed that FB had no significant cytotoxicity toward HaCaT cells when its content was no more than 8 mg/mL. The FB with a concentration of 8 mg/mL had a good protective effect against oxidative damage, which can effectively reduce the ROS level to 125.94% ± 13.46% (p < 0.001) compared with 294.49% ± 11.54% of the control group in H₂O₂-damaged HaCaT cells. The outstanding antioxidant ability and protective effect against H₂O₂-induced oxidative damage in HaCaT cells promote the potential for the FB of PP&SC as a functional raw material of cosmetics.     

Bauhinia forficata Link Infusions: Chemical and Bioactivity of Volatile and Non-Volatile Fractions

This study aimed to evaluate Bauhinia forficata infusions prepared using samples available in Rio de Janeiro, Brazil. As such, infusions at 5% (w/v) of different brands and batches commercialized in the city (CS1, CS2, CS3, and CS4) and samples of plant material botanically identified (BS) were evaluated to determine their total phenolic and flavonoid contents (TPC and TFC), antioxidant capacity (ABTS^•+, DPPH^•, and FRAP assays), phytochemical profile, volatile compounds, and inhibitory effects against the α-amylase enzyme. The results showed that infusions prepared using BS samples had lower TPC, TFC and antioxidant potential than the commercial samples (p < 0.05). The batch averages presented high standard deviations mainly for the commercial samples, corroborating sample heterogeneity. Sample volatile fractions were mainly composed of terpenes (40 compounds identified). In the non-volatile fraction, 20 compounds were identified, with emphasis on the CS3 sample, which comprised most of the compounds, mainly flavonoid derivatives. PCA analysis demonstrated more chemical diversity in non-volatile than volatile compounds. The samples also inhibited the α-amylase enzyme (IC₅₀ value: 0.235–0.801 mg RE/mL). Despite the differences observed in this work, B. forficata is recognized as a source of bioactive compounds that can increase the intake of antioxidant compounds by the population.     

Box–Behnken Design (BBD)-Based Optimization of Microwave-Assisted Extraction of Parthenolide from the Stems of Tarconanthus camphoratus and Cytotoxic Analysis

Parthenolide, a strong cytotoxic compound found in different parts of Tarchonanthus camphoratus which motivated the authors to develop an optimized microwave-assisted extraction (MEA) method using Box–Behnken design (BBD) for efficient extraction of parthenolide from the stem of T. camphoratus and its validation by high-performance thin-layer chromatography (HPTLC) and cytotoxic analysis. The optimized parameters for microwave extraction were determined as: 51.5 °C extraction temperature, 50.8 min extraction time, and 211 W microwave power. A quadratic polynomial model was found the most suitable model with R² of 0.9989 and coefficient of variation (CV) of 0.2898%. The high values of adjusted R² (0.9974), predicted R² (0.9945), and signal-to-noise ratio (74.23) indicated a good correlation and adequate signal, respectively. HPTLC analyzed the parthenolide (R_f = 0.16) content in T. camphoratus methanol extract (TCME) at λ_max = 575 nm and found it as 0.9273% ± 0.0487% w/w, which was a higher than expected yield (0.9157% w/w). The TCME exhibited good cytotoxicity against HepG2 and MCF-7 cell lines (IC₅₀ = 30.87 and 35.41 µg/mL, respectively), which further supported our findings of high parthenolide content in TCME. This optimized MAE method can be further applied to efficiently extract parthenolide from marketed herbal supplements containing different Tarconanthus species.     

Tandem Transesterification–Esterification Reactions Using a Hydrophilic Sulfonated Silica Catalyst for the Synthesis of Wintergreen Oil from Acetylsalicylic Acid Promoted by Microwave Irradiation

SiO₂–SO₃H, with a surface area of 115 m²/g and pore volume of 0.38 cm³g⁻¹, and 1.32 mmol H⁺/g was used as a 20% w/w catalyst for the preparation of methyl salicylate (wintergreen oil or MS) from acetylsalicylic acid (ASA). A 94% conversion was achieved in a microwave reactor over 40 min at 120 °C in MeOH. The resulting crude product was purified by flash chromatography. The catalyst could be reused three times.     

Correlation of Solubility Thermodynamics of Glibenclamide with Recrystallization and In Vitro Release Profile

The solubility of glibenclamide was evaluated in DMSO, NMP, 1,4-dioxane, PEG 400, Transcutol^® HP, water, and aqueous mixtures (T = 293.15~323.15 K). It was then recrystallized to solvate and compressed into tablets, of which 30-day stability and dissolution was studied. It had a higher solubility in 1,4-dioxane, DMSO, NMP (X_exp = 2.30 × 10³, 3.08 × 10⁴, 2.90 × 10⁴) at 323.15 K, its mixture (X_exp = 1.93 × 10³, 1.89 × 10⁴, 1.58 × 10⁴) at 298.15 K, and 1,4-dioxane (w) + water (1−w) mixture ratio of w = 0.8 (X_exp = 3.74 × 10³) at 323.15 K. Modified Apelblat (RMSD ≤ 0.519) and CNIBS/R-K model (RMSD ≤ 0.358) suggested good comparability with the experimental solubility. The minimum value of ΔG° vs ΔH° at 0.70 < x₂ < 0.80 suggested higher solubility at that molar concentration. Based on the solubility, it was recrystallized into the solvate, which was granulated and compressed into tablets. Among the studied solvates, the tablets of glibenclamide dioxane solvate had a higher initial (95.51%) and 30-day (93.74%) dissolution compared to glibenclamide reference (28.93%). There was no stability issue even after granulation, drying, or at pH 7.4. Thus, glibenclamide dioxane solvate could be an alternative form to improve the molecule’s properties.     

Supercritical CO2 Extraction of High-Added Value Compounds from Chlorella vulgaris: Experimental Design,Modelling and Optimization

Microalgae are well-known for their high-added value compounds and their recovery is currently of great interest. The aim of this work is the recovery of such components from Chlorella vulgaris through supercritical fluid extraction (SFE) with CO₂. The effect of the extraction temperature (40–60 °C), pressure (110–250 bar), and solvent flow rate (20–40 g/min) was tested on yield, the extract’s antioxidant activity, and the phenolic, chlorophyll and carotenoid content. Thus, data analysis indicated that the yield was mainly affected by temperature, carotenoids by pressure, while the extract’s phenolics and antioxidant activity were affected by the synergy of temperature and pressure. Moreover, SFE’s kinetic study was performed and experimental data were correlated using Sovová’s mass transfer-based model. SFE optimization (60 °C, 250 bar, 40 g/min) led to 3.37% w/w yield, 44.35 mg_extr/mg_DPPH antioxidant activity (IC50), 18.29 mg_GA/g_extr total phenolic content, 35.55, 21.14 and 10.00 mg/g_extr total chlorophyll, carotenoid and selected carotenoid content (astaxanthin, lutein and β-carotene), respectively. A comparison of SFE with conventional aq. ethanol (90% v/v) extraction proved SFE’s superiority regarding extraction duration, carotenoids, antioxidant activity and organoleptic characteristics of color and odor despite the lower yield. Finally, cosolvent addition (ethanol 10% w/w) at optimum SFE conditions improved the extract’s antioxidant activity (19.46%) as well as yield (101.81%).     

Resistant Starch Contents of Starch Isolated from Black Longan Seeds

A large quantity of longan fruits (Dimocarpus longan Lour.) produced annually are processed into many products, one of which is black longan, from which the dried, dark-brown meat has been used medicinally in traditional medicine, while the starch-containing seeds are discarded. In this study, starch samples (BLGSs) were isolated from seeds of black longan fruits prepared using varied conditions. The in vitro digestibility was determined in comparison with those extracted from fresh (FLGS) and dried (DLGS) seeds. Scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy were employed to evaluate the starch properties. The results showed that the yields of FLGS, DLGS, and BLGSs were 20%, 23%, and 16–22% w/w, respectively. SEM images showed starch granules of mixed shapes, with sizes up to 15 µm in all samples. XRD patterns confirmed an A-type crystallinity for FLGS and DLGS, with strong refraction peaks at 2θ = 15°, 17°, 18°, and 23°, while BLGSs also showed detectable peaks at 2θ = 10° and 21°, which suggested V-type structures. Thermal properties corroborated the changes by showing increases in peak gelatinization temperature (T_p) and enthalpy energy (ΔH) in BLGSs. The paste viscosity of BLGSs (5% w/w) decreased by 20–58% from that of FLGS. The FTIR peak ratio at 1045/1022 and 1022/995 cm⁻¹ also indicated an increase in ordered structure in BLGSs compared to FLGS. The significant increase in the amounts of slowly digestible starch (SDS) and resistant starch (RS) in BLGSs compared to FLGS, especially at a prolonged incubation time of 20 (4.2×) and 30 days (4.1×), was proposed to be due to the heat-induced formation of starch inclusion with other components inside the seed during the black longan production process. Thus, black longan seed could be a new source of starch, with increased RS content, for potential use in the food and related industries.     

Liquid-liquid phase equilibria for some polystyrene-methylcyclohexane mixtures

Liquid-liquid cloud point diagrams of solutions of nearly monodisperse samples of polystyrene (PS), and binary mixtures of nearly monodisperse PS’s, both in methylcyclohexane (MCH), were determined for several polymer molecular weights (M_w) at 0.1 MPa. The bimodal mixtures (PS[M_w(1),ρ(1)] + PS[M_w(2),ρ(2)], M_w(1)=90×10³ g/mol, M_w(2)=13×10³ g/mol, 5.78 × 10³ g/mol, and 2.2 × 10³ g/mol, ρ=1.06) were prepared constraining 〈M_w〉=38.6×10³ g/mol, ρ=M_w/M_n is the polydispersity index. In each case the cloud point curves (CPC’s) for the bimodal mixtures are strongly skewed, lying well above CPC for 〈M_w〉 when φ<φ_CRITICAL, and below CPC for 〈M_w〉 when φ>φ_CRITICAL; φ is volume fraction polymer in the polymer/solvent mixture. The experimental results are discussed in the context of empirical and mean-field representations.     

Comparative Hydrodynamic Study on Non-Aqueous Soluble Archaeological Wood Consolidants: Butvar B-98 and PDMS-OH Siloxanes

Butvar B-98 and PDMS-OH both have a demonstrable ability as consolidants for archaeological wood. This makes them both potential treatment options for the Oseberg collection, which is one of the most important archaeological finds from the Viking era. Both Butvar B-98 and PDMS-OH are soluble in organic solvents, offering a useful alternative to aqueous-based consolidants. Extensive characterisation studies were carried out on both of these polymers, with the use of analytical ultracentrifugation and viscometry, for the benefit of conservators wanting to know more about the physical properties of these materials. Short column sedimentation equilibrium analysis using SEDFIT-MSTAR revealed a weight-average molar mass (weight-average molecular weight) M_w of (54.0 ± 1.5) kDa (kg · mol⁻¹) for Butvar B-98, while four samples of PDMS-OH siloxanes (each with a different molar mass) had an M_w of (52.5 ± 3.0) kDa, (38.8 ± 1.5) kDa, (6.2 ± 0.7) kDa and (1.6 ± 0.1) kDa. Sedimentation velocity confirmed that all polymers were heterogeneous, with a wide range of molar masses. All molecular species showed considerable conformational asymmetry from measurements of intrinsic viscosity, which would facilitate networking interactions as consolidants. It is anticipated that the accumulated data on these two consolidants will enable conservators to make a more informed decision when it comes to choosing which treatment to administer to archaeological artefacts.     

Physicochemical,Structural, Thermal and Rheological Properties of Flour and Starch Isolated from Avocado Seeds of Landrace and Hass Cultivars

The objective of this study was to obtain and characterize flours and starches from the avocado seeds of Hass and landrace cultivars. The morphological, physical-chemical, structural, thermal and rheological characteristics were evaluated. The flour yield of the Hass and landrace cultivars was 41.56 to 46.86% (w/w), while for starch, it was 35.47 to 39.57% (w/w) (cv. Hass and landrace, respectively). Scanning electron microscopy (SEM) revealed the presence of oval starch granules and other particles in flour, in contrast to flours, starches showed lower ash, proteins and lipids content. However, the amylose content was higher in starches (42.25–48.2%). Flours showed a higher gelatinization temperature (T_p = 73.17–73.62 °C), and their starches presented greater gelatinization enthalpy (∆H_gel = 11.82–13.43 J/g). All samples showed a B-type diffraction pattern, and the crystallinity was higher in the flours. The rheological analysis (flow curves and viscoelastic tests) evidenced a pseudoplastic (n = 0.28–0.36) behavior in all samples analyzed, but the consistency index (k) was higher in starches. In general, the flours and starches from avocado seeds presented interesting proximal, thermal and functional properties for possible application in food systems, and these findings could contribute to the revaluation of this by-product.     

Ion-pair extractions by the use of planar and non-planar extracting solvents

The effect of extracting solvent was studied on the ion-pair extraction reactions with a special interest in the effect of molecular shape (planar or non-planar) of the solvent. The following two reactions were investigated: (HNN)_o + (Q⁺)_W (Q·NN)_o + (H⁺)_W (Extraction I); (Q-ClO₄)_o + (Pi^–)_w (Q·Pi)_o + (ClO ₄ ^– )_w (Extraction II), where HNN, NN^–, Pi^–, and Q⁺ represent 1-nitro-2-naphthol, its base form (1-nitro-2-naphtholate), picrate, and a cationic species, respectively. Above extraction equilibria were confirmed to hold in cases of various extracting solvents including planar solvents (1-chloronaphthalene, etc.) and non-planar solvents (1,2-dichloroethane, chloroform). An approximately linear relationship was found to exist between the extraction constants of Extraction I (logK _ex ^I ) and the Kosower's Z-value of extracting solvents. It was also found that the compatibility between the molecular shape of the ion-pair complexes and that of the extracting solvents affected the extractability to a considerable extent.     

Struktur und Eigenschaften von Makromolekülen im Strömungsgefälle

Zusammenfassung Messungen der Röntgenkleinwinkelstreuung wurden an einem Polystyrol hoher molekularer Einheitlichkeit (M _w :M _n 1.10:1,M _w = 6 · 10⁵ g mol^–1) in Cyclohexan bei 45 °C durchgeführt. Die Meßtemperatur liegt etwa 10° C oberhalb der Thetatemperatur. Die Konzentration der Lösung beträgt 3 · 10^–2 g cm^–3. Die Drehzahlen lagen beiv = 0, 300, 817 und 2670 rpm, was Schergefällen von 0, 900, 2446 und 8000 sec^–1 entspricht.Alle Röntgenaufnahmen lieferten zentrosymmetrische Streudiagramme, d. h. eine Orientierung der Kettenmoleküle durch die Scherung konnte nicht festgestellt werden. Zur Auswertung der Streukurven konnten deshalb Formeln herangezogen werden, die für unorientierte, optisch isotrope Systeme abgeleitet wurden.Die Meßwerte wurden mit Gaußfunktionen und mit der Debyeschen Streuformel angepaßt und ausgewertet. Zur Darstellung der Streukurve im physikalischen Raum wurde durch Fouriertransformationen dieQ-Funktion berechnetDie Messungen ergaben eine Vergrößerung der Teilchen mit zunehmendem Schergefälle, gleichzeitig erhöht sich dabei die Streuintensität, besonders ausgeprägt bei kleinem Streuwinkel. Dieser Effekt wird auf die Zusammenlagerung von Makromolekülen bei der Scherung, d. h. die Ausbildung von Clustern zurückgeführt.Die Zahl der ein Cluster bildenden Makromolekülep (v) wächst mit der Scherbeanspruchung, und zwar gilt die empirische Gleichungp(v) = 1 +v/440. Bei der größten vermessenen Drehzahl vonv = 2670 rpm unter den o.a. Bedingungen bilden etwa 8 Makromoleküle ein Cluster.

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Summary The measurements were carried out at 45 °C on polystyrene with narrow molecular weight distribution (M _w :M _n 1,10:1,M _w = 6 · 10⁵ g/mol^–1 in cyclohexane. The measuring temperature was about 10° above the theta-temperature. The concentration of the solution was 3 · 10^-3. The speeds of rotation werev = 0, 300, 817 and 2670 rpm, which is equivalent to shear gradients of 0, 900, 2446 and 8000 sec^–1.All x-ray radiographs gave centro-symmetric scattering diagramms, i.e. an orientation of the chain molecules by the shear force could not be found. In the interpretation of the scattering diagramms formulas could therefore be used, which had be developed for non-orientated, optically isotropic systems.The measured values were adapted to suit Ganß functions and evaluated with the Debye scattering formula. To represent the scattering curve in physical space itsQ-function was calculated by Fourier-transform.The measurements showed an enlargement of the particles with increasing shear gradient and at the same an increase of the scattering intensity, in particular, by smaller scattering angles. This effect could be interpreted as a conglomeration of the macromolecules, i.e. the building of clusters by the shear force. The number of macromolecules building a clusterp(v) increases with the shear force and in accordance with the empirical formulap(v) = 1 +v/440 Under the above conditions, ca. 8 macromolecules would build a cluster at the highest measured speed of rotationv = 2670 rpm.

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Mit 14 Abbildungen und 2 Tabellen

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2. Mitteilung Colloid & Polymer Sci. 258,1015 (1980).

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Teil der Dissertation TU Berlin (1979), D. 83.     

Preconcentration and determination of boron in milk,infant formula,and honey samples by solid phase extraction-electrothermal atomic absorption spectrometry

This work presents alternative procedures for the electrothermal atomic absorption spectrometric determination of boron in milk, infant formulas, and honey samples. Honey samples (10% m/v) were diluted in a medium containing 1% v/v HNO₃ and 50% v/v H₂O₂ and introduced in the atomizer. A mixture of 20 µg Pd and 0.5 µg Mg was used for chemical modification. Calibration was carried out using aqueous solutions prepared in the same medium, in the presence of 10% m/v sucrose. The detection limit was 2 µg g^− 1, equivalent to three times the standard error of the estimate (s_y/x) of the regression line. For both infant formulas and milk samples, due to their very low boron content, we used a procedure based on preconcentration by solid phase extraction (Amberlite IRA 743), followed by elution with 2 mol L^− 1 hydrochloric acid. Detection limits were 0.03 µg g^− 1 for 4% m/v honey, 0.04 µg g^− 1 for 5% m/v infant formula and 0.08 µg mL^− 1 for 15% v/v cow milk. We confirmed the accuracy of the procedure by comparing the obtained results with those found via a comparable independent procedure, as well by the analysis of four certified reference materials.     

Quantification of Arbutin in Cosmetics,Drugs and Food Supplements by Hydrophilic-Interaction Chromatography

Arbutin, the glucoside of hydroquinone, exists in two isomers, α-arbutin and β-arbutin. The synthetic α isomer is mainly used as a skin brightening agent, while β-arbutin occurs naturally, for instance in bearberry, and is used in drugs for treatment of lower urinary tract infections and as a food supplement. Since both isomers can be harmful at high concentrations, methods for their quantification are required. Classically they have been determined by reversed-phase chromatography, but separation of both isomers is often unsatisfactory. Here we present a simple and reliable method for quantification of α- and β-arbutin based on hydrophilic-interaction chromatography. Prior to analysis, interfering compounds that would frequently be present in cosmetics and drugs, particularly biopolymers, were efficiently removed by precipitation with acetonitrile. In this paper, for separation, a Cyclobond I 2000 5 µm 250 × 4.6 mm column was employed as stationary phase and acetonitrile/water 92/8 (v/v) was used as an eluent at a flow rate of 0.8 mL min⁻¹. For quantification, a UV detector operating at 284 nm was applied. Although analysis took less than 10 min, baseline separation of α- and β-arbutin was achieved. The response was highly linear (r > 0.999) and the method had, for both α- and β-arbutin, a LOD of 0.003% (w/w) and a LOQ of 0.009% (w/w). Moreover, the method showed excellent intra-day and inter-day repeatability with relative standard deviations in the range of 0.5% to 2.3% and 1.0% to 2.2%, respectively, with cosmetics, drugs and food supplements as samples.     

Determination of 77 Multiclass Pesticides and Their Metabolitesin Capsicum and Tomato Using GC-MS/MS and LC-MS/MS

A quick, sensitive, and reproducible analytical method for the determination of 77 multiclass pesticides and their metabolites in Capsicum and tomato by gas and liquid chromatography tandem mass spectrometry was standardized and validated. The limit of detection of 0.19 to 10.91 and limit of quantification of 0.63 to 36.34 µg·kg⁻¹ for Capsicum and 0.10 to 9.55 µg·kg⁻¹ (LOD) and 0.35 to 33.43 µg·kg⁻¹ (LOQ) for tomato. The method involves extraction of sample with acetonitrile, purification by dispersive solid phase extraction using primary secondary amine and graphitized carbon black. The recoveries of all pesticides were in the range of 75 to 110% with a relative standard deviation of less than 20%. Similarly, the method precision was evaluated interms of repeatability (RSDr) and reproducibility (RSD_wR) by spiking of mixed pesticides standards at 100 µg·kg⁻¹ recorded anRSD of less than 20%. The matrix effect was acceptable and no significant variation was observed in both the matrices except for few pesticides. The estimated measurement uncertainty found acceptable for all the pesticides. This method found suitable for analysis of vegetable samples drawn from market and farm gates.     

Determination of Anthelmintic and Antiprotozoal Drug Residues in Fish Using Liquid Chromatography-Tandem Mass Spectrometry

The objective of this study is to develop a comprehensive and simple method for the simultaneous determination of anthelmintic and antiprotozoal drug residues in fish. For sample preparation, we used the “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) method with a simple modification. The sample was extracted with water and 1% formic acid in acetonitrile/methanol (MeCN/MeOH) (95:5, v/v), followed by phase separation (salting out) with MgSO₄ and NaCl (4:1, w/w). After centrifugation, an aliquot of the extract was purified by dispersive solid-phase extraction (d-SPE) prior to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The method was validated at three concentration levels for all matrices, in accordance with the Codex guidelines (CAC/GL-71). Quantitative analysis was performed using the method of matrix-matched calibration. The recoveries were between 60.6% and 119.9%, with coefficients of variation (CV) <30% for all matrices. The limit of quantitation (LOQ) of the method ranged from 0.02 μg kg⁻¹ to 4.8 μg kg⁻¹ for all matrices. This comprehensive method can be used for the investigation of both anthelmintic and antiprotozoal drugs belonging to different chemical families in fishery products.     

Determination of Lead, Chromium, Manganese and Zinc in Slurries of Botanical and Biological Samples by Electrothermal Atomic Absorption Spectrometry Using Tungsten-Containing Chemical Modifiers

Lead, Cr, Mn and Zn in slurries of botanic and biological samples were determined by electrothermal atomic absorption spectrometry (ETAAS) using W, Ir, NH₄H₂PO₄, W and NH₄H₂PO₄, Ir and NH₄H₂PO₄, W and Ir, and W + Ir + NH₄H₂PO₄ chemical modifiers in an 0.2% (v/v) Triton X-100 plus 0.2% (v/v) nitric acid mixture. Zeeman effect background correction was performed and platforms inserted into graphite tubes were used. Comprehensive comparative studies were carried out with respect to pyrolysis and atomization temperatures, atomization and background absorption profiles, characteristic masses, detection limits and accuracy of the determinations in the presence and absence of modifiers. The mixture of W + Ir + NH₄H₂PO₄ was found to be preferable for the determination of Pb, Cr, Mn and Zn in slurry samples. The pyrolysis temperatures of the analytes were increased up to 1250 °C for Pb, 1000 °C for Zn, 1400 °C for Cr and Mn by using W + Ir + NH₄H₂PO₄ with an 0.2% (v/v) Triton X-100 plus 0.2% (v/v) nitric acid mixture used as diluent solution. The optimum masses of the mixed modifier components were found to be 20 µg W + 4 µg Ir + 50 µg NH₄H₂PO₄. The characteristic masses of Pb, Cr, Mn and Zn obtained are 16.3, 5.6, 0.1 and 1.1 pg, respectively. The detection limits of Pb, Cr, Mn and Zn based on integrated absorbance for 0.5% (m v⁻¹) slurries were found to be 0.14, 0.06, 0.02 and 0.01 µg g⁻¹, respectively. The slurries of botanic and biological certified and standard reference materials were analyzed with and without the modifiers. Depending on the sample type, the percent recoveries increased from 63 up to 104% for analytes when using the proposed modifier mixture.     

Density Functional Method Study on the Cooperativity of Intermolecular H-bonding and π-π+ Stacking Interactions in Thymine-[Cnmim]Br (n = 2, 4, 6, 8, 10) Microhydrates

The exploration of the ionic liquids’ mechanism of action on nucleobase’s structure and properties is still limited. In this work, the binding model of the 1-alkyl-3-methylimidazolium bromide ([C_nmim]Br, n = 2, 4, 6, 8, 10) ionic liquids to the thymine (T) was studied in a water environment (PCM) and a microhydrated surroundings (PCM + wH₂O). Geometries of the mono-, di-, tri-, and tetra-ionic thymine (T-wH₂O-y[C_nmim]⁺-xBr⁻, w = 5~1 and x + y = 0~4) complexes were optimized at the M06-2X/6-311++G(2d, p) level. The IR and UV-Vis spectra, QTAIM, and NBO analysis for the most stable T-4H₂O-Br⁻-1, T-3H₂O-[C_nmim]⁺-Br⁻-1, T-2H₂O-[C_nmim]⁺-2Br⁻-1, and T-1H₂O-2[C_nmim]⁺-2Br⁻-1 hydrates were presented in great detail. The results show that the order of the arrangement stability of thymine with the cations (T-[C_nmim]⁺) by PCM is stacking > perpendicular > coplanar, and with the anion (T-Br⁻) is front > top. The stability order for the different microhydrates is following T-5H₂O-1 < T-4H₂O-Br⁻-1 < T-3H₂O-[C_nmim]⁺-Br⁻-1 < T-2H₂O-[C_nmim]⁺-2Br⁻-1 < T-1H₂O-2[C_nmim]⁺-2Br⁻-1. A good linear relationship between binding E_B values and the increasing number (x + y) of ions has been found, which indicates that the cooperativity of interactions for the H-bonding and π-π⁺ stacking is varying incrementally in the growing ionic clusters. The stacking model between thymine and [C_nmim]⁺ cations is accompanied by weaker hydrogen bonds which are always much less favorable than those in T-xBr⁻ complexes; the same trend holds when the clusters in size grow and the length of alkyl chains in the imidazolium cations increase. QTAIM and NBO analytical methods support the existence of mutually reinforcing hydrogen bonds and π-π cooperativity in the systems.     

Supercritical Fluid Extraction of Phenolic Compounds from Mango (Mangifera indica L.) Seed Kernels and Their Application as an Antioxidant in an Edible Oil

Phenolic compounds from mango (M. indica) seed kernels (MSK) var. Sugar were obtained using supercritical CO₂ and EtOH as an extraction solvent. For this purpose, a central composite design was carried out to evaluate the effect of extraction pressure (11–21 MPa), temperature (40–60 °C), and co-solvent contribution (5–15% w/w EtOH) on (i) extraction yield, (ii) oxidative stability (OS) of sunflower edible oil (SEO) with added extract using the Rancimat method, (iii) total phenolics content, (iv) total flavonoids content, and (v) DPPH radical assay. The most influential variable of the supercritical fluid extraction (SFE) process was the concentration of the co-solvent. The best OS of SEO was reached with the extract obtained at 21.0 MPa, 60 °C and 15% EtOH. Under these conditions, the extract increased the OS of SEO by up to 6.1 ± 0.2 h (OS of SEO without antioxidant, Control, was 3.5 h). The composition of the extract influenced the oxidative stability of the sunflower edible oil. By SFE it was possible to obtain extracts from mango seed kernels (MSK) var. Sugar that transfer OS to the SEO. These promissory extracts could be applied to foods and other products.     

Fractionation of Cellulose

Cellulose samples with molecular weight distributions that are considerably narrower than those of the natural products can be obtained by at least three fundamentally different routes. (i) Synthesis of easily soluble derivatives, fractionation by means of well-established methods and subsequent regeneration, (ii) selective extraction of short chains from activated cellulose, using solvents of suitable marginal quality, and (iii) partition of the homologs between two coexisting phases formed by the demixing of homogeneous solutions. All three methods can be applied successfully. However, the efforts in terms of labor and required solvent differ considerably. Most of the experiments were performed with the following three cellulose samples: Avicel (M _w = 30 kg mol^–1, U = (M _w/M _n)–1 = 2.0), Solucell (M _w = 230 kg mol^–1, U = 1.8), and Stockstadt (M _w = 320 kg mol^–1, U = 5.7). Options (ii) and (iii) emerged most promising for large scale fractionation. The mixed solvent consisting of DMAc and LiCl turned out to be particularly versatile in both cases. In the pure state it can be used for incremental extraction (yielding quick access to orienting information on the width of the molecular weight distribution) as well as for one-step extraction. In combination with suitable precipitants (like acetone) it enables the realization of the coexistence of two liquid phases required with route (iii). One obstacle for fractionation that all methods share is the high viscosity of cellulose solutions. With the last method it is possible to mitigate this limitation considerably by the use of spinning nozzles for the mixing of feed and extracting agent.