Novel separation method for highly sensitive speciation of cancerostatic platinum compounds by HPLC–ICP–MS

A high-performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC–ICP–MS) method is presented for analysis of cisplatin, monoaquacisplatin, diaquacisplatin, carboplatin, and oxaliplatin in biological and environmental samples. Chromatographic separation was achieved on pentafluorophenylpropyl-functionalized silica gel. For cisplatin, carboplatin, and oxaliplatin limits of detection of 0.09, 0.10, and 0.15 g L^–1, respectively, were calculated at m/z 194, using aqueous standard solutions. (3 L injection volume). The method was utilized for model experiments studying the stability of carboplatin and oxaliplatin at different chloride concentrations simulating wastewater and surface water conditions. It was found that a high fraction of carboplatin is stable in ultrapure water and in solutions containing 1.5 mol L^–1 Cl^–, whereas oxaliplatin degradation was increased by increasing the chloride concentration. In order to support the assessment of oxaliplatin eco-toxicology, the method was tested for speciation of patient urine. The urine sample contained more than 17 different reaction products, which demonstrates the extensive biotransformation of the compound. In a second step of the study the method was successfully evaluated for monitoring cancerostatic platinum compounds in hospital waste water.     

Highly hydrophobic sisal chemithermomechanical pulp (CTMP) paper by fluorotrimethylsilane plasma treatment

Fluorinated thin layers were created on chemithermomechanical pulp (CTMP) sisal paper surfaces with fluorotrimethylsilane (FTMS) radio frequency-plasma conditions. It was found that the FTMS-discharge environments caused implantation of fluorine and –Si(CH₃) _x groups into the surface layers of the paper substrates. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy and Electron Spectroscopy for Chemical Analysis, as well as Atomic Force Microscopy and Scanning Electron Microscopy analyses revealed a smooth surface for the FTMS plasma-treated paper, apparently covered completely with a cross-linked polymerized network. Although the plasma reaction takes place with the cellulose, hemicelluloses and lignin, it appears that the chemical linkage is mainly to the lignin component on the CTMP paper surface by means of mainly C–O–Si–F, with some C–Si–F structures. The CTMP fibers apparently have a high lignin surface concentration. The water absorption for the plasma-treated CTMP paper was reduced from greater than 300 to 17 g of water/m² and the contact angle increased from less than 15° to greater than 120° the strength properties were only slightly reduced and the brightness was essentially unaffected with the FTMS plasma treatment.     

Solubility of methane in aqueous solutions of triethylenediamine

The solubilities of methane were measured in water and aqueous solutions of triethylenediamine (TED), triethylenediamine hydrochloride (TED·HCl), and HCl at several concentrations up to 1M at 5° intervals from 5 to 25°C. Methane solubilities in solutions of TED·HCl and HCl are lower than those in water and decrease with increasing cosolute concentration. In contrast, the solubilities in TED solutions are greater than those in water and increase with increasing TED concentration. The order of methane solubilities at 25°C in water and in 0.5M aqueous solutions is TED>H₂O>HCl>TED·HCl with Ostwald coefficients of 3.57×10^–2, 3.44×10^–2, 3.26×10^–2, and 3.19×10^–2, respectively, and with an experimental precision of about ±0.2×10^–3. Thermodynamic functions for the transfer of methane from water to 0.25, 0.50, and 0.75M aqueous solutions have been calculated on the molar concentration scale. The free energies of transfer are compared with previous results for methane in aqueous solutions of tetraalkylammonium halides.     

K+-montmorillonite: its electric double layer extension and point of zero charge by diffusion potential

The dependence of the counterion transference number on the distance from the charged surface, that is, on the water (solution) thickness, is used for an approximation of the extension of the electric double layer (edl) in K⁺-montmorillonite.The extension of edl in K⁺-montmorillonite in 10^–2–10^–3 M KCl solutions is approximately 3.7k ^–1, wherek ^–1 is the Debye length.The dependence of the counterion transference number on the pH of water (solution) is used for estimating the point of zero charge (pzc) of K⁺-montmorillonite; the estimated pzc=1.     

Improvement of PBO fiber surface and PBO/PPESK composite interface properties with air DBD plasma treatment

The interface of fibrous composites is a key factor to the whole properties of the composites. In this study, the effects of air dielectric barrier discharge (DBD) plasma discharge power density on surface properties of poly(p‐phenylene benzobisoxazole) (PBO) fiber and the interfacial adhesion of PBO fiber reinforced poly(phthalazinone ether sulfone ketone) (PPESK) composite were investigated by several characterization methods, including XPS, SEM, signal fiber tensile strength, interlaminar shear strength, and water absorption. After the air DBD plasma treatment at a power density of 41.4 W/cm³, XPS analysis showed that some polar functional groups were introduced on the PBO fiber surface, especially the emergence of a new oxygen‐containing group (?O–C = O group). SEM observations revealed that the air DBD plasma treatment had a great influence on surface morphologies of the PBO fiber, while the signal fiber tensile strength results showed only a small decline of 5.9% for the plasma‐treated fiber. Meanwhile, interlaminar shear strength value of PBO/PPESK composite was increased to 44.71 MPa by 34.5% and water absorption of the composite decreased from 0.46% for the untreated specimen to 0.27%. The results showed that the air DBD plasma treatment can effectively improve the properties of the PBO fiber surface and the PBO/PPESK composite interface. Results obtained from the above analyses also showed that both the fiber surface and the composite interface performance would be reduced when an undue plasma discharge power density was applied. Copyright © 2011 John Wiley & Sons, Ltd.     

Polarographic behaviour of 2-benzilidenimino-benzohydroxamic acid (2-BIBH) and 2-BIBH-Mo(VI) system

The polarographic behaviour of 2-benzilideniminobenzohydroxamic acid (2-BIBH) solutions and of 2-BIBH solutions in the presence of Mo(VI) have been studied by using differential pulse polarography and cyclic voltammetry. The polarographic characteristics of the resulting waves have been studied and possible mechanisms of the processes involved have been proposed. A linear relationship has been observed betweenI _p and Mo(VI) concentration in the range 2×10^–6 to 1.6×10^–5 M when using 3×10^–4 M 2-BIBH. Standard deviations of 5.6×10^–8 and 1.2×10^–8 M were found for 3×10^–6 and 8 × 10^–6 M Mo(VI), respectively.     

Direct and Indirect Bactericidal Effects of Cold Atmospheric-Pressure Microplasma and Plasma Jet

The direct and indirect bactericidal effects of dielectric barrier discharge (DBD) cold atmospheric-pressure microplasma in an air and plasma jet generated in an argon-oxygen gas mixture was investigated on Staphylococcus aureus and Cutibacterium acnes. An AC power supply was used to generate plasma at relatively low discharge voltages (0.9–2.4 kV) and frequency (27–30 kHz). Cultured bacteria were cultivated at a serial dilution of 10⁻⁵, then exposed to direct microplasma treatment and indirect treatment through plasma-activated water (PAW). The obtained results revealed that these methods of bacterial inactivation showed a 2 and 1 log reduction in the number of survived CFU/mL with direct treatment being the most effective means of treatment at just 3 min using air. UV–Vis spectroscopy confirmed that an increase in treatment time at 1.2% O₂, 98.8% Ar caused a decrease in O₂ concentration in the water as well as a decrease in absorbance of the peaks at 210 nm, which are attributed NO₂⁻ and NO₃⁻ concentration in the water, termed denitratification and denitritification in the treated water, respectively.     

The wettability of polytetrafluoroethylene by aqueous solution of cetylpyridinium bromide and propanol mixtures

Measurements of advancing contact angles (θ) were carried out for aqueous solutions of cetylpyridinium bromide (CPBr) and propanol mixtures at constant CPBr concentration equal to 1 × 10⁻⁵, 1 × 10⁻⁴, 6 × 10⁻⁴, 1 × 10⁻³ M, respectively, on polytetrafluoroethylene (PTFE). The obtained results indicate that the wettability of PTFE by aqueous solutions of these mixtures depends on their composition and concentration. In contrast to Zisman, there is no linear dependence between the cos θ and surface tension of aqueous solutions of CPBr and propanol mixtures (γ_LV), but a linear relationship exists between the adhesion tension and the surface tension of aqueous solutions of CPBr and propanol mixtures which have a slope equal to −1, and between cos θ and the reciprocal of the surface tension of solution. The slope equal to −1 and the intercept on the cos θ axis close to −1 suggest that adsorption of CPBr and propanol mixtures and the orientation of their molecules at aqueous solution–air and PTFE–aqueous solution interfaces are the same. This also suggests that the work of solution adhesion to the PTFE surface does not depend on the concentration of propanol and CPBr. Extrapolation of the straight line to the point corresponding to the surface tension of solution, which completely spreads over the PTFE surface, gives the value of the critical surface tension of PTFE wetting equal to 24.84 mN/m. This value is higher than PTFE surface tension (20.24 mN/m) and the values of the critical surface tension of PTFE wetting determined by other investigators from the contact angle of nonpolar liquids (e.g. n-alkanes). The differences between the value of the critical surface tension obtained here and those which can be found in the literature were discussed on the basis of the simple thermodynamic rules. Using the measured values of the contact angles and Young equation the PTFE–aqueous solution interfacial tension was determined. The values of PTFE–aqueous solution interfacial tension were also calculated from Miller and co-workers equation in which the correction coefficient of nonideality of the surface monolayer was introduced. From comparison of the obtained values it appears that good agreement exists between the values of PTFE–solution interfacial tension calculated on the basis of Young and Miller and co-workers equations in the whole range of propanol concentration.     

The phase diagram and supercooling conditions for the Ca(NO3)2−CaCl2−H2O system

The liquidus temperature and induction periods were measured for crystallization in a system of calcium nitrate, calcium chloride, and water over a concentration range of 5–20 mole% Ca(II), i.e., R=4–18 [R=moles H₂O/moles Ca(II)] and y_cl=0–1 [y_cl=moles Cl^–/moles (NO ₃ ^– +Cl^–)]. A ternary phase diagram was constructed, and qualitative dependences of the supercooling at which the solution began to crystallize on the system composition were found. A wide range of stability toward crystallization was found for solutions withR=4–10 and y_cl=0–0.7 The relationships between the system stability toward crystallization and the viscosity, glass-transition temperature, and the liquidus temperature are discussed.     

Solvation Phenomena of Potassium Thiocyanate in Methanol–Water Mixtures

This paper reports the results of a variety of experiments carried out for understanding the solvation behavior of potassium thiocyanate in methanol–water mixtures. Electrical conductivity, speed of sound, viscosity, and FT-Raman spectra of potassium thiocyanate solutions in 5 and 10% methanol–water (w/w) mixtures were measured as functions of concentration and temperature. The conductivity and structural relaxation time suggest the ion–solvent and solvent-separated ion–ion associations increase as the salt concentration increases in the mixtures. The Raman band shifts due to the C–O stretching mode of methanol for the solvent mixtures reveal the formation of methanol–water complexes. The significant changes in the Raman bands for the C–N, C–S and O–H stretching modes indicate the presence of SCN⁻−solvent interactions through the N-end, “free” SCN⁻ and the solvent-shared ion pairs as potassium thiocyanate is added to the methanol–water mixtures. The relative changes corresponding to H–O–H bending and C–O stretching frequencies indicate that K⁺ is preferentially solvated by water in these solvent mixtures. The appearance and increase of the intensity of a broad band at ≈940 cm⁻¹ upon salt addition was attributed to the SCN⁻–H₂O–K⁺ solvent-shared ion pairs. No Raman spectral evidence for K⁺(H₂O)_n species was observed. The preferential solvation of K⁺ and SCN⁻ in the methanol−water mixtures was verified by the application of the Kirkwood−Buff theory of solutions. This theory confirms that K⁺ is strongly preferentially solvated by water, whereas SCN⁻ is preferentially solvated by the methanol component.     

Determination of propazine by differential pulse polarography in micellar and emulsified media

An electroanalytical study of the herbicide propazine's reduction process in micellar solutions and oil-in-water emulsions is reported. The anionic surfactant sodium pentanesulphonate was chosen as the most suitable. The differential pulse polarograms of micellar solutions had two reduction peaks below pH 2.0, whereas only one peak was obtained above pH 2.O. Ethyl acetate was chosen as the organic solvent to form propazine emulsions. Unlike in micellar solutions, the DPP polarograms of propazine emulsions showed only one peak even at pH < 2.0, suggesting that propazine hydrolysis was hindered in the emulsified medium. The limiting current is diffusion-controlled and the electrode process is irreversible. Propazine can be determined by differential pulse polarography over the 1.0 × 10^–1 – 1.0 × 10^–1moll^–1 and 1.0 × 10^–15 – 4.0 × 10^–1 moll^–1 concentration ranges and the limit of detection was 2.8 × 10^–1 moll^–1. Of the potential interferents simazine, methoprotryne and terbutryn (alls-triazines), thiram (a dithiocarbamate), dinoseb (nitrophenolic), and heptachlor (chlorinated cyclo-diene herbicide), only the first two were significant (10% error for equimolar concentrations). The method was applied to the determination of propazine in spiked drinking water. At a concentration level of 2.0 × 10^–1 moll^–1 a recovery of 94 ± 6% was obtained, after tenfold concentration on Sep-Pak.     

Study of interaction between nitrogen DBD plasma-treated viscose fibers and divalent ions Ca2+ and Cu2+

Viscose fibers were treated with atmospheric pressure dielectric barrier discharge (DBD) plasma obtained in nitrogen in order to activate the fiber surface prior to sorption of the divalent ions Ca²⁺ and Cu²⁺. Methylene blue sorption was used for estimation of carboxyl group formation on the surface after DBD plasma treatment, through the degree of fabric staining (K/S). Sorption of divalent ions was performed from solutions of each individual ion and from solutions of calcium and copper in succession onto untreated and plasma-treated viscose samples. The quantity of sorbed metal was determined from the neutralization and iodometric titration method. Scanning electron microscopy coupled with energy dispersive X-ray analysis was used for fiber morphology and surface characterization before and after plasma treatment, and after metal ions sorption. Experiments revealed copper microparticles formation on the fiber surface when sorption of copper was performed on samples with bonded calcium. Further analysis confirmed that for growth of copper particles, both calcium ions and nitrogen DBD plasma pretreatments are necessary.     

Diffusional transport of urokinase and acyl-urokinase into fibrin and plasma clots: time of contact and fibrinolytic response in vitro

The effect of short-time contacts (2—20 min) of fibrin and plasma clots with solutions of urokinase and acyl-urokinase in a buffer or human blood plasma on the degree and duration of fibrinolysis was studied in vitro. Both plasminogen activators readily diffuse into clots in these time intervals and initiate prolonged dose-dependent lysis of washed fibrin clots devoid of plasma inhibitors. In a plasma clot—plasma system containing inhibitors, the fibrinolytic action of urokinase that penetrated is rapidly suppressed. Acyl-urokinase that penetrated into plasma clots supports prolonged thrombolysis in the absence of an activator in the surrounding plasma due to its resistance to the action of inhibitors and slow reactivation (k _deac = 6·10^–5 s^–1).     

Densities and Excess Molar Volumes of Binary and Ternary Mixtures of Aqueous Solutions of 2,2,2-Trifluoroethanol with Acetone and Alcohols at the Temperature of 298.15 K and Pressure of 101 kPa

Excess molar volumes V_m^E of the binary mixtures of (trifluoroethanol + 1-propanol), (trifluoroethanol + 2-propanol), (acetone + water), (methanol + water), (ethanol + water), (1-propanol + water), (2-propanol + water), and the ternary mixtures of (trifluoroethanol + methanol + water), (trifluoroethanol + ethanol + water), (trifluoroethanol~+ 1-propanol + water), (trifluoroethanol + 2-propanol + water) and (trifluoroethanol + acetone + water) were measured with a vibrating tube densimeter at the temperature of 298.15 K and the pressure 101 kPa. The extrema in V_m^E of trifluoroethanol mixtures occur at –0.690 cm³-mol^–1 for (trifluoroethanol + 1-propanol), at –0.990~cm³-mol^–1 for (trifluoroethanol + 2-propanol); at 0.562 and –0.973 cm³-mol^–1 for (trifluoroethanol + methanol + water), at 0.629 and –0.973 cm³-mol^–1 for (trifluoroethanol + ethanol + water), at 1.082 and –0.659 cm³-mol^–1 for (trifluoroethanol~+ 1-propanol + water), at 0.998 and –0.991 cm³-mol^–1 for (trifluoroethanol~+ 2-propanol + water), and at 0.515 and –1.472 cm³-mol^–1 for (trifluoroethanol + acetone + water). The experimental ternary V_m^E values were predicted by empirical expressions using binary solution data.     

A sensitive and specific HPLC-MS method for the determination of sophoridine,sophocarpine and matrine in rabbit plasma

A sensitive and specific method was developed for the determination of sophoridine (SRI), sophocarpine (SC) and matrine (MT) in rabbit plasma by HPLC-MS. After an administration of Kuhuang by injection, blood samples were collected and extracted with methanol. The extract solutions were analysed by HPLC-MS method. The separation was performed on a ZORBAX Extend-C18 column using methanol/water/diethylamine (50:50:0.07, v/v/v) as mobile phase. The quinolizidine alkaloids were detected by using mass spectrometry in the SIM mode. There was a good linear relationship between peak area and concentration of analytes over the concentration range of 13.2–995.0 ng mL^–1 for SRI, 7.0–530.0 ng mL^–1 for SC and 8.8–655.0 ng mL^–1 for MT, respectively. The absolute recovery of this method was more than 57% for SRI, 87% for SC and 91% for MT. The accuracy of assay was more than 90%. The limits of detection (LODs) were 6.8 ng mL^–1 for SRI, 3.5 ng mL^–1 for SC and 4.2 ng mL^–1 for MT, respectively. The limits of quantitation (LOQs) were 13.2 ng mL^–1 for SRI, 7.0 ng mL^–1 for SC and 8.8 ng mL^–1 for MT, respectively. The intra-day and inter-day coefficients of variation (RSDs) were less than 10.1, 6.3 and 5.8% for SRI, SC and MT, respectively. The developed method was applied to determine the concentration–time profiles of SRI, SC and MT in rabbit plasma after injection of Kuhuang.     

Surface characterization and heats of adsorption of chromatographic alumina gel

The porous nature of chromatographic alumina gel has been investigated by adsorption/condensation processes and electron microscopy. Having 63% porosity, the gel is very porous. Total pore volume as determined by the fluid-displacement method is 0.497 cm³ g^–1. Its specific surface area, as determined by water vapor adsorption, is 225 m² g^–1. Micropore volume, as determined by utilizing Gurwitsch's rule, turns out to be 0.262 cm³ g^–1. The greater portion of the surface area and pore volume occurs in small and transitional pores, with average pore radii (hydraulic) less than 2.1 nm.Organic vapors, such as methyl ethyl ketone, acetone, methyl acetate, and methyl alcohol, were adsorbed on the gel between 0 and 36°C under vacuum, and the data were recorded on a Cahn-1000 electrobalance device. Isosteric heats of adsorption were calculated by applying the Clausius Clapeyron equation to the adsorption isosters at different surface coverages. Two types of adsorption processes, one with low activation energy and other with high activation energy can be distinguished. The increase in values ofq _st indicates that increasing temperature changes physical adsorption into chemisorption.     

Dielectric Relaxation of Aqueous Trimethylamineoxide Solutions

Dielectric relaxation was examined for aqueous trimethylamineoxide (TMAO) solutions over a wide concentration (c) range. The dielectric relaxation of TMAO was described by a Debye-type function with a relaxation time of about 3 × 10^–11 s, with the strength proportional to c. The number of water molecules tightly hydrated to unprotonated TMAO was estimated to be two. Ab initio calculations predict the magnitudes of the dipoles for individual TMAO and TMAO tightly hydrated by two water molecules, to be 4.9 and 4.2 D, respectively. When the amount of HBr added was increased, dielectric spectra were described by two modes with relaxation times, about 3 × 10^–11 and the about 8 × 10^–10. The fast relaxation was assigned to the rotational mode of unprotonated TMAO tightly hydrated by two water molecules, and the slow mode to the rotational mode of dimers formed between a protonated and unprotonated TMAO due to hydrogen bonding.     

Soft template synthesis of cobalt(III) chelates with 2,8-dithio-3, 7-diaza-5-oxa-nonandithioamide-1,9 and with 2,7-dithio-3,6-diazaoctadien-3, 5-dithioamide-1,8 into cobalt(III)hexacyanoferrate(II) gelatin-immobilized matrix materials

The complexing processes in the triple Co^III–dithiooxamide–methanal and Co^III–dithiooxamide–glyoxal systems taking place in the KCoFe(CN)₆-gelatin-immobilized matrix in contact with aqueous-alkaline solutions (pH~12) containing (dithiooxamide + methanal) and (dithiooxamide + glyoxal), have been studied. Template synthesis leading to macrocyclic Co^III coordination compounds with tetradentate N,N,S,S-donor ligands-(2,8-dithio-3,7-diaza-5-oxanonandithioamide-1,9) and (2,7-dithio-3,6-diazaoctadien-3,5-dithioamide-1,8) occurs under these specific conditions. Dithiooxamide, methanal and glyoxal are the ligand synthons in these processes.     

Cationic and Anionic Effects on the Glass Transition Temperature for Aqueous Electrolyte Solutions

Glass-forming composition regions of aqueous CH₃COOM (M = Li, Na, K, Rb, Cs, and Tl), CF₃COOM (M = Li, Na, K, Rb, and Cs), and Et₄NX (Et₄ = C₂H₅, X = OH, CH₃COO, Cl, Br, NO₃, and SCN) solutions are reported as a function of water concentration R (R = moles of water per moles of salt). Glass transition temperatures (T _g) were measured by a simple differential thermal analysis (DTA) method with a cooling rate of about 600 K-min^–1. The T _g of all solutions decrease with increasing R (decreasing salt concentration). It is found that T _g at the same R value decrease in the order Na⁺ > Li⁺ > K⁺ > Rb⁺ > Cs⁺ in all glass-forming composition regions of the alkali acetate salt and alkali trifluoroacetate salt solutions. T _g for Et₄NX solutions decrease in the order CH₃COO^– ~OH^– > Cl^– > Br^– > NO ₃ ^– > SCN^–. The effects of the cation and anion on the glass-forming behavior in these aqueous solutions are discussed.     

Thermodynamic Properties of Aqueous Solution of 2-Isopropoxyethanol at 25°C

Excess enthalpy, excess isobaric heat capacity, density, and speed of sound for aqueous 2-isopropoxyethanol solutions were measured at 25°C. The density was also measured at 20°C. The excess enthalpy was –800 J-mol^–1 at the minimum (mole fraction alcohol, x = 0.2), showing that the hydrogen bonds formed between unlike molecules are stronger than those in both pure liquid states. The excess volume also was large and negative, more than –1.2 cm³-mol^–1 at the minimum (x = 0.35). Excess isentropic and isothermal compressibilities are extremely negative. These results suggest that breaking the hydrogen bond network in water and forming the stronger hydrogen bonds between unlike molecules reduces the volume of the solution and makes the solution less compressible. The excess isobaric heat capacity is positive and large, up to 10 J-K^–1-mol^–1 and shows anomalous behavior in the neighborhood of x = 0.15.