Trace analysis of fungicides in grape juice and wine using glass capillary gas chromatography

The fungicides Bupirimate, Fenarimol, and Vinclozolin were sprayed on Vines. The fruits were harvested 8 and 21 days after the final application and processed to juice and wine. The fungicide residues were determined by filtration of the samples throug XAD-2 after pH adjustment, elution with methylene chloride, and glass capillary gas chromatography with SE-30 as stationary phase. Residue values of the three compounds were reported before and after fermentation. The precision of the analytical method was established by spiking portuguese white wine and spanish grape juice with the three fungicides and Triadimefon. The recoveries were in the range 80%-100%, except for Vinclozolin.     

Characterization of silk fibroin/hyaluronic acid polyelectrolyte complex (PEC) films

This study aimed the characterization of the films casted from the aqueous mixtures of the pH induced complexes between silk fibroin (SF) and hyaluronic acid (HA). The insoluble and transparent films were subjected to scanning electron microscopy (SEM) analyses to show the morphological changes. Thermal analysis of complex films was determined by a differential scanning calorimeter (DSC). The changes in the crystalline state were monitored by X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). It was shown that the complexation between HA and SF was dominantly induced by pH. It was shown that the complex films comprised mixtures of crystalline and non-crystalline regions.     

高效液相色谱法分离和测定酒石酸和马来酸

１引言 酒石酸（２,３一二羟基丁二酸）和马来酸（顺丁烯二酸）都是重要的有机化工原料,它们被广泛地应用于有机合成和其它化工生产领域［１］． 酒石酸的制备常用钨酸作为催化剂,由马来酸识水溶液与过氧化氢进行环氧化反应再经水解精制而成,其中常含有微量的没有反应的马来酸,因此,建立有效的分离和测定酒石酸和马来酸的方法,对于酒石酸生产条件的选择与控制,以及产品的质量检测等都有十分重要的意义． 目前尚未发现有关同时分离和测定酒石酸和马来酸的文献报道．我们首次采用反相高效液相色谱法,跟踪监测了酒石酸生产过程中的物…     

Linear polyurethanes made from naturally occurring tartaric acid

Naturally occurring tartaric acid was used as raw material for the synthesis of novel linear polyurethanes (PURs) bearing two carboxylate side‐groups in the repeating unit. Aliphatic and aromatic PURs were obtained by reaction in solution of alkyl and benzyl tartrates with hexamethylene diisocyanate and 4,4′‐methylene‐bis(phenyl isocyanate), respectively. All the novel PURs were thermally stable and optically active. The aliphatic carboxylate‐containing PURs had M_w in the 40–70 kDa range, with PD between 2.1 and 2.5; all were semicrystalline polymers with melting temperatures between 100 and 150 °C and T_g in the 50–80 °C range. The aromatic PURs were amorphous materials with molecular weights between 18 kDa and 25 kDa and T_g above 130 °C. Hydrogenolysis of the PUR made from hexamethylene diisocyanate and benzyl tartrate yielded PURs containing up to 40% of free carboxylic side‐groups. The tartrate‐derived PURs displayed enhanced sensitivity to hydrolysis compared with their unsubstituted 2,6‐PUR homologs. The PURs bearing free carboxylic groups were unique in being degraded by water upon incubation under physiological conditions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2391–2407, 2009     

立体选择性萃取分离反式DV菊酸对映体

研究了反式DV菊酸对映体在含有手性选择体酒石酸酯的水-有机相双相体系中的萃取分配行为,考察了有机稀释剂种类、酒石酸酯的浓度、温度、水相的pH值、酒石酸酯烷基链长度对分配系数(D)和分配因子(α)的影响.研究表明:三氯甲烷作稀释剂时萃取分离效果较好;温度升高使分配系数增大,分离因子减小;分配系数随pH的升高而降低,随着酒石酸酯浓度的增大而增大,分离因子随pH的升高和酒石酸酯浓度的增大先增加后降低,pH和酒石酸酯浓度分别为4.50和0.40mol/L时取得较好的分离效果;取代烷基链长对分配系数(D)和分离因子(α)亦有较大影响.     

Synthesis and characterization of novel chiral imidazolium and pyridinium ionic liquids derived from tartaric acid and 2-oxazolidinone

Abstract

Novel chiral imidazolium and pyridinium ionic liquids based on tartaric acid and 2-oxazolidinone were designed. Symmetrical dicationic ionic liquids based on tartaric acid have been synthesized and characterized. These chiral ionic liquids were designed by employing very short and simple methods. Incorporation of alkyl halide over tartaric acid and 2-oxazolidinone is an important step. N-methyl imidazole and pyridine were used for preparation of quaternary salts. These ionic liquids have been evaluated for the asymmetric sulfide oxidation. Chiral ionic liquids based on tartaric acid showed superior chiral inducing property as compare to 2-oxazolidinone based chiral ionic liquids.     

天然酒石酸在合成手性含膦配体中的应用

本文综述了以天然酒石酸为光活性原料的手性含膦配体合成, 对三十三种手性含膦配体进行归类,同时也简要地介绍了部分配体的Rh(I)配合物催化剂对(Z)-α-乙酰氨基肉桂的催化氢反应结果。     

Comparison of volatile constituents extracted from model grape juice and model wine by stir bar sorptive extraction-gas chromatography-mass spectrometry

A stir bar sorptive extraction (SBSE) method coupled with gas chromatography-mass spectrometry was optimised for the analysis of volatile components of a model wine, based on a previously optimised method used for analysis of the same components in model grape juice. The presence of ethanol in the model wine sample matrix resulted in decreased sensitivity of the method toward most of the volatile constituents. Mean percent relative recoveries and reproducibilities (%CV) were 22.8% and 7.1%, respectively, compared with 28.4% and 8.5% for model grape juice. The mean limit of detection (LoD) ratio (juice:wine) was 0.25. Similar sensitivities for the two sample matrices using this method were achieved by changing the split ratio from 20:1 (grape juice) to 5:1 (wine), giving a mean limit of detection ratio (juice:wine) of 1.0, thus allowing direct comparison of chromatograms of volatile components in the two matrices. This enabled direct comparisons of grape juices and the wines derived from them by alcoholic yeast fermentation. The influence of ethanol concentration in the range 9-15% on method sensitivity is discussed, using an overlay of the total ion chromatograms. The use of a gas saver device for the 5:1 split ratio analysis of desorbed model wine aroma compounds is discussed in terms of preventing extraneous reaction of sorbent and stationary phases with air during analysis.     

The Characterization of Organic Modified Montmorillonite and Its Filled PMMA Nanocomposite

Thermogravimetric analysis (TG) and Fourier transform infrared (FTIR)results of commercial montmorillonite were compared to that exchanged with trimethyloctadecyl quaternary ammonium chloride (SCPX2048), both were treated up to500°C. The time-of-flight mass spectrometer (TOF/MS) results of SCPX2048 trapped under300 and 500°C were compared with that of N,N,Ntrimethyl-1-dodecanammonium chloride(A 18-50) trapped under 200 and 300°C. The degradation mechanism of organic modified montmorillonite was proposed. PMMA-clay nanocomposite was synthesized through intercalation method and its properties were examined by both TG and DSC techniques. The thermal stability and glass transition temperature of montmorillonite filled PMMA increase comparing with that of the pure PMMA. This revised version was published online in July 2006 with corrections to the Cover Date.     

Investigation of molecular interactions in the complex formation of tartaric acid derivatives with di(2-ethylhexyl) phosphoric acid

The molecular interactions in the complex formation of two tartaric acid derivatives with di(2-ethylhexyl) phosphoric acid are investigated. The complex formation with a 1:1 stoichiometry between tartaric acid derivatives and D2EHPA can be obtained through UV-Vis titration, NMR chemical shifts and molecular dynamic simulations. Furthermore, the differences of the two complexes on the binding constants and strength of hydrogen bonds can also be determined. Such research will ideally provide insight into ways of regulating the complex forming properties of tartaric acid derivatives for composing or syn- thesizing new chiral resolving agents.     

A study of partial molar volumes of citric acid and tartaric acid in water and binary aqueous mixtures of ethanol at various temperatures

Partial molar volumes of citric acid and tartaric acid have been determined in water and binary aqueous mixtures of ethanol (5, 10, 15, 20 and 25% by weight of ethanol) at different temperatures and acid concentrations from the solution density measurements. The data have been evaluated by using Masson equation and the obtained parameters have been interpreted in terms of solute-solvent interactions. The partial molar volumes vary with temperature as a power series of temperature. Structure making/breaking capacities of the organic acids have been inferred from the sign of i.e. second derivative of partial molar volume with respect to temperature at constant pressure. Both the organic acids behave as structure breakers in water and water + ethanol.     

Thermal studies on mixtures of benzoic and salicylic acids with cyclodextrins

The thermal behaviour of benzoic and salicylic acids is compared with the behaviour of 1:1 molar ratio physical and kneaded mixtures of these acids with each of three different cyclodextrins (b-, hydroxypropyl-b-, and g-cyclodextrin). Differential scanning calorimetry and thermogravimetry coupled with evolved gas analysis by Fourier transform infrared spectroscopy were used for the thermal studies and X-ray powder diffraction and infrared spectroscopy provided complementary information. Thermal studies of benzoic acid with the cyclodextrins showed significant interactions in both physical and kneaded mixtures of benzoic acid/b-cyclodextrin and benzoic acid/hydroxypropyl-b-cyclodextrin. Interactions in the kneaded benzoic acid/g-cyclodextrin mixtures were the most extensive as might be expected for the cyclodextrin with the largest molecular cavity. The results for the salicylic acid/b-cyclodextrin and salicylic acid/hydroxypropyl-b-cyclodextrin mixtures were similar to those for benzoic acid/b-cyclodextrin and benzoic acid/hydroxypropyl-b-cyclodextrin. Again, the kneaded salicylic acid/g-cyclodextrin mixture showed the most interaction. This revised version was published online in July 2006 with corrections to the Cover Date.     

手性酒石酸二酰胺配体的合成及其锡络合物与苯甲醛的不对称加成

通过酒石酸乙酯和不同胺的酰胺化, 相应地合成到(+)N,N'-二苯基酒石酸二酰胺(2), (+)N,N'-二苄基酒石酸二酰胺(3),(+)N,N'-二环己基酒石酸二酰胺(4)和(+)N,N'-二正辛基酒石酸二酰胺(5).氯化亚锡与2当量的酒石酸二酰胺反应, 再加入烯丙基溴可制得手性锡络合物6, 锡络合物与苯甲醛反应,得到光学活性的高烯丙基化合物, 产率42～64％ , e.e.值24～62％.     

Stability evaluation of n-alkyl hyaluronic acid derivates by DSC and TG measurement

The thermal and thermooxidative behavior of sodium salt of hyaluronic acid (HA) and its n-hexyl, n-decyl, n-tetradecyl and n-hexadecyl ether derivatives having an equal degree of substitution have been studied by means of differential scanning calorimetry (DSC) and thermogravimetry (TG). Derivatives were prepared by a substitution of H atom at the OH bound to the sixth C of N-acetyl-D-glucosamin of HA unit by n-hexyl, n-decyl, n-tetradecyl and n-hexadecyl chains. Both thermal and thermooxidative degradation of HA and derivatives resulted in multistep process. The main interest of this work was focused on processes occurring in the course of the first decomposition step. Experimental DSC data showed lower stability of derivatives and, remarkably lower heat evolution in comparison with original HA. On the other hand, TG measurement recorded lower mass loss for derivates which indicated appearance of new types of crosslinking reactions. Oxidative stability was evaluated by means of DSC that provided the induction period and the protection factor determination. Derivates showed remarkably lower stability in comparison with original HA; comparing each other, the highest oxidation stability showed n-decyl and n-tetradecyl derivates.     

Thermal Characterization of Warifteine by Means of TG and a DSC Photovisual System

This work proposes thermal characterization as analytical methodology for the identification and purity assay of warifteine, an alkaloid in Cissampelos sympodialis Eichl. Thermal and kinetic parameters were determined by means of TG and DSC photovisual studies. The TG results showed that the decomposition of warifteine in air and nitrogen atmospheres proceeds in three and four steps, respectively. The TG data allowed calculation of the kinetic parameters of warifteine. The activation energy values obtained by different methods displayed a good correlation. With the DSC photovisual system applied it is possible to detect the impurity level in warifteine after its purification. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of acrylamide concentration on the kinetics of oxidation of tartaric acid by cerium(IV) in sulfuric-perchloric acid media

The kinetics of oxidation of tartaric acid by Ce(IV) in the absence and presence of acrylamide has been investigated spectrophotometrically in aqueous H₂SO₄–HClO₄ media at a constant ionic strength 2.0M and 25°C. Oxidation of tartaric acid in both cases was first order with respect to Ce(IV). Kinetic data showed that the reaction involves the formation of an unstable complex and an intermediate free radical. The activation parameters were calculated to be E _a =91.3±0.4 kJ-mol^–1, S=20.2±1.0 J-mol^–1-K^–1, H=88.8±0.4 kJ-mol^–1. A polymerization mechanism is discussed.     

Electrochemical behavior of tartaric acid at solid electrodes in aqueous and mixed solutions

Electrochemical behavior of D-tartaric acid at the Pt-, Cu-, Ta-, Cu-Hg-electrodes and the Cd-alloys with Sn, Ni, Hg, and In in aqueous and mixed solutions (water mixtures with acetone, ethanol, dimethylformamide, and pyridine) is studied by voltammetry. It is shown that the tartaric acid voltammograms always show waves related to the hydrogen ion discharge. A method recently suggested by authors allowed calculating the dissociation degrees at different stages, the concentrations of ionized and not ionized forms in dilute solutions of stereoisomers: DL-tartaric, L-tartaric, D-tartaric, and meso-tartaric acids. Simple empiric equations are suggested for the approximate calculating of some dissociation parameters for these acids.     

Biodegradable polymers based on renewable resources. IX. Synthesis and degradation behavior of polycarbonates based on 1,4:3,6‐dianhydrohexitols and tartaric acid derivatives with pendant functional groups

Novel polycarbonates, with pendant functional groups, based on 1,4:3,6‐dianhydrohexitols and L ‐tartaric acid derivatives were synthesized. Solution polycondensations of 1,4:3,6‐dianhydro‐bis‐O‐(p‐nitrophenoxycarbonyl)hexitols and 2,3‐di‐O‐methyl‐L ‐threitol or 2,3‐O‐isopropylidene‐L ‐threitol afforded polycarbonates having pendant methoxy or isopropylidene groups, respectively, with number average molecular weight (M_n) values up to 3.6₁ × 10⁴. Subsequent acid‐catalyzed deprotection of isopropylidene groups gave well‐defined polycarbonates having pendant hydroxyl groups regularly distributed along the polymer chain. Differential scanning calorimetry (DSC) demonstrated that all the polycarbonates were amorphous with glass transition temperatures ranging from 57 to 98 °C. Degradability of the polycarbonates was assessed by hydrolysis test in phosphate buffer solution at 37 °C and by biochemical oxygen demand (BOD) measurements in an activated sludge at 25 °C. In both tests, the polycarbonates with pendant hydroxyl groups were degraded much faster than the polycarbonates with pendant methoxy and isopropylidene groups. It is noteworthy that degradation of the polycarbonates with pendant hydroxyl groups was remarkably fast. They were completely degraded within only 150 min in a phosphate buffer solution and their BOD‐biodegradability reached nearly 70% in an activated sludge after 28 days. The degradation behavior of the polycarbonates is discussed in terms of their chemical and physical properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3909–3919, 2005     

Dehydration studies of Co(II), Cu(II) and Zn(II) methanesulfonates

The dehydration process of Co(II), Cu(II) and Zn(II) methanesulfonates was studied by thermogravimetry/derivative thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC) techniques in dynamic N₂ atmosphere. The TG/DTG curves show that all of them contain four crystallization water molecules, which are lost in two steps. The peak temperature and dehydration enthalpies ΔH were measured from DSC curves for each compound. The effect of procedural variables on the TG and DSC curves was investigated. In this work, the procedural variables included heating rate, Al pan state (unsealed and sealed) and sample mass.     

Thermoanalytical and Microscopic Investigation of Interaction between Paracetamol and Fatty Acid Crystals

The objective of this study was to investigate the possibility of interaction between paracetamol and saturated fatty acids. Although literature is replete with the interaction study of fatty acids with different drugs, few have examined the interaction with NSAIDs. Keeping in view the crystalline nature of paracetamol and fatty acids and to provide the intimate contact between the interacting molecules, crystals of binary mixture of drug with fatty acids were prepared by the solvent evaporation method. These crystals were subjected to FT‐IR, DSC, XRD, optical microscopy, SEM and AFM. DSC and XRD studies were unable to detect any interaction. Some changes were observed in FT‐IR spectrum of a binary mixture of drug with fatty acid. A better probe into interaction was obtained by microscopic techniques, especially atomic force microscopy.