Comparative Fatty Acid Analysis of Telekia Speciosa

Fatty acids in petroleum-ether extracts prepared from the flower, stem, and leaf of Telekia speciosa (Schreb.) Baung. were studied by capillary gas chromatography-mass spectrometry (GC-MS). The flower and leaf extracts were found to contain similar fatty acids, namely palmitic, linoleic, and oleic acids, whereas the stem extract contained only caproic acid.     

己酸铁对乙醇稀溶液的络合萃取

乙醇是重要的化工产品,一般通过发酵法和合成法生产,其在发酵液及合成液中的浓度较低［１～３］．一些工业过程产生的大量废水中往往含有微量乙醇,需要进行脱除或回收．传统上,乙醇的分离和回收多采用蒸馏法［１,４］．但稀溶液蒸馏需要消耗大量的能量．对于含微量醇...     

顶空气相色谱质谱法快速测定液体食品中的挥发性酸

建立了一种用于快速测定食品中挥发性有机酸的分析方法.利用顶空技术对样品进行前处理,并与气相色谱质谱联用,用离子选择对11种挥发性有机酸进行定量分析.在优化的实验条件下,方法线性关系良好,线性范围为0.20 ～5 mg/L.11种挥发性有机酸的相关系数均大于0.998 6,检出限为0.000 2 ～35.5 mg/L,比全扫描检出限低1 ～3个数量级.11种挥发性有机酸的回收率为93% ～99%,相对标准偏差均小于10%.该方法简便、快速、重复性好、定性定量准确,适于食品中挥发性有机化合物的检测.     

Studies on some radical transfer reactions by entrapping the radicals as polymer end groups. II. Reactions of ȮH radicals with amino acids

The reaction of ?H radicals with a number of aliphatic amino acids has been studied by entrapping the resultant radicals as end groups of poly(methyl methacrylate) that have been detected and estimated by the sensitive dye partition technique. The rate constants of the reaction (in mol^?1 L S^?1) of 7 amino acids at 25°C and at pH 1.00 have been determined as 8.33 × 10⁸ for glycine, 2.56 × 10⁹ for β-alanine, 2.01 × 10⁹ for β-alanine, 3.99 × 10⁹ for 4-amino butyric acid, 7.56 × 10⁹ for (1+) valine, 1.42 × 10¹⁰ for (1?) leucine, and 5.98 × 10¹⁰ for 6-amino caproic acid. Glycine, α-alanine, β-alanine, and 4-amino butyric acid produced radicals that underwent deamination and incorporated only carboxyl-bearing end groups in the polymer. The other amino acids, leucine, valine, and 6-amino caproic acid, produced at least two types of radicals, radicals that underwent deamination and those that remained intact, and incorporated in the polymer both carboxyl- and amine-bearing end groups but in different amounts. The latter type of radicals were about 29% from 6-amino caproic acid, 23% from leucine, and 18% from valine. The change of pH from 0.80 to 2.72 did not produce any significant change in the end group profile of the polymer obtained, indicating no appreciable change in the rate of the reaction of ?H radicals with the simplest amino acid glycine in the pH range studied.     

High-temperature transnitrilation of 2-bromocaproic acid

Chromato-mass spectrometry and IR and PMR spectroscopy were used to study the high-temperature reaction of 2-bromocaproic, 2-iodocaproic, and 2-bromo-2-phenylacetic acids with acetonitrile. The formation of anomalous transnitrilation products (capronitrile and benzyl cyanide) is a consequence of the initial conversion of 2-halo-substituted caproic and phenylacetic acids to caproic and phenylacetic acids, respectively.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1682–1684, July, 1990.     

Improved gas chromatographic method for the determination of the individual free fatty acids in cheese using a capillary column and a PTV injector

Summary A gas chromatographic method with a capillary column and a programmed temperature vaporizer injector has been used to analyze the individual free fatty acids in cheese. The lipids were extracted from an acidified cheese slurry with diethyl ether and treated with tetramethylamonium hydroxide (TMAH) to convert the free fatty acids to tetramethylammonium soaps (TMA-soaps), which were subsequently pyrolyzed to methyl esters in the injector. Carrying out injection at the initial column temperature resulted in lower dispersion of the results, but the solvent front prevented quantitative determination of butyric and caproic acids, and an injector temperature of 300°C was therefore employed. Under the conditions tested, trimethylamine (tma) flash-off did not affect the determinations. The accuracy of the method improved at higher free fatty acid contents (coefficient of variation of 0.53% for a total free fatty acid content of 9000 mg/kg as opposed to 7.0% for a total free fatty acid content of 1400 mg/kg). The recovery rate for individual free fatty acids ranged between 91 and 103%.     

Application of zirconium-modified silica gel as a stationary phase in the ion-exclusion chromatography of carboxylic acids II. Separation of aliphatic carboxylic acids with pyromellitic acid as eluent and with suppressed conductimetric detection

The application of zirconium-modified silica gels (Zr-Silica) as stationary phases for ion-exclusion chromatography with conductimetric detection (IEC–CD) for C₁–C₈ aliphatic carboxylic acids (formic, acetic, propionic, butyric, valeric, caproic, heptanoic and caprylic acids) was carried out using pyromellitic acid as the eluent. Zr-Silicas were prepared by the reaction of the silanol group on the surface of silica gel with zirconium tetrabutoxide [Zr(OCH₂CH₂CH₂CH₃)₄] in ethanol solution. An ASRS-Ultra anion self-regenerating suppressor in the K⁺ form was used for the enhancement of conductimetric detector response of these aliphatic carboxylic acids. A Zr-Silica adsorbed on 10 mg zirconium g⁻¹ silica gel was the most suitable stationary phase in IEC–CD for the separation of these aliphatic carboxylic acids. Excellently simultaneous separation and highly sensitive detection for these aliphatic carboxylic acids were achieved in 25 min by IEC–CD with the Zr-Silica column (250×4.6 mm I.D.) and a 0.2 mM pyromellitic acid containing 0.15% heptanol as the eluent.     

Ion-exclusion chromatographic behavior of aliphatic carboxylic acids and benzenecarboxylic acids on a sulfonated styrene--divinylbenzene co-polymer resin column with sulfuric acid containing various alcohols as eluent

The addition of C1-C7 alcohols (methanol, ethanol, propanol, butanol, heptanol, hexanol and heptanol) to dilute sulfuric acid as eluent in ion-exclusion chromatography using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as the stationary phase was carried out for the simultaneous separations of both (a) C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, 2-methylvaleric, isocaproic, caproic, 2,2-dimethyl-n-valeric, 2-methylhexanoic, 5-methylhexanoic and heptanoic acids) and (b) benzenecarboxylic acids (pyromellitic, hemimellitic, trimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic and salicylic acids and phenol). Heptanol was the most effective modifier in ion-exclusion chromatography for the improvement of peak shapes and a reduction in retention volumes for higher aliphatic carboxylic acids and benzenecarboxylic acids. Excellent simultaneous separation and relatively highly sensitive conductimetric detection for these C1-C7 aliphatic carboxylic acids were achieved on the TSKgel SCX column (150 x 6 mm I.D.) in 30 min using 0.5 mM sulfuric acid containing 0.025% heptanol as eluent. Excellent simultaneous separation and highly sensitive UV detection at 200 nm for these benzenecarboxylic acids were also achieved on the TSKgel SCX column in 30 min using 5 mM sulfuric acid containing 0.075% heptanol as eluent.     

Diazabicycloalkanes with nitrogen atoms in the nodal positions. 5. Synthesis and some reactions of 2-hydroxymethyl-1,4-diazabicyclo [2.2.2]octane

2-Hydroxymethyl-1,4-diazabicyclo[2.2.2]octane was synthesized by reduction of 1,4-diazabicyclo[2.2.2]octane-2-carboxylic acid or its methyl ester with lithium aluminum hydride in tetrahydrofuran and by hydrolysis or hydrogenation of 2-benzyloxymethyl-1,4-diazabicyclo[2.2.2]octane. Depending on the conditions, 2-hydroxymethyl-1,4-diazabicyclo[2.2.2]octane reacts with methyl iodide to give primarily either a bisquaternary or a monoquaternary derivative. The latter is the only product in its alkylation with methyl esters of benzoic and caproic acids.See [1] for Communication 4.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1404–1407, October, 1980.     

Determination of volatile carboxylic acids in animal wastes by (GC)2 of their benzyl esters

The C₁ -C₆ fatty acids present in various types of heterogeneous animal wastes were isolated by steam distillation and determined as benzyl esters by high resolution gas chromatography. Glass capillary columns, deactivated with barium carbonate and coated with UCON HB 5100, allowed the analysis of benzyl formate, acetate, propionate, isobutyrate, butyrate, isovalerate, valerate, and caproate in less than 20 minutes. Recovery tests, performed on more than 50 different samples, indicated a benzylation yield and an overall efficiency higher than 99%, with a standard deviation of 2.6% (C₅) to 6.0% (C₁). The absolute detection limit ranged from 0.3 picomole (caproic acid) to 1.0 picomole (formic acid).     

High performance ion exclusion chromatographic characterization of the vaginal organic acids in women with bacterial vaginosis.

Vaginal organic acids have previously been detected by gas-liquid chromatography, but we have applied an ion exclusion high performance liquid chromatographic procedure to the analysis of vaginal discharge samples. This procedure has the advantage of not requiring derivitization of non-volatile acids and provides the convenience of a technique which does not require the use of flammable gasses, while allowing the identification of at least 18 different acids from the same chromatographic analysis. Vaginal discharge from women with symptoms of bacterial vaginosis was collected on weighed swabs and analysed for the presence of organic acids. The results were compared to the organic acid content of samples obtained from the same cohort of women after treatment with metronidazole. In addition, samples were obtained from asymptomatic women and these samples were analysed in the same manner. The number of organic acids present in samples from women with bacterial vaginosis was greater than the number found after treatment or among asymptomatic women. Succinic acid appeared to be inversely related to lactate concentration and succinate:lactate ratios were greater among women with bacterial vaginosis before treatment than after treatment. Liquid chromatography has proven useful as a means of evaluating the metabolic end-products of vaginal microorganisms in situ.     

Induction periods in the polymerization of lactams initiated with carboxylic acids in an anhydrous medium

The polymerizations of capro-, enantho-, capryl- and laurolactam were investigated. It was found that polymerization initiated with aliphatic carboxylic acids proceeds prevailingly via addition of the lactam group to the carboxyl group. In the case of capro-, enantho- and capryllactam, addition of the lactam group to the forming primary amino groups also becomes operative with increasing extent of polymerization. Determination of the content of free initiator during caprolactam polymerization showed that incorporation of the initiator ended approximately at the end of the induction period. The induction period of caprolactam polymerization initiated with lauric or caproic acid is longer than for N-caproyl-6-aminocaproic acid as initiator. The acceleration of polymerization is due to the fact that addition of the first caprolactam molecule to the initiating carboxylic acid proceeds considerably more slowly than addition of the second and further molecules.     

6-马来酰亚胺基己酸的合成与表征

以氨基己酸和马来酸酐为原料,乙酸酐、乙酸钠作催化剂,在室温下反应5h,合成了一种新的可用于蛋白质、多肽药物修饰的“间隔臂”6-马来酰亚胺基己酸,产率90．34％,其结构经。HNMR,IR和LC-MS表征。     

Determination of domoic acid by on-line coupled capillary isotachophoresis with capillary zone electrophoresis

An on-line coupled capillary isotachophoresis--capillary zone electrophoresis (cITP-CZE) method for the determination of domoic acid in shellfish and algae is described. The optimised cITP-CZE electrolyte system was 10 mM HCl + 20 mM beta-alanine (BALA) + 0.05% hydroxyethylcellulose (leading electrolyte), 5 mM caproic acid (terminating electrolyte) and 20 mM caproic acid + 20 mM BALA + 0.1% HPMC (background electrolyte). A clear separation of the domoic acid from the other components of methanolic sample extract was achieved within 25 min. Method characteristics, i.e., linearity (0-200 microg/l), accuracy (recovery 101+/-3%), intra-assay repeatability (2.4%) and detection limit (1.5 microg/l) were determined. Speed of analysis, low laboriousness, high sensitivity and low running cost are the typical attributes of the cITP-CZE method. Developed method was successfully applied to analysis of shellfish samples and food supplements containing algae extract.     

Comprehensive Evaluation of Amino Acids and Polyphenols in 69 Varieties of Green Cabbage (Brassica oleracea L. var. capitata L.) Based on Multivariate Statistical Analysis

The biological activities of the primary metabolites and secondary metabolites of 69 green cabbage varieties were tested. The LC-MS detection method was used to determine the content of 19 free amino acids (lysine, tryptophan, phenylalanine, methionine, threonine, isoleucine, leucine, valine, arginine, asparagine, glycine, proline, tyrosine, glutamine, alanine, aspartic acid, serine, and glutamate). The content of 10 polyphenols (chlorogenic acid, gallic acid, 4-coumaric acid, ferulic acid, gentisic acid, cymarin, erucic acid, benzoic acid, rutin, and kaempferol) was determined by the HPLC detection method. Considering the complexity of the data obtained, variance analysis, diversity analysis, correlation analysis, hierarchical cluster analysis (HCA), and principal component analysis (PCA) were used to process and correlate amino acid or polyphenol data, respectively. The results showed that there were significant differences between the different amino acids and polyphenols of the 69 cabbage varieties. The most abundant amino acids and polyphenols were Glu and rutin, respectively. Both amino acids and polyphenols had a high genetic diversity, and multiple groups of significant or extremely significant correlations. The 69 cabbage varieties were divided into two groups, according to 19 amino acid indexes, by PCA. Among them, seven varieties with high amino acid content all fell into the fourth quadrant. The HCA of amino acids also supports this view. Based on 10 polyphenols, the 69 cabbage varieties were divided into two groups by HCA. Based on 29 indexes of amino acids and polyphenols, 69 cabbage varieties were evaluated and ranked by PCA. Therefore, in this study, cabbage varieties were classified in accordance with the level of amino acids and polyphenols, which provided a theoretical basis for the genetic improvement of nutritional quality in cabbage.     

Composition of the essential oil of rootstock from Cimicifuga simplex

The composition of the essential oils from rootstock of Cimicifuga simplex has been investigated by capillary GC and GC/MS. The main components in essential oil were m-acetanisole (27.57%), (E)-cinnamaldehyde (6.84%), paeonol (5.58%), caproic acid (5.07%) and atractylone (3.10%). The oil was characterized by a high content of aromatic components (52.59%).     

Assessment of formation channels of cyclohexyl mono- and dicarboxylates in oxidation of cyclohexane

Russian Journal of Applied Chemistry - Temperature dependences of the rate constants of the esterification reactions of the main carboxylic acids contained in oxidized cyclohexane (adipic, caproic,...     

北柴胡挥发油的成份研究I.

The chemical constituents of essential oil from the roots of Bupleurum chinense DC. were examined by means of GC-MS technique combined with preparative GC TLC and IR. As a result of the analyses, twenty components were identified namely: pentanoic acid, caproic acid, heptanoic acid, 2-heptenoci acid, caprylic acid, 2-octenoic acid, pelargonic acid, 2-nonenoic acid, phenol, cresol, ethylphenol, thymol, eugenol, 0-methoxyphenol, γ-heptalactone, γ-octalactone, γ-decalactone, γ-undecalactone, messoialactone and vanillin acetate.     

Effects of Carboxylic Acids on Calcite Formation in the Presence of Mg2+ Ions

The effects of seven carboxylic acids on calcite formation in the presence of Mg2+ ions, whose molar concentration ratio Mg2+/Ca2+ = 0.5 exclusively induced aragonite precipitation in the absence of carboxylic acids, were studied using a double diffusion technique. The presence of carboxylic acids, acrylic acid, maleic acid, tartaric acid, malonic acid, malic acid, succinic acid, and citric acid in the gel medium favored the formation of magnesian calcite relative to the amount of the additives. Induction time and the positions of the first precipitation were measured to analyze the behavior of crystallization based on the equivalency rule. The formation of magnesian calcite was also studied with the help of Avrami's equation (solid-state model for transformation). The results of applying this equation suggested that aragonite transformed into calcite through a solid-to-solid process. The formation of magnesian calcite was interpreted as the following process: aragonite nuclei, formed owing to Mg2+ ions at the initial stage of CaCO3 crystallization, transformed into calcite nuclei through a solid-to-solid process while their growth was inhibited by the adsorption of carboxylic acids. The magnesian calcite crystals grew on crystal seeds of calcite formed from aragonite nuclei. Copyright 1999 Academic Press.     

Lipid content and fatty acid composition in lemon wax

Lipids were extracted from lemon wax and fractionated into four classes on a silicic acid glass packed column by thin-layer chromatography (TLC). The free fatty acids, the fatty acid composition and the amount of each separated lipids were determined by capillary column gas chromatography (GC). Total lipids (TL) were 60 mg per 100 g raw weight and the ratio of nonpolar lipids (NPLs): glycolipids (GLs): phospholipids (PLs) was about 47:2:2. The main free fatty acids in lemon wax were hexadecanoic acid, cis-9-octadecenoic acid and cis,cis-9,12-octadecadienoic acid, while in the lipid fractions the main fatty acids were hexadecanoic acid in all the fractions, cis-cis-9,12-octadecadienoic and decanoic acids in triglyceride (TG) fraction, dodecanoic and cis-9-octadecenoic acids in diglyceride (DG) fraction and tetradecanoic, octadecanoic and cis-9-octadecenoic acids in GL and PL fractions. The ratio of unsaturated to saturated fatty acids showed a remarkable difference among these four lipid fractions. In PL and GL fractions this ratio was similar, 47.7% and 47.1% respectively, and in TG fraction it was 42.4% while in DG fraction this value was 23.5%.