Studies on the Ion Exchange Separation of Aspirin,Salicylic Acid and Acetic Acid

The liquid chromatography of aspirin, salicylic acid and acetic acid using cation exchange resins with aqueous alcohol and water as eluent was described. The results indicated that acetic acid could be separated from aspirin and salicylic acid by hydrogen form cation exchange resin with 25% ethanol or water as eluent. The possibility of using this method to determine the degree of hydrolysis of aspirin was discussed.     

Liquid Chromatography of Adenine,Caffeine, Theobromine,Theophylline, Tannic Acid,Xanthine and its Application to Tea Analysis

A polystyrenesulfonic acid resin in the hydrogen form is a useful stationary phase for chromatographic separation of adenine, caffeine, theobromine, theophylline, tannic acid, xanthine and tea components with aqueous ethanol as eluent. The results indicated that caffeine, theophylline, theobromine, adenine, xanthine and tannic acid could be separated on a column of Dowex-50W-X8(H)⁺ by elution with 25% ethanol as eluent.     

基于子空间夹角判据监测阿司匹林合成体系中的水杨酸和阿司匹林

利用水杨酸、阿司匹林、乙酸酐和乙酸的多波长紫外光谱作为本底光谱库和样本光谱库,建立一种基于子空间夹角判据的快速定量分析阿司匹林合成体系中水杨酸和阿司匹林的方法。水杨酸、阿司匹林质量浓度范围分别在1.16～34.684,9.84～188.928μg/mL内,所测得水杨酸和阿司匹林检验集的R分别为0.999 7和0.999 1,RMSE分别为0.509 5,2.624 0μg/mL,效果优于普通波峰点最小二乘法和偏最小二乘法。水杨酸和阿司匹林的加标回收率在94.01%～106.44%之间,测定结果的相对标准偏差分别为3.45%和4.80%(n=7)。该方法可用于监测阿司匹林合成体系中的水杨酸和阿司匹林。     

Fluorination of polyhydrofluoroethylenes. II. Formation of perfluoroalkyl carboxylic acids on the surface region of poly(vinylidene fluoride) film by oxyfluorination,fluorination, and hydrolysis

Oxyfluorination and postfluorination behaviors of poly(vinylidene fluoride) films, as well as hydrolysis of the films treated so far, have been studied by infrared (IR) spectrometry. By exposing the polymer film to a mixture of oxygen and fluorine at about 90°C acyl fluoride groups attendant on the scission of the polymer chains were formed. The oxyfluorinated molecules could be further perfluorinated with fluorine alone at about 90°C, leaving many of the acyl fluoride groups. When the properly oxyfluorinated and postfluorinated film was further treated with a hot 6M sodium hydroxide solution the opaque layer of perfluoroalkyl sodium carboxylate of high molecular weight was formed on the surface of the film, to about 3 μm in thickness, which behaved as a cation exchanger. This new type of cation exchanger of perfluoroalkyl carboxylic acid was significantly more acidic than the usual methacrylic acid exchanger. It was able to adsorb the sodium ions from a neutral sodium chloride solution up to about 70% of the exchange capacity and to keep the ions stable while washing them with water, though it could be regenerated to the hydrogen form with a dilute acetic acid solution. The nature of the new ion exchanger has been examined in some detail by IR spectrometry with Li⁺, Na⁺, and Cs⁺ ions.     

Über die abtrennung kleiner phosphorsauremengen von eisen und vanadin durch verteilung und durch ionenaustausch

The extraction of phosphoric acid as the molybdate complex from aqueous acid solution by means of ethyl acetate has been examined, with regard to the concentration of the two constituents and the hydrogen ion concentration and in the presence of a large excess of Fe and V. The separation of these two elements can be achieved within a certain range of concentration in free acid. The phosphoric acid is obtained in the form of acid sodium salts of dodecamolybdic acid in the esterphase. The influence of the concentration of the constituents and the hydrogen ion concentration is pointed out. Using a cation exchanger (Lewatit KS 22) small quantities of phosphoric acid can not be separated from large amounts of iron(III), but the separation from iron(II) and vanadium(IV) is very successful.     

紫外多波长光谱法监测阿司匹林合成过程的水杨酸和阿司匹林

建立测定阿司匹林合成过程中水杨酸、阿司匹林含量和转化率的分析模型。采用紫外多波长扫描乙醇溶液中阿司匹林和水杨酸的紫外光谱,建立水杨酸和阿司匹林紫外光谱的向量长度与其质量浓度的标准曲线,通过斜投影算法分离出待测样本中阿司匹林和水杨酸的紫外光谱。计算光谱向量长度,代入标准曲线得到待测样本中阿司匹林和水杨酸的含量。实验结果表明,水杨酸、阿司匹林的质量浓度与其紫外光谱的向量长度呈良好的线性关系,线性范围分别为2.00~40.00,10.00~200.00μg/m L。水杨酸和阿司匹林测定结果的相对标准偏差为0.16%~2.19%(n=5),加标回收率在93.3%~106.9%之间。该方法快速简便、准确可靠,可满足阿司匹林和水杨酸的同时测定及反应过程中水杨酸转化率监测要求。     

Hydroxylation of benzene in the system vanadium(V)-hydrogen peroxide-acetic acid

Hydroxylation of benzene in acetic acid at 323 K was studied in the presence of a sodium orthovanadate catalyst. With hydrogen peroxide as aqueous solution, the yield of phenol was 12–14%. With hydrogen peroxide generated from dry sodium peroxide, the yield of phenol could be improved to 21–23%. The apparent decomposition rate constants of hydrogen peroxide in acetic acid are presented.     

Cation-exchange separation of uranium in dimethylsulphoxide medium

Cation-exchange chromatography in a dimethylsulphoxide (DMSO) medium is a suitable means for separating uranium from metal ions, including copper, iron, nickel and molybdenum. Quantitative separations of uranium from 26 elements can best be effected on a column of Dowex 50W-X8 (200-400 mesh), using as the eluent a 20% v/v DMSO solution which is 0.6Min hydrochloric acid and 0.25M in sodium acetate. Only calcium is eluted with the uranium and all other elements studied are eluted either before or after uranium. The elution characteristics of uranium and of other metal ions were investigated with respect to changes in eluent and resin compositions. Separations were much less effective at higher concentrations of sodium ion or DMSO. None of the organic solvents methanol, ethanol, methyl glycol, acetone, dioxan or acetic acid was found to produce favourable separation conditions. Results with Dowex 50 resins of lower or higher cross-linkage were inferior to those obtained with the X8 resin.     

单柱离子色谱法测定一价阳离子的流动相研究

对单柱离子色谱法测定一价阳离子的流动相进行了系统研究，阐述了一价阳离子的保留行为和电导检测行为与流动相之间的关系，分别对无机酸（硝酸）、有机酸（柠檬酸）和芳香碱（苯胺）为流动相测定一价阳离子进行了讨论，其中有机酸和无机酸是较为适宜的流动相。     

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.     

Absorptiometric Determination of Acetylsalicylic Acid in Aqueous Ethanolic Solution

Abstract

Acetylsalicylic acid (ASA) was found to be quite soluble and quite stable in a 50/50% volume/volume water–ethanol solution. In this solution, a well-defined spectrum with a maximum absorbance, λ_max, of 276 nm of ASA was observed, and a molar absorptivity, ε, of 1.1 × 10³ M-cm was determined. These characteristic physical properties were used to determine ASA concentration in different brands of aspirin. The λ_max and the ε of salicylic acid were also determined. The characteristic values determined were 300 nm and 3.83 × 10³ M-cm, respectively. In this solution and using the method developed here, the concentrations of salicylic acid and ASA in a given aspirin formulation can be determined simultaneously.     

Quantitation of P-Aminohippuric Acid and N-Acetyl-P-Aminohippuric Acid from Blood by HPLC

Abstract

P-aminohippuric acid, N-acetyl-p-aminohippuric acid, and p-aminobenzoic acid can be separated by a reverse-phase, isocratic high-pressure liquid chromatographic procedure in less than 4 minutes. The eluent is 10 mM sodium phosphate buffer, pH 3.5, containing 30% methanol. Detection is by absorbance at 270 nm; quantitation is accomplished by peak height. Linear response was obtained from 3 to 1600 nmoles of each compound in aqueous standards and in blood deproteinized with perchloric acid.     

阿司匹林合成体系三组分的拉曼光谱测定及应用

阿司匹林合成过程中所采集的阿司匹林、水杨酸和乙酸酐的拉曼光谱存在交迭现象,很难从光谱数据中分离各组分含量。根据反应体系的组成和浓度配制样本溶液并采集拉曼光谱,运用多种方法对光谱进行预处理结合偏最小二乘法（PLS）对混合体系中阿司匹林、乙酸酐和水杨酸3组分浓度和光谱矩阵建立回归模型,对回归结果进行比较,根据交互验证均方根误差RMSECV,预测相关系数帮,预测均方根误差RMSEP。结果表明预处理方案可以有效降低基线漂移对预测精度的影响,根据Q值检验法和严检验法确定经矢量归一＋Savitzky-Golay五点二次平滑一阶卷积求导＋均值中心化对拉曼光谱预处理,PLS主成分选4,交互验证选用“逐一法”可时阿司匹林反应体系3组分进行同时测定,此训练集为阿司匹林合成体系的拉曼光谱在线监测提供了良好的数据支持。     

螯合离子色谱法分析复杂基体中痕量金属离子的研究

发展了应用螯合离子色谱法分析复杂基体中痕量金属离子的新方法。针对不同的检测目的,利用螯合柱（ＭｅｔＰａｃＣＣ－１）和浓缩柱（ＴＭＣ－１）,采用适当的洗脱液在线将基体中的阴离子、一价阳离子、碱土金属离子以及其它干扰离子除去,同时,浓缩富集待测的痕量金属离子,然后再选择适当的梯度淋洗体系,在含有双功能基的分析柱上分离Ｐｂ,Ｃｕ,Ｃｄ,Ｃｏ,Ｚｎ和Ｎｉ等过渡金属离子和１４种镧系金属离子,继而用在线柱后衍生和光度法检测。方法简单快速,样品经适当的酸消解成溶液后即可进样,灵敏度高,检测限为１０－９级甚至更低。     

高效液相法测定注射用赖氨匹林中的阿司匹林及游离水杨酸

 建立了高效液相法 (HPLC)同时测定注射用赖氨匹林中阿司匹林和游离水杨酸含量的方法。采用的柱为HypersilBDSC18柱 ,流动相为甲醇 水 冰醋酸 (体积比为 35∶6 5∶3) ,检测波长为 2 80nm。阿司匹林和水杨酸的质量浓度分别为 0 0 2 8g/L～ 0 14 1g/L和 0 77mg/L～ 3 85mg/L时线性关系良好 ,其线性相关系数分别为0 9999和 0 9998;加样回收率分别为 99 2 7% (RSD =0 8% )及 99 6 1% (RSD =1 3% )。     

Synthesis and some reactions of 7-methyl-5-phenyl-5H-pyrazolo[3,4-e]1,2,4-triazine-3-thiol

The title compound II has been prepared by the reaction of 3-methyl-1-phenyl-4-oxo-5-pyrazolone with thiosemicarbazide in aqueous potassium carbonate. Alkylation of II on the sulfur atom in aqueous sodium hydroxide afforded the 3-alkylthio derivatives III. Interaction of II or III with different amines yielded the 3-amino derivatives IV. The 3-hydrazino derivative IVa condensed with aromatic aldehydes in ethanol or acetic acid giving the corresponding hydrazones V.     

Liquid structure of acetic acid-water and trifluoroacetic acid-water mixtures studied by large-angle X-ray scattering and NMR

The structures of acetic acid (AA), trifluoroacetic acid (TFA), and their aqueous mixtures over the entire range of acid mole fraction xA have been investigated by using large-angle X-ray scattering (LAXS) and NMR techniques. The results from the LAXS experiments have shown that acetic acid molecules mainly form a chain structure via hydrogen bonding in the pure liquid. In acetic acid-water mixtures hydrogen bonds of acetic acid-water and water-water gradually increase with decreasing xA, while the chain structure of acetic acid molecules is moderately ruptured. Hydrogen bonds among water molecules are remarkably formed in acetic acid-water mixtures at xA相似文献   

Catalytic epoxidation of β-pinene with aqueous hydrogen peroxide

Epoxidation of β-pinene with 35–38% aqueous hydrogen peroxide in a new catalytic system containing manganese sulfate, salicylic acid, sodium bicarbonate and polar solvent (DMF, acetonitrile, methanol) is described. The method of quantitavive determination of β-pinene and its epoxide is developed.