GDX短柱快速GC分析空气中苯、甲苯和二甲苯

空气中苯、甲苯和二甲苯 (简称三苯 )测定 ,通常采用的气 液色谱及长柱[1～ 3 ] ,保留时间长。本法采用ＧＤＸ10 2担体和 0 .4 5ｍ短柱 ,只需 1ｍｉｎ即可完全分离 ,且具有简便快速 ,线性良好的特点。测定苯、甲苯和二甲苯的精密度分别为 1.84 % ,1.78%和 0 .6 3% ,检出限分别为 0 .8,1.0和 1.8ｍｇ·ｍ-3 。1　试验部分1.1　仪器与试剂ＳＰ2 30 5Ｅ气相色谱仪 ,ＦＩＤ检测器 ,附六通阀及1ｍｌ定量管 (北京分析仪器厂 )。三苯标准液 :苯、甲苯、二甲苯以 1.0 + 1.5 + 3 0混合。1.2　色谱条件色谱柱 :用 0 .4 5ｍ× 3.5ｍｍ玻璃管加工成Ｕ…     

微柱高效液相色谱法测定环境样品中的铁、钴、镍、铜、锌、锰

研究了用 2-(2-喹啉偶氮 )-间苯二酚 (QAR)为柱前衍生试剂 ,以WatersXterraTM RP18(1 .0×5 0mm ,2. 5 μm)微柱为固定相 ,60 %的甲醇 (内含 0 . 5 %的醋酸 )为流动相 ,高效液相色谱分离、二极管矩阵检测器测定铁、钴、镍、铜、锌和锰的方法。根据信噪比 (S N =3 )得各金属离子的检测限分别为 :铁3 μg L、钴 4μg L、镍 2 μg L、铜 4μg L、锌 5 μg L、锰 8μg L ,方法用于环境样品中痕量铁、钴、镍、铜、锌、锰的测定 ,相对标准偏差在 1 . 6%～ 3 . 5 %之间 ,标准回收率为 93 %～ 1 0 7%。     

反相高效液相色谱法测定大黄药材中游离及结合型蒽醌类衍生物的含量

建立了同时测定大黄药材中蒽醌类衍生物含量的RP HPLC法。色谱柱为HypersilC1 8柱 (2 5 0mm×4 6mmi.d .,1 0 μm) ,流动相为甲醇 乙腈 水 (3∶5∶2 ,磷酸调pH 2 .8) ,流速为 1 .0mL min ,柱温为 2 5℃ ,检测波长为 2 2 5nm。在此色谱条件下 ,各组分在 2 0min内均得到良好分离。平均回收率为 98.83 %～ 1 0 0 .9% ;相对标准偏差 0 .68%～ 1 .5 8%。     

低压液相色谱法分离、制备西红花甙

采用低压液相色谱法制备西红花有效成分西红花甙。最佳分离、制备条件 :填料为键合正丁烷的苯乙烯 二乙烯苯聚合物 ,其粒度为 57～ 76μm ;制备柱为 50cm× 1 .5cm ;纯化柱为 60cm×0 .80cm ;流动相为甲醇 水溶液 ,梯度洗脱范围是 50 / 50～ 95/ 5(V/V) ;样品量为 2 0mL( 1 0 0g/L) ;工作压力为 2× 1 0 5Pa。在上述条件下 ,制备了 5种西红花甙 ,经过高效液相色谱法测定 ,其纯度均在 97%以上。其中 ,西红花甙 1和西红花甙 5的纯度在 99%以上。此方法具有操作简便 ,制备纯度高且运行成本低等优点 ,在西红花对照品的制备中具有广泛的应用前景     

大口径毛细管气相色谱法测定油脂、果蔬中20种有机氯农药的残留量

 对水果、蔬菜样品采用混合溶剂提取 ,对油脂样品则采用乙腈分配处理 ,然后运用柱色谱净化方式 ,以HP 1 0 1大口径弹性石英毛细管柱为分离柱 ,以电子捕获检测器检测 ,用气相色谱法测定油脂、水果、蔬菜中 2 0种有机氯农药的残留量。方法的检测限为 1 .0ng/g～ 2 0 .0ng/g ,回收率为 83.2 %～ 1 0 6.8% ,RSD为 2 .0 %～9.5%。     

流动注射协同增强化学发光免疫分析法的建立与评价

以兔IgG为模型 ,NaTPB与PPP协同增强的Luminol H2 O2 HRP混合液为发光体系 ,HRP标记抗体 ,建立了灵敏度高、特异性强、重现性好的流动注射协同增强化学发光免疫分析法。结果表明 :在 2～ 6 0 μg L范围内兔IgG量与发光强度有良好的线性关系 ,相关系数r=0 .994 1 (P <0 .0 1 ) ;绝对检测限为 0 .6 5fmol;方法精密度为 4 .72 %～ 9.31 % ;回收率为 92 .5 0 %～ 99.4 0 %。免疫柱可反复使用 2 0 0次以上。本法测定不同浓度兔IgG标准溶液的结果与RIA法的测定结果基本一致     

反相高效液相色谱法测定烧伤大鼠体内的肠三叶因子

 采用反相高效液相色谱法测定烧伤大鼠体内的肠三叶因子 (ITF) ,其中色谱柱为HypersilC4柱 ( 4 6mmi.d .× 2 5 0mm ,柱填料的孔径为 3 0nm ,粒度为 5 μm) ,流动相为乙腈 水 (含体积分数为 0 1%的三氟乙酸 )溶液 ,梯度洗脱 ,流速为 1mL/min。在 2 14nm检测波长下 ,ITF在 1mg/L～ 10 0mg/L时具有良好的线性关系 ,相关系数为0 9989,最低检测限为 0 5mg/L。ITF的加标回收率为 93 95 %～ 10 5 90 % ,日内测定结果的RSD <5 3 3 % ,日间测定结果的RSD <6 10 %。方法准确、灵敏 ,可作为一种有效的分析手段。     

离子色谱法同时测定果汁中20种有机胺、生物胺和阳离子

建立了梯度淋洗-电导抑制-离子色谱法测定果汁中20种有机胺、生物胺和阳离子的方法,通过对流速、色谱柱温度、p H等因素的考察,探索出了适合20种组分测定的多级梯度淋洗条件。结果表明,当流速为0. 25 mL/min,pH在3. 5～4. 5,柱温在40℃时,20种组分在0. 05～2. 00 mg/L浓度范围内具有良好的线性关系(R 0. 99)。20种组分检出限(S/N=3)在0. 0006～0. 0503 mg/L之间;在0. 10,0. 20,1. 00 mg/L 3个添加浓度水平下,回收率为78. 4%～108. 9%,相对标准偏差(RSDs)在2. 1%～7. 3%之间。该方法适用于果汁中20种有机胺、生物胺和阳离子的分析测定。     

高效液相色谱法测定饮料中糖、甘油和乙醇

研究了高效液相色谱法测定饮料中糖、甘油和乙醇的方法。饮料样品用WatersSep Pak C18固相萃取小柱预分离 ,以WatersSugar Pak 1钙型阳离子交换柱为固定相 ,0 .0 5 g·L- 1ED TA钙钠水溶液为流动相 ,示差折光仪为检测器 ,一次进样测定饮料样品中的糖、甘油和乙醇。检出限在微克级 ,RSD在 0 .6 8%～ 2 .1%之间 ,标准回收率在 96 %～ 10 7%之间。方法用于几种饮料样品的测定 ,结果满意     

CTMAB对反相高效液相色谱-电化学检测法测定水中痕量酚类化合物的增敏、增稳作用

研究了阳离子表面活性剂CTMAB对高效液相色谱 -电化学检测法测定水中痕量酚类化合物的增敏、增稳作用。流动相中CTMAB的最佳浓度为 0 .80mmol/L。使用NucleosilC8色谱柱 (2 0 0mm× 4 .6mmi.d .) ,流动相为甲醇 - 0 .0 2 5mol/L邻苯二甲酸氢钾缓冲液 (体积比为 6 0∶4 0 ,pH =5 .0 ,含 0 .0 6mmol/LEDTA、0 .80mmol/LCTMAB)。该方法测定苯酚、4 氯苯酚、2 ,4 二氯苯酚、2 ,4 ,5 三氯苯酚的线性范围分别为 0 .10～ 15 .0 0、0 .15～ 12 .5 0、0 .15～ 2 2 .5 0、0 .30～ 5 0 .0 0 μg/mL ,检出限分别为 0 .0 0 8、0 .0 10、0 .0 16、0 .0 34μg/mL ,测定结果的相对标准偏差分别为 7.0 %、7.2 %、6 .0 %、7.0 % ,回收率分别为 4 8.0 %、80 .0 %、76 .0 %、85 .0 %。     

Reactions of 2-methylthiazolines and N-methyl cyclic ketene-N,S-acetals with acid chlorides

Carbon-carbon bond formation occurs under mild conditions when 2-methylthiazolines react with acid chlorides to form N-acyl-β-keto cyclic ketene-N,S-acetals. N-Methyl cyclic ketene-N,S-acetals, generated from 2-methyl-thiazolines, can react further with acid chlorides to form N-methyl-β-keto cyclic ketene-N,S-acetals.     

The use of BrCCl3-PPh3 in Appel type transformations to esters,O-acyloximes,amides, and acid anhydrides

Esters, acyloximes, amides and acid anhydrides have been prepared from the respective carboxylic acids, oximes, amines and alcohols by the use of the reagent combination BrCCl₃-PPh₃. The reactions obviate the handling acyl halides or more aggressive reagents PCl₃, POCl₃, or SOCl₂. Furthermore, the environmentally hazardous CCl₄ used in Appel-type reactions is replaced with BrCCl₃, a reagent of less environmental concern.     

GLC-MS analysis of the fatty acids of the seed oil,triglycerides, and cyanolipid of Paulliania elegans (Sapindaceae) – a rich source of cis-13-eicosenoic acid (paullinic acid)

The fatty acids of the total lipids, triglycerides, and the cyanolipid of Paullinia elegans (Sapindaceae) have been analyzed as their methyl esters and 4,4-dimethyloxazoline derivatives by gas chromatography-mass spectrometry. It was shown that the gas chromatographic separation of the oxazoline derivatives was sufficient to ensure the correct identification of the monoenic fatty acid positional isomers. Stereochemistry of the double bonds has been confirmed by infrared and ¹³C-nuclear magnetic resonance (NMR) spectroscopy. cis-13-Eicosenoic Acid (Paullinic acid) (44.4%) and cis-11-octadecenoic acid (cis-vaccenic acid) (19.8%) were found to be the main components beside other monoenoic acid positional isomers. The cyanolipid of P. elegans was identified as 2,4-dihydroxy-3-methylenebutyronitrile derivative by IR, ¹H-NMR, ¹³C-NMR spectroscopy and was quantified by ¹H-NMR spectroscopy (71.4%).     

Microwave-assisted water extraction of acid herbicides from soils coupled to continuous filtration, pre-concentration, chromatographic separation and UV detection

A microwave-assisted extraction procedure using water as extractant has been performed for the extraction of acid herbicides (namely, bentazone, 2,4-D, trichlopyr, 2,4,5-T and 2,4,5-Tp) from different types of soil. Two experimental designs were used for the optimization of the leaching step. The selection of water as extractant provided a clean approach by avoiding the use of organic solvents. The use of water also enhanced the extraction efficiency due to the high interaction of the microwave irradiation with polar solvents. The time required for total removal of the target compounds was 35 min. The recoveries yield were from 87.64 to 106.14% with a repeatability (expressed as relative standard deviation) ranging between 1.34 and 9.24%. A within-laboratory reproducibility, also expressed as relative standard deviation, varied from 3.97 to 10.41%. A flow-injection manifold allowed automation of the whole process by hyphenating the steps subsequent to extraction (namely, filtration, preconcentration, chromatographic separation and UV detection) for the determination of the analytes.     

On the corrosion inhibition of iron in hydrochloric acid solutions,Part I: Electrochemical DC and AC studies

The inhibitive action of 4-methyl pyrazole (4MP) against the corrosion of iron (99.9999%) in solutions of hydrochloric acid has been studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). At inhibitor concentration range (10^?3–10^?2 M) in 1.0 M acid, the results showed that 4MP suppressed mainly the anodic processes of iron corrosion in 1.0 M HCl by adsorption on the iron surface according to Temkin adsorption isotherm. Both potentiodynamic and EIS measurements reveal that 4MP inhibits the iron corrosion in 1.0 M HCl and that the efficiency increases with increasing inhibitor concentration. Data obtained from EIS were analyzed to model the corrosion inhibition process through an equivalent circuit.     

Adsorption, desorption and activities of acid phosphatase on various colloidal particles from an Ultisol

Adsorption, desorption and activity of acid phosphatase on various soil colloidal particles and pure clay minerals were studied. Higher adsorption amounts and low percentage of desorption of acid phosphatase were found on fine soil clays (<0.2 μm). Electrostatic force and ligand exchange are the major driving forces that are involved in the adsorption of enzymes on soil clays. More enzyme molecules were adsorbed on soil clays in the presence of organic components. However, enzymes on organic clays were more easily released. One-third of the enzyme on goethite was adsorbed via ligand exchange process. Some other interactions, such as van der Waals force, hydrophobic force and hydrogen bonding may be more important in the adsorption of enzyme on kaolinite and the enzyme in this system cannot be easily removed. Coarse clays (0.2–2 μm) and inorganic soil clays had higher affinities for enzyme molecules than fine clays and organic clays, respectively. The activity of enzyme bound on soil clays was inhibited and the thermal stability was increased in the presence of organic matter. Data obtained in this study are helpful for a better understanding of the interactions of enzymes with inorganic and organic constituents in soil and associated environments.     

Synthesis,characterization and dyeing assessment of novel acid azo dyes and mordent acid azo dyes based on 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid on wool and silk fabrics

Novel acid mono azo and mordent acid mono azo dyes were synthesized by the coupling of diazonium salt solution of different aromatic amines with 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid. The resulting dyes were characterized by spectral techniques like elemental analysis, IR, ¹H-NMR and UV visible spectroscopy. The dyeing performance of all the dyes was evaluated on wool and silk fabrics. The dyeing of chrome pre-treated wool and silk fabrics showed better hues on mordented fabrics. Dyeing of wool and silk fabrics resulted in pinkish blue to red shades with very good depth and levelness. The dyed fabrics showed excellent to very good light, washing, perspiration, sublimation and rubbing fastness.     

Calculation of reference pH values for standard solutions from the corresponding acid dissociation constants

Making the simplest possible assumption about the activity coefficient of the charged species, pH values of standard buffer solutions have been evaluated from the thermodynamic acidity constants, K, of the weak acids involved. A general equation is given for a triprotic acid, H₃A, as it can be simplified to derive the equations for other systems. A computer program for the solution of the equation was written giving m_H values, species distribution coefficients, α, buffer capacities, β, species activity coefficients, γ, and ionic strength, I. Iteration was continued until agreement between successive values to within 1 ± 10^?6 was reached.The activity coefficients of singly charged ions were taken as equal to γ_Cl, where log γ_Cl=?AI^1/2 (1 + 1.5I^1/2), which is the Bates-Guggenheim convention, and those of doubly and triply charged ions were given by the valence relations of the Debye-Hückel theory as γ⁴_Cl and γ⁹_Cl, respectively.     

浸提法-ICP-AES测定化妆品中有害元素铅、砷、汞

建立了浸提法-电感耦合等离子体发射光谱(ICP-AES)测定化妆品中Pb、As、Hg的方法,并对ICP-AES工作参数及条件进行了优化和选择.Pb、As、Hg检出限分别为0.0078,0.011和0.023 μg/mL.线性范围为0～500 μg/L,相对标准偏差为1.3%～3.9%;回收率为90%～101%.适用于化妆品中Pb、As、Hg的日常检测.     

A new panaxadiol from the acid hydrolysate of Panax ginseng

A new panaxadiol(compound 1) was obtained from the acid hydrolysate of the total ginsenosides of Panax ginseng C.A.Meyer (Araliaceae).On the basis of spectroscopic data and single-crystal X-ray diffraction data,its chemical structure was elucidated to be dammar-(E)-20(22)-ene-3β,12β,25-triol.