高效阴离子交换色谱分离-脉冲安培检测法测定烟草料液中的糖、糖醇和醇类化合物

建立了高效阴离子交换色谱分离-脉冲安培检测法测定烟草料液中的糖、糖醇以及醇类化合物的方法。以NaOH为淋洗液,在CarboPac MA1阴离子交换柱上等度分离了肌醇、甘油、丙二醇、半乳糖醇、木糖醇、山梨醇、甘露醇、葡萄糖、果糖、蔗糖、甘露糖和半乳糖等12种化合物。对影响分离和检测的条件进行了优化,并在此优化条件下分析了烟草料液中的糖、糖醇以及醇类化合物。12种化合物的检出限为2.0~216μg/L(25.0μL进样,以3倍信噪比计算检出限)。12种化合物浓度为1~5mg/L的标准溶液连续7次进样的RSD为0.7%~4.3%。方法对烟草料液中12种化合物的加标回收率为80%~108%。方法灵敏、高效、简便、快捷。     

离子色谱-质谱联用技术测定污泥样品中的痕量高氯酸盐

建立了离子色谱-质谱联用技术测定活性污泥样品中高氯酸盐的分析方法。以高容量、强亲水性的IonPacAS20(2mm)阴离子交换柱为分析柱,EGC在线产生等浓度KOH为淋洗液,淋洗液经抑制成水后将样品带入质谱检测。ESI-MS-MS以多元反应监测模式监控100.8/84.9、98.8/66.9、100.8/68.9和98.8/82.9离子对,以98.8/82.9离子对的峰面积进行定量。该方法对高氯酸盐的检出限(S/N=3)为0.01μg/L,高氯酸盐在0.05~100μg/L浓度范围内具有良好的线性,线性相关系数r=0.9988。0.2μg/L的标准溶液重复进样9次,高氯酸盐峰面积的相对标准偏差(RSD)为2.3%。运用该方法测定采自不同地区的活性污泥样品中的高氯酸盐,并对样品加标回收,得回收率在88.5%~102.2%之间。     

Anchored palladium bipyridyl complex in nanosized MCM-41: a recyclable and efficient catalyst for the Kumada-Corriu reaction

A palladium bipyridyl complex anchored onto nanosized mesoporous silica MCM-41 catalyzed the cross-coupling of aryl iodides or bromides with Grignard reagents to provide the corresponding biaryls in high yields. The reaction proceeded smoothly with an equal molar amount of substrate and Grignard reagent in the presence of 0.2-0.02 mol % of catalyst in THF at 50 °C or under refluxing conditions. The catalyst prepared may be used in a very low percentage, recovered after reaction, and re-used.     

烟叶和烟草料液中氨基酸的直接检测及碳水化合物的去除

建立了高效阴离子交换色谱-积分脉冲安培法(HPAEC-IPAD)直接检测烟叶和烟草料液中氨基酸的方法。利用离线除糖的方法,去除烟叶和烟草料液中大量干扰糖类,包括葡萄糖、果糖和蔗糖及麦芽低聚糖等。采用AminoPac PA10阴离子交换柱,以NaOH和NaAc的强碱性溶液为淋洗液,采用梯度洗脱,流速为0.25 mL/min;积分脉冲安培法对氨基酸进行检测,回收率可达76%~105%。此方法可以有效的解决烟叶、烟草料液等含糖量高的样品中糖类化合物的干扰,对氨基酸实现灵敏、准确的定量分析。     

Electrodeposition of nanocrystalline zinc from acidic sulfate solutions containing thiourea and benzalacetone as additives

Nanocrystalline zinc coatings were produced by pulse electrodeposition in acid sulfate bath containing thiourea and benzalacetone additives and characterized by X-ray diffraction and scanning electron microscopy techniques. The influence of benzalacetone concentration and pulse peak current density on the grain size and crystallographic orientation of zinc deposits was investigated. Zinc electrodeposited from additive-free solutions or with one of the two additives is not composed of nanosized crystals. The mixture additives of thiourea and benzalacetone give rise to the formation of particle-like nanocrystalline zinc with a (10ī1) random orientation. A change in peak current density from 2 to 1 A/cm² only increases the grain size from 60 to 62 nm.     

Synthesis of 1,3,4‐Oxadiazole‐Based Aromatic and Heterocyclic/Phenylpyrazole Derivatives

A new series of 1,3,4‐oxadiazole‐based aromatic and heterocyclic/phenylpyrazole derivatives 6a–c , 7a–d , and 8 were synthesized via sequential 1,3‐dipolar cyclization, hydrazidation, benzoylation, dehydrative cyclization, and the Suzuki coupling reaction. Among the derivatives, compounds 7a and 7c with the corresponding 2‐thienyl and 2‐benzo[b]thienyl (Ar) at the phenyl group located at the N‐1 position of pyrazole showed a better conjugation range.      

A Novel Simplified Column-Switching Technique for the Determination of Traces of Bromate in High Concentration Matrices

The column-switching technique has been widely used to determine trace level ions in the presence of high concentration matrix. A novel simplified column-switching method is proposed where bromate (as a model compound) was determined using this technique. The switching time window was confirmed by the retention time of determined ions. This technique can completely carry out the same function as the other column-switching technique do, but only one extra ten-way injection valve coupled to ion chromatograph was used. By using column-switching technique, it is possible to determine 0.2 μg L⁻¹ bromate in the presence of 100 mg L⁻¹ chloride by direct injection of 2000 μL without any pretreatment and the relative standard deviation (RSD) of the peak height for the eleven successive injections of 0.2 μg L⁻¹ bromate solution is 23.1%. The detection limit for bromate is 0.09 μg L⁻¹, which showed the method was very sensitive. The technique has been applied to the determination of bromate in drinking water, and the spike recovery is in the range of 96–104%.     

Direct amino acid analysis method for speciation of selenoamino acids using high-performance anion-exchange chromatography coupled with integrated pulsed amperometric detection

Speciation analysis of selenomethylcysteine (SeMeCys), selenomethionine (SeMet) and selenocystine (SeCys) has been performed using a direct amino acid analysis method with high-performance anion-exchange chromatography (HPAEC) coupled with integrated pulsed amperometric detection (IPAD). Three selenoamino acids could be baseline-separated from 19 amino acids using gradient elution conditions for amino acids and determined under new six-potential waveform. Detection limits for SeMeCys, SeMet and SeCys were 0.25, 1 and 20 microg/L (25 microL injection, 10 times of the baseline noise), respectively. The relative standard deviations (RSDs) of 200 microg/L SeMeCys, SeMet and SeCys were 3.1, 4.1 and 2.8%, respectively (n=9, 25 microL injection). The proposed method has been applied for determination of selenoamino acids in extracts of garlic and selenious yeast granule samples. No selenoamino acids were found in garlic. Both SeMet and SeCys were detected in selenious yeast tablet with the content of 45 and 129 microg Se/g, respectively. Selenoamino acids standards were spiked in garlic and yeast granule samples and the recovery ranged from 90 to 106%.