制备条件对Au/TiO2催化CO氧化性能的影响

采用沉积沉淀法和化学沉积法，分别制备了Au/TiO2催化剂，比较详尽地探讨了制备方法及制备条件对其催化CO氧化性能的影响，并对催化剂进行XRD表征，优化了制备条件，结果显示，控制沉积－沉淀反应液的pH值范围为6．5－7．0，浓度为40mL水／g载体，温度70℃，还原温度85℃,时间60min，以沉积－沉淀法制备的3％Au/TiO2催化剂可于－35℃将CO完全转化，经还原预处理比经焙烧得到的催化剂的活性更高，用光化学沉积法制备的Au/TiO2催化剂的活性欠佳。     

还原温度对超细K－Co－Mo催化剂合成低碳醇性能的影响

 用溶胶－凝胶法合成了K－Co－Mo催化剂．样品经不同温度还原后，用于低碳醇的合成．XRD和HRTEM结果表明，样品是超细粒子，粒子尺寸为2～5nm．考察了催化剂的还原温度和反应条件对催化剂性能的影响．实验结果表明，还原温度对催化剂的活性有较大的影响，最佳还原温度为500℃．最佳反应温度范围为310～330℃．升高压力和空速可以提高醇的收率和选择性．在空速14400h－1，压力6．0MPa和温度310℃的条件下，醇的选择性为55．8％，收率为520．0g／（kg·h），MeOH／C2＋OH为0．27．催化剂稳定性良好，在200h的寿命实验中，活性基本不变．与文献中催化剂相比，超细K－Co－Mo催化剂对合成醇具有较高的活性和选择性，尤其是对C2＋OH的合成明显高于其他合成醇催化剂体系．     

微生物电极法测定啤酒中乙醇含量

用自制的乙醇微生物电极建立了一种测定啤酒中乙醇含量的新方法。该法具有良好的精密度和准确度，其测定结果与比重瓶法和气相色谱法相一致，回收率为９７．３％－１０４．９％。该电极线性范围为０．３－１２．０ｍｇ／Ｌ，６０天测定６００余次，其灵敏度基本稳定。测试的最适酸度范围为ｐＨ６．４－７．３，温度为３２－３４℃，测定一个样品需５－８ｍｉｎ。     

超临界流体萃取和气相色谱—质谱联用测定薄荷中有效成份

介绍用超临界流体萃取和气相色谱－质谱联用（ＳＦＥ／ＧＣ－ＭＳ）法提取和测定薄荷中的有效成分，ＳＦＥ的试验条件为：Ｄ：８－２６ＭＰａ，温度：３５－６５℃，改性剂？：１％－１０％乙醇，结果表明，在２３ＭＰａ，５５℃和７％极性剂条件下撮效率最佳，在此条件下其主成分薄荷醇的提取量为０．１６％（Ｗ／Ｗ），比水蒸气蒸馏法提取量约高３倍，比有机溶剂法提取量约高０．６倍。     

H2SiW12O40—La2O3／γ—Al2O3催化甲醇脱水制备二甲醚

用浸渍法制备了负载型复合杂多酸催化剂H2Si12O40-La2O3/γ-Al2O3,用于甲醇脱水制备二甲醚,用N2吸附、吡啶吸附外光谱、NH3－TPD、XRD光谱等手段对催化剂进行了表征,考察了杂多酸负载量、浸渍时间、反应温度、质量空速等因素对催化活性的影响。实验结果表明,催化剂中H2SiW12O40负载量为10％－16％时催化剂的活性最好,在常压下反应温度为300℃,质量空速为1．6h^-1时,甲醇转化率达85％,二甲醚的选择性为99．9％,加压可提高催化剂的活性。     

制备条件对Pd催化剂上C3H6选择性还原NO性能的影响

采用浸渍法和溶胶凝胶法,制备了Pd/AI2O3和Pd/AI2O3-CeO2样品,并测定了不同温度焙烧后催化剂的物相、比表面积及对丙烯选择性还原NO的活性。对于Pd/AI2O3,随着焙烧温度的提高,其NO的最大转化率逐渐下降,对应的反应温度在290－310℃左右,而溶胶凝胶法制备的样品活性略高于浸渍法制备的样品;对于Pd/AI2O3-CeO2,经600℃焙烧后,其NO的最大转化率为22％,900℃焙烧的催化剂样品上NO的最大转化率达到40％左右,对应的反应温度也逐渐下降,说明活性随焙烧温度的提高而明显提高,溶胶凝胶法和浸渍法制备的样品结果很接近,浸渍法制备了若干不同Pd负载量的Pd/AI2O3样品,活性测定的结果表明,Pd含量在0．5％左右的催化剂样品中具有最高的活性。     

石墨炉原子吸收法测定壳聚糖中的痕量镉

采用石墨炉原子吸收法直接测定了壳聚糖中的痕量镉，以HF-HClO4体系消化试样，用Pd(NO3)2作基本改进剂，灰化温度1000℃：，原子化温度2200℃。本法相对标准偏差为2．8％，回收率在97．0％-106．3％之间，快速，简便，准确。     

丙烯气相一步氧化制环氧丙烷用Ag-Mo催化剂的研究

 用浸渍法和溶胶－凝胶法制备了一系列以银及氧化钼为活性组分，负载于不同载体上的催化剂．在以分子氧为氧化剂，且原料气中不添加任何抑制剂的情况下，采用微反－色谱联合装置考察了催化剂对丙烯气相一步氧化制环氧丙烷的催化性能．结果表明，载体和助剂对催化剂上丙烯环氧化性能产生明显的影响．以TiO2－ZrO2为载体，CsNO3－NaCl为助剂的Ag－MoO3催化剂具有较好的催化性能，在400℃下，氧的转化率和环氧丙烷的选择性可分别达到11．3％和34．8％；在450℃下，氧的转化率和环氧丙烷的选择性可分别提高到33．0％和35．3％．采用溶胶－凝胶法制备的MoO3／SiO2催化剂对丙烯气相一步环氧化反应也具有一定的催化活性．     

AA/AMPS共聚型吸水树脂反相悬浮合成工艺研究

以过硫酸铵－亚酸钠为引发剂，用反相悬浮法合成丙烯酸／2－丙烯酰胺基－2－甲基丙烷磺酸共聚型吸水树脂，最佳工艺条件为：N，N－亚基双丙烯酰胺浓度＝1．082mmol.L^-1，丙烯酸中和度为80％，2－丙烯酰胺基－2－甲基丙烷磺酸的质量分数w=0.30,OP4-PEG的质量分数w=0.003，双组分引发剂浓度＝22．64mmol.L^-1，反应温度50摄氏度，共聚物吸液率（水及生理盐水）A为：AH2O=1070mL.g^-1,Anormal aaline=220mL.g^-1，抗电解质能力高于聚丙烯酸钠或丙烯酸钠与丙烯酰胺的共聚物（反相悬浮法合成），140℃以上热稳定性低于聚丙烯酸钠，保水性与其相当。     

乙二胺在ZSM—5分子筛催化剂上脱氨制哌嗪

研究了反应温度，反应物浓度及空速对乙二胺在Ｈ－ＺＳＭ－５和Ｋ－ＺＳＭ－５分子筛催化剂上转化为哌嗪反应的影响。在反应温度为３４０℃，乙二胺浓度为５０％和空速为２．３ｈ＾－１条件下，乙二胺在２．６％Ｋ－ＺＳＭ－５催化剂上的转化率为９５％，哌嗪的选择性为９６５。     

Development and validation of an HPLC method for the quantitation of 1,3-dihydroxy-2-methylxanthone in biodegradable nanoparticles

A rapid and simple high-performance liquid chromatographic method for the analysis of 1,3-dihydroxy-2-methylxanthone (DHMXAN) in biodegradable poly(D,L-lactide-co-glycolide) (PLGA) nanosphere and nanocapsule formulations is developed and validated. The method does not require any complex sample extraction procedure. Chromatographic separation is made with a reversed-phase C18 column, using methanol-water (90:10, v/v) containing 1% (v/v) acetic acid as a mobile phase at a flow rate of 1 mL/min. Identification is made by UV detection at 237 nm. The isocratic system operates at ambient temperature and requires 7.5 min of chromatographic time. The developed method is statistically validated according to ICH guidelines and USP 29 for its specificity, linearity, accuracy, and precision. The assay method proposed in this study is specific for DHMXAN in the presence of nanosphere and nanocapsule excipients. Diode-array analyses confirm the purity of DHMXAN peak in stress conditions (> 99.0%). The method is shown to be linear (r > or = 0.999) over the concentration range of 0.25-3.0 microg/mL. Recovery ranges from 99.0% to 102.7% (RSD: 1.49%) and from 98.3% to 101.6% (RSD: 1.07%) for nanospheres and nanocapsules, respectively. Repeatability (intra-assay precision) and intermediate precision is acceptable with RSD values ranging from 0.6% to 1.9% and from 0.3% to 2.0%, respectively. The method is shown to be suitable for the evaluation of DHMXAN content entrapped in PLGA nanoparticles.     

蔬菜和食用菌中氨基甲酸酯类农药残留检测技术

建立了丙酮和乙腈(体积比85:15)提取,凝胶渗透色谱(GPC)法和PSA(N-丙基乙二胺)固相萃取柱2种方法净化,超高效液相色谱-串联质谱（UPLC-MS/MS）同时检测菠菜、黄瓜、大葱、蘑菇、香菇、木耳、牛肝菌和胡萝卜中19种氨基甲酸酯类农药,同位素稀释法定量。实验结果表明,GPC法净化,回收率为70.1%～95.7%;PSA固相萃取柱净化,回收率为70.2%～94.9%。方法的检出限均为1×10-5 g/kg。各种NMCs在确定的添加范围内线性关系良好,线性相关系数r均＞0.99,所建立的检测方法实用、准确、灵敏度高。     

Automated online and off-line solid-phase extraction methods for measuring isoflavones and lignans in urine

Automated online and off-line solid-phase extraction (SPE) methods coupled to isotope dilution-high-performance liquid chromatography-tandem mass spectrometry for measuring four isoflavones (daidzein, genistein, equol, and O-desmethylangolensin) and two lignans (enterolactone and enterodiol) in urine are developed. The SPE recoveries for the online SPE method are excellent for most analytes (83-94%) and somewhat lower for enterolactone (61%). The recoveries for all analytes with the off-line SPE method are also very good (65-80%). The limit of detection is lower for the online method (0.1-0.7 ng/mL) than for the off-line method (0.4-3.3 ng/mL). Similarly, the reproducibility is generally better for the online method [coefficient of variation (CV) of 4-12%) than for the off-line method, except for enterolactone, which has a higher CV (18-19%) that is consistent with its lower online SPE recovery. Both methods are adequate for analyzing a large number of samples for epidemiological studies to assess the prevalence of human exposure to isoflavones and lignans.     

Solid Phase Extraction Chemiluminescence Determination of Methamidaphos on Vegetables

IntroductionDuring recent years,organophosphorus pesticides(OPPs)have been widely used in agriculture becauseof their low environmental persistence and high effec-tiveness.However,they have a high acute toxicity.Trace amounts of OPPs may remain in foodstu…     

间接原子吸收法测定黄姜中的薯蓣皂甙元

提出了间接测定黄姜中薯蓣皂甙元的原子吸收光谱法。该法基于薯蓣皂甙元能与碱式醋酸铅发生络合反应,生成难溶于水的白色沉淀,经离心分离后,用原子吸收法测定上清液中过量的铅离子,可间接测定薯蓣皂甙元的含量。该法线性范围为0.0~40.0 mg/L;相对标准偏差(relative standard deviation,RSD)为0.9%~1.1%;回收率为98.9%~102.9%。     

Simultaneous determination of imazalil and its major metabolite in citrus fruit by solid-phase extraction and capillary gas chromatography with electron capture detection

A method was developed for the simultaneous determination of imazalil and its major metabolite, R 14821, in citrus fruit. This method (designated the SPE method) is based on solid-phase extraction (SPE) and capillary gas chromatography (GC) with electron-capture detection (ECD). The SPE method is highly sensitive for both compounds (limit of detection for each: 0.001 microg/g) and is less time consuming than the previously reported method based on repeated liquid-liquid partitioning and GC-ECD. Recoveries for 3 levels of fortification (0.02, 0.2, and 2.5 microg/g) from satsuma mandarins ranged from 94.3 to 96.5% for imazalil and from 93.9 to 96.3 % for R 14821, with coefficients of variation (CVs) ranging from 3.1 to 6.3% for imazalil and from 4.5 to 5.6% for R 14821. Average residual levels found in grapefruit, oranges, and lemons by the SPE method and the previously reported method, and the corresponding CVs, were similar.     

食用菌中多种氨基甲酸酯类农药残留的超高效液相色谱-串联质谱法测定研究

建立了同时测定食用菌中19种氨基甲酸酯类农药(NMCs)残留的超高效液相色谱-串联质谱法(UPLC-MS/MS)。通过丙酮和乙腈(85∶15,V/V)提取,GPC法和PSA固相萃取柱两种方法净化,UPLC-MS/MS同时测定蘑菇、香菇、木耳和牛肝菌中19种氨基甲酸酯类农药,同位素稀释法定量。以GPC法净化,回收率为74.0%～93.2%;以PSA固相萃取柱净化,回收率为70.2%～91.8%,两种方法的检出限均为0.01mg/kg。各种NMCs在确定的添加范围内线性关系良好,线性相关系数R均大于0.99。所建立的检测方法实用、准确、灵敏度高。     

A rapid and environmental friendly determination of the dithiocarbamate metabolites ethylenethiourea and propylenethiourea in fruit and vegetables by ultra high performance liquid chromatography tandem mass spectrometry

Previous published methods for the analysis of ETU and PTU are time-consuming and furthermore use dichloromethane (DCM) for extraction or clean-up. This study details the development and validation of a rapid method that combines a simple extraction step with UHPLC-ESI(+)-MS/MS. This is the first application of UHPLC-MS/MS to analyse these compounds. Besides that, we replaced DCM with a more environmental-friendly solvent. The analytical performance was evaluated with the analysis of spiked celery samples at 50 μg kg(-1) (LOQ) and 300 μg kg(-1). The recoveries were between 65% and 90% for ETU and between 71% and 127% for PTU with RSDs in repeatability and reproducibility conditions below 10% for ETU. This method is rapid (a chromatographic run time of 2 min) and can easily be performed (no laborious clean-up). The presented method is environmental friendly with significant reduction in solvent consumption.     

Determination of aflatoxins in animal feeds by liquid chromatography/tandem mass spectrometry with isotope dilution

The objective of the present study is to develop a simple, fast method for detection of aflatoxins in animal feeds. Simultaneous quantitation of four aflatoxins (AFB(1), AFB(2), AFG(1) and AFG(2)) in animal feeds was achieved in a single liquid chromatography/tandem mass spectrometry (LC/MS/MS) run. The solid-phase extraction cleanup step is eliminated with the stable isotope dilution method. Matrix effects were observed and overcome by isotope dilution. The method was tested in a variety of animal feed matrices and proved to be accurate and reliable. Method ruggedness tests resulted in recoveries of 78% to 122% with an intra-day assay precision of 2% to 15% and an inter-day assay precision of 3% to 17%. These results indicate that this method is suitable for quantitation of aflatoxins in animal feeds.     

塞曼火焰原子吸收光谱法间接测定苯三唑

在乙酸铵介质中,加入过量硝酸银标准溶液,离心分离苯三唑银沉淀 ,火焰原子吸收光谱法测定上清液中剩余的银,根据过剩银的吸收信号与其浓度的线性关系,利用光度滴定法原理,以作图法或计算法测定工业合成样品及内烯机车冷却水样品中苯三唑含量。测定0.60mg/50ml的苯三唑,RSD为0.8%,回收率（n=5） 为99.5%-101.3%。检出限为60ug/50ml.