空气——乙炔火焰原子吸收法测定钙所用的有机增效剂及其应用

分别考察了９种有机试剂对火焰原子吸收法测定水中钙的影响。结果表明，ＴｒｉｔｏｎＸ－１００、ＣＴＭＡＢ的抗坏血酸对有明显的增敏作用。其中抗坏血酸体系不仅使灵敏度提高的一倍，且抗干扰能力也最强，是一种较好的增效剂。该体系可用于测定天然水中的钙含量。方法灵敏、简便、快速、结果令人满意。     

空气—乙炔火焰原子吸收法测定钙所用的有机增效剂及其应用

分别考察了9种有机试剂对火焰原子吸收法测定水中钙的影响。结果表明,Triton X—100、CTMAB和抗坏血酸对测定有明显的增敏作用。其中抗坏血酸体系不仅使灵敏度提高约一倍,且抗干扰能力也最强,是一种较好的增效剂。该体系可用于测定天然水中钙的含量,方法灵敏、简便、快速,结果令人满意。     

火焰原子吸收光谱法中有机试剂的增感效应

详细研究了11种有机试剂对火焰原子吸收光谱法的增感效应。通过测定这些有机试剂对Cu、Mg、Li、Na、K、Rb、Cr、Mo、Sr、Ba等金属离子吸光度的影响,得到了有机试剂增感的规律性。     

原子吸收光谱法测定土壤及钾素肥料中钾

钾是植物三大必需元素之一 ,土壤中钾的测定多用火焰光度法[1] ,钾素肥料中钾的测定一般以四苯硼钾重量法测定[2 ] 。钾的原子吸收光谱法测定 ,多通过稀释并加入铯盐作电离抑制剂后测定。这一方面增加分析手续和试剂消耗 ,同时大倍量的稀释也引入分析误差 ,在次灵敏线下用原子吸收光谱法直接测定高含量的钾 ,所见报道不多。本法较详细的试验了用次灵敏线原子吸收光谱法测定高含量钾的条件 ,确定了适宜的方法 ,测定了标准参考样[3] 、三元复合肥、硫酸钾、磷酸二氢钾等样品 ,测定结果与标准值及重量法结果一致。1　试验部分1.1　主要仪器与试…     

火焰原子发射法测定甜味剂安赛蜜中可溶性钾

安赛蜜 (Ａ Ｋ糖 )主要用于软饮料、酒类、口香糖、速溶咖啡、乳制品等甜味剂 ,还可用于药物、牙膏、化妆品等一系列新型无热量甜味剂 ,钾元素的含量是该产品质量的一项重要指标。对钾的检测方法有重量法和比色法 ,通常采用原子吸收光谱法。本文利用ＡＡ 670型原子吸收 /火焰发射分光光度计所提供的原子发射测定程序 ,测量安赛蜜中钾。1　试验部分1.1　仪器与试剂ＡＡ 670型原子吸收 /火焰发射分光光度计 (日本岛津 )钾标准储备液 :1.0 0 0ｍｇ·ｍｌ- 1,称取 1.90 7ｇ氯化钾 (光谱纯 ,预先在 10 5℃烘 2ｈ)用水溶解并稀释至 1Ｌ ,摇匀 ,保…     

溶剂萃取-石墨炉原子吸收光谱法测定土壤中痕量钼

提出用抗坏血酸、硫氰酸铵和甲基异丁酮(MIBK)萃取分离,石墨炉原子吸收光谱法(GFAAS)测定土壤中痕量钼的方法。研完了水相酸度,各试剂用量,不同有机溶剂以及共存干扰离子对萃取和测定的影响,无须去掉水相直接测定有机相中的钼。当进样量为20μl时,方法特征质量为7．9×10-12g,线性范围为0～64μg·L-1,回收率在95．5％～107．4％之间。分析了土壤标准样和土样,结果满意。     

稀土元素的原子吸收光谱分析研究(Ⅵ)——有机试剂中磺酸基对镱火焰原子化的影响

在空气-乙炔焰中,研究了有机试剂分子中磺酸基对镱原子化行为的影响.发现含磺酸基的有机试剂,无论其分子中有无键合原子,键合原子为氮或氧,对镱均具有显著的增感效应;试剂中磺酸基的数目影响其增感程度,而其相对位置基本上无影响.并初步探讨了有机试剂分子中磺酸基的作用机理.     

有机试剂雾化进样电感耦合等离子体原子发射光谱特性的研究

利用流动注射技术对有机试剂雾化进样情况下电感耦合等离子体（ＩＣＰ）的特性进行了研究。考察了有机试剂对ＩＣＰ放电外观的影响。对ＩＣＰ的局部热平衡状态作了判定。由Ｍｇ２７８．３０ｎｍ和Ｍｇ３３３．６７ｎｍ二线法对有机试剂负载和水负载情况下ＩＣＰ的激发温度分别作了计算。讨论了试剂分子裂解产物的光谱干扰问题。     

石墨炉原子吸收法直接测定葡萄酒中铅

铅含量是葡萄酒卫生检验的重要指标。石墨炉原子吸收光谱法测定铅具有灵敏度高、干扰少等特点 ,但通常需要将样品消化分解制成水溶液 ,然后上机测试 ,因此影响了测定速度。如果能将稀释后的样品直接上机就会大大简化试验步骤 ,缩短试验时间 ,同时也可避免环境及试剂对样品的污染。本文对与此有关的试验条件进行了研究 [1] 。1　试验部分1 .1　仪器与试剂PE- 30 30型原子吸收分光光度计 ,GHA- 40 0型石墨炉原子化器 ,铅空心阴极灯。硝酸、硝酸镁均为优级纯试剂 ,铅标准溶液由光谱纯铅粒经酸溶后配制而成。1 .2　试验条件波长 2 38.3nm,光谱…     

火焰原子吸收光谱法测定水痕量银

测定银的方法有高温石墨炉原子吸收光谱法和巯基棉富集高碘酸钾吸光光度法[1] ,但前者受仪器设置的限制 ,不易普及 ,后者由于水中银含量很低 ,往往受灵敏度的限制 ,需要富集 ,必须向水样中加入许多试剂 ,操作比较复杂 ,易造成误差。本文采用加热浓缩[2 ] 火焰原子吸收光谱法 ,操作简便、快速 ,精确度和准确度都比较理想 ,适用天然水样的测定。1　试验部分1.1　仪器与试剂ＷＦＸ 1Ｆ2Ｂ2型原子吸收分光光度计 (北京瑞利分析仪器公司 )银标准溶液 :1.0 μｇ·ｍｌ- 1水为离子交换水1.2　试验方法1.2 .1　操作方法取水样 2 0 0ｍｌ及 0 ,0 .5 ,…     

Spectrofluorimetric Flow Injection Determination of Glycerol & Ethylene Glycol with Alizarin Navy Blue

ABSTRACT

A simple and accurate procedure for indirect spectrofluorimetric determination of glycerol and ethylene glycol in aqueous media was developed. Alizarin Navy Blue can be oxidized by potassium periodate to produce a fluorescent compound, that can be detected fluorimetrically (λ_ex = 370 nm, λ_em = 516 nm) by a flow through method. Glycerol and ethylene glycol react with periodate decreasing its concentration and thus the forming the basis for an indirect determination of these compounds. The influence of acid concentration, reagent concentration and manifold variables were studied. For glycerol and ethylene glycol linear calibration curves were obtained in the ranges of 4.8 × 10^-7 – 8.7 × 10^-5 M and 6.4 × 10^-7 – 8.7 × 10^-5 M, respectively. The limit of detection (defined as the concentration that gives a signal three times the standard deviation of the background signal) for glycerol and ethylene glycol was 3.2 × 10^-7 M and 4.3 × 10^-7 M, respectively. The proposed method was applied for determination of glycerol and ethylene glycol in synthetic and real samples. The results obtained were satisfactory.     

基于气液相化学发光技术的臭氧在线检测方法

基于鲁米诺(luminol) 化学发光体系,采用自主研发的在线臭氧浓度检测仪,建立了一种实时在线检测臭氧浓度的方法,用于分析测定痕量浓度水平的臭氧气体。 考察了鲁米诺、氢氧化钾、部分醇类化合物和表面活性剂等因素对化学发光强度的影响。 结果表明,在鲁米诺(0.005 mol/L)、氢氧化钾(0.05 mol/L)体系中加入乙二醇(体积分数1.5%)、甲醇(体积分数1.5%)、乙醇(体积分数1.0%)、丙三醇(体积分数3.0%)能显著增强鲁米诺体系检测O₃的化学发光信号,而甲醛溶液 (体积分数3.0%)能有效抑制NO₂信号的干扰。 同时,测得检测臭氧的检出限为1.26 μg/m³、相对标准偏差为0.32%,相对误差为0.75%。 利用该体系测定臭氧,具有信号稳定、精密度好、准确度高、检出限低等优点,适用于大气中微量O₃的在线连续检测。     

A mycelium with polyelectrolyte complex-bunched hyphae: several important factors affecting on the fermentation performance at a very high cell density

We have reported in the previous paper (Colloids Surf. B (2006) in press) a marked increase in the rate of gluconic acid production at a very high cell concentration (40 g/l) of filamentous fungus (Aspergillus niger IFO 31012) which was immobilized with polyelectrolyte complex consisting of potassium poly(vinyl alcohol) sulfate and trimethylammonium glycol chitosan iodide [6-O-(2-hydroxyethyl)-2-(trimethylammonio)-chitosan iodide]. The present study was carried out to look at what factors play a crucial role in this enhancement. We measured viscosity of broth, mass-transfer coefficient (k(L)a) for oxygen and diffusion coefficient of glucose (substrate). It has become apparent that there is only a difference in the diffusion coefficient of glucose between the free and immobilized cells. Therefore, we believe that the diffusion limitation by substrates as a problem in submerged mycelial processes is improved by immobilization based on polyelectrolyte complexes.     

Determining the second-harmonic signal in electrochemical systems

Processes of adsorption and desorption of the butanol-1, butanol-2, hexanol, pentanol, and isoamyl alcohol molecules on a mercury electrode are studied with use made of the method of a second-harmonic signal in the region of radiowave frequencies. Two potentials are simultaneously applied to the metal/solution interface, specifically, a constant potential and a weak variable potential. The magnitude of the constant potential is close to the corresponding potential of adsorption and the variable potential has an amplitude in the limits of 2 to 20 mV and a frequency varying from a few tens of hertzs to a few tens of kilohertzs. Despite the absence of charge transport during the adsorption between the alcohol molecules and the electrode, the quadratic dependence between a signal of electromagnetic radiation of the radiowave frequencies U and the amplitude of the variable potential E _v1 applied to the metal/solution interface is discovered for all peaks in the curves of the second-harmonic signal for various concentrations of alcohols, various frequencies, and various values of the amplitude of the variable potential. Investigations for systems containing chlorides of sodium, potassium, and cesium in addition to ethylene glycol are conducted. According to an analysis of obtained experimental data, the number of peaks increases with decreasing concentration of chlorides, whereas the size of the sodium, potassium, and cesium cations makes no impact on the magnitude of the emitted signal. At the same time, diminishing the concentration of the chlorides leads to a certain amplification of the signal.     

Synthesis and properties of noncyclic polyether compounds. Part V : The influence of acid and concentration of cations on the uphill transport rates of cations and selectivities through liquid membranes by synthetic,noncyclic polyether ionophores

The effects of acid and cation concentration on the uphill transport rates of cations and selectivities through chloroform liquid membrane by noncyclic polyether ionophores, which are pentaethylene glycol derivatives containing both 8-quinolyt and o-carboxylphenyl terminal groups, have been demonstrated. Using sulfuric, oxalic, or polyphosphoric acid in aqueous solution, the initial transport rates and the amount of cation transported by the ionophores after two days were larger than those using hydrochloric or nitric acid. Using picric acid, the amount of cation transported decreased greatly. It was confirmed that it decreased where an acid could easily be counter-transported by the ionophore through liquid membranes. On the other hand, it was found that the rates, amounts of cation transported, and selectivities, change with the changing of the cation concentration in the aqueous solutions. When the cation concentration in both aqueous solutions is high enough compared with the pH gradient between the two aqueous solutions, the rate, amount, and selectivity of the ionophore for potassium ion increases compared with when the cation concentration is low.     

Universal method for the determination of nonionic surfactant content in the presence of protein

A new analytical method has been developed for the quantitative determination of ethylene glycol‐containing nonionic surfactants, such as polyethylene glycol 8000, polysorbate 80, and Pluronic F‐68. These surfactants are commonly used in pharmaceutical protein preparations, thus, testing in the presence of protein is required. This method is based on the capillary gas chromatographic analysis of ethylene glycol diacetate formed by hydrolysis and acetylation of surfactants that contain ethylene glycol. Protein samples containing free surfactants were hydrolyzed and acetylated with acetic anhydride in the presence of p‐toluene sulfonic acid. Acetylated ethylene glycol was extracted with dichloromethane and analyzed by gas chromatography using a flame ionization detector. The amount of nonionic surfactant in the sample was determined by comparing the released ethylene glycol diacetate signal to that measured from calibration standards. The limits of quantitation of the method were 5.0 μg/mL for polyethylene glycol 8000 and Pluronic F‐68, and 50 μg/mL for polysorbate 80. This method can be applied to determine the polyethylene glycol content in PEGylated proteins or the final concentration of polysorbate 80 in a protein drug in a quality control environment.     

Permanganate-based chemiluminescence analysis of ferulic acid using flow injection.

A simple, sensitive and rapid flow-injection chemiluminescence method has been developed for the determination of ferulic acid based on the chemiluminescence reaction of ferulic acid with potassium permanganate in a nitric acid medium. A strong chemiluminescence signal was observed when ferulic acid was injected into an acidic potassium permanganate solution in a flow-cell. The present method allowed the determination of ferulic acid in the concentration range of 6.0 x 10(-6) to 2.0 x 10(-4) mol l(-1); the detection limit (3sigma) for ferulic acid was 9.6 x 10(-8) mol l(-1). The relative standard deviation was 1.0% for 11 replicate analyses of 2.0 x 10(-4) mol l(-1) ferulic acid. The proposed method was applied to the determination of ferulic acid in real samples with satisfactory results. Moreover, the reaction mechanism of the chemiluminescence system was primarily considered.     

Functionalization of poly(<Emphasis Type="Italic">N</Emphasis>-ethylmethacrylamide) thermosensitive particles by phenylboronic acid

The synthesis of poly(N-ethylmethacrylamide) (NEMAM) thermosensitive particles functionalized with phenylboronic acid (PhBA) groups has been performed by emulsion/precipitation polymerization of NEMAM in water at 90 °C, using ethylene glycol dimethacrylate (EGDMA) as an hydrophobic crosslinker, phenylboronic acid methacrylamide (PhBAMA) as a functional monomer, and potassium persulfate (KPS) as an initiator. The influences of the PhBAMA concentration and mode of monomer addition (batch or shot-growth processes) have been examined both on the polymerization kinetics and on the physicochemical and colloidal properties of the final particles. Results have been discussed according to the ionogenic and hydrophobic nature of the functional monomer. We have directly and clearly provided evidence that PBA was successfully incorporated at the particle surface by using ESCA analysis, especially when using a shot-growth process, a result that was indirectly confirmed by investigating the electrophoretic mobility behavior of the various latexes as a function of pH.     

On the role of initiator in emulsion polymerization

The use of nonionic poly(ethylene glycol)-azo-initiators instead of ionic initiators in emulsion polymerizations offers interesting possibilities for modifying the colloidal and polymeric properties of polymer dispersions. Experimental results are presented for various kinds of anionic, cationic, and nonionic stabilizers as well as for peroxodisulfate initiators with different counter ions (ammonium and potassium). For example, in a styrene emulsion polymerization (with monomer to water mass ratio of 1:4 at a given concentration of 1% with respect to monomer mass of either an anionic or a cationic surfactant), the replacement of either peroxodisulfate or 2,2'-azobis(2-amidinopropane)dihydrochloride by a poly(ethylene glycol)-azo-initiator (with a poly(ethylene glycol) molecular weight of 200 g mol^-1) leads to particles with considerably smaller size, polymers with higher molecular weight, and latexes with higher viscosity.     

Quantification of RNase A and Its PEGylated Conjugates on Polymer-Salt Rich Environments Using UV Spectrophotometry

Ribonuclease A (RNase A) from bovine pancreas and its PEGylated conjugates has proven to have potential therapeutic applications. Aqueous Two-Phase Systems (ATPS) is a promising primary recovery strategy for the fractionation of proteins and their PEGylated conjugates. However, in order to characterize the partition behavior of these molecules in ATPS, an easy-to-implement method is needed to estimate protein concentration in each phase. This paper presents a novel methodology based on UV absorbance to quantify RNase A and its PEGylated conjugates on polymer (polyethylene glycol) and salt (potassium phosphate) rich environments, simulating conditions found on polymer-salt ATPS.