A Novel Potentiometric Membrane Sensor Based on Aryl Palladium Complex for Selective Determination of Thiocyanate in the Saliva and Urine of Cigarette Smokers

A highly selective potentiometric sensor for thiocyanate ion based on the use of a newly synthesized organo‐palladium ion exchanger complex dispersed in a plasticized poly(vinyl chloride) membrane is described. The sensor displays a Nernstian response (?57.8±0.2 mV decade^?1) over a wide linear concentration range of thiocyanate (1.0×10^?6–1.0×10^?1 mol L^?1 ), low detection limit (6.3×10^?7 mol L^?1), fast response (20 s), stable potential readings (±0.4 mV), good reproducibility (±0.9%), long term stability (8 weeks), high precision (±0.7%) and applicability over a wide pH range (4–10). Negligible interferences are caused by F^?, Cl^?, I^?, Br^?, NO₃^?, NO₂^?, CN^?, SO₄^2?, S₂O₃^2?, PO₄^3?, citrate, acetate and oxalate ions. Under hydrodynamic mode of operation (FIA), the calibration slope is ?51.1±0.1 mV decade^?1, the linear response range is 1.0×10^?5–1.0×10^?1 mol L^?1 SCN^? and the sample throughput is 40–45 per hour. The sensor is satisfactory used for manual and flow injection potentiometric determination of SCN^? in the saliva and urine of cigarette smokers and non smokers. The data agree fairly well with results obtained by the standard spectrophotometric technique. Direct potentiometry and potentiometric titration of SCN^? with Ag⁺ are also monitored with the sensor.     

Evaluation of performance of three different hybrid mesoporous solids based on silica for preconcentration purposes in analytical chemistry: From the study of sorption features to the determination of elements of group IB

Several studies involving the physicochemical interaction of three silica based hybrid mesoporous materials with metal ions of the group IB have been performed in order to employ them for preconcentration purposes in the determination of traces of Cu(II), Ag(I) and Au(III). The three solids were obtained from mesoporous silica functionalized with 3-aminopropyl (APS), 3-mercaptopropyl (MPS) and N-[2-aminoethyl]-3-aminopropyl (NN) groups, respectively. Adsorption capacities for Au, Cu and Ag were calculated using Langmuir's isotherm model and then, the optimal values for the retention of each element onto each one of the solids were found. Physicochemical data obtained under thermodynamic equilibrium and under kinetic conditions - imposed by flow through experiments - allowed the design of simple analytical methodologies where the solids were employed as fillings of microcolumns held in continuous systems coupled on-line to an atomic absorption spectrometry. In order to control the interaction between the filling and the analyte at short times (flow through conditions) and thus, its effect on the analytical signal and the presence of interferences, the initial adsorption velocities were calculated using the pseudo second order model. All these experiments allowed the comparison of the solids in terms of their analytical behaviour at the moment of facing the determination of the three elements.Under optimized conditions mainly given by the features of the filling, the analytical methodologies developed in this work showed excellent performances with limits of detection of 0.14, 0.02 and 0.025 μg L⁻¹ and RSD % values of 3.4, 2.7 and 3.1 for Au, Cu and Ag, respectively.A full discussion of the main findings on the interaction metal ions/fillings will be provided. The analytical results for the determination of the three metals will be also presented.     

流动注射化学发光法测定丹皮酚

丹皮酚有解热、消炎、止痛、镇静等功效[1]。目前测定丹皮酚的方法有高效液相色谱法[2,3]、薄层色谱法[4]、毛细管气相色谱法[5]、毛细管电泳法[6,7]、紫外分光光度法[8]。流动注射是一种高度重现的进样技术[9],它同化学发光法联用,具有快速、灵敏和仪器简单等优点。用化学发光     

流动注射褪色光度法测定食品中的亚硫酸盐

基于亚硫酸盐在碱性条件下与碱性品红的褪色反应,建立了流动注射光度分析测定食品中亚硫酸盐的新方法.在38样/h采样频率下检出限为0.016μg/mL,SO32-质量浓度在0.04～1.5 μg/mL范围符合朗伯比耳定律,测定1.2μg/mL SO32- 11次,相对标准偏差为0.41%.该法可用于食品中亚硫酸盐的测定.     

鲁米诺-过氧化氢体系流动注射化学发光法测定维生素B4

维生素B4(VB4),又名磷酸腺嘌呤。它是核酸的组成成分,在体内参与RNA和DNA的合成。传统测定嘌呤类的方法是利用其在260 nm附近有最大吸收的性质,用紫外分光光度法定量[1],但此方法灵敏度不高。已报道的测定维生素B4的方法还有磷光法[2]、高效液相色谱法[3]、极谱法[4]、伏安法[5     

Signal optimisation in cw-laser crossed-beam photothermal spectrometry: influence of the chopping frequency, sample size and flow rate

Optimisation of the optical design for cw-laser crossed-beam thermal lens spectrometry in infinite and finite samples has been investigated using different excitation beam waists and various lens combinations. The characteristics of the photothermal signal depending on the position of the sample with respect to the probe beam waist, the chopping frequency, the sample size and the flow rate have been considered. Depending on the irradiation duration, the size of the thermal element at the measurement time can be much greater than the waist of the excitation beam. As a result, the optimum sample position is closely related to the probe beam to thermal element size ratio and therefore depends on the chopping frequency and of the sample size. At low frequencies, the size of the thermal element is almost independent of the degree of focusing of the excitation beam because a smaller beam waist induces a faster thermal expansion. As a result, the amplitude of the optimum signal does not depend on the waist of the excitation beam. In contrast, at high frequency, the size of the thermal element remains closer to the size of the excitation beam and the signal is inversely proportional to the waist of the excitation beam as previously demonstrated under pulsed-laser excitation. Moreover, at moderate flow velocities, the signal is significantly enhanced because the negative effect produced by the displacement of the thermal element across the probe beam axis is more than compensated by a decrease of the effective thermal time constant due to radial mixing.     

流动注射双安培法测定盐酸苯肼

使用经过恒电位预阳极化处理的双铂电极,在外加电压差为0.20 V时,通过偶合盐酸苯肼在一支电极上的氧化和氧化铂在另一支电极上的还原两个不可逆电极过程,建立快速准确分析测定盐酸苯肼的流动注射双安培检测法.结果表明:在pH为2.36的B-R缓冲溶液中,外加电位差为0.20 V时测得盐酸苯肼的氧化电流与其浓度在1.0×10~(-6)～1.0×10~(-4)mol/L范围内呈线性关系(r=0.9949,n=9),检出限为1.0×10~(-7)mol/L.对1.0×10~(-5)mol/L的盐酸苯肼溶液的连续23次测定,电流值的相对标准偏差为2.26%.常见离子均不干扰测定.样品处理方法简单,且有较高的选择性和灵敏性,结果令人满意.     

桑枝中桑色素的双安培法在线测定

桑色素是桑枝中的主要成分之一,属黄酮类化合物。该化合物是一种天然的生物活性物质,在自然界分布广泛,具有祛风湿、通血络、消浮肿和抗氧化等多种药理作用。同时,桑色素可与多种金属离子形成配合物作为配体进行分析。目前,有关桑色素的电化学行为及分析应用方法见报道的有高效     

流动分析技术在微波等离子体炬原子发射光谱分析中的应用

本文系统地介绍了微波等离子体煤（MPT）原子发射光谱分析技术从基础研究到商品化仪器的发展过程中流动分析技术所起的作用。论证了几项较简单技术的联用对于解决分析工作者所面临的一些复杂问题的可能性。     

Rapid determination of chromium(VI) in electroplating waste water by use of a spectrophotometric flow injection system

A new rapid and sensitive FI method is reported for spectrophotometric determination of trace chromium(VI) in electroplating waste water. The method is based on the reaction of Cr(VI) with sodium diphenylamine sulfonate (DPH) in acidic medium to form a purple complex (lambda(max) = 550 nm). Under the optimized conditions, the calibration curve is linear in the range 0.04-3.8 microg ml(-1) at a sampling rate of 30 h(-1). The detection limit of the method is 0.0217 microg ml(-1), and the relative standard deviation is 1.1% for eight determinations of 2 microg ml(-1) Cr(VI). The proposed method was applied to the determination of chromium in electroplating waste water with satisfactory results.