Cu2+-H2O2-罗丹明B-西咪替丁化学发光体系的研究

在弱碱性的多聚磷酸钠介质中,二价铜离子、过氧化氢和染料罗丹明B混合可以产生较强的化学发光,西咪替丁对此发光有较强的抑制作用,其抑制发光强度与西咪替丁P43的质量浓度在5.0-1000μg.L-1范围内呈良好的线性关系,基于此,结合流动注射技术,建立了一种直接测定西咪替丁的化学发展发光新方法。该方法具有较高的灵敏度,检出限为2.2μg.L-1(IUPAC),对500μg.L-1西咪替丁平行测定11次,其相对标准偏差为2.1%。该方法已成功用于西咪替丁胶囊和针剂含量的测定。     

流动注射化学发光法测定工业废水中苯酚

采用流动注射技术,研究了高锰酸钾-过氧化氢-苯酚的化学发光行为,对影响化学发光强度的因素进行了试验,建立了流动注射化学发光法测定苯酚的方法。方法的检出限为3×10-5g.L-1,线性范围为1.0×10-4~1.0×10-1g.L,对浓度为4.0×10-4g.L的苯酚作试验,求得其相对标准偏差(n=11)值为1.6%。方法用于废水中苯酚含量的测定,结果与分光光度法测得值一致。     

流动注射双安培法测定葛根素

利用不可逆电对的双安培检测原理,建立了流动注射双安培直接检测葛根素的电化学新方法.使用经过恒电位预阳极化处理的双铂电极,通过耦合葛根素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,构成流动注射双安培检测体系.在外加电位差为0.2 V时,pH 8.94的碳酸钠-碳酸氢钠缓冲溶液中,测得氧化电流与葛根素浓度在6.0×10-6～1.0×10-3 mol/L范围内呈线性关系(r=0.997 4,n=8),检出限为1.0×10-6 mol/L.连续40次测定6.0 ×10-4 mol/L的葛根素,RSD=1.58%.用该方法对葛根素含量进行了测定,结果令人满意.     

流动注射化学发光法测定青霉素G钾

在甲醛的存在下,酸性KMnO4与青霉素G钾能够产生很强的化学发光,从而建立了KMnO4-甲醛-青霉素G钾化学发光体系来测定青霉素G钾.青霉素G钾的测定线性范围为2.0×10-7～1.0×10-5 g/mL,方法的检出限为1.4×10-7 g/mL,对4.0×10-7 g/mL的青霉素G钾进行11次平行测定,相对标准偏差为1.0%,用此法测定青霉素G钾取得了较好的结果.     

微型固相萃取柱结合胃袋式大体积进样-气相色谱-质谱法同时快速测定菠菜中的13种有机磷农药残留

利用微型固相萃取柱对样品进行前处理,采用胃袋式大体积进样技术结合气相色谱-质谱(GC-MS),建立了菠菜中13种有机磷农药残留的同时快速分析方法。以保留时间和特征离子丰度比定性,以峰面积外标法定量,以3倍信噪比实验值确定方法的检出限(LODs),以10倍信噪比实验值确定方法的定量限(LOQs)。结果表明,除乐果外,其余12种有机磷农药的添加回收率为76.8%～114.0%,相对标准偏差为1.5%～17.6%,LODs为0.5～25 μg/kg。该方法前处理简单快速,分析成本低,分析时间短,灵敏度、准确度和精密度均符合农药多残留检测技术的要求,适用于食品中多种有机磷农药残留的快速灵敏检测。     

氟甲砜霉素注射液含量及其有关物质的HPLC测定

为建立测定氟甲砜霉素注射液含量的方法,采用高效液相色谱法,选用Agilent EclipseXDB-C8柱(4.6 mm×250 mm,5μm),Lab Alliance C8保护柱(4.6 mm×10 mm,5μm),流动相为(V乙腈) V(水)=35 65,流量1.0 mL.min-1,检测波长224 nm,进量样20μL,柱温为室温。结果表明,方法的线性范围为10.0～400μg.mL-1(r=0.999 6),最低检测限2.0 ng。回收率98.7%～101.2%,RSD 0.30%～1.22%(n=5)。方法简便灵敏,结果准确可靠,可用于氟甲砜霉素注射液的质量控制。     

Evaluation of different mediator-modified screen-printed electrodes used in a flow system as amperometric sensors for NADH

This work presents a comparative study between two different methods for the preparation of mediator-modified screen-printed electrodes, to be used as detectors in a reliable flow injection system for the determination of the nicotinamide adenine dinucleotide (NADH) coenzyme. The best strategy was selected for the final development of compact biosensors based on dehydrogenase enzymes. For the first immobilisation strategy, different redox mediators were electropolymerised onto the SPE surface. The second immobilisation strategy was carried out using polysulfone–graphite composites, which were deposited by screen-printing technology onto the screen-printed electrode (SPE) surface. Both methods achieved an effective and reliable incorporation of redox mediators to the SPE configuration. Finally, a flow system for ammonium determination was developed using a glutamate dehydrogenase (GlDH)-Meldola's Blue (MB)-polysulfone-composite film-based biosensor.

The stability of the redox mediators inside the composite films as well as the negligible fouling effect observed on the electrode surface improve the repeatability and reproducibility of the sensors, important features for continuous analysis in flow systems. Furthermore, the optimised bio/sensors, incorporated in a flow injection system, showed good sensitivities and short response times. Such a good analytical performance together with the simple and fast sensor construction are interesting characteristics to consider the polysulfone-composite films as attractive electrochemical transducer materials for the development of new dehydrogenase-based SPEs.     

Application of an in-line imprinted polymer column in a potentiometric flow-injection chemical sensor to the determination of the carbamate pesticide carbaryl in complex biological matrices

A flow-injection biosensor-like system based on a nonenzymatic approach has been developed to determine the carbamate pesticide carbaryl in complex biological samples without lengthy and expensive extraction steps. Molecularly imprinted polymeric beads were used to immobilize carbaryl from biological samples. pH variation permitted the elution of carbaryl from the binding cavity to the flow cell. A pH electrode was used to detect changes in the charge of carbaryl in the sample solution resulting from the protonation and deprotonation of the molecule over different pH ranges. At pH 2.0, the secondary amine group is protonated, giving a (+1) charge to the carbaryl molecule. At pH 8.0, the ionized carbaryl loses a proton to become neutral, changing the local pH of the flow cell. The pH change at the flow cell generated by the deprotonation of carbaryl ion in alkaline medium was used to determine the carbaryl concentration. Parameters influencing the performance of the system were optimized for use in the detection procedure. The validated biosensor-like system had a carbaryl detection limit of 10.0 μg/mL and a response that was linear (r ² > 0.98) over the concentration range of 10.0–00 μg/mL.     

热解吸直接进样气相色谱法分析室内空气中的总挥发性有机化合物

建立室内空气中总挥发性有机化合物的热解吸直接进样气相色谱分析方法。采集的空气样品吸附于Tenax吸附管中,将吸附管置于热解吸仪上,解吸气体直接由进样阀快速进入气相色谱仪进行分析,采用非极性石英毛细管柱,氢火焰离子化检测器检测。8种组分的线性范围为0.01～11.04μg,检测限为0.001～0.006μg,测定结果的相对标准偏差RSD≤4.8%。该方法符合室内空气中总挥发性有机化合物分析的要求。     

Flow injection visible diffuse reflectance quantitative analysis of nickel

Flow injection (FI) methodology, using diffuse reflectance in the visible region of the spectrum, for the analysis of nickel, precipitated in the form of dimethylglyoximate, is presented. A reflectance cell, constructed in polytetrafluoroethylene, using a LED (light emitting diode) as light source and a LDR (light dependent resistor) as detector, is described. The analytical signal (S) correlates with nickel concentration (C) between 1.6 × 10⁻⁴ and 6.6 × 10⁻⁴ mol L⁻¹. This correlation is described by the equation S = −1.108 + 3.314 × 10⁴C − 2.081 × 10⁷C² (r = 0.9996). The experimentally observed limit of detection is about 1.3 × 10⁻⁴ mol L⁻¹, as in lower concentrations the formation of precipitate is not observed. The experimental quantitation limit is about 1.6 × 10⁻⁴ mol L⁻¹. The mean R.S.D. (relative standard deviation) is about 2.7%. Samples containing nickel were analyzed and the results obtained in this method were compared with those of other methods using the statistical Student's t-test.