Flow-injection chemiluminescence determination of polyphenols using luminol-NaIO4-gold nanoparticles system

It was found that gold nanoparticles with different sizes could enhance the chemiluminescence (CL) of the luminol-NaIO4 system in alkaline solution. The most intensive CL signals were obtained with gold nanoparticles in diameter of 4 nm and the CL intensity increased linearly with the concentration of gold nanoparticles. The studies of UV-vis spectra, CL spectra, effects of concentrations of luminol and periodate solution were carried out to explore the CL enhancement mechanism. Catechol, hydroquinone and resorcinol were found to inhibit the CL signals of the luminol-NaIO4 reaction catalyzed by gold nanoparticles, which made it applicable for the determination of these polyphenols. Under the selected experimental conditions, the detection limits (3sigma) were in the range of 2.1 x 10(-9) to 1.0 x 10(-10) g ml(-1), the relative standard deviation (R.S.D., n=11) were in the range of 1.7-2.9%. The method has been successfully applied to the determination of catechol in tap water and synthesized samples with satisfactory results.     

NBS-二氯荧光素化学发光体系测定西索米星

在碱性奈件下，西索米星被NBS（N-溴代琥珀酰亚胺）氧化，其能量可激发共存的二氯荧光素（DCF）而产生化学发光，发光强度与西索米星的质量浓度在一定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索米星的化学发光新方法。该方法具有较高的灵敏度，检出限为73μg／L（IUPAC），线性范围为0．1～10mg／L，对5．0mg／L西索米星平行测定11次，其相对标准偏差为2．3％。已用于针剂中西索米星的测定。     

NBS-荧光素-盐酸头孢吡肟化学发光体系的研究

盐酸头孢吡肟(Cefepime Hydrochloride)作为第四代头孢菌素类抗菌新药,具有高效、广谱、低毒、耐细菌β-内酰胺酶等特点。目前测定盐酸头孢吡肟的方法有液相色谱[1]、高效液相色谱法[2-7]、红外与X-射线[8]等。本文研究发现,在氢氧化钠介质中,盐酸头孢吡肟可被N-溴代琥珀酰亚胺(NBS)氧化产生微弱的化学发光,在荧光素共存时产生较强的化学发光,其发光强度与盐酸头孢吡肟的质量浓度在0·05mg·L-1~10mg·L-1范围内呈良好的线性关系。基于此,结合流动注射技术,建立了测定盐酸头孢吡肟的流动注射化学发光方法。该法的检出限(3σ)为29μg·L-…     

A reaction-rate method for the determination of thiocyanate,based on its inhibitory effect on the iodate-hypophosphite reaction

An automatic spectrophotometric reaction-rate method is described for the determination of thiocyanate in aqueous solutions, based on its inhibitory effect on the iodate-hypophosphite reaction. The time required for the reaction to proceed between two pre-determined levels is measured automatically and related directly to the thiocyanate concentration. The recommended reaction-rate method is fast, simple, sensitive, accurate (to 2%) and precise (1.7%, relative standard deviation). The useful analytical range of concentrations of thiocyanate is 4 × 10^?5 to 5 × 10^?4M. Maximum tolerable amounts of interfering ions are also presented.     

Flow-injection chemiluminescence method for determination of critical micelle concentration of surfactants

In this study, chemiluminescence (CL) behaviour of Luminol-H₂O₂ in the presence of the different concentrations of four surfactants, cetyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB), sodium dodecyl sulphate (SDS) and polyoxyethylene dodecyl ether (Brij-35), was investigated. A novel method for the direct determination of critical micelle concentration (CMC) of the surfactants using flow-injection CL is described. Under the optimum conditions, the luminescence intensity of the Luminol-H₂O₂ system increased gradually with increasing concentration of the surfactants before the CMC, but rapidly reached to the emission maximum at the CMC, followed by a decrease after the CMC. The concentrations of the surfactants corresponding to the luminescence maximum are in agreement with the literature CMC values. The main factors affecting the determination of CMC are discussed. The mechanistic studies show that the luminescence peaks observed in the experiment were mainly because of the protective effect of the micelle against the transition of the excited species and the retarding effect of the micelle structures on the CL reaction rate.     

A sensitive chemiluminescence method for the determination of cysteine based on silver nanoclusters

We have developed a sensitive chemiluminescent (CL) assay for cysteine. It is based on the use of water-soluble and fluorescent silver nanoclusters (Ag NCs) which are found to be able to strongly enhance the weak CL signal resulting from the redox reaction between Ce(IV) ion and sulfite ion. This enhancement is inhibited by cysteine under appropriate conditions. Taking advantage of this specific CL inhibition, a novel CL method for the sensitive and selective detection of cysteine was developed. This effect is interpreted in terms of an electronic energy transfer from excited state intermediate sulfur dioxide (originating from the CL reaction between Ce(IV) and sulfite ions) to the Ag-NCs. The latter become electronically excited and thus can act as a new source of emission. The method was applied to the determination of cysteine in the range from 5.0?nM to 1.0?μM, with a detection limit at 2.5?nM (S/N?=?3).

流动注射化学发光法测定样品中的白藜芦醇

白藜芦醇具有抗菌、抗氧化、抗衰老、抗癌的作用[1-2],能阻碍血小板凝聚、调节血脂,防止低密度脂蛋白氧化,能抑制生物体内过氧化作用,能消除自由基。植物体内的白藜芦醇作为一种植物抗毒素而存在,其结构同己烯雌酚,有雌激素作用。白藜芦醇在虎杖,花生,葡萄,桑椹中含量最高,白藜     

A new spectrofluorometric method for the determination of ascorbic acid based on its activating effect on a hemoglobin-catalyzed reaction.

A spectrofluorometric method for the determination of ascorbic acid (AA) based on its activation on the hemoglobin-catalyzed reaction was proposed. The fluorescence intensity of the product was measured under the optimal experimental conditions, i.e. 4.0 x 10(-6) M H2O2, 6.0 x 10(-5) M p-cresol, 1.2 M NH3-NH4Cl (pH 10.4) and 2.0 x 10(-7) M hemoglobin. The order of additions of the reagents was also studied. The activation of AA was found to be associated with a high ammonia concentration. The linear range of the method was 9.0 x 10(-10)-3.6 x 10(-8) M of AA. The detection limit was calculated to be 3.0 x 10(-10) M. The relative standard deviation of this method is 1.6% at 7.0 x 10(-9) M for 11 determinations.     

曙红Y分光光度法测定阳离子表面活性剂及其机理研究

在弱酸性的HCl-NaAc缓冲介质中,阳离子表面活性剂(CS)与曙红Y(EY)染料反应,形成离子缔合物,溶液颜色发生明显改变,最大褪色波长分别在514 nm(EY-CPB体系)、516 nm(EY-CTAB体系),同时在548 nm(CPB体系)、544 nm(CTAB体系)处有吸收峰,在褪色波长处阳离子表面活性剂的浓度与褪色程度呈良好线性关系,从而建立测定阳离子表面活性剂的光度法。在最大褪色波长处,CPB体系、CTAB体系中CS的浓度在0~4.79×10-5mol/L、0~2.90×10-5mol/L范围内遵守比尔定律,表观摩尔吸光系数为2.94×104、2.86×104L.mol-1.cm-1,检出限为8.97×10-7mol/L、7.87×10-7mol/L。若用双波长叠加,表观摩尔吸光系数达5.58×104、5.20×104L.mol-1.cm-1,检出限为5.87×10-7、6.25×10-7mol/L。方法适用于水样中CS的测定。本文还用密度泛函理论对反应机理进行了探讨。     

荧光猝灭法测定痕量亚硝酸根

基于在酸性介质中,NO-2与藏红T直接反应,使藏红T的荧光猝灭,加入强碱弱酸盐对体系有增敏作用,据此提出了荧光法测定痕量NO-2的新方法。方法的线性范围为2.8～294ng/mL,方法的检出限为2.8ng/mL。可直接用于水样及蔬菜中痕量NO-2的测定。     

鲁米诺-铁氰化钾化学发光体系测定双嘧达莫

在碱性条件下,铁氰化钾氧化鲁米诺产生化学发光,双嘧达莫对该体系的化学发光有显著的增强作用。基于此并结合流动注射技术建立了测定双嘧达莫的新方法。该方法检出限为5.7×10-11g mL(IUPAC),线性范围为1.0×10-10～5.0×10-8g mL,对5.0×10-9g mL双嘧达莫平行测定11次,其相对标准偏差为1.9%。     

A radiometric method for the determination of non-ionic surfactants

A radiometric method for the determination of non-ionic surfactants of ethylene oxide type has been elaborated. The principle of the method is the formation of an associate¹³³Ba-non-ionic surfactant — dicarbolide and its extraction into a mixture nitrobenzene-chloroform /41/. The extracted activity of¹³³Ba is proportional to the non-ionic surfactant concentration in the sample. The factors influencing the determination of non-ionic surfactants in the real waste solution after washing have been studied. The possibility of the determination of non-ionic surfactants by the calibration graph method and by the method of standard addition was verified.     

荧光猝灭法测定壳聚糖含量

在pH 6.3的NaH2PO4-Na2HPO4缓冲溶液中,壳聚糖对荧光素的荧光强度具有明显的猝灭作用,且在一定浓度范围内,其猝灭程度与加入的壳聚糖浓度成线性关系,据此建立了一种新的测定壳聚糖含量的荧光猝灭分光光度法。该方法的回归方程为ΔF=64.02+42.28ρ(mg/L),R2=0.9942,线性范围为0.50~10.0 mg/L,检出限为0.27 mg/L。样品测定的RSD为4.5%(n=6),平均回收率为99.3%。采用该方法可测定复杂样品中的壳聚糖含量。     

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。     

New method for the photo-chemiluminometric determination of benzoylurea insecticides based on acetonitrile chemiluminescence

The viability of tandem photochemical reaction–chemiluminescence detection has been studied for the determination of five benzoylurea insecticides, namely, diflubenzuron, triflumuron, hexaflumuron, lufenuron and flufenoxuron. The ‘on-line’ photochemical reaction of benzoylurea pesticides provides an enhanced chemiluminescence response of the pesticides during their oxidation by potassium hexacyanoferrate(III) and sodium hydroxide, whose signal increases with the percentage of acetonitrile in the reaction medium. The determination was performed using a photoreactor consisting of a PFA (perfluoroalkoxy) tube reactor coil (5 m × 1.6-mm O.D. and 0.8-mm I.D.) and an 8-W xenon lamp. As the yield of the photoderivatization process and the chemiluminescent signals depend on the percentage of acetonitrile, the chromatographic column (a Gemini C18, Phenomenex 150 mm × 4.6 mm, 5-μm particle size) was chosen with the aim of using high percentages of this organic solvent in the mobile phase. Previous studies showed that the rate of the chemiluminescent reaction was very fast. Therefore, a modification was carried out in the detector in order to mix the analytes and reactants as near as possible to the measure cell. The optimised method was validated with respect to linearity, precision, limits of detection and quantification accuracy. Under the optimised conditions, linear working range extends three orders of magnitude with the relative standard deviation of intra-day precision below 10% and detection limits between 0.012 and 0.18 μg mL⁻¹, according to the compound. The proposed method has been successfully applied to the determination of benzoylureas in cucumber with good results. Figure     

Flow injection chemiluminescence determination of thiamine based on its enhancing effect on the luminol-hydrogen peroxide system

A new flow injection chemiluminescence (CL) method is proposed for the determination of thiamine, based upon its enhancing effect on the CL reaction of luminol with hydrogen peroxide in alkaline solution. The method allows the determination of thiamine within 0.05-8 mug ml(-1) range with a detection limit (3sigma) of 0.01 mug ml(-1). The relative standard deviation is 1.4% (n=11, 0.5 mug ml(-1) thiamine) and the sample throughput is about 90 samples h(-1). The method was successfully applied to the determination of thiamine in pharmaceutical preparations.     

Continuous chemiluminescence determination of formaldehyde in air based on Trautz-Schorigin reaction

A new continuous method for the determination of formaldehyde in air is described. A cylindrical wet effluent diffusion denuder is used for the collection of formaldehyde from air into a thin film of absorption liquid (distilled-deionized water). Formaldehyde in the denuder concentrate is on-line detected employing a chemiluminescence flow method based on a reaction of formaldehyde and gallic acid with hydrogen peroxide in an alkaline solution. The collection efficiency of formaldehyde is quantitative at the air flow rate of 0.5 L min⁻¹ (absorption liquid flow rate of 336 μL min⁻¹). The limit of detection (S/N = 3) is 0.60 μg m⁻³ HCHO (0.49 ppb). The calibration graph is linear up to 300 μg m⁻³ HCHO (244 ppb). The relative standard deviations of chemiluminescence method for 1 × 10⁻⁶ and 5 × 10⁻⁶ M HCHO are 2.87% and 1.49%, respectively. Acetaldehyde interferes negligible, other compounds do not interfere. The method was employed for formaldehyde measurement in ambient air. The comparison measurement illustrates the good agreement of results obtained by proposed method with those obtained by reference fluorimetric method.     

A new chemiluminescence method for the determination of nickel ion

A new chemiluminescence (CL) phenomenon described as the second-chemiluminescence (SCL) was observed and a strong CL signal was detected, when Ni(II) ion was injected into the mixture after the end of the reaction of potassium permanganate with alkaline luminol. The possible CL mechanism is proposed based on the kinetic curve of the CL reaction, CL spectra, UV-vis spectra and some other experiments. A flow-injection analysis for the determination of nickle(II) ion has been developed, based on the catalysis of nickel(II) ion on the CL reaction between potassium manganate produced on-line and luminol under alkaline condition. Under the optimum conditions, the SCL intensity is linear with the concentration of nickel(II) ion in the range of 8.0-200.0 microg l-1 and 0.2-2.0 mg l-1. The R.S.D. was 4.5% for 11 determinations of 250 microg l-1 nickel(II) ion and the detection limit (3sigma) for nickel(II) ion was 0.33 microg l-1. The method was applied to determine nickel(II) ion in synthetic samples with satisfactory results.     

A monitor for the specific determination of nickel carbonyl based on the chemiluminescence reaction with ozone and carbon monoxide

The chemiluminescence, measured at 500 nm, allows nickel carbonyl to be measured in the range 1 ppb to several ppm in combustion gases. Interferences from iron pentacarbonyl and nitrogen monoxide are eliminated by optical and spatial discrimination and by choice of the pressure in the reaction chamber.