荧光猝灭法测定痕量六价铬

本文研究了用荧光猝灭法测定痕量六价铬。本方法是基于六价铬与碘化钾反应生成了单质碘,碘可以使2’,7’-二氯荧光素(DCF)发生荧光猝灭,从而间接测定六价铬。六价铬浓度在0.20-2.50μAg/25ml范围内,荧光强度差值与六价铬浓度呈线性关系,线性回归方程△F=12.12C+0.19,相关系数γ=0.9993,检测限为0.1μg/25mL。本法简便、灵敏度高,已用于合成样中六价铬的测定,回收率在100～103％,结果令人满意。     

用1-(2-苯并噻唑)-3-(3,5-二溴吡啶)-三氮烯荧光光度法测定电镀废水中的微量铜(Ⅱ)

目前,利用1-（2-苯并噻唑）-3-（3,5-二溴吡啶）-三氮烯（BTPYBT）与铜的荧光反应测定铜的研究未见报道。合成了BTPYBT,依据其与铜（Ⅱ）的荧光反应,建立了一种测定微量铜（Ⅱ）的新的荧光光度法。结果表明:在pH值9.2的Na₂B₄O₇-NaOH缓冲溶液中,该试剂与铜（Ⅱ）形成2:1稳定的配合物,体系的激发波长和发射波长分别为359 nm和401 nm;铜含量在0⁸0.0μg/L内与荧光响应值△F（配合物溶液和空白试剂荧光强度之差）呈良好的线性关系,其线性回归方程为△F=一0.177+1.19ρ,相关系数r=0.998 6,检出限为0.2μg/L,本方法用于测定电镀废水中的微量铜,与原子吸收光度法（AAS）结果相符,6次测定值的相对标准偏差小于3%,加标回收率为98.8%¹03.0%。     

茶叶中维生素C的荧光测定法

目的建立荧光分光光度法测定茶叶中维生素C的含量。方法茶叶经草酸提取,活性炭氧化后,与邻苯二胺反应,在激发波长355nm,发射波长425nm测定荧光强度。结果维生素C在2-20mg/L浓度范围内呈现良好的线性关系,相关系数为0.9996。平均回收率为99.5%。结论采用荧光法测定茶叶中维生素C含量,具有准确、简便、快速、灵敏等优点。     

4-(2-吡啶偶氮)-间二苯酚光度法测定奶粉中的锌含量

研究了显色剂4-(2-吡啶偶氮)-间二苯酚与锌的显色反应。在pH=9.0的硼砂-盐酸缓冲溶液中,非离子表面活性剂OP存在下,锌与4-(2-吡啶偶氮)-间二苯酚反应形成红色配合物,其最大吸收波长为500nm,表观摩尔吸光系数为6.24×104L·moL-1·cm-1。锌含量在0-60μg/50mL范围内符合比尔定律。该方法用于测定奶粉中的锌含量测定,加标回收率为97.8%-103.6%,相对标准偏差小于3.6%。     

荧光法同时测定环境水中的As(Ⅲ)和As(V)

研究了一种快速、灵敏的同时测定水中的As(Ⅲ)和As(V)的荧光新方法。在pH=6.5~7.5的缓冲介质中,利用2’,7’-二氯荧光素(DCF)作为荧光试剂,激发波长λex=510nm,发射波长λem=528nm下,As(Ⅲ)和DCF竞争碘,引起荧光强度的增强,从而测定痕量As(Ⅲ)。同时利用L一半胱氨酸还原剂将水中的As(V)还原成As(Ⅲ),从而测定As(Ⅲ)和As(v)的总量,差减间接测定As(V)。As(Ⅲ)浓度在4~180ng/mL范围内,相对荧光强度差值与As(Ⅲ)浓度呈线性关系,线性方程△F=7.82C+0.76,相关系数为o.9991,本法快速、简便、灵敏度高,已用于检测自来水和池塘水中痕量的As(Ⅲ)和As(V),回收率在96%~105%,结果令人满意。     

4-(2-吡啶偶氮)-间二苯酚光度法测定奶粉中的锌含量

研究了显色剂4-(2-吡啶偶氮)-间二苯酚与锌的显色反应.在pH=9.0的硼砂-盐酸缓冲溶液中,非离子表面活性剂OP存在下.锌与4-(2-吡啶偶氮)-间二苯酚反应形成红色配合物,其最大吸收波长为500nm,表观摩尔吸光系数为6.24×104L·,moL-1·cm-1.锌含量在0～60μg/50mL范围内符合比尔定律.该方法用于测定奶粉中的锌含量测定,加标回收率为97.8%～103.6%,相对标准偏差小于3.6%.     

用副品红褪色光度法测定镀锌液中的痕量铜

沸水浴中Cu2 能催化H2O2氧化副品红褪色反应,建立了褪色光度法测定Cu2 的新方法.在最大吸收波长为540 nm,0～5μg/mL Cu2 范围内遵守比尔定律,表观摩尔吸光系数4.038×105 L/mol·cm,检出限为1.2μg/mL.该催化反应用于酸性氯化钾镀锌液中Cu2 的测定,结果令人满意.     

邻甲氧基苯酚偶联光度法测定水中亚硝酸钠

用邻甲氧基苯酚偶联光度法测定水中亚硝酸钠。在室温下,亚硝酸钠和苯胺反应生成重氮盐,在碱性介质中(pH＞9.5),重氮盐与邻甲氧基苯酚偶联显色,其最大吸收波长为452nm。线性范围为0～4．2mg/L,检出下限为8．5μg／L,此方法可用于水样分析。     

气相-动态顶空进样-气相色谱/质谱法间接测定饮用水源水中苦味酸

建立气相-动态顶空进样-气相色谱/质谱法(D-HS-GC/MS)间接测定饮用水源水中苦味酸(即2,4,6-三硝基苯酚)的方法。基于苦味酸与次氯酸钠反应生成挥发性有机物———氯化苦(硝基三氯甲烷),气相-动态顶空进样技术可对水样液上气相空间的氯化苦进行吹脱捕集,通过气相色谱/质谱法测定氯化苦含量来间接测定苦味酸的浓度。结果表明:苦味酸浓度在1.00²0.0μg/L范围内呈良好的线性关系(r=0.9993),方法检出限为0.40μg/L;1.00,2.50,10.0μg/L标准点测得结果的相对标准偏差(RSD)分别为12.5%、9.2%和10.5%(n=7)。对实际水样进行分析,加标回收率为102%20.0μg/L范围内呈良好的线性关系(r=0.9993),方法检出限为0.40μg/L;1.00,2.50,10.0μg/L标准点测得结果的相对标准偏差(RSD)分别为12.5%、9.2%和10.5%(n=7)。对实际水样进行分析,加标回收率为102%¹31%,RSD为3.5%131%,RSD为3.5%¹6.6%(n=3)。     

微波消解-原子荧光光谱法测定中药中的砷和硒

建立了微波消解-原子荧光光谱测定中药中砷和硒含量的方法。该方法测定砷和硒的检出限分别为0.087μg/L和0.123μg/L,荧光强度与砷及硒的质量浓度在0~200μg/L及0~100μg/L范围内呈线性关系。用于中药中砷和硒的测定,相对标准偏差(n=6)均小于3.6%,砷的回收率在95.2%~102.8%之间,硒的回收率在94.5%~104.8%之间。     

Development of a precolumn derivatization method for the determination of free amines in wastewater by high-performance liquid chromatography via fluorescent detection with 9-(2-hydroxyethyl)acridone.

A simple, sensitive, and mild method for the determination of amino compounds based on a condensation reaction with fluorescence detection has been developed. 9-(2-Hydroxyethyl)acridone reacts with coupling agent N,N'-carbonyldiimidazole at ambient temperature to form activated amide intermediate 9-(2-acridone)oxyethylcarbonylimidazole (AOCD). The amide intermediate (AOCD) preferably reacts with amino compounds under mild reactions in the presence of 4-(dimethylamino)pyridine (base catalyst) in acetonitrile to give the corresponding sensitively fluorescent derivatives with an excitation maximum at lambda(ex) 404 nm and an emission maximum at lambda(em) 440 nm. The labeled derivatives exhibit high stability under reversed-phase conditions. The fluorescence intensities of derivatives in various solvents or at different temperatures were investigated. The method, in conjunction with a gradient elution, offers a baseline resolution of the common amine derivatives on a reversed-phase C18 column. The LC separation for the derivatized amines shows good reproducibility with acetonitrile-water including 2.5% DMF as mobile phase. The relative standard deviations (n = 6) for each amine derivative are <4.5%. The detection limits (at a signal-to-noise ratio of 3) per injection were 0.16-12.8 ng/mL. Further research for the field of application, based on the AOCD amide intermediate as derivatization reagent, for the determination of free amines in real water samples is achieved.     

Removal of phenols in water using chitosan-conjugated thermo-responsive polymers

A chitosan-conjugated thermo-responsive polymer containing 15% chitosan, PNIPAAm-15CS, was used for the removal of different phenols in water. The polymer was synthesized by a 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide-mediated condensation of poly(N-isopropylacrylamide-co-acrylic acid) and chitosan in the aqueous solution (pH 6). At 30 °C, phenol, 4-methylphenol, 4-methoxyphenol, and 4-chlorophenol were converted to dark brown oxidized compounds by the tyrosinase-induced enzymatic reaction and subsequently bound to the amino moiety of PNIPAAm-15CS. In the presence of 1.0 g L(-1) PNIPAAm-15 CS and 50 k UL(-1) tyrosinase, phenols (20 mg L(-1)) decreased to undetectable levels (<0.01 mg L(-1)) within 2h. By the vigorous mixing of the solution at 40 °C, the polymer deposited and became a small coagulate that can be easily taken up from water. Accompanying the polymer deposition, the oxidized compounds were completely (>98%) removed. The proposed method was successfully applied to the removal of phenols from wastewaters.     

3,3',5,5'-tetramethyl-N-(9-anthrylmethyl)benzidine: a dual-signaling fluorescent reagent for optical sensing of aliphatic aldehydes

A new optical chemical sensor for continuous monitoring of aliphatic aldehydes has been proposed based on the reversible chemical reaction between a new sensing reagent, 3,3',5,5'-tetramethyl-N-(9-anthrylmethyl)benzidine (TMAB), and the analytes. TMAB, containing two receptors and two fluorescent reporters, can perform dual fluorescence responses corresponding to the reactions of hydrogen ion and carbonyl compound. When immobilized in a plasticized poly(vinyl chloride) membrane, TMAB extracts aliphatic aldehydes from aqueous solution into the bulk membrane phase and reacts with the analyte by forming a Schiff base. Since the extraction equilibrium and chemical reaction are accompanied by fluorescence increase of the sensing membrane, the chemical recognition process could be directly translated into an optical signal. At pH 3.20, the sensor exhibits a dynamic detection range from 0.017 to 4.2 mM n-butyraldehyde with a limit of detection of 0.003 mM. The forward response time (t95) of the sensor is 3-5 min, and the reverse response time is 5-7 min. The responses of the sensor toward different kinds of aldehydes and ketones depend on the lipophilicity and the reactivity of the analytes. Since the fluorescence enhancement of the sensing membrane at 296 nm/410 nm is only related to the formation of Schiff base, the measurement of aldehydes is independent of pH.     

Use of fluorescent DNA-templated gold/silver nanoclusters for the detection of sulfide ions

We have developed a one-pot approach to prepare fluorescent DNA-templated gold/silver nanoclusters (DNA-Au/Ag NCs) from Au(3+), Ag(+), and DNA (5'-CCCTTAATCCCC-3') in the presence of NaBH(4) in order to detect sulfide (S(2-)) ions on the basis of fluorescence quenching. The as-prepared DNA-Au/Ag NCs have been characterized by UV-vis absorption, fluorescence, circular dichroism, X-ray photoelectron spectroscopy, and electrospray ionization-mass spectrometry measurements. Relative to DNA-Ag NCs, DNA-Au/Ag NCs are much more stable in high ionic strength media (e.g., 200 mM NaCl). The quantum yield of the as-prepared DNA-Au/Ag NCs is 4.5%. We have demonstrated that the fluorescence of DNA-Au/Ag NCs is quenched by S(2-) ions through the interaction between sulfide ions and gold/silver atoms/ions, a result which leads to changes in the conformation of the templated DNA from packed hairpin to random coil structures. These changes in fluorescence intensity allow sensitive detection of S(2-) ions at concentrations as low as 0.83 nM. To minimize interference from I(-) ions for the detection of S(2-) ions using the DNA-Au/Ag NCs, the addition of sodium peroxydisulfate to the solution is essential. We have validated the practicality of this probe for the detection of S(2-) ions in hot spring and seawater samples, demonstrating its advantages of simplicity, sensitivity, selectivity, and low cost.     

Anaerobic biogranulation in a hybrid reactor treating phenolic waste

Granulation was examined in four similar anaerobic hybrid reactors 15.5L volume (with an effective volume of 13.5L) during the treatment of synthetic coal wastewater at the mesophilic temperature of 27+/-5 degrees C. The hybrid reactors are a combination of UASB unit at the lower part and an anaerobic filter at the upper end. Synthetic wastewater with an average chemical oxygen demand (COD) of 2,240 mg/L, phenolics concentration of 752 mg/L and a mixture of volatile fatty acids was fed to three hybrid reactors. The fourth reactor, control system, was fed with a wastewater containing sodium acetate and mineral nutrients. Coal waste water contained phenol (490 mg/L); m-, o-, p-cresols (123.0, 58.6, 42 mg/L); 2,4-, 2,5-, 3,4- and 3,5-dimethyl phenols (6.3, 6.3, 4.4 and 21.3mg/L) as major phenolic compounds. A mixture of anaerobic digester sludge and partially granulated sludge (3:1) were used as seed materials for the start up of the reactors. Granules were observed after 45 days of operation of the systems. The granules ranged from 0.4 to 1.2 mm in diameter with good settling characteristics with an SVI of 12 mL/gSS. After granulation, the hybrid reactor performed steadily with phenolics and COD removal efficiencies of 93% and 88%, respectively at volumetric loading rate of 2.24 g COD/Ld and hydraulic retention time of 24 h. The removal efficiencies for phenol and m/p-cresols reached 92% and 93% (corresponding to 450.8 and 153 mg/L), while o-cresol was degraded to 88% (corresponding to 51.04 mg/L). Dimethyl phenols could be removed completely at all the organic loadings and did not contribute much to the residual organics. Biodegradation of o-cresol was obtained in the hybrid-UASB reactors.     

An optical fiber chemical sensor for mercury ions based on a porphyrin dimer

The synthesis of a novel fluoroionophore, 5-p-[[4-(10',15',20'-triphenyl-5'-porphinato) phenyloxyl]-1-butyloxyl]phenyl-10,15,20-triphenylporphine (DTPP), and its application for preparation of a Hg(II)-sensitive optical fiber chemical sensor are described. The response of the sensor is based on the fluorescence quenching of DTPP by coordination with Hg(II). The porphyrin dimer-based sensor shows a linear response toward Hg(II) in the concentration range 5.2 x 10(-7)-3.1 x 10(-4) mol x L(-1), with a working pH range from 2.4 to 8.0. The sensor shows excellent selectivity for Hg(II) over transition metal cations including Cd(II), Co(II), Cu(II), Ni(II), Pb(II), Zn(II), and Fe(III). As a sensing agent, the porphyrin dimer shows obviously better fluorescence response characteristics toward Hg(II) compared to porphyrin monomer or metalloporphyrin. The effect of the composition of the sensor membrane was studied, and the experimental conditions were optimized. The sensor has been used for determination of Hg(II) in water samples.     

Competitive quenching fluorescence immunoassay for chlorophenols based on laser-induced fluorescence detection in microdroplets

An improved biomonitoring system for the analysis of 2,4,6-trichlorophenol (TCP) in urine samples has been developed. The principle of the biosensor device is the detection of laser-induced fluorescence (LIF) in single microdroplets by a homogeneous quenching fluorescence immunoassay (QFIA). The competitive immunoassay occurs in microdroplets (d = 58,4 microm) produced by a piezoelectric generator system with 10-microm-diameter orifice. A continuous Ar ion laser (488 nm) excites the fluorescent tracer; its fluorescence is detected by a spectrometer attached to a 512 x 512 cooled, charge-coupled device camera. Fluorescence is quenched by specific binding of TCP polyclonal antibodies to the fluorescent tracer (hapten A-fluorescein); the quenching effect is diminished by the presence of the analyte. Thus, an increase in the signal is produced in a positive dose-dependent manner when TCP is present in the sample. In 10 mM PBS buffer, the IC50 of the LIF-microdroplet QFIA is 0.45 microg L(-1) reaching a LOD of 0.04 microg L(-1). The QFIA with the same reagents performed in microtiter plate format achieved a LOD of 0.36 microg L(-1) in buffer solution. Performance in human urine was similar to that observed in the buffer. A LOD of 1.6 ,g L(-1), with a dynamic range between 4 and 149.5 microg L(-1) in urine, was obtained without any sample treatment other than dilution with the assay buffer. The detectability achieved is sufficient for occupational exposure risk assessment.     

偶氮氯膦——mA分光光度法测定钢样及食盐中钡

在pH9.0的NH_3—NH_4Cl缓冲溶液中,Ba(Ⅱ)与间乙酰基偶氮氯膦(CPAmA)生成紫蓝色络合物。络合物的最大吸收位于635nm。络合物的组成Ba(Ⅱ):CPAmA为1∶4,表现摩尔吸光系数ε_(max)=1.95×10~41·mol~(-1)·cm~(-1),钡(Ⅱ)含量在0-3.2×10~(-3)g/L范围内遵守比尔定律。本法用于测定钢样及食盐中的钡,结果满意。     

Novel functionalized ternary copolymer fluorescent nanoparticles: synthesis, fluorescent characteristics and protein immobilization

Novel fluorescent poly(styrene-acrylamide-acrylic acid) nanoparticles (FPSAAN) were synthesized by means of soapless emulsion polymerization and being modified with hydrazine hydrate by hydrazinolysis. The azidocarbonyl groups which can be rapidly coupled with proteins under mild condition were introduced onto the fluorescent nanoparticles by azido-reaction. Bovine serum albumin (BSA) was selected as a model protein to be covalently immobilized on the azidocarbonyl FPSAAN. Atom force microscopy (AFM), Transmission electron microscopy (TEM), Ultraviolet-visible (UV/Vis) spectrometer, Fourier transforms infrared spectrometer (FTIR), nanoparticle size analyzer and fluorescence spectrophotometer were used to characterize the FPSAAN. Results showed that FPSAAN had a regular spherical shape, and a dramatic narrow size distribution (polydispersity index 0.046 +/- 0.009). The fluorescence intensity of FPSAAN (lambda(ex)/lambda(em) = 253/306 nm), hydrazide-FPSAAN (lambda(ex/)lambda(em) = 260/326 nm), and protein-immobilized FPSAAN (lambda(ex)/lambda(em) = 258/325 nm) was linearly related to the concentration ranging from 1.0 x 10(-3) g l(-1) to 10.0 x 10(-3) g l(-1). The linear relationship was obtained. The equations are y = 52.808x + 16.465 (R (2) = 0.9927), y = 5.1814x + 4.1535 (R (2) = 0.9935) and y = 5.2227x + 5.2883 (R (2) = 0.9937), respectively. In addition, external factors such as pH and ionic strength exert a slight influence on fluorescent properties. The experiments of the immobilization of BSA indicated that FPSAAN with azidocarbonyl groups could be covalently coupled with BSA at the rate of 41.1%. Meanwhile, hCG antibody immobilized FPSAAN have the similar fluorescence characteristics to BSA immobilized FPSAAN. Only negligible difference of the fluorescence characteristics can be found. Furthermore, the fluorescence characteristics of hCG antibody immobilized FPSAAN have not been obviously affected after mixed with the hCG antigen and human plasma. These novel azidocarbonyl FPSAAN with stable fluorescence and active functional azidocarbonyl groups could be used as a promising fluorescent probe for quantitative detection, protein immobilization, cell labeling research and early rapid clinical diagnostics.