流动注射在线光化学荧光法测定药物制剂中叶酸的含量

叶酸接受紫外光照后可转变成最大激发波长为274nm、最大发射波长为466nm的强荧光化合物。对光化学反应介质进行考察，发现在NaC03—NaHC03缓冲体系中所产生的光化学荧光最强，据此建立了流动注射在线光化学荧光分析法。试样在水载流的携带下与PH9．5的Na2C03—NaHC03缓冲溶液汇流后，通过一个盘绕在6—W低压汞灯上的PTFE编结式光化学反应器。在反应器中所生成的荧光化合物直接通入荧光计的流通池测定荧光强度。在最佳条件下，动态线性范围可达0．001-4mg／L，检测限为0．16μg/L，采样速率达80／h，11次测定浓度分别为0．01和0．1mg／L的叶酸标准溶液所得到的RSD分别为1．0％和0．2％。所建立的方法已成功地用于片剂中叶酸含量的测定。     

Indirect spectrofluorimetric determination of arsenic at nanotrace levels in alloys, underground water, industrial waters and sewage sludge

An inexpensive and virtually specific nonextractive Spectrofluorimetric method for the determination of As(III) (1 ng/ml-1 g/ml) in 0.18–1.08N H₂SO₄ has been developed. A known excess of Cr(VI) is allowed to quantitatively oxidize As(III) in the essential presence of a mixture of iodide and chloride as catalyst, followed by the addition of excess 2-(-pyridyl) thioquinaldinamide and measurement of the fluorescence intensity (_em(max) = 488 nm _ex(max) = 360 nm) caused by Cr(VI) remaining after As(III) oxidation. The measurement is repeated without As(III) addition and the decrease in fluorescence intensity gives the As(III) concentration with the help of a calibration graph. The method is very precise and accurate (S. D. = ± 0.474, R. S. D. = 0.95%, for the analysis of 50ng/ml As(III), 11 replicates). The detection limit is 0.3ng/ml As(III). Large excesses of over fifty cations, anions and some complexing agents do not interfere. The method has been successfully applied for arsenic determination in various complex matrices: environmental waters, sewage sludges and several certified reference materials (alloys). This method has also been extended to determine As(V), after its reduction to As(III), in water samples, waste discharge water and sewage sludges.Presented at International Conference Arsenic in Ground Water: Cause, Effect and Remedy, Calcutta, India, February, 1995     

Spectrofluorimetric determination of nucleic acids as 8-hydroxyquinoline/ yttrium ternary complexes

The formation of nucleic acids/8-hydroxyquinoline/yttrium(III) ternary complexes and their fluorescent properties have been studied. The nucleic acids studied include native and thermally denatured calf thymus DNA, fish sperm DNA and yeast RNA. In the range of pH 7.6–8.5, controlled by NH₃-NH₄C1 buffer, ternary complexes are formed that fluoresce at different wavelengths with different nucleic acids. Based on the fluorescence reactions, sensitive spectrofluorimetric methods for nucleic acids are proposed. In optimal conditions, the calibration curves were linear in the range 0.5–4.0 gml^–1 for calf thymus DNA, 0.5–2.5 g ml^–1 for fish sperm DNA and 0.5–4.0 g ml^–1 for yeast RNA. The limits of determination (3 ) were 0.030 g ml^–1 for calf thymus DNA, 0.020 g ml^–1 for fish sperm DNA and 0.090 g ml^–1 for yeast RNA. Corresponding to the interferences of coexisting substances, six synthetic samples were constructed and the results of determination were satisfactory.     

Determination of the antioxidant capacity of different food natural products with a new developed flow injection spectrofluorimetry detecting hydroxyl radicals

This paper presents an automatic spectrofluorimetric method (flow injection analysis spectrofluorimetry) for detecting hydroxyl radicals. Based on H₂O₂ catalyzed by Co²⁺ yielding HO, the method utilized sodium terephthalate to trap hydroxyl radicals and obtained sodium 2-hydroxyterephthalate by aromatic hydroxylation, which resulted in an increase in the fluorescence intensity. The relative fluorescence intensity was proportional to the concentration of hydroxyl radicals. Hydroxyl radicals could be determined indirectly, based on the increase of fluorescence. It was a simple, rapid, precise, sensitive and automatic technique for the determination of HO. The relative standard deviation of 11 determinations was 0.57%. The method can be used to sieve antioxidant medicines and will have theoretical and practical guidance on the mechanism of hydroxyl radicals-damaging biology.     

Highly sensitive spectrofluorimetric kinetic determination of ultratrace amounts of vanadium(V) based on the oxidation of 1,8-diaminonaphthalene by bromate

A highly sensitive catalytic quenching spectrofluorimetric method was described for the determination of V(V) based on its catalytic effect on the oxidation of 1,8-diaminonaphthalene by potassium bromate with Tiron as an activator in weakly acidic medium and the reaction mechanism was investigated. The reaction was followed spectrofluorimetrically by measuring the fluorescence intensity of 1,8-diaminonathphlene (DAN) (λ_ex=356 nm, λ_em=439 nm) at a fixed time of 5 min from initiation of the reaction. Under the optimum conditions, vanadium(V) can be determined in the range 0.05-50.0 ng ml⁻¹ with a S.D.=0.024 for 15 times measurements. The detection limit of the method was down to 0.0088 ng ml⁻¹ and the catalytic reaction activation energy was found to be 43.92 kJ mol⁻¹. The proposed method was tested for the determination of vanadium(V) in rice and natural water samples.     

Spectrofluorimetric Determination of Piroxicam in Pharmaceutical Preparations and Spiked Human Serum Using Micellar Media

The fluorescence properties of piroxicam in various micellar media were investigated. It was found that the presence of 0.05M sodium dodecyl sulfate (SDS) surfactant (pH 1.5–2, nitric acid) causes an approximately 5-fold enhancement in the fluorescence of this drug. An experimental design approach based on central composite design was used to investigate the influence of the main variables (pH, SDS concentration and temperature) on the fluorescence signal. Based on the obtained results, a micelle-enhanced fluorescence method was developed for the determination of piroxicam in pharmaceuticals and also in spiked human serum (after extraction with diethyl ether). The linear calibration ranges of the methods were 0.05–1.5 and 0.2–10µgmL^–1 for aqueous solution and serum samples, respectively. The detection limits were 0.015 and 0.10µgmL^–1 in aqueous and serum samples, respectively.Received November 24, 2002; accepted April 13, 2003 Published online August 8, 2003     

中空纤维三相液相微萃取荧光光度法测定绿豆芽中的吲哚类植物生长素

基于中空纤维液相微萃取技术,建立了绿豆芽中吲哚类植物生长素的荧光检测方法。通过L9(34)正交实验,对中空纤维液相微萃取条件进行优化,得到的优化条件为:样品溶液的p H值调为4.0,萃取溶剂为正辛醇,接受相为p H 12.0的Na OH,搅拌速度为1 000 r/min,萃取时间为60 min。在最优萃取条件下,吲哚类植物生长素的富集倍数可达92倍。供体相中吲哚类植物生长素的质量浓度在1.71~50.0 mg/L范围内呈良好的线性关系,相关系数为0.997 9,检出限(S/N=3)为0.57 mg/L,样品的加标回收率为88.6%~100.7%,相对标准偏差(RSD)不大于4.8%。该方法操作简单,环境友好,可用于绿豆芽中吲哚类植物生长素含量的准确快速测定。     

Sequential Extraction-Spectrofluorimetric Determination of Mercury Using Cryptand Ethers

Abstract

A spectrofluorimetric study of the extraction of mercury with 1,2-dichloroethane as an ion-pair formed between the cryptand 2.2.1-mercury complex and the eosinate counter-ion is described.

The detection limit for mercury is 0.7 ng/ml, and the linear working range up to 125 ng/ml of mercury.

The relative standard deviation is found to be 2.0% at the 100 ng/ml level. The proposed method has been tested for the determination of mercury in coal.     

Pyrocatechol-1-Aldehyde 2-Benzothiazolylhydrazone As Reagent for the Spectrofluorimetric Determination of Nanogram Amounts of Gallium in Urine and Blood Serum

Abstract

A method is developed for the spectrofluorimetric determination of 1–80 ng.ml^?1 of gallium with pyrocatechol-1-aldehyde 2-benzothiazolylhydrazone, in a 50% (v/v) DMSO-Water medium at apparent pH 4.0 (monochloracetic/monochloracetate buffer). Λ_ex = 400nm, Λ_em = 504 nm (corrected). Interferences have been evaluated and the method applied to the determination of gallium in human urine and blood serum samples.     

Fluorescence Spectrometric Study on the Interactions of Terazosin Hydrochloride and Prazosin Hydrochloride with Bovine Serum Albumin Using Warfarin and Diazepam as Site Markers

Abstract

The binding interaction of the terazosin hydrochloride and prazosin hydrochloride with bovine serum albumin (BSA) was studied by spectrofluorimetry. Both of these two compounds quenched the fluorescence of BSA. The thermodynamic parameters (ΔH ⁰, ΔS ⁰ and ΔG ⁰) obtained from the fluorescence data measured at two different temperatures showed that the binding of terazosin hydrochloride to BSA involved hydrogen bonds and that of prazosin hydrochloride to BSA involved hydrophobic and electrostatic interactions. In this work, the competitive interaction of the terazosin hydrochloride and prazosin hydrochloride with BSA was studied by three-way excitation-emission fluorescence with the aid of parallel factor analysis (PARAFAC).