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At least 19 recordsLinked to original sources
PubMedDate not supplied

[Study of interaction of cytochrome P450 2B4 with riboflavin by fluorescence spectrometry].

Fluorescence quenching of riboflavin by cytochrome P450 2B4 was used to probe the ligand--enzyme binding interaction ((lambda ex = 385 nm, lambda em = 520 nm). Riboflavin is a component of a flavoprotein NADPH dependent cytochrome P450 reductase, an essential electron carrier during cytochrome P450 catalysis. Fluorescence titration measurements revealed that cytochrome P450 2B4 and riboflavin formed a complex with an apparent Kd = 8.8 +/- 1 microM. The fluorescence intensity of riboflavin decreased upon the addition of cytochrome P450 2B4, which may be caused by the resonance excitation energy transfer from the fluorescent donor riboflavin to the cytochrome P450 2B4 heme acceptor. These data suggest that there may exist specific sites of binding of riboflavin with the protein globule of cytochrome P450 2B4.

Aryl Hydrocarbon Hydroxylases↗
PubMed2002

Cold vapour atomic fluorescence spectrometry and gas chromatography-pyrolysis-atomic fluorescence spectrometry for routine determination of total and organometallic mercury in food samples.

Two procedures have been investigated for the quantification of the different forms of mercury in food. A two-stage procedure has been developed to determine firstly total inorganic and organometallic species, and then the full separation of all organomercury species. The procedure involves solubilisation of the samples using alkaline extractions or enzymolysis, followed by the extraction of organic mercury in an organic solvent, preferably a mixture of dichloromethane and hexane (3:2). For the total organic mercury determination, the organic extract is analysed for "total" mercury after nitric acid/peroxide digestion, evaporation of the solvent and detection by cold vapour-atomic fluorescence spectrometry. Full organomercury speciation requires a clean-up step before analysis of the final extract in dichloromethane by gas chromatography coupled to a pyrolyser and an atomic fluorescence detector (GC-pyro-AFS). A detection limit of 6 ng l-1, and reproducibility of 2% was achieved for the CV-AFS method; GC-pyro-AFS yielded 200 ng l-1 and 5% for detection limit and coefficient of variation, respectively. Both procedures were validated with the use of various certified reference materials over a wide range of mercury concentrations, and by spiking experiments. The validated methods were tested successfully on a wide range of commercially available food samples.

Chromatography, Gas↗
PubMed2002

[Determination of arsenic in animal liver by atomic fluorescence spectrometry].

An atomic fluorescence spectrometry for the determination of micro arsenic in animal liver was developed with high sensitivity and fine accuracy. Under the selected experimental conditions, there was a linear relationship between the fluorescence intensity and arsenic concentration in the range of 0-160 ng.mL-1 with correlation coefficient of 0.9996. The limit of detection was 0.4 ng.mL-1, and the recovery was 94.2%-98.5%.

Animals↗
PubMed2006

Classification of black powder toners on the basis of integrated analytical information provided by Fourier transform infrared spectrometry and X-ray fluorescence spectrometry.

Differentiating between black powder toners used in laser printers and copiers can be challenging for forensic examiners. One hundred and sixty-two samples from 82 different types of cartridges produced by 21 manufacturers that are currently available on the Polish market were studied using Fourier transform infrared spectrometry (FT-IR) and energy-dispersive X-ray fluorescence spectrometry (XRF). The spectra obtained by these two methods were classified into 14 groups and 28 groups using FT-IR and XRF, respectively. These classifications served as a basis for the development of an analytical scheme for differentiating black powder toners. This scheme can be used with any two methods that supply different information about an examined sample. The research will show that if two samples are similar in polymer composition (e.g., FT-IR spectra), additional quantitative elemental composition from XRF analyses may provide more discrimination. It was possible to differentiate 82.5% pairs of examined samples using only FT-IR, 90.8% pairs of examined samples using only XRF, and 95.8% pairs of examined samples using these two methods. Obtained spectra and all the available information could be used to create/build a database. The results obtained confirm the multiplicity and compatibility of toners. Additionally, it was stated that not all the samples were original (OEM).

Journal Article↗
PubMed2002

[Determination of trace arsenic and mercury in medicine animal horns by hydride atomic fluorescence spectrometry].

A hydride atomic fluorescence spectrometry has been developed for the determination of trace arsenic and mercury in medicinal animal horns. This method was simple, rapid and sensitive. The samples were digested with HNO3-HClO4(5:1), under the optimum conditions, the allowable amounts of 26 coexist elements were determined. The detection limits of this method were as follows: As 1.50 ng.mL-1, Hg 0.80 ng.mL-1. The relative standard deviations of 11 determinations were 1.2%-2.3% for As and 2.5%-4.7% for Hg. The recoveries were 98.9%-103.8% for As and 95.4%-105.0% for Hg.

Animals↗
PubMed2002

[Atomic/ionic fluorescence in microwave plasma torch discharge with excitation of high current and microsecond pulsed hollow cathode lamp: Ca atomic/ionic fluorescence spectrometry].

A system of atomic and ionic fluorescence spectrometry in microwave plasma torch (MPT) discharge excited by high current microsecond pulsed hollow cathode lamp (HCMP HCL) has been developed. The operation conditions for Ca atomic and ionic fluorescence spectrometry have been optimized. Compared with atomic fluorescence spectrometry (AFS) in argon microwave induced plasma (MIP) and MPT with the excitation of direct current and conventional pulsed HCL, the system with HCMP HCL excitation can improve AFS and ionic fluorescence spectrometry (IFS) detection limits in MPT atomizer and ionizer. Detection limits (3 sigma) with HCMP HCL-MPT-AFS/IFS are 10.1 ng.mL-1 for Ca I 422.7 nm, 14.6 ng.mL-1 for Ca II 393.4 nm, and 37.4 ng.mL-1 for Ca II 396.8 nm, respectively.

Aluminum↗
PubMed2004

Concentrations of hazardous heavy metals in environmental samples collected in Xiamen, China, as determined by vapor generation non-dispersive atomic fluorescence spectrometry.

Non-dispersive atomic fluorescence spectrometry (NDAFS) coupled with vapor generation (VG) sample introduction was applied to the determination of the concentrations of hazardous heavy metals, such as arsenic, cadmium, lead and mercury, in seawater, soils and total airborne particulate matter (PM) collected around the Xiamen area in China. Almost 100% sample introduction efficiency was achieved by using thiourea and ascorbic acid for the pre-reduction of As(V) to As(III), K3Fe(CN)6 and tartaric acid for pre-oxidation of Pb(II) to Pb(IV), and masking the interferences arising from the co-existing transition metals to As, Cd, Hg and Pb during their vapor generation process. Moreover, a novel sample pretreatment device was developed to avoid the loss of mercury, lead, cadmium and arsenic during sample pretreatment. With such methods, the detection limit (DL) of arsenic, cadmium, lead and mercury was down to 0.08, 0.03, 0.05, 0.01 ng mL(-1) (3sigma), respectively. The relative standard deviations (RSD, n = 11) for arsenic, cadmium, lead and mercury at 10 ng mL(-1) were 0.9%, 1.6%, 1.3% and 2.0%, respectively. The concentrations of hazardous heavy metals in the environmental samples collected in Xiamen, China are in the range from 0.02 +/- 0.001 ng mL(-1) in seawater to 15.3 +/- 0.2 microg g(-1) in soils. Besides flame/GF-AAS and ICP-AES/MS, VG-NDAFS should be another choice for the determination of hazardous heavy metals in environmental samples.

China↗
PubMed2004

[Determintion of trace lead in the traditional Chinese medicine using hydride generation atomic fluorescence spectrometry].

A hydride generation atomic fluorescence spectrometry method has been developed for the determination of trace lead in traditional Chinese medicines. A high pressure digestion using HNO3-H2O2 system was applied for the pretreatment of traditional Chinese medicine samples and the interval flow precedure was used. The experimental conditions and instrumental operating parameters such as KBH4 concentration, flow rates of carrier and shield gases, current of the lamp and height of the atomizer, have been optimized. Under the optimum conditions the detection limit is 0.08 microg x L(-1). The relative standard deviation is 0.34%. This method is simple, rapid and sensitive, so it can be successfully used for the determination of lead in traditional Chinese medicines.

Animals↗
PubMed2002

Simultaneous determination of trace cadmium and arsenic in biological samples by hydride generation-double channel atomic fluorescence spectrometry.

Hydride generation atomic fluorescence spectrometry (HG-AFS) has been used for determination of hydride-forming elements because of its high sensitivity, simplicity, and low costs, but most of such work has been concentrated on single element analysis, and reports dealing with multielement determination by HG-nondispersive (ND)AFS are rare. In this work, a sensitive HG-NDAFS method was developed for simultaneous determination of trace cadmium and arsenic in biological materials. The conditions for the generation of volatile cadmium and arsenic species from the reaction with KBH4 in aqueous solution were investigated using a double-channel AFS integrated with an intermittent flow reactor. Like thiourea and Co(II), ascorbic acid was found to significantly enhance the generation efficiency of volatile Cd and As species. The interferences of coexisting ions were evaluated. Under optimal conditions, the detection limits for Cd and As were determined to be 10 and 150 ng L(-1), respectively. The precision for 11 replicate determinations at the 1 microg L(-1) Cd level and the 10 microg L(-1) As level were 3.5 and 2.7% (RSD), respectively. The recoveries of spike analytes in the biological samples studied ranged from 94 to 109%. The proposed method was successfully applied to the simultaneous determination of Cd and As in a variety of biological samples.

Animals↗
PubMed2004

[Determination of trace mercury in the Chinese traditional medicine by hydride generation-atomic fluorescence spectrometry].

A hydride generation atomic fluorescence spectrometry method has been developed for the determination of trace mercury in traditional Chinese medicines. A high-pressure digestion using HNO3-H2O2 system was applied to the pretreatment of traditional Chinese medicine samples and an interval flow precedure was used. The experimental conditions and instrumental operation parameters such as KBH4 concentration, flow rates of carrier and shield gases, currents of lamp and height of atomic oven, which affect the determination, have been optimized respectively as 0.05%, 400 and 800 mL x min(-1), 20 mA and 6 mm. Under the optimum conditions, there is a linear relationship between the fluorescence intensity and the mercury concentration with correlation coefficient of 0.9999, while the detection limit is 0.021 microg x L(-1). Trace mercury in the standard reference substance peach leaf (GBW08501, produced by the Environmental Science Committee of Chinese Scientific Institute) was also determinated in this way and the results of six times were in good agreement with the certified value, with a variation coefficient not more than 0.34%. This method is simple, rapid, sensitive, convinent and accurate, so it can be successfully used for the determination of trace mercury in traditional Chinese medi-

Chromatography, High Pressure Liquid↗
PubMed2005

Characterization of hypoglycemiant plants by total reflection X-ray fluorescence spectrometry.

In this work, synchrotron radiation total reflection X-ray fluorescence spectrometry (SRTXRF) was used to determine trace elements in eight hypoglycemiant plants (Trigonella foenum graecum, Panax ginseng, Pfaffia paniculata, Myrcia speciosa, Zea mays, Harpagophytum procumbens, Syzygium jambolona, and Bauhinia forficate). The elements P, K, Ca, Ti, Mn, Fe, Cu, Zn, Rb, and Sr were detected in all medicinal plants investigated, whereas Si, S, Sc, V, Cr, Co, Ni, Se, Nb, Mo, Sn, Sb, Ba, Hg, and Pb were detected only in some of the samples. The concentration of elements in hypoglycemiant plants varied from 0.15 microg/g of Co to 3.0 x 10(4) microg/g of K and the mean of experimental limit of detection for these elements were 0.14 and 3.6 microg/g, respectively.

Diabetes Mellitus, Type 2↗
PubMed2005

[Determination of trace arsenic and selenium in jellyfish by microwave digestion-hydride generation-atomic fluorescence spectrometry].

A method of hydride generation-atomic fluorescence spectrometry was proposed in the present paper for the determination of trace arsenic and selenium in jellyfish. The samples were treated by the combination of microwave digestion and lyophilization. The optimal conditions for treating and analyzing samples were established. The problem of the effect of the superfluous acid in the digesting solution on the results was solved, and the influence of coexisting foreign ions on the determination of arsenic and selenium was investigated. The accuracy of the method was confirmed by the method of standard additions. This method proved to be simple, rapid and repeatable, and is suitable for the analysis of biologic samples containing water.

Animals↗
PubMed1983

The use of ion-exchange filters for the determination of iodide in milk by X-ray fluorescence spectrometry.

An X-ray fluorescence spectrometric method has been developed for the quantitative determination of iodide in milk which makes use of anion-exchange filters for the isolation and concentration of iodide from the liquid samples. The milk is deproteinized with trichloroacetic acid, filtered then passed through an anion-exchange paper disc to remove the iodide. The disc is removed, dried then analysed by X-ray fluorescence spectrometry. Six samples, consisting of homogenized, 2% fat and skim milk were analysed and found to contain between 0.37-0.67 ppm iodide. Detection limits in milk were estimated to be 0.05 ppm.

Animals↗
PubMed1999

[Atomic/ionic fluorescence in microwave plasma torch discharge excited by high current microsecond pulsed hollow cathode lamp-europium atomic/ionic fluorescence spectrometry].

Eu atomic and ionic fluorescence spectrometry in microwave plasma torch discharge excited by high current microsecond pulsed hollow cathode lamp (HCMP HCL-MPT AFS/IFS) was studied. Operating conditions were optimized. The best detection limits for AFS and IFS obtained with a desolvated ultrasonic nebulization system were 42.0 ng/mL for Eu I 462.7 nm and 21.8 ng/mL for Eu II 381.97 nm, respectively, both were better than those given by the instruction manual of a Baird ICP AFS-2000 spectrometer using pneumatic concentric nebulizer with desolvation for AFS, but were significantly higher than those obtained by using the Baird spectrometer with a mini-monochromator and a ultrasonic nebulzer system.

English Abstract↗
PubMed1998

[Analysis of trace Pd in marine deposit samples using laser-excited atomic fluorescence spectrometry].

Laser-excited atomic fluorescence spectrometry and its experimental set-up are introduced in this paper. Using this spectrometer, Pd contents in 36 marine deposit samples of the East-sea continental shelf were analyzed. The results show that the detection limit and the precision of this spectrometer are 50 pg/mL and 6% respectively, and the measurements of Pd in marine deposit samples are reliable.

English Abstract↗
PubMed1999

[Determination of inorganic arsenic in food by hybrid generation-atomic fluorescence spectrometry (HG-AFS)].

A hybrid generation-atomic fluorescence spectrometry method (HG-AFS) was developed for determining total inorganic arsenic, As(III) and As(V). The inorganic arsenic in food extracted by 6 mol/L HCl and total inorganic arsenic could be determined in 2 mol/L HCl. As(III) was determined selectively in mixtures of As(III) with As(V) by the different acidities of As(III) and As(V) at hybrid generation. The linear correlation ranges of total inorganic arsenic and As(III) are 0-400 micrograms/ml and 0-300 micrograms/ml respectively. The RSD of inorganic arsenic is 1.93% and As(III) is 2.49%. The detection limits are 1.6 and 1.1 micrograms/ml for inorganic arsenic and As(III) respectively. There is no interference in the determination of general food samples.

Arsenic↗