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At least 37 records · Page 2Linked to original sources
PubMed2004

Simultaneous determination of twelve inorganic and organic arsenic compounds by liquid chromatography-ultraviolet irradiation-hydride generation atomic fluorescence spectrometry.

A coupling between column liquid chromatography (LC) and atomic fluorescence spectrometry was developed for arsenic speciation. After separation, the compounds are oxidised on-line by UV irradiation, volatilised by hydride-generation and carried to the detector by a stream of argon. A combination of anion-exchange and hydrophobic interactions in a single column (Dionex AS7) was found suitable for the simultaneous separation of organic and inorganic species. Twelve compounds (arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine, trimethylarsine oxide, tetramethylarsonium ion and four arsenosugars) were separated using an acetate buffer and a nitric acid solution as mobile phases. Limits of detection are 4-22 pg. The technique was applied to three marine samples. Arsenobetaine was detected as the main species in all samples, with concentrations varying from 59 to 1947 ng(As) g(-1) of fresh mass.

Animals↗
PubMed2006

[Analysis of films by X-ray fluorescence spectrometry].

As a quantitative method of film sample, the X-ray fluorescence (XRF) technique has been used extensively because it is non-destructive, fast and accurate. Moreover it could determine the concentration and thickness of film sample simultaneously. A review was given of the study on the quantitative method of films by X-ray fluorescence spectrometry, in which the theoretical calculation of fluorescence intensity, the matrix effects and the methods for their correction, the sources of errors, the software for quantitative analysis, and the application of the method were summarized and discussed. New development and application of films characterization by X-ray fluorescence spectrometry were also expected. Because the similar calibration specimen for film sample is difficult to prepare and the fundamental parameter method could quantitatively analyze film samples even if only the pure element specimen is employed, the fundamental parameter method is studied extensively. The fundamental parameter method was introduced mainly in the present article, including the fundamental parameter equations to calculate the theoretical intensity of fluorescence, the source of error in calculation, and the software for analysis.

English Abstract↗
PubMed1975

Determination of toxic metals in blood by x-ray fluorescence spectrometry.

An application of X-ray fluorescence spectrometry for the analysis of various toxic metals (lead, cadmium, manganese, chromium, nickel, vanadium) in whole blood was studied, and two techniques for sample preparation (vacuum drying and nitric acid combustion) were compared. The acid combustion method appeared to be superior on the basis of the accuracy and precision of the determinations. The tungsten-target X-ray tube was suitable for determining manganese, nickel, and vanadium, the lowest limits of detection being 0.021 mug/ml, 0.035 mug/ml and 0.017 mug/ml, respectively, and the precisions being between 4.25 and 6.92%. The sensitivity and reproducibility for lead, cadmium, and chromium were unsatisfactory. A comparison between the recoveries of X-ray fluorescence and atomic absorption analyses demonstrated that the X-ray method is suitable for determining manganese, vandium, nickel, cadmium, and lead. The poor sensitivity of the X-ray method, however, restricts its practical use. For vandium the results obtained by X-ray fluorescence were superior to those measured by a colorimetric method. No significant differences were observed between the results of single component and multicomponent analyses at the metal concentrations usual in physiological and toxicological cases.

Animals↗
PubMed2003

Ultratrace determination of mercury in water following EN and EPA standards using atomic fluorescence spectrometry.

Chemical vapour generation has been used in combination with atomic fluorescence spectrometry to determine mercury at ultratrace concentrations down to 0.1 ng L(-1). A time-based injection of 1 mL of solution for measurement was sufficient to generate a steady-state detector response in the direct mode of measurement. The detection limit calculated from a ten-point calibration curve according to DIN 32645 was 0.26 ng L(-1). Instrument noise is limited by reflected radiation from the light source rather than by the dark current of the photomultiplier. The detection limit is directly influenced by the reagent blank which was 2 ng L(-1) in the experiments described. Focusing by amalgamation and subsequent thermal desorption generates a detector response which is about eight times higher in peak intensity and about twice as large in integrated intensity. The detection limit under these conditions is 0.09 ng L(-1) which can be further improved by preconcentration of larger volumes of solution for measurement. The cycle time for one individual reading is about 40 s without amalgamation and 125 s with amalgamation. The linear dynamic range of the system is five orders of magnitude with a single photomultiplier gain setting. The carry-over is less than 0.3% in direct measurement mode. Reference water samples and a surface water containing approximately 5 ng L(-1) were used to prove the validity of the method for real samples. Good accuracy and recoveries of 103% were calculated using the fast direct determination technique.

Environmental Monitoring↗
PubMed1992

Acousto-optic tunable filter as a polychromator and its application in multidimensional fluorescence spectrometry.

Acousto-optic tunable filter (AOTF) is an electronically driven dispersive device which operates on the principle of acousto-optic interaction in an anisotropic medium. Incident white light will be diffracted by the AOTF into a specific wavelength when a specific rf is applied to it. The diffracted light needs not be a monochromatic light. Multiwavelength light can be diffracted from the AOTF when several rf signals are simultaneously applied into the filter. Compared to conventional polychromators, advantages of this electronic AOTF polychromator include its ability to individually amplitude-modulate each wavelength of the diffracted multiwavelength light at different frequency. This is accomplished by individually and sinusoidally modulating each applied rf signal at the desired frequency. This feature makes it possible to develop a novel AOTF-based multidimensional fluorimeter in which the sample was simultaneously excited by two different wavelengths (514.5 and 488.0 nm) whose amplitudes were sinusoidally modulated at two different frequencies (100 and 66 Hz). Multicomponent samples, e.g., mixtures of rhodamine 6G and rhodamine B, were successfully analyzed using this novel fluorimeter and the developed data analysis.

Filtration↗