Atomic Fluorescence Spectrometer (AFS)
Fundamentals of atomic fluorescence spectrometry Atomic fluorescence spectroscopy (AFS) is a spectroscopic analysis technique between atomic emission spectrometry and atomic absorption spectrometry. The basic principle of atomic fluorescence spectrometry (AFS) is to measure the atomic vapors of the elements to be detected under the excitation of radiant energy Fluorescence emission intensity to determine the content of the element to be measured. Vapor Generation - Atomic Fluorescence Spectrometry (VG-AFS) and Cold Vapor Atomic Fluorescence Spectrometry (CV-AFS) are a new ... More >>
Fundamentals of atomic fluorescence spectroscopy
Atomic fluorescence spectroscopy (AFS) is a spectroscopic analysis technique between atomic emission spectrometry and atomic absorption spectrometry. Its basic principle is to determine the emission intensity of the atomic vapors of the element to be detected under the excitation of radiant energy The method of measuring the content of elements.
VG-AFS and CV-AFS are a new combined analytical technique and the most practical analytical technique in the field of atomic fluorescence spectrometry. It combines the features of vapor-based injection with non-dispersive atomic fluorescence spectrometry. Vapor generation injection technology can be under normal temperature and pressure sample solution with strong reducing agent into a gaseous form of covalent hydride, simplex gaseous mercury atoms or volatile compounds, without special high temperature, you can instantaneous atoms At present, the measurable elements have been expanded to 11 species (As, Sb, Bi, Se, Te, Pb, Sn, Ge, Hg, Zn and Cd). Among them, 8 elements of As, Sb, Bi, Se, Te, Pb, Sn and Ge can form gaseous hydride, Cd and Zn form gaseous components, and Hg forms atomic vapor.
The use of steam injection technology allows the element to be measured with a large number of matrix phase separation, thus greatly reducing the matrix interference. And because it is the gas injection, which greatly improves the efficiency of injection; the carrier gas (Ar) will generate hydride or volatile compounds into argon argon flame atomization, and argon hydrogen flame in atomic fluorescence spectrometry has a very High fluorescence efficiency and low background. Moreover, the main resonance fluorescence spectra of all the tested elements are in the range of 190-310 nm, which is exactly the band with the best sensitivity of a non-dispersive atomic fluorescence photodiode photodiode.
Atomic Fluorescence Spectroscopy Classification
Points from the optical system, AFS can be divided into two types of dispersion and non-dispersive. The structure of the two types of instruments is basically the same, with the difference that the non-dispersive AFS does not have a monochromator.
Non-dispersive AFS lighting solid angle, spectrum pass bandwidth, light gathering ability, fluorescence signal intensity, the instrument structure is simple, easy to operate. The disadvantage is the impact of scattered light. Because there is no monochromator, in order to prevent the impact of laboratory light, the general use of the working wavelength of 160nm-320nm blind photomultiplier tubes. Dispersion type AFS monochromators are used to select the desired fluorescence line and to exclude interference from other lines. Dispersion system is not demanding on the resolution, but requires a greater concentration of light, the commonly used dispersion element grating. Currently, commercialized AFS instruments are predominantly non-dispersive.
The main advantages of atomic fluorescence spectrometry
(1) higher sensitivity and lower detection limit, the element detection limit at ppb-ppt level;
(2) Since the intensity of atomic fluorescence is proportional to the intensity of excitation light source, the new detection limit of high intensity excitation light source can be further reduced to provide a promising way to improve the detection limit of atomic fluorescence spectrometry.
(3) less interference, spectral line is relatively simple, non-dispersive AFS structure is simple, cheap;
(4) Analytical calibration curve linear range, up to 3 to 5 orders of magnitude;
(5) As the atomic fluorescence is emitted to all directions of the space, and the spectral lines are in the ultraviolet region, using a solar-blind photomultiplier tube as a detector, it is relatively easy to make a multi-channel instrument so that the simultaneous determination of multiple elements can be realized.
Although the AFS method has many advantages, due to the fluorescence quenching effect, there may be some interference in the determination of a sample containing a matrix of a volatile substance. In addition, scattered light interference is also a problem to be solved in AFS analysis.
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