![]() ![]() The technique is extremely sensitive as it allows one to detect a few μg/ml concentrations of the analyte. Since the analyte is atomized and retained within a small volume furnace, this procures a dense atom population. This atomizer also produces temperatures up to 3000 K which allows to form an atomic vapor of refractory elements such as aluminum and chromium. ![]() With this atomizer, 10–50 μl of test solution is dried, organic material is destroyed, and the analyte ions dissociated from anions for reduction to ground state atoms. A programmed sequence of the furnace temperature is used in electrically heated graphite tube. ![]() Most systems use a graphite tube which is heated electrical energy, a technique called graphite furnace atomization, although other materials are sometimes employed. Atomization can be reached to 100% and the devices can also generate the sample as a pulse flow rather than the continuous flow. Devices are being developed to overcome these limitations of the typical nebulizer. The typical pneumatic nebulizer for sample introduction is insufficient, and although elements such as Na and K can be determined in biological samples by flame AES, flame atomization is more suitable for AAS and AFS. AAS measurements can detect concentrations at approximately 1 μg/ml (ppm) or more. Flame atomizers contain a pneumatic nebulizer, an expansion chamber, and an air-acetylene laminar flame with a 10 cm path length. The flame provides for easy and fast measurements with few interferences and is preferred at any appropriate concentration for the analyte. ![]() Many atomizers utilized for AFS are similar to those used for AAS and AES. The atomizers most commonly used in these techniques are flames and electrothermal atomizers. The atomizer is any device which will produce ground state atoms as a vapor into the light path. It follows from Eqs. 1– 3 that the wavelengths of the absorbed or emitted light are unique to a given element. The high temperature inductively coupled plasma has been successfully used as an effective ion source for a mass spectroscopy, the type of method of inductively coupled plasma-mass spectroscopy (ICP-MS) is routinely used for measurements of trace elements in clinical and biological samples. the wavelength is characteristic of the atom (element) from which it originated while the intensity of the emission is related to concentration of the atoms in the sample. This process is called X-ray fluorescence (XRF). The transition is created by an emission of an X-Ray photon. The forming inner orbital vacancy can be filled with an outer shell electron. When high-energy photons strike to a massive particle, it can excite an inner shell electron of the atom. Some of the radiant energy absorbed by ground state atoms can be emitted as light as the atom returns to the ground state i.e. As Figure 1b shows, some of this energy is emitted as light, which can be measured with a detector, this is AES. As these electrons return to the more stable ground state, energy is lost. Under appropriate circumstances, outer shell electrons of vaporized atoms may be excited by heating. As a result, the amount of light transmitted from the system to detector will be reduced, this is understood as AAS ( Figure 1a). When light of a specific wavelength enters an analytical system, outer shell electrons of the corresponding atoms will be excited as energy is absorbed. And a specific transition, ΔE, is associated with a unique wavelength. ![]()
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