Fluorescence spectrometry

The application of fluorescence spectrometry presupposes that the substances to be analyzed display fluorescence which can be measured, or can be made fluorescent by such measures as producing derivatives. Precisely these processes of producing derivatives are becoming increasingly important, as in many cases they make it possible to take advantage of the benefits of fluorimetry and its low detection limits. 

The four main components of a fluorescence spectrophotometer are as follows  

The sources of excitation frequently employed in spectrophotometers for measuring fluorescence are gas discharge lamps. These have the advantage of a high radiation intensity and of emitting over a wide range of wavelength from approximately 200 nm to above 1000 nm. The most important types are 

The wavelengths in fluorescence spectrophotometers are generally selected with the aid of monochromators line emitters are predominantly used in simple filter fluorimeters, but continuum radiators can also be employed in conjunction with cut-off filters. Fig. 32 clearly shows the basic principle 

In contrast to cuvettes for measuring absorption, the standards of measuring cuvette accuracy required in fluorimetry are not so high, as only a 

The various techniques involved in fluorescence spectrometry are of great importance in analytical studies of phosphoproteins, and in DNA technology. In the latter case they are employed to detect or estimate the fractions separated by gel electrophoresis and stained with fluorescent dyes. These techniques have become invaluable for DNA sequencing (Section 14.3). 

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Elemental Analysis Atomic absorption spectrometry X-Ray fluorescence spectrometry Plasma emission spectrometry... 

Chemical analysis of the metal can serve various purposes. For the determination of the metal-alloy composition, a variety of techniques has been used. In the past, wet-chemical analysis was often employed, but the significant size of the sample needed was a primary drawback. Nondestmctive, energy-dispersive x-ray fluorescence spectrometry is often used when no high precision is needed. However, this technique only allows a surface analysis, and significant surface phenomena such as preferential enrichments and depletions, which often occur in objects having a burial history, can cause serious errors. For more precise quantitative analyses samples have to be removed from below the surface to be analyzed by means of atomic absorption (82), spectrographic techniques (78,83), etc. 

Elemental chemical analysis provides information regarding the formulation and coloring oxides of glazes and glasses. Energy-dispersive x-ray fluorescence spectrometry is very convenient. However, using this technique the analysis for elements of low atomic numbers is quite difficult, even when vacuum or helium paths are used. The electron-beam microprobe has proven to be an extremely useful tool for this purpose (106). Emission spectroscopy and activation analysis have also been appHed successfully in these studies (101). 

AH of these properties of x-rays are used to measure various properties of materials. X-ray appHcations can be placed into three categories based on which of the above phenomena are exploited. These categories are x-ray radiography, x-ray fluorescence spectrometry, and x-ray diffraction. 

X-ray fluorescence spectrometry consists of the measurement of the incoherent scattering of x-rays (phenomenon 3 above). It is used primarily to determine the elemental composition of a sample. 

X-ray fluorescence spectrometry is a technique for measuring the elemental composition of samples. The basis of the technique is the relationship between the wavelength or energy of the emitted incoherently scattered x-ray photons and the atomic number of the element. This relationship estabHshed in 1913 is... 

Zinc smelters use x-ray fluorescence spectrometry to analyze for zinc and many other metals in concentrates, calcines, residues, and trace elements precipitated from solution, such as arsenic, antimony, selenium, tellurium, and tin. X-ray analysis is also used for quaUtative and semiquantitative analysis. Electrolytic smelters rely heavily on AAS and polarography for solutions, residues, and environmental samples. 

The determination of cesium in minerals can be accompHshed by x-ray fluorescence spectrometry or for low ranges associated with geochemical exploration, by atomic absorption, using comparative standards. For low levels of cesium in medical research, the proton induced x-ray emission technique has been developed (40). 

GENERALIZED DESCRIPTION OF POWDER AND POWDER SLURRY-LIKE MATERIALS IN X-RAY FLUORESCENCE SPECTROMETRY... 

The very low Hg concentration levels in ice core of remote glaciers require an ultra-sensitive analytical technique as well as a contamination-free sample preparation methodology. The potential of two analytical techniques for Hg determination - cold vapour inductively coupled plasma mass spectrometry (CV ICP-SFMS) and atomic fluorescence spectrometry (AFS) with gold amalgamation was studied. 

DETERMINATION OF ARSENIC (As) IN NATURAL AND WASTE WATER USING HIDRIDE GENERATION ATOMIC FLUORESCENCE SPECTROMETRY... 

Arsenic is both toxic and cai cinogenic element. It is necessary to have a fast, reliable and accurate method for determination of ai senic in water. The hydride-generation atomic fluorescence spectrometry (HG AFS) is one of the simple and sensitive techniques for the determination of this element in various types of waters. 

In this work, atomic fluorescence spectrometry (AFS) with vapor generation is used for Hg determination in different types of waters (drinking, surface, underground, industrial waste). 

Among the vitally necessary elements the most important are Fe, Zn, K, Ca, S. Some of them are imbedded in the stmcture of many ferments, amino acids, intracellular liquid, the other define transmembrane electrical potential. In the paper the contents of elements in whole blood and semm by X-ray fluorescence spectrometry is studied. 

PL is often referred to as fluorescence spectrometry or fluorometry, especially when applied to molecular systems. Uses for PL are found in many fields, including... 

Tetra-alkyl lead compounds in air Personal monitoring with atomic absorption analysis or electrothermal atomization or X-ray fluorescence spectrometry or on-site colorimetry 9... 

MDHS 7 Lead and inorganic compounds of lead in air (X-ray fluorescence spectrometry)... 

FCC feedstocks contain sulfur in the form of organic-sulfur compounds such as mercaptan, sulfide, and thiophenes. Frequently, as the residue content of crude oil increases, so does the sulfur content (Table 2-5). Total sulfur in FCC feed is determined by the wavelength dispersive x-ray fluorescence spectrometry method (ASTM D-2622), The results are expressed as elemental sulfur. 

Several books and symposium proceedings on luminescence standards and measurements have been published in the last several years, including "Advances in Standards and Methodology in Spectrophotometry" (i), "Measurement of Fhotolumlnescence" (2), "Standards in Fluorescence Spectrometry" (J), and "Modern Fluorescence Spectroscopy" (Volumes 1-4) (4). These books, the references within them, and the classic in the field, "Photoluminescence of Solutions" by C.A. Parker (5), provide the researcher with extensive information about luminescence standards and measurements. 

The dosimeter can detect various polynuclear aromatics at the pph level after 1 hour of exposure. It has been shown that the RTF of aza-arenes can he enhanced by using mercury(II) chloride as a heavy atom (21). Also, sensitized fluorescence spectrometry with a solid organic substrate can be used to detect trace amounts of polynuclear aromatic compounds (22). 

Nineteen bone samples were prepared for analysis of the trace elements strontium (Sr), rubidium (Rb), and zinc (Zn). The outer surface of each bone was removed with an aluminum oxide sanding wheel attached to a Dremel tool and the bone was soaked overnight in a weak acetic acid solution (Krueger and Sullivan 1984, Price et al. 1992). After rinsing to neutrality, the bone was dried then crushed in a mill. Bone powder was dry ashed in a muffle furnace at 700°C for 18 hours. Bone ash was pressed into pellets for analysis by x-ray fluorescence spectrometry. Analyses were carried out in the Department of Geology, University of Calgary. 

Montaser, A., Goode, S. R., and Crouch, S. R. "Graphite Braid Atomizer for Atomic Absorption and Atomic Fluorescence Spectrometry . Anal. Chem. (1974), 46, 599-601. 

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