Fluorescence spectrometry preparation

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. 

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. 

Techniques for analysis of different mercury species in biological samples and abiotic materials include atomic absorption, cold vapor atomic fluorescence spectrometry, gas-liquid chromatography with electron capture detection, and inductively coupled plasma mass spectrometry (Lansens etal. 1991 Schintu etal. 1992 Porcella etal. 1995). Methylmercury concentrations in marine biological tissues are detected at concentrations as low as 10 pg Hg/kg tissue using graphite furnace sample preparation techniques and atomic absorption spectrometry (Schintu et al. 1992). 

The amount of Fe203 supported on zeolite and the Si02/Al203 molar ratio (S/A ratio) of the prepared catalysts were obtained by X-ray fluorescence spectrometry (Rigaku Denki, 3080E). Specific surface areas were measured by BET method (Yuasa, QUANTACHROME). Unit cell dimension (U.D.) was determined from the diffraction angles of (642) with an X-ray powder diffractometer (Rigaku Denki, RU-200). Silicon was used as the reference. 

The use of second-derivative synchronous fluorescence spectrometry was reported by Ruiz et al. [42] to develop a simple, rapid and sensitive fluorimetric method for the determination of binary mixtures of the nonsteroidal antiinflammatory drugs flufenamic (FFA), meclofenamic (MCFA) and mefenamic (MFA) acids in serum and in pharmaceutical formulations. The method is based on the intrinsic fluorescence of these compounds in chloroform. A differential wavelength of 105 nm was used for the resolution of FFA-MFA and MFA-MCFA mixtures, whereas the FFA-MCFA mixture was determined at a differential wavelength of 40 nm. Serum samples were treated with trichloroacetic acid to remove the proteins, and the analytes were extracted in chloroform prior to determination. Pharmaceutical preparations were analyzed without prior separation steps. 

Whatever the analytical method and the determinand may be, the greatest care should be devoted to the proper selection and use of internal standards, careful preparation of blanks and adequate calibration to avoid serious mistakes. Today the Antarctic investigator has access to a multitude of analytical techniques, the scope, detection power and robustness of which were simply unthinkable only two decades ago. For chemical elements they encompass Atomic Absorption Spectrometry (AAS) [with Flame (F) and Electrothermal Atomization (ETA) and Hydride or Cold Vapor (HG or CV) generation]. Atomic Emission Spectrometry (AES) [with Inductively Coupled Plasma (ICP), Spark (S), Flame (F) and Glow Discharge/Hollow Cathode (HC/GD) emission sources], Atomic Fluorescence Spectrometry (AFS) [with HC/GD, Electrodeless Discharge (ED) and Laser Excitation (LE) sources and with the possibility of resorting to the important Isotope... 

Many researchers have attempted to determine mercury levels in the blood, urine, tissues, and hair of humans and animals. Most methods have used atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), or neutron activation analysis (NAA). In addition, methods based on mass spectrometry (MS), spectrophotometry, and anodic stripping voltametry (ASV) have also been tested. Of the available methods, cold vapor (CV) AAS is the most widely used. In most methods, mercury in the sample is reduced to the elemental state. Some methods require predigestion of the sample prior to reduction. At all phases of sample preparation and analysis, the possibility of contamination from mercury found naturally in the environment must be considered. Rigorous standards to prevent mercury contamination must be followed. Table 6-1 presents details of selected methods used to determine mercury in biological samples. Methods have been developed for the analysis of mercury in breath samples. These are based on AAS with either flameless (NIOSH 1994) or cold vapor release of the sample to the detection chamber (Rathje et al. 1974). Flameless AAS is the NIOSH-recommended method of determining levels of mercury in expired air (NIOSH 1994). No other current methods for analyzing breath were located. 

Nickel and vanadium along with iron and sodium (from the brine) are the major metallic constituents of crude oil. These metals can be determined by atomic absorption spectrophotometric methods (ASTM D-5863, IP 285, IP 288, IP 465), wavelength-dispersive X-ray fluorescence spectrometry (IP 433), and inductively coupled plasma emission spectrometry (ICPES). Several other analytical methods are available for the routine determination of trace elements in crude oU, some of which allow direct aspiration of the samples (diluted in a solvent) instead of time-consuming sample preparation procedures such as wet ashing (acid decomposition) or flame or dry ashing (removal of volatile/combustible constituents) (ASTM D-5863). Among the techniques used for trace element determinations are conductivity (IP 265), flameless and flame atomic absorption (AA) spectropho-... 

The homogeneity of the sample is very important for successful x-ray fluorescence spectrometry. Hence, the preparation of solid samples for this analysis by melting. The samples analyzed by crude oil chemist are, in most cases, liquids or... 

X-ray fluorescence spectrometry, gas chromatography and neutron activation analysis (NAA). An older book edited by Hofstader, Milner and Runnels on Analysis of Petroleum for Trace Metals (1976), includes one chapter each on principles of trace analysis and techniques of trace analysis and others devoted to specific elements in petroleum products. Markert (1996) presents a fresh approach to sampling, sample preparation, instrumental analysis, data handling and interpretation. The Handbook on Metals in Clinical and Analytical Chemistry, edited by Seiler,... 

ScHMELiNG M and Klockow D (1997) Sample collection and preparation for analysis of airborne particulate matter by total reflection X-ray fluorescence spectrometry. Anal Chim Acta 346 121-126. 

Human biological materials to be investigated include (a) hard calcified tissues, e.g. bone, teeth, other calcified formations (b) semi-hard tissue, e.g. hair, nails (c) soft body tissues and (d) various biological fluids and secretions in the human body. The treatment of each of these materials varies from one material to another and, as stated earlier, is often determined by the instrumental method to be employed for measuring the analytical signal, the elements to be determined and the concentration levels at which these are present. For the purposes of this discussion, it shall be generally assumed that the analytical techniques employed include atomic absorption spectrometry both with (F-AAS) as well as with a furnace (GF-AAS), neutron activation analysis (NAA), flame emission spectrometry (FES) voltammetric methods and the three inductively coupled plasma spec-trometric methods viz. ICP-atomic emission spectrometry, ICP-mass spectrometry and ICP-atomic fluorescence spectrometry. The sample preparation of biological methods for all ICP techniques is usually similar (Guo, 1989). 

With proper correction for matrix effects. X-ray fluorescence spectrometry is one of the most powerful tools available for the rapid quantitative determination of all but the lightest elements in complex samples. For example. Rose, Bornhorst. and Sivonon have demonstrated that twenty-two elements can bo determined in powdered rock samples with a commercial EDXRF spectrometer in about 2 hours (1 hour instrument time), including grinding and pellet preparation. Relative standard deviations for the method are better than 1% for major elements and better than y/o for trace elements. Accuracy and detection limits as determined by comparison to results from international standard rock samples were comparable or better than other published procedures. For an e.xcellent overview of XRF analysis of geological materials, see the paper by Anzelmo and Lindsay. ... 

A bottle of tonic water is to be analyzed for its quinine content by fluorescence spectrometry, with excitation at 350 nm and emission intensity measured at 430 nm. One milliliter of tonic water is diluted to 100 ml with 0.05 M HaS04 its emission Intensity is 8.44 (arbitrary units). A series of quinine standards, in 0.05 M HaSO, is prepared and the emission intensities measured (in parentheses) 100 ppm (293 units), 10.0 ppm (52.3), 1.00 ppm (12.0), 0.100 ppm... 

X-ray fluorescence spectrometry has been established as the prime analytical technique for cement works control since the early 1970s. During the 20 years that have followed. X-ray spectrometers have been incorporated into complete control systems, which include sample transport from the sampling points to the works laboratory, sample preparation and transport into the spectrometer, analysis, calculation of control moduli, and generation and feedback of control signals to the plant to modify the process when necessary. 

X-ray fluorescence spectrometry This technique is extensively used in the industrial analysis of plastics for routine determination of traces of metals and nonmetal elements, i.e., iron, cobalt, nickel, chromium, copper, zinc, chlorine, bromine, titanium, aluminum, sodium, potassium, calcium, magnesium, vanadium, cadmium, and selenium. The main advantages are simple sample preparation and independence on the element state in chemical combination. 

X-ray fluorescence spectrometry is a technique for rapid simultaneous multielement analysis that exceeds the capabilities of normal clinical or toxicological laboratories. However, time-consuming sample preparation for trace elements and detection limits diminishes the usefulness to arsenic [157-159]. 

Basically, the I content in the purified iodine fraction can be measured by different techniques. Due to the low specific activity of this long-lived radionuclide, direct 3 , y and X-ray measurement techniques show only a moderate detection capability better detection limits can be obtained by determination of the I mass present in the sample. Here, laser-induced fluorescence spectrometry offers in principle favorable results however, when this technique is applied, the difficulties associated with the preparation of the h chemical species at very low iodine concentrations have to be taken into consideration. The most sensitive I determination technique is neutron activation analysis, which leads to the formation of the... 

X-ray fluorescence spectrometry has several advantages over other methods. The analysis is non-destructive, specimen preparation is simple, measurement time is usually less than for other methods and x-rays interact with elements as such, ie. the intensity measurement of a constituent element is independent of its state of chemical combination. However, the technique does have some drawbacks, eg. absorption effects of other elements present, for instance, the carbon and hydrogen of the polyethylene matrix and excitation of one element by x-rays from another, eg. cadmium and selenium mutually affect one another. 

The complex of the following destmctive and nondestmctive analytical methods was used for studying the composition of sponges inductively coupled plasma mass-spectrometry (ICP-MS), X-ray fluorescence (XRF), electron probe microanalysis (EPMA), and atomic absorption spectrometry (AAS). Techniques of sample preparation were developed for each method and their metrological characteristics were defined. Relative standard deviations for all the elements did not exceed 0.25 within detection limit. The accuracy of techniques elaborated was checked with the method of additions and control methods of analysis. 

Prange et al. [809,810] carried out multielement determinations of the stated dissolved heavy metals in Baltic seawater by total reflection X-ray fluorescence (TXRF) spectrometry. The metals were separated by chelation adsorption of the metal complexes on lipophilised silica-gel carrier and subsequent elution of the chelates by a chloroform/methanol mixture. Trace element loss or contamination could be controlled because of the relatively simple sample preparation. Aliquots of the eluate were then dispersed in highly polished quartz sample carriers and evaporated to thin films for spectrometric measurements. Recoveries (see Table 5.10), detection limits, and reproducibilities of the method for several metals were satisfactory. 

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