Fluorescence analytical spectrometry

Tsolakidou, A. and Kilikoglou, V. (2002). Comparative analysis of ancient ceramics by neutron activation analysis, inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry, and X-ray fluorescence. Analytical and... 

Fluorescence detection is sensitive to naturally fluorescent analytes or to fluorescent derivatives. Amperometric detection is sensitive to analytes that can be oxidized or reduced at an electrode (Figure 26-29). Conductivity detection with ion-exchange suppression of the background electrolyte (as in Figure 26-4) can detect small analyte ions at 1-10 ng/mL. Electrospray mass spectrometry (Figure 22-18) provides low detection limits and gives qualitative information about analytes.33... 

Modern analytical chemistry, especially for trace analysis, is mainly dependent on physical techniques (Broekaert and Tdig, 1987). For inorganic trace element analysis several different methods exist such as activation analysis, x-ray fluorescence, mass spectrometry, electrochemical methods and the different techniques in atomic spectrometry. There is no universal analytical method which is able to solve all the analytical problems in the different fields of application. 

As of this time, atomic fluorescence flame spectrometry has not been reported as having been applied to any specific analytical problem. One can readily ascertain that it should be apphcable in many areas where atomic absorption is commonly used. In addition, for the analysis of multiple elements in a single sample, for example cations in water, atomic fluorescence flame spectrometry incorporating a xenon arc source should have major advantages. 

The composition of a specimen is often determined by X-ray fluorescence (XRF) spectrometry, which performs rapid, qualitative, and semiquantitative determination of major and minor surface elements. Although both wavelength- and energy-dispersive (ED) analyzers can be used to detect the secondary X-rays, ED-XRE instruments are more common for the compositional determination of archaeological and conservation samples. Detection limits of 0.1% are expected therefore, the analysis is difficult for trace elements. A laboratory XRE system, commonly used to quantify elements in metal and ceramic samples (noninsulating materials need to be coated), is considered to be an indispensable tool. As with all these surface analytical techniques, care has to be taken that weathering products (thick patinas or corrosion crusts) do not obscure bulk analysis results. Thus, samples are normally prepared to provide a flat polished surface to produce quantitative results. 

A wide range of analytical techniques is necessary to provide an unambiguous identification of pigments in a sample. Elemental techniques are often used, such as scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), X-ray fluorescence (XRE) spectrometry, scanning electron microprobe analysis (EPMA), X-ray photoelectron spectroscopy (XPS), particle-induced X-ray emission (PDCE), neutron activation analysis (NAA), atomic absorption spectrometry (AAS), inductively coupled... 

Butcher DJ, Dougherty JP, Preli FR, et al. (1988) Laser excited atomic fluorescence spectrometry in flames, plasmas and electrothermal atomizers. Journal of Analytical Spectrometry 3 1059-1078. 

Modern analytical such as infrared (IR) spectroscopy, liquid chromatography (LC), and gas-liquid chromatography (GLC) are in use for the identification of organic components, whilst the mineral constituents can be estimated by using X-ray fluorescence (XRF) spectrometry. X-ray diffraction (XRD), atomic absorption spectrometry (AAS), or inductively coupled plasma (ICP) atomic emission spectrometry (AES). 

Numerous methods have been pubUshed for the determination of trace amounts of tellurium (33—42). Instmmental analytical methods (qv) used to determine trace amounts of tellurium include atomic absorption spectrometry, flame, graphite furnace, and hydride generation inductively coupled argon plasma optical emission spectrometry inductively coupled plasma mass spectrometry neutron activation analysis and spectrophotometry (see Mass spectrometry Spectroscopy, optical). Other instmmental methods include polarography, potentiometry, emission spectroscopy, x-ray diffraction, and x-ray fluorescence. 

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. 

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. 

The active state of luminescence spectrometry today may be judged ly an examination of the 1988 issue of Fundamental Reviews of Analytical Chemistry (78), which divides its report titled Molecular Fluorescence, Phosphorescence, and Chemiluminescence Spectrometry into about 27 specialized topical areas, depending on how you choose to count all the subdivisions. This profusion of luminescence topics in Fundamental Reviews is just the tip of the iceberg, because it omits all publications not primarily concerned with analytical applications. Fundamental Reviews does, however, represent a good cross-section of the available techniques because nearly every method for using luminescence in scientific studies eventually finds a use in some form of chemical analysis. Since it would be impossible to mention here all of the current important applications and developments in the entire universe of luminescence, this report continues with a look at progress in a few current areas that seem significant to the author for their potential impact on future work. 

The most significant differences (i.e. independence) in the analytical methods are provided in the final chromatographic separation and detection step using GC/ MS and LC-FL. GC and reversed-phase LG provide significantly different separation mechanisms for PAHs and thus provide the independence required in the separation. The use of mass spectrometry (MS) for the GC detection and fluorescence spectroscopy for the LG detection provide further independence in the methods, e.g. MS can not differentiate among PAH isomers whereas fluorescence spectroscopy often can. For the GC/MS analyses the 5% phenyl methylpolysiloxane phase has been a commonly used phase for the separation of PAHs however, several important PAH isomers are not completely resolved on this phase, i.e. chrysene and triphenylene, benzo[b]fluoranthene and benzofjjfluoranthene, and diben-z[o,h]anthracene and dibenz[a,c]anthracene. To achieve separation of these isomers, GC/MS analyses were also performed using two other phases with different selectivity, a 50% phenyl methylpolysiloxane phase and a smectic liquid crystalline phase. 

The most common final separation techniques used for agrochemicals are GC and LC. A variety of detection methods are used for GC such as electron capture detection (BCD), nitrogen-phosphorus detection (NPD), flame photometric detection (FPD) and mass spectrometry (MS). For LC, typical detection methods are ultraviolet (UV) detection, fluorescence detection or, increasingly, different types of MS. The excellent selectivity and sensitivity of LC/MS/MS instruments results in simplified analytical methodology (e.g., less cleanup, smaller sample weight and smaller aliquots of the extract). As a result, this state-of-the-art technique is becoming the detection method of choice in many residue analytical laboratories. 

There are methods available to quantify the total mass of americium in environmental samples. Mass spectrometric methods provide total mass measurements of americium isotopes (Dacheux and Aupiais 1997, 1998 Halverson 1984 Harvey et al. 1993) however, these detection methods have not gained the same popularity as is found for the radiochemical detection methods. This may relate to the higher purchase price of a MS system, the increased knowledge required to operate the equipment, and the selection by EPA of a-spectrometry for use in its standard analytical methods. Fluorimetric methods, which are commonly used to determine the total mass of uranium and curium in environmental samples, have limited utility to quantify americium, due to the low quantum yield of fluorescence for americium (Thouvenout et al. 1993). 

Principles and Characteristics Atomic fluorescence spectrometry (AFS) is based on excitation of atoms by radiation of a suitable wavelength (absorption), and detection and measurement of the resultant de-excitation (fluorescence). The only process of analytical importance is resonance fluorescence, in which the excitation and fluorescence lines have the same wavelength. Nonresonance transitions are not particularly analytically useful, and involve absorption and fluorescence photons of different energies (wavelength). 

Chemical Analysis. The chemical composition of ancient objects is important for their authentication. The nature as well as the relative amounts of major, minor, and trace elements in any object are of use for determining the authenticity or otherwise of ceramics, glass, or alloys. A wide range of analytical techniques, depending on the nature of the material studied, have been used for this purpose, including X-rays fluorescence analysis, mass spectrometry, atomic absorption spectroscopy, and neutron activation analy-... 

Mass spectrometry (MS) is also being used to add another dimension of analysis to achiral-chiral analysis. Recently, an achiral-chiral column-switching LC/LC-MS/MS method was reported for the pindolol enantiomers in human serum (Motoyama et al., 2002) and phenprocoumon metabolites (Kammerer et al., 1998). For analytes that have very poor chromophores or cannot naturally fluoresce, MS detection can be more sensitive for the underivatized form of the analyte. Also, MS detection can be particularly useful when very similar analytes that differ in mass (such as some amino acids and metabolites) cannot be satisfactorily separated chromatographically,... 

A variety of analytical techniques are used to measure PCP, including gas chromatography-mass spectrometry (GC-MS), which has a detection limit of 7.6 pg/kg honey (Muino and Taiza.no 1991), liquid chromatography with fluorescence detection (de Ruiter et al. 1990), and liquid chromatography-electrochemistry (LC-ED) procedures (Butler and Pont 1992). At present, GC-MS is the most accurate, but LC-ED is used most frequently (Butler and Pont 1992). 

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