Fluorescence spectrophotometry applications

Fluorescence spectrophotometry, 232-236 quantitative applications, 235 Fluoride, 66 Fluoroacetamide, 626 Fluoroacetic acid, 627 Fluorobenzoylpropionic acid, 648... 

In the early 1950s, liqnid colnmn chromatography on column packings snch as alnmina, silicic acid, or Fluorosil of the neutral, acidic, or basic fractions, as appropriate, permitted further separation of the components prior to application of the classical chemical techniqnes. UV and IR spectrometry were also available and nsed not only to combine chromatographic fractions rich in a specific component bnt also to assist in the identification of the component. UV absorption and fluorescence spectrophotometry were extremely nse-ful in identification of the PAHs in tobacco smoke. 

The purpose of this chapter is to review the articles on the interior cited aspects published since 2000 about various aspects of application of fluorescence spectrophotometry in chemical analysis. 

In this section, the applications of fluorescence spectrophotometry as a powerful tool for quantitative analysis, characterization, and quality control in different fields will be reviewed and discussed in details. This section will include the use of fluorescence spectrophotometry as a powerful spectroscopic tool in several fields of science. 

See alsa Atomic Absorption Spectrometry Electrothermal. Atomic Emission Spectrometry Flame Photometry. Cadmium. Carbon. Chemiiuminescence Overview. Fluorescence Environmental Applications. Gas Chromatography Environmental Applications. Laser-Based Techniques. Lead. Nitrogen. Ozone. Polycyclic Aromatic Hydrocarbons Environmental Applications. Remote Gas Sensing Overview. Spectrophotometry Inorganic Compounds. Sulfur. X-Ray Fluorescence and Emission X-Ray Fluorescence Theory. 

Optical sensors based on UV-visible and fluorescence spectrophotometry and a visual color change in a material are other directions for mesoporous silicates application (Melde et al. 2008). Several examples of such sensors are presented in Table 8.2. Usually optical detection of gases in mesoporous silica-based sensors takes place through the use of an incorporated dye. In particular, oxygen sensing... 

Fluorometry and absorption spectrophotometry are competing techniques in the sense that both analyze for molecular species and complex ions. Each offers its own advantages and disadvantages. As stated above, the number of chemical species that exhibit fluorescence is very limited. However, for those species that do fluoresce, the fluorescence is generally very intense. Thus we can say that while absorption spectrophotometry is much more universally applicable, fluorometry suffers less from interferences and... 

Photodiode detectors have already been cited in this chapter in relation to near-IR fluorescence measurements on singlet oxygen,(8 16 18) in decay-time temperature sensing,(50) in liquid chromatography,(62) the study of proteins labelled with Nile Red,(64) and diode laser spectrometry,(67) Photodiodes are also conveniently packaged for many applications in an array form enabling rapid data acquisition e.g., in spectrophotometry, (35)... 

HPLC units have been interfaced with a wide range of detection techniques (e.g. spectrophotometry, fluorimetry, refractive index measurement, voltammetry and conductance) but most of them only provide elution rate information. As with other forms of chromatography, for component identification, the retention parameters have to be compared with the behaviour of known chemical species. For organo-metallic species element-specific detectors (such as spectrometers which measure atomic absorption, atomic emission and atomic fluorescence) have proved quite useful. The state-of-the-art HPLC detection system is an inductively coupled plasma/MS unit. HPLC applications (in speciation studies) include determination of metal alkyls and aryls in oils, separation of soluble species of higher molecular weight, and separation of As111, Asv, mono-, di- and trimethyl arsonic acids. There are also procedures for separating mixtures of oxyanions of N, S or P. 

Frequently industrial hygiene analyses require the identification of unknown sample components. One of the most widely employed methods for this purpose is coupled gas chromatography/ mass spectrometry (GC/MS). With respect to interface with mass spectrometry, HPLC presently suffers a disadvantage in comparison to GC because instrumentation for routine application of HPLC/MS techniques is not available in many analytical chemistry laboratories (3). It is, however, anticipated that HPLC/MS systems will be more readily available in the future ( 5, 6, 1, 8). HPLC will then become an even more powerful analytical tool for use in occupational health chemistry. It is also important to note that conventional HPLC is presently adaptable to effective compound identification procedures other than direct mass spectrometry interface. These include relatively simple procedures for the recovery of sample components from column eluate as well as stop-flow techniques. Following recovery, a separated sample component may be subjected to, for example, direct probe mass spectrometry infra-red (IR), ultraviolet (UV), and visible spectrophotometry and fluorescence spectroscopy. The stopped flow technique may be used to obtain a fluorescence or a UV absorbance spectrum of a particular component as it elutes from the column. Such spectra can frequently be used to determine specific properties of the component for assistance in compound identification (9). 

Lasers. Laser sources (discussed earlier in the Spectrophotometry section) are widely used in fluorescence applications in which highly intense, well-focused, and essentially monochromatic light is required. Examples of these applications include time-resolved fluorometry, flow cytometry, pulsed laser confocal microscopy, laser-induced fluorometry, and light-scattering measurements for particle size and shape. Several different types of lasers are available as an excitation source for fluorescence measurements (see Table 3-3). 

Many inorganic cations and anions catalyze indicator reactions—that is, reactions whose rates are readily measured by instmmental methods, such as absorption spectrophotometry, fluorescence spectrometry, or electrochemistry. Conditions are then employed such that the rate is proportional to the concentration of catalyst, and, from the rate data, the concentration of catalyst is determined. Such catalytic methods often allow extremely sensitive detection of the catalyst concentration. Kinetic methods based on catalysis by inorganic analytes are widely applicable. For example, the literature in this area lists more than 40 cations and 15 anions that have been determined by a variety of indicator reactions. Table 29-3 gives catalytic methods for several inorganic species along with the indicator reactions used, the method of detection, and the detection limit. 

Atomic absorption spectrophotometry already then in its second edition. Price (1974) (Analytical Atomic Absorption Spectrometry) published about thelOth book on AAS since inception of the technique with the aim of being a textbook on practical AAS (FAAS). It contains the usual introduction to principles, instrumenttation and analytical techniques, with a large detailed chapter of applications to different materials followed by details for individual elements. A nice expanded version of the author s first book (Price 1979) on Spectrochemical Analysis by Atomic Absorption, includes newer developments such as EAAS. Kirkbright and Sargent (1974) (Atomic Absorption and Fluorescence Spectrometry) produced a massive, excellent, comprehensive treatise on the techniques of atomic absorption and fluorescence spectrometries, with details on... 

Similarly, bilirubin and methotrexate can be determined in serum with a Hber-optic system terminated in a 19-gauge hypodermic needle and a reflective cap at its end so to produce a small absorbance cell [50]. Although these methods usually do not yield absolute analyte concentrations owing to background absorption or fluorescence of serum, they do reflect relative concentration changes sufflciently correctly. This kind of sensor was expected to be applicable also to the photometric determination of other important clinical analytes such as drugs, toxins, and biomolecules, but the limited selectivity and sensitivity of spectrophotometry will possibly also limit the scope of the method when applied directly to serum or whole blood. 

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