Detectors, absorption photometric

For biomedical trace analysis, three types of detectors are currently popular—the absorption photometric detector, the fluorescence detector, and the electrochemical detector. Although there are other kinds of detectors, only these have the ability to detect 10 -10 g of analyte, the kind of detectability needed in biomedical analysis, especially where small amounts of drugs are concerned. 

The most widely used detectors, the absorption photometric detectors, are those based on the absorbance of UV light. They are not universal in applica-tion,f but a great many substances do absorb UV radiation, including all substances having H-bonding electrons and also those with unshared (non-bonded) electrons, such as olefins, aromatics, and compounds containing C=0, C-S, -N=0, and N=N. In UV detectors, the absorbance A is directly proportional... 

The detectors used most often for LC are absorption photometric detectors and these are exemplified by the following description of some particular UV and IR photometers. 

When using the current commercially available CE systems equipped with photometric detectors, it is not possible to detect some compounds that do not show light absorption. For example the detection of low-molecular-weight organic and inorganic ions " is not... 

Elemental composition H 2.49%, Se 97.51%. The gas may be analyzed by GC using a TCD, FID or a flame photometric detector. The compound may be identified by GC/MS the molecular ions have masses 82 and 80. The compound may be absorbed in water and the solution analyzed for elemental selenium by flame or furnace atomic absorption—or by ICP atomic emission spectrophotometry. 

AAS = atomic absorption spectrometry GC/FID = gas chromatography/f1ame ignition detector GC/FPD = gas chromatography/f1ame photometric detector ICP/AES = inductively coupled plasma atomic emission spectroscopy ICP/MS = inductively coupled plasma with mass spectrometric detection... 

FID FIFRA FLAA FPD FSP flame ionization detector Federal Insecticide, Fungicide, and Rodenticide Act flame atomic absorption flame photometric detector Field Sampling Plan... 

Maguire, R.J. and Tkacz, R.J. (1983) Analysis of butyltin compounds by gas chromatography. Comparison of flame photometric and atomic absorption spectrophotometric detectors./. Chromatogr., 268, 99-101. 

Abbreviations FID flame ionization detector BCD electron capture detector FPD flame photometric detector MS mass spectrometer MED microwave emission detector AAS atomic absorption spectrometer. 

Any type of detector with a flow-through cell can be used for FIA. Photometric detectors are most often used in FIA (15-18, 25). However, many other analyses using fluorimeters (28, 29), refractometers (24), atomic absorption (30, 31), and inductively coupled plasma emission spectrometers (32) have been described. Electrochemical detectors based on potentiometry with ion-selective electrodes (15, 33), anodic stripping voltammetry (15, 34), potentiometric stripping (35), and amperometry (36) have also been used. 

The UV detector is the most widely used detector for LC. It is a solute property detector that is suitable for those solute compounds that absorb radiation in the UV range ( 190-400 nm). Ultraviolet-photometric detectors are relatively insensitive to temperature and flow rate fluctuations. The sensitivity to solute detection is high (noise equivalent concentration 10 °g/ml).f Ultraviolet-photometric detectors are also well suited to applications that use gradient elution, given that many common LC solvents have low UV absorptivities. 

Many other detectors have been used to monitor ion chromatography separations. Most of these detectors have been used only in special cases. Flame photometric detection [72, 73] has been used to detect alkali, alkaline earth, and some rare earth metals. Atomic absorption (AA) detectors [74-76] have been used for arsenite, arsenate, monomethyl arsenate, dimethyl arsinate, and p-aminophenoarsenate separations. Detectors of this type can be extremely sensitive detecting arsenic down to 10 ng/mL. 

AAS = atomic absorption spectrophotometry EPA = Environmental Protection Agency GC/ECD = gas chromatography/electron capture detector GC/FPD = gas chromatography/flame photometric detector GC/HECD = gas chromatography/ Hall s electrolytic conductivity detector GC/MS = gas chromatography/mass spectrometry GC/PID = gas chromatography/photoionization detector ILS = isotopically labelled standard NR = not reported SCD = Sievers chemiluminescence detector... 

Detectors used in atomic absorption spectroscopy are usually photometric detectors. 

An even more specific detection method uses radioactivity, as introduced by Kaniansky [18]. As an example of dual-wavelength UV-absorption detection, an analysis will be given performed with the computerized dual-wavelength photometric detector. 

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