Atomic absorption detector for

Andreae [712] used four different detectors in his investigations the electron capture detector (for the methylarsines), the quartz cuvette atomic absorption detector (for arsenic and antimony species), the graphite furnace atomic... 

Brinkman, F.E., Blair, W.R., Jewett, K.L., and Iverson, W.P. Application of a liquid chromatograph coupled with a flameless atomic absorption detector for speciation of trace organometallic compounds, J. Chrom. Sci. 15, 493-503 (1977). 

Table 8.80 shows the present status of speciation methodology. For trace-metal speciation, atomic absorption detectors feature a relatively high absolute detection limit (10 pg level), as compared to the 0.1 to 1 pg sensitivity level for molecular ion MS techniques as well as for MIP-AES. The detection limit of LEI-ToFMS is in the attogram range. Speciation has been reviewed [550]. Various monographs deal with speciation analysis [542,551,552]. 

The electron-capture detector was originally found to be a sensitive detector for the methylarsines [716]. After improvements of the atomic absorption detectors had been made (especially concerning adsorptive losses and peak shapes of the methylarsines), it was found that this detector could be used to replace the electron-capture detector, which because of its lack of specificity and its sensitivity to contamination and changes in operating conditions was very inconvenient to work with. 

The exploitation of atomic-absorption spectrophotometry for monitoring HPLC column effluents has been recently examined by Funasaka et al. [46]. An eluent-vaporizing system was designed which introduced the effluent into the atomic-absorption unit. The limit of detection of compounds such as ethylmercury chloride was ca. 10 ng compared to 30 jug for a UV detector at 210 nm. The extreme selectivity of atomic absorption could make this technique of great value for the analysis of trace amounts of organometallic compounds and metal chelates. 

Parris and coworkers calculated figures of merit for the various modes of operation studied with their atomic absorption detector utilizing the procedure of Mandel and Stiehler . The latter devised a simple quantitative measure of merit for comparing proportionality quantities such as these calibration curves. They define sensitivity as a criterion which takes into account not only the reproducibility of precision of the test procedure, but which is also diagnostic of small variations in the property measured. Thus,... 

SEC coupled with an in-line graphite furnace atomic absorption detector was applied for characterization of organometallic copolymers of MMA and tributyltin methacrylate [61]. A third component in substantial amounts present in a typical organotin polymer formation was adsorbed on PS gel columns with THF as the mobile phase, and quantitatively desorbed when acetic acid was introduced into the mobile phase. The adsorbed... 

A schematic diagram showing the disposition of these essential components for the different techniques is given in Fig. 21.3. The components included within the frame drawn in broken lines represent the apparatus required for flame emission spectroscopy. For atomic absorption spectroscopy and for atomic fluorescence spectroscopy there is the additional requirement of a resonance line source, In atomic absorption spectroscopy this source is placed in line with the detector, but in atomic fluorescence spectroscopy it is placed in a position at right angles to the detector as shown in the diagram. The essential components of the apparatus required for flame spectrophotometric techniques will be considered in detail in the following sections. 

The simplest analytical method is direct measurement of arsenic in volatile methylated arsenicals by atomic absorption [ 11 ]. A slightly more complicated system, but one that permits differentiation of the various forms of arsenic, uses reduction of the arsenic compounds to their respective arsines by treatment with sodium borohydride. The arsines are collected in a cold trap (liquid nitrogen), then vaporised separately by slow warming, and the arsenic is measured by monitoring the intensity of an arsenic spectral line, as produced by a direct current electrical discharge [1,12,13]. Essentially the same method was proposed by Talmi and Bostick [10] except that they collected the arsines in cold toluene (-5 °C), separated them on a gas chromatography column, and used a mass spectrometer as the detector. Their method had a sensitivity of 0.25 xg/l for water samples. 

Another variation on the method [4] with slightly higher sensitivity (several ng/1) used the liquid nitrogen cold trap and gas chromatography separation, but used the standard gas chromatography detectors or atomic absorption for the final measurement. These workers found four arsenic species in natural waters. 

Atomic absorption spectrometry used either by direct aspiration (to determine total mercury) or as an element-specific detector for gas chromatography (to determine organically bound mercury) are now discussed. 

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