GC-FAAS

Other techniques used for organotin speciation comprise GC-FAAS, GC-GFAAS, GC-ICP-MS, HPLC-FAAS, HPLC-GFAAS, HPLC-DCP (after continuous on-line hydride generation), HPLC-ICP-AES, HPLC-ICP-MS, etc. [555], Whereas ICP-AES does not provide an adequate response for ng levels of tin, ICP-MS can detect sub-ng to pg levels. GC-ICP-ToFMS... 

A number of techniques have been used for the speciation of arsenic compounds. The most important has been the formation of volatile hydrides of several species, separation by gas chromatography and detection by AAS. HPLC has been used to separate arsenic species. Several types of detectors have been studied for the determination of arsenic species in the column effluent. These have included AAS both off- and on-line, ICPAES and ICP-MS. An important comparative study of coupled chromatography-atomic spectrometry methods for the determination of arsenic was published (Ebdon et al., 1988). Both GC and HPLC were used as separative methods, and the detectors were FAAS, flame atomic fluorescence spectrometry (FAFS) and ICPAES. The conclusions were (1) that hydride generation and cryogenic trapping with GC-FAAS was the most... 

Another group of analytical methodologies which can be used for mercury determination within aquatic samples exists, and includes a large diversity of techniques like preconcentration on coated graphite tubes and ETAAS [346,347] as well as with other matrix modifiers [348,349] atomic fluorescence spectrometry (AES) [350-352]) ICP-MS coupled with CV generation [353,354], isotope dilution [355,356], or LC [357 58] GC— FAAS coupled with reversed-phase liquid chromatography [73359360] or, the use of biological substrates for studies on metal speciation [361-363]. 

Method abbreviations D-AT-FAAS (derivative flame AAS with atom trapping), ETAAS (electrothermal AAS), GC (gas chromatography), HGAAS (hydride generation AAS), HR-ICP-MS (high resolution inductively coupled plasma mass spectrometry), ICP-AES (inductively coupled plasma atomic emission spectrometry), ICP-MS (inductively coupled plasma mass spectrometry), TXRF (total reflection X-ray fluorescence spectrometry), Q-ICP-MS (quadrapole inductively coupled plasma mass spectrometry)... 

A number of analytical techniques have been used for measuring aluminum concentrations in environmental samples. These include GFAAS, FAAS, NAA, ICP-AES, ICP-MS, spectrophotometry using absorbance and fluorescence detection, phosphorimetry, chromatography and gas chromatography equipped with an electron capture detector (GC/ECD) (Andersen 1987, 1988 Benson et al. 1990 ... 

GFAAS and FAAS are the techniques (Methods 202.1 and 202.2) recommended by EPA for measuring low levels of aluminum in water and waste water (Kopp and McKee 1978). Detection limits of 100 g of aluminum/L of sample and 3 g of aluminum/L of sample were obtained using the FAAS and GFAAS techniques, respectively (Kopp and McKee 1978). Spectrophotometry and GC/ECD have also been employed to measure low-ppb ( g/L) levels of aluminum in water (Dean 1989 Ermolenko and Dedkov 1988 Gosink 1975). Flow-injection systems using absorbance (Benson et al. 1990) and fluorescence detection (Carrillo et al. 1992) have been used to monitor aqueous aluminum levels in the field and in the laboratory setting, with detection limits as low as 0.3 g/L. 

AMS = accelerated mass spectroscopy FAAS = flame atomic absorption spectrometry GC/ED = gas chromatography/electron capture detector GFAAS graphite furnace atomic absorption spectrometry ICP-AES = inductively couples plasma-atomic absorption spectrometry NA = not applicable NAA = neutron activation analysis... 

A flame AAS (FAAS) detector can monitor the GC effluent continuously to provide on-line analysis. However, as the gas flow rates for the flame are quite high, the residence time in the flame is short, and this can adversely affect the detection limits. Detection limits in the microgram range are usually achieved. Improved detection limits can be obtained if the additional techniques of hydride generation or cold vapour mercury detection are used as described in Section 4.6. 

FAAS, ICP-AES, IDMS, INAA, TITR INAA, RNAA, SPEC FAAS, FAES, ICP-AES, INAA FAAS, ICP-AES, IDMS GC-AAS, CS-CA, CS-VO KJEL, IDMS... 

The method of preference for methyl mercury determination has involved determination of methyl mercury halides by gas chromatography after certain preconcentration extractions (1,5,23,28). However, we have discovered that by the removal of the potassium persulfate reagent and the reduction of the digestion temperature to 800 in the standard method (10), it can be used for obtaining an estimate of the methyl mercury species in water. An evaluation of this method compared to results using the GC method is illustrated in Table VIII. Clearly the GC method is more selective but the FAA method appears to give a reasonable, though lower concentration for methyl mercury in water. 

The GC method is extremely slow requiring at least one whole day for each determination. Therefore, any improvements in the much faster automated FAA technique to include determination of methyl mercury species would be most welcome. 

ISE, ion-selective electrode FAAS, flame atomic absorption spectrometry ETAAS, electrothermal atomic absorption spectrometry FES, flame emission spectrometry FIG, hydride generation CV, cold vapor AFS, atomic fluorescence spectrometry Bl, biamperometry FIPLC, high-performance liquid chromatography LC, liquid chromatography GC-MS, gas chromatography-mass spectrometry Br-PADAP, 2- 5-bromo-2-pyridylazo)-5-(diethylamino)phenol Cig, octadecyl-chemically modified silicagel PAN, 1-(2-thiazolylazo)-2-naphthol. 

Russell J, Lewis RJ, Johnson RD, and Canfield DV (2002) An accurate method for the determination of carbon monoxide in postmortem blood using GC/TCD. Office of Aerospace Medicine, Washington, DC 20591, DOT/ FAA/AM-02/15. 

ECD, electron capture detector FAAS, flame atomic absorption spectrometry FID, flame ionization detector GC, gas chromatography LC, liquid chromatogr hy TCD, thermal conductivity detector UVA IS, ultravio-let/visible spectrometry. 

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