Graphite furnace GFAAS

Metals contained in samples are determined by a wide variety of analytical methods. Bulk metals, such as copper in brass or iron in steel, can be analyzed readily by chemical methods such as gravimetry or electrochemistry. However, many metal determinations are for smaller, or trace, quantities. These are determined by various spectroscopic or chromatographic methods, such as atomic absorbance spectrometry using flame (FAAS) or graphite furnace (GFAAS) atomization, atomic emission spectrometry (AES), inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), x-ray fluorescence (XRF), and ion chromatography (IC). 

We consider the determination of the concentration of elements in various materials studied in agricultural and environmental applications, by the use of the following methods atomic absorption spectroscopy (AAS) using a flame (FAAS) or a graphite furnace (GFAAS) as an atom cell inductively coupled plasma atomic emission spectroscopy (ICPAES) inductively coupled plasma mass spectrometry (ICPMS) and X-ray fluorescence (XRF). The analytical characteristics of the methods as normally practised are compared with the requirements of fitness for purpose in the examination of soils and sediments, waters, dusts and air particulates, and animal and plant tissue. However, there are numerous specialized techniques that cannot be included here. 

In order to derive a quantitative relation between emission Intensity as measured by EMI and actual metal content, cell samples were subjected to graphite furnace atomic absorption (GFAA) analysis (14). Atomic absorption experiments were performed both on cells which had been stained with a fluorescent reagent and on cells not exposed to a lumlnophore. After EMI analysis, 50 fiL of cell suspension were withdrawn from the 0.30 mL of sample used for EMI and were digested In 150 iiL of concentrated HNO3 for 90 minutes at 85° . These solutions were then diluted to 1/10 of their concentration with deionized water, and the 150 liL of these diluted... 

FIM Field ion microscopy GFAAS Graphite furnace atomic absorption... 

ASTM. 1998a. ASTME1613. Standard test method for analysis of digested samples for lead by inductively coupled plasma atomic emission spectrometry (ICP-AES). Flame Atomic Absorption (FAAS), or Graphite Furnace Atomic Absorption (GFAA) Techniques. American Society for Testing and Materials. 

Table 5.6 compares the ICP-AES results with data generated for the same sample by two other independent methods - isotope dilution spark source mass spectrometry (IDSSMS), and graphite furnace atomic absorption spectrometry (GFAAS). The IDSSMS method also uses 25-fold preconcentration of the metals and matrix separation using the ion exchange procedure, following isotope... 

FLAA, flame atomic absorption, is termed AAS in most instances in this book and in other places ICP, inductively coupled plasma AES, atomic emission spectroscopy GFAA, graphite furnace atomic absorption ICP-MS, ICP coupled to mass spectroscopy. 

Note GFAA = graphite furnace atomic absorption. 

The major anions and cations in seawater have a significant influence on most analytical protocols used to determine trace metals at low concentrations, so production of reference materials in seawater is absolutely essential. The major ions interfere strongly with metal analysis using graphite furnace atomic absorption spectroscopy (GFAAS) and inductively coupled plasma mass spectroscopy (ICP-MS) and must be eliminated. Consequently, preconcentration techniques used to lower detection limits must also exclude these elements. Techniques based on solvent extraction of hydrophobic chelates and column preconcentration using Chelex 100 achieve these objectives and have been widely used with GFAAS. 

GFAAS Graphite Furnace Atomic Absorption Spectroscopy... 

Flame atomic absorption spectrometry (FAAS) can be used to detect most elements present at levels greater than about 100 pg 1 . For more sensitive determinations graphite furnace atomic absorption spectrometry (GFAAS) is the technique of choice. In addition, if the volume of the fraction is limited GFAAS is ideally suited for the determination because only a few microfitres (5-20 pi) of sample... 

B. Hilligsoe and E. H. Hansen, Application of factorial designs and simplex optimisation in the development of flow injection-hydride generation-graphite furnace atomic absorption spectrometry (FI-HG-GFAAS) procedures as demonstrated for the determination of trace levels of germanium, Fresenius J. Anal. Chem., 358(7-8), 1997, 775-780. 

Wet chemical methods involve sophisticated sample preparation and standardization with National Bureau of Standards reference materials but are not difficult for the analytical chemist nor necessarily time consuming (Figure 1). The time from sample preparation to final results for various analytical methods, such as GFAA (graphite furnace atomic absorption), ICP (inductively coupled plasma spectroscopy), ICP-MS (ICP-mass spectrometry), and colorimetry, ranges from 0.5 to 5.0 h, depending on the technique used. Colorimetry is the method of choice because of its extreme accuracy. Typical results of the colorimetric analysis of doped oxides are shown in Tables I and II, which show the accuracy and precision of the measurements. 

---