Sample FAAS

Regarding FAAS, only a study by Flores et al. [74] employed PLS to quantify Cd in marine and river sediments measured by direct solid sampling FAAS. 

The literature on procedures for PbB determination is abundant. Those techniques that have been shown to provide accurate and precise PbB determinations in routine use include anodic stripping voltammetry (ASV), flame atomic absorption spectrophotometry (FAAS), discrete sampling FAAS, and graphite furnace AAS (GF-AAS). The method most widely used for routine determination is AAS in its various modifications. The relatively slow analysis rate of ASV tends to limit the application of this technique to that of a backup or reference method. Whatever the technique which is applied, it should be emphasized that avoidance of contamination, careful handling of the blood samples and frequent intra- and interlaboratory checks are more important for ensuring precision and reliability than the method itself. 

In this work, a simple, rapid and sensitive Flame Atomic Absolution Spectrometry (FAAS) method has been developed for the determination of trace amount of Co + in vaiious samples after adsoi ption of its complex on modified Analcime using a Schiff base Bis-[(2,2 -dihydroxy)-N,N -diethylen-triamino-l,r-naphtaldimine] by column method in the pH range (4-7) at flow rats 1 ml-minf... 

ICP-OES is a destructive technique that provides only elemental composition. However, ICP-OES is relatively insensitive to sample matrix interference effects. Interference effects in ICP-OES are generally less severe than in GFAA, FAA, or ICPMS. Matrix effects are less severe when using the combination of laser ablation and ICP-OES than when a laser microprobe is used for both ablation and excitation. 

Althoi h nonspectral interference effects are generally less severe in ICP-OES than in GFAA, FAA, or ICPMS, they can occur. In most cases the effects produce less than a 20% error when the sample is introduced as a liquid aerosol. High concentrations (500 ppm or greater) of elements that are highly ionized in the... 

Magnesium deficiency has been long recognized, but hypermagnesia also occurs (Anderson and Talcott 1994). Magnesium can be determined in fluids by FAAS, inductively coupled plasma atomic emission spectrometry (ICP-AES) and ICP-MS. In tissue Mg can be determined directly by solid sampling atomic absorption spectrometry (SS-AAS) (Herber 1994a). Both Ca and Mg in plasma/serum are routinely determined by photometry in automated analyzers. 

DCP-AES can be used for high-viscosity matrices, slurries, etc. Organic solvents and acids can be handled without problems. Sample preparation is simpler than for ICP. Operating costs are much lower than for ICP-AES. Table 8.32 compares DCP-AES to ICP-AES and FAAS Table 8.33 shows typical detection limits. DCP and its applications were reviewed [208]. 

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. 

Flow injection analysis is based on the injection of a liquid sample into a continuously flowing liquid carrier stream, where it is usually made to react to give reaction products that may be detected. FIA offers the possibility in an on-line manifold of sample handling including separation, preconcentration, masking and color reaction, and even microwave dissolution, all of which can be readily automated. The most common advantages of FIA include reduced manpower cost of laboratory operations, increased sample throughput, improved precision of results, reduced sample volumes, and the elimination of many interferences. Fully automated flow injection analysers are based on spectrophotometric detection but are readily adapted as sample preparation units for atomic spectrometric techniques. Flow injection as a sample introduction technique has been discussed previously, whereas here its full potential is briefly surveyed. In addition to a few books on FIA [168,169], several critical reviews of FIA methods for FAAS, GF AAS, and ICP-AES methods have been published [170,171]. 

Operating Principles — There are many similarities between ICP-AES and the combustion flame spectroscopy techniques of flame atomic emission (FAE) and flame atomic absorption (FAA). In fact, the source of the ICP-AES has been referred to by Fassel as an electric flame. The final prepared analytical sample is presented in liquid form for analysis except for unique situations. The liquid sample is drawn (or... 

Nebulizers — Nebulizers of existing systems have been the object of extensive controversy. An ICP nebulizer can be the source of serious problems, if either the nebulizer or sample solutions are not treated properly, since most ICP nebulizers are fragile and easily clogged by excessive amounts of undissolved matter. However, the failure rate of the cross flow nebulizer is no greater than that of most FAA nebulizers. (This is... 

Fruchier rial. (1980), determined by X-ray fluorescence IXRF), except Aland Naby ncuiran activation analysis (NA At. Mg by flame atomic absorption tlidnum borate fusion (FAA), and B by plasma emission spectroscopy (sodium carbonate fusion) (PE5) Saether (1980), determined by XRF after low-temperature ashing (LTA) of raw oil shale samples In = 10). 

Flame AAS (often abbreviated FAAS) was until recently the most widely used method for trace metal analysis. However, it has now largely been superseded by inductively coupled plasma atomic emission spectrometry (see Chapter 4). It is particularly applicable where the sample is in solution or readily solubilized. It is very simple to use and, as we shall see, remarkably free from interferences. Its growth in popularity has been so rapid that on two occasions, the mid-1960s and the early 1970s, the growth in sales of atomic absorption instruments has exceeded that necessary to ensure that the whole face of the globe would be covered by atomic absorption instruments before the end of the century. 

Flame atomic absorption spectrometry can be used to determine trace levels of analyte in a wide range of sample types, with the proviso that the sample is first brought into solution. The methods described in Section 1.6 are all applicable to FAAS. Chemical interferences and ionization suppression cause the greatest problems, and steps must be taken to reduce these (e.g. the analysis of sea-water, refractory geological samples or metals). The analysis of oils and organic solvents is relatively easy since these samples actually provide fuel for the flame however, build-up of carbon in the burner slot must be avoided. Most biological samples can be analysed with ease provided that an appropriate digestion method is used which avoids analyte losses. 

The commonest form of sample introduction is by means of an aerosol generated using a pneumatic nebulizer. Several types of nebulizer can be used. All-glass concentric nebulizers (Fig. 4.7a) operate in a similar manner to those used for FAAS. Cross-flow nebulizers (Fig. 4.7b) operate by directing a high-velocity stream of gas across the mouth of a capillary... 

The solution to be nebulized is usually pumped to the nebulizer using a peristaltic pump, unlike for FAAS, where the solution uptake is by free aspiration. The solution is pumped through polymeric tubing [usually poly(vinyl chloride)] and also connecting tubing (usually Teflon) to the nebulizer. Both of these materials can be manufactured to a high degree of purity, hence contamination is minimized. The solution is pumped at a rate of 1 -2 ml min, which is much slower than the 5-10 ml min uptake rate for FAAS. This tends to favour the formation of fewer but smaller droplets, which results in less noise but a lower overall sample transport efficiency. 

Sample preparation methods are similar to those used for FAAS and ICP-AES. However, nitric acid is favoured for sample digestion since the other mineral acids contain elements which cause spectroscopic inteferences. 

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... 

---